Indicates that the method completed successfully. This reply code is reserved for future use - the current protocol design does not use positive confirmation and reply codes are sent only in case of an error. The client asked for a specific message that is no longer available. The message was delivered to another client, or was purged from the queue for some other reason. The client attempted to transfer content larger than the server could accept at the present time. The client may retry at a later time. When the exchange cannot route the result of a .Publish, most likely due to an invalid routing key. Only when the mandatory flag is set. When the exchange cannot deliver to a consumer when the immediate flag is set. As a result of pending data on the queue or the absence of any consumers of the queue. An operator intervened to close the connection for some reason. The client may retry at some later date. The client tried to work with an unknown virtual host. The client attempted to work with a server entity to which it has no access due to security settings. The client attempted to work with a server entity that does not exist. The client attempted to work with a server entity to which it has no access because another client is working with it. The client requested a method that was not allowed because some precondition failed. A session.resume was attempted for a session already attached to another channel. The client sent a malformed frame that the server could not decode. This strongly implies a programming error in the client. The client sent a frame that contained illegal values for one or more fields. This strongly implies a programming error in the client. The client sent an invalid sequence of frames, attempting to perform an operation that was considered invalid by the server. This usually implies a programming error in the client. The client attempted to work with a channel that had not been correctly opened. This most likely indicates a fault in the client layer. The server could not complete the method because it lacked sufficient resources. This may be due to the client creating too many of some type of entity. The client tried to work with some entity in a manner that is prohibited by the server, due to security settings or by some other criteria. The client tried to use functionality that is not implemented in the server. The server could not complete the method because of an internal error. The server may require intervention by an operator in order to resume normal operations. An invalid or illegal argument was passed to a method, and the operation could not proceed. A session.open was sent on a channel that was already attached to a session. XA return code: Normal execution completion (no error). XA return code: The rollback was caused for an unspecified reason. XA return code: A transaction branch took too long. XA return code: The transaction branch may have been heuristically completed. XA return code: The transaction branch has been heuristically committed. XA return code: The transaction branch has been heuristically rolled back. XA return code: The transaction branch has been heuristically committed and rolled back. XA return code: The transaction branch was read-only and has been committed. Octet of unspecified encoding 8-bit signed integral value (-128 - 127) 8-bit unsigned integral value (0 - 255) 8-bit representation of single character in the iso-8859-15 character set Boolean value (0 represents false, 1 represents true) Two octets of unspecified binary encoding 16-bit signed integral value 16-bit unsigned integral value Four octets of unspecified binary encoding 32-bit signed integral value 32-bit unsigned integral value Single precision IEEE 754 32-bit floating point Single unicode character in UTF-32 encoding Eight octets of unspecified binary encoding 64-bit signed integral value 64-bit unsigned integral value Double precision IEEE 754 floating point Datetime in POSIX time_t format Sixteen octets of unspecified binary encoding UUID as defined by RFC4122 Thirty two octets of unspecified binary encoding Sixty four octets of unspecified binary encoding One hundred and twenty eight octets of unspecified binary encoding A sequence of up to 255 octets representing opaque binary data A sequence of up to 255 characters in the iso-8859-15 character set A sequence of unicode characters in the utf8 encoding which is able to be encoded in at most 255 bytes A sequence of unicode characters in the utf16 encoding which is able to be encoded in at most 255 bytes A sequence of unicode characters in the utf32 encoding which is able to be encoded in at most 255 bytes (i.e. of 0-63 utf32 characters) A sequence of up to 65535 octets representing opaque binary data A sequence of up to 65535 characters in the iso-8859-15 character set A sequence of unicode characters in the utf8 encoding which is able to be encoded in at most 65535 bytes A sequence of unicode characters in the utf16 encoding which is able to be encoded in at most 65535 bytes A sequence of unicode characters in the utf32 encoding which is able to be encoded in at most 65535 bytes (i.e. of 0-16383 utf32 characters) A sequence of up to 4294967295 octets representing opaque binary data A sequence of up to 4294967295 characters in the iso-8859-15 character set A sequence of unicode characters in the utf8 encoding which is able to be encoded in at most 4294967295 bytes A sequence of unicode characters in the utf16 encoding which is able to be encoded in at most 4294967295 bytes A sequence of unicode characters in the utf32 encoding which is able to be encoded in at most 4294967295 bytes (i.e. of 0-1073741823 utf32 characters) A field table following the encoding specification given here A sequence is a series of consecutive type-value pairs; using the same type designators as the field table An array represents a collection of values of the same type. The array is encoded as a single octet type designator (using the same system as given here for the field table), followed by a four-octet unsigned integer which represents the number of elements in the collection, followed by the encoding of that number of values of the given type Five octets of unspecified binary encoding Encoded as an octet representing the number of decimal places followed by a signed 4 octet integer. The 'decimals' octet is not signed Eight octets of unspecified binary encoding Encoded as an octet representing the number of decimal places followed by a signed 8 octet integer. The 'decimals' octet is not signed The void type An access ticket granted by the server for a certain set of access rights within a specific realm. Access tickets are valid within the session where they were created, and expire when the session closes. Identifier for the consumer, valid within the current connection. The server-assigned and session-specific delivery tag The delivery tag is valid only within the session from which the message was received. i.e. A client MUST NOT receive a message on one session and then acknowledge it on another. The server MUST NOT use a zero value for delivery tags. Zero is reserved for client use, meaning "all messages so far received". The exchange name is a client-selected string that identifies the exchange for publish methods. Exchange names may consist of any mixture of digits, letters, and underscores. Exchange names are scoped by the virtual host. This regular expression checks that all characters are one of a-z (lower case), A-Z (upper case), 0-9 (any digit) and the underscore character. There may be between 1 and 127 of these characters. Specifies the list of equivalent or alternative hosts that the server knows about, which will normally include the current server itself. Clients can cache this information and use it when reconnecting to a server after a failure. This field may be empty. Message-id is an optional property of UUID type which uniquly identifies a message within the message system. The message producer is usually responsible for setting the message-id. Note that the server may discard a message as a duplicate if the value of the message-id matches that of a previously received message. A message MUST be unique within a given server instance. A message SHOULD be globally unique (i.e. across different systems). A message ID is immutable. Once set, a message-id MUST NOT be changed or reassigned, even if the message is replicated, resent or sent to multiple queues. If this field is set the server does not expect acknowledgements for messages. That is, when a message is delivered to the client the server automatically and silently acknowledges it on behalf of the client. This functionality increases performance but at the cost of reliability. Messages can get lost if a client dies before it can deliver them to the application. If the no-local field is set the server will not send messages to the connection that published them. Must start with a slash "/" and continue with path names separated by slashes. A path name consists of any combination of at least one of [A-Za-z0-9] plus zero or more of [.-_+!=:]. This string provides a set of peer properties, used for identification, debugging, and general information. The queue name identifies the queue within the vhost. Queue names must have a length of between 1 and 255 chatacters inclusive, must start with a digit, letter or underscores ('_') character, and must be otherwise encoded in UTF-8. This regular expression checks that the first character is one of a-z (lower case), A-Z (upper case), 0-9 (any digit) and the underscore character. Following may be between 0 and 254 characters of any value. This indicates that the message has been previously delivered to this or another client. The server SHOULD try to signal redelivered messages when it can. When redelivering a message that was not successfully acknowledged, the server SHOULD deliver it to the original client if possible. Create a shared queue and publish a message to the queue. Consume the message using explicit acknowledgements, but do not acknowledge the message. Close the connection, reconnect, and consume from the queue again. The message should arrive with the redelivered flag set. The client MUST NOT rely on the redelivered field but should take it as a hint that the message may already have been processed. A fully robust client must be able to track duplicate received messages on non-transacted, and locally-transacted sessions. Serial number defined in RFC1982 which defines the arithmatic, operators and ranges of such numbers. The reply code. The AMQ reply codes are defined as constants at the start of this formal specification. The localised reply text. This text can be logged as an aid to resolving issues. Duration of an event or process measured in milliseconds. Offset in bytes into a message body. Identifier to be used as a reference to a message body. Specifies the destination to which the message is to be transferred. The destination can be empty, meaning the default exchange or consumer. Code specifying the reason for a message reject. The reject code must be one of 0 (generic) or 1 (immediate delivery was attempted but failed). String describing the reason for a message transfer rejection. A security token used for authentication, replay prevention, and encrypted message bodies. Controls whether message transfer needs to be confirmed. One of: - off (0): confirmation is not required, once a message has been transferred in pre-acquire mode (or once acquire has been sent in no-acquire mode) the message is considered transferred - on (1): an acquired message (whether acquisition was implicit as in pre-acquire mode or explicit as in no-acquire mode) is not considered transferred until the original transfer is complete (signaled via execution.complete) Indicates whether a transferred message can be considered as automatically acquired or whether an explicit request is necessary in order to acquire it. One of: - no-acquire (0): the message must be explicitly acquired - pre-acquire (1): the message is acquired when the transfer starts If set on a message that is not routable the broker can discard it. If not set unroutable should be handled by reject when confirmation is on or by routing to the alternate-exchange if defined when confirmation is off. This boolean flag indicates that the message has been previously delivered to this or another client. Message priority, which can be between 0 and 9. Messages with higher priorities may be delivered before those with lower priorities. The delivery mode may be non-persistent (1) or persistent (2). A persistent message is one which must be stored on a persistent medium (usually hard drive) at every stage of delivery so that it will not be lost in event of failure (other than the medium itself). This is normally accomplished with some additional overhead. A persistent message may be delivered more than once if there is uncertainty about the state of its delivery after a failure and recovery. Conversely, a non-persistent message may be lost in event of a failure, but the nature of the communication is such that an occasional message loss is tolerable. This is the lowest overhead mode. Non-persistent messages are delivered at most once only. If this is set to a non zero value then a message expiration time will be computed based on the current time plus this value. Messages that live longer than their expiration time will be discarded (or dead lettered). If a message is transferred between brokers before delivery to a final consumer the ttl should be decremented before peer to peer transfer and both timestamp and expiration should be cleared. The timestamp is set by the broker on arrival of the message. The expiration header assigned by the broker. After receiving the message the broker sets expiration to the sum of the ttl specified in the publish method and the current time. (ttl=expiration - timestamp) The exchange name is a client-selected string that identifies the exchange for transfer methods. Exchange names may consist of any mixture of digits, letters, and underscores. Exchange names are scoped by the virtual host. The value of the key determines to which queue the exchange will send the message. The way in which keys are used to make this routing decision depends on the type of exchange to which the message is sent. For example, a direct exchange will route a message to a queue if that queue is bound to the exchange with an identical key to that of the message. The length of the message content in bytes. This is a unique identifier for the message that is guaranteed to be unique across multiple instances, sessions and in time. This allows duplicate messages to be detected. This may be a UUID. Note that this is usually set by the server when it first receives a message. If a client wishes to identify a message, it should use the correlation-id instead. This is a client-specific id that may be used to mark or identify messages between clients. The server ignores this field. The destination of any message that is sent in reply to this message. The RFC-2046 MIME type for the message content (such as "text/plain"). This is set by the originating client. The encoding for character-based message content. This is set by the originating client. Examples include UTF-8 and ISO-8859-16. The JMS message type. The identity of the user responsible for producing the message. The identity of the client application responsible for producing the message. An identifier that links this message to a distributed transaction. A security token used for authentication, replay prevention, and encrypted message bodies. This is a collection of user-defined headers or properties which may be set by the producing client and retrieved by the consuming client. Similar to JMS Properties. An xid uniquely identifies a transaction branch. xid contains a format identifier, two length fields and a data field: format_id long gtrid_length octet bqual_length octet data gtrid_length + bqual_length 4 1 1 g b +---+---+---+---+---+---+---+- -+---+---+- -+---+ | format_id | g | b | txn-id | br-id | +---+---+---+---+---+---+---+- -+---+---+- -+---+ 0 4 5 6 6+g 6+g+b format_id: an implementation specific format identifier gtrid_length: how many bytes of this form the transaction id bqual_length: how many bytes of this form the branch id data: a sequence of octets of at most 128 bytes containing the txn id and the branch id Note - The sum of the two lengths must equal the length of the data field. Detached-lifetime is an integer encoded as follows: * the maximum representable value means unbounded - the maximum length permitted by the peer * otherwise, any other value (including zero) is the number of seconds the session's state is retained during periods when no channel (or equivalent) is attached to the session (DetachedLifetimeFinite above). Identifies a set of commands inside the window of open conversations. Any typed struct whose size width is long. The execution header appears on commands after the class and method id, but prior to method arguments. Indicates that the peer sending the request wants to be notified when this command is completed. Content of a message. It should be considered opaque binary data. The length of the message is determined from the context of this type (the message length field of the message.transfer method). Set of pairs of RFC-1982 numbers representing a discontinuous range. Each pair represents a closed interval within the list. For example, the set (1,3), (6,6), (8,9) represents the sequence 1,2,3,6,8,9. The connection class provides methods for a client to establish a network connection to a server, and for both peers to operate the connection thereafter. connection = open-connection *use-connection close-connection open-connection = C:protocol-header S:START C:START-OK *challenge S:TUNE C:TUNE-OK C:OPEN S:OPEN-OK | S:REDIRECT challenge = S:SECURE C:SECURE-OK use-connection = *channel close-connection = C:CLOSE S:CLOSE-OK / S:CLOSE C:CLOSE-OK This method starts the connection negotiation process by telling the client the protocol version that the server proposes, along with a list of security mechanisms which the client can use for authentication. If the server cannot support the protocol specified in the protocol header, it MUST close the socket connection without sending any response method. The client sends a protocol header containing an invalid protocol name. The server must respond by closing the connection. The server MUST provide a protocol version that is lower than or equal to that requested by the client in the protocol header. The client requests a protocol version that is higher than any valid implementation, e.g. 9.0. The server must respond with a current protocol version, e.g. 1.0. If the client cannot handle the protocol version suggested by the server it MUST close the socket connection. The server sends a protocol version that is lower than any valid implementation, e.g. 0.1. The client must respond by closing the connection. The protocol version, major component, as transmitted in the AMQP protocol header. This, combined with the protocol minor component fully describe the protocol version, which is written in the format major-minor. Hence, with major=1, minor=3, the protocol version would be "1-3". The protocol version, minor component, as transmitted in the AMQP protocol header. This, combined with the protocol major component fully describe the protocol version, which is written in the format major-minor. Hence, with major=1, minor=3, the protocol version would be "1-3". The properties SHOULD contain at least these fields: "host", specifying the server host name or address, "product", giving the name of the server product, "version", giving the name of the server version, "platform", giving the name of the operating system, "copyright", if appropriate, and "information", giving other general information. Client connects to server and inspects the server properties. It checks for the presence of the required fields. A list of the security mechanisms that the server supports, delimited by spaces. A list of the message locales that the server supports, delimited by spaces. The locale defines the language in which the server will send reply texts. The server MUST support at least the en_US locale. Client connects to server and inspects the locales field. It checks for the presence of the required locale(s). This method selects a SASL security mechanism. The properties SHOULD contain at least these fields: "product", giving the name of the client product, "version", giving the name of the client version, "platform", giving the name of the operating system, "copyright", if appropriate, and "information", giving other general information. A single security mechanisms selected by the client, which must be one of those specified by the server. The client SHOULD authenticate using the highest-level security profile it can handle from the list provided by the server. If the mechanism field does not contain one of the security mechanisms proposed by the server in the Start method, the server MUST close the connection without sending any further data. Client connects to server and sends an invalid security mechanism. The server must respond by closing the connection (a socket close, with no connection close negotiation). A block of opaque data passed to the security mechanism. The contents of this data are defined by the SASL security mechanism. A single message locale selected by the client, which must be one of those specified by the server. The SASL protocol works by exchanging challenges and responses until both peers have received sufficient information to authenticate each other. This method challenges the client to provide more information. Challenge information, a block of opaque binary data passed to the security mechanism. This method attempts to authenticate, passing a block of SASL data for the security mechanism at the server side. A block of opaque data passed to the security mechanism. The contents of this data are defined by the SASL security mechanism. This method proposes a set of connection configuration values to the client. The client can accept and/or adjust these. The maximum total number of channels that the server allows per connection. Zero means that the server does not impose a fixed limit, but the number of allowed channels may be limited by available server resources. The largest frame size that the server proposes for the connection. The client can negotiate a lower value. Zero means that the server does not impose any specific limit but may reject very large frames if it cannot allocate resources for them. Until the frame-max has been negotiated, both peers MUST accept frames of up to frame-min-size octets large, and the minimum negotiated value for frame-max is also frame-min-size. Client connects to server and sends a large properties field, creating a frame of frame-min-size octets. The server must accept this frame. The delay, in seconds, of the connection heartbeat that the server wants. Zero means the server does not want a heartbeat. This method sends the client's connection tuning parameters to the server. Certain fields are negotiated, others provide capability information. The maximum total number of channels that the client will use per connection. If the client specifies a channel max that is higher than the value provided by the server, the server MUST close the connection without attempting a negotiated close. The server may report the error in some fashion to assist implementors. The largest frame size that the client and server will use for the connection. Zero means that the client does not impose any specific limit but may reject very large frames if it cannot allocate resources for them. Note that the frame-max limit applies principally to content frames, where large contents can be broken into frames of arbitrary size. Until the frame-max has been negotiated, both peers MUST accept frames of up to frame-min-size octets large, and the minimum negotiated value for frame-max is also frame-min-size. If the client specifies a frame max that is higher than the value provided by the server, the server MUST close the connection without attempting a negotiated close. The server may report the error in some fashion to assist implementors. The delay, in seconds, of the connection heartbeat that the client wants. Zero means the client does not want a heartbeat. This method opens a connection to a virtual host, which is a collection of resources, and acts to separate multiple application domains within a server. The server may apply arbitrary limits per virtual host, such as the number of each type of entity that may be used, per connection and/or in total. The name of the virtual host to work with. If the server supports multiple virtual hosts, it MUST enforce a full separation of exchanges, queues, and all associated entities per virtual host. An application, connected to a specific virtual host, MUST NOT be able to access resources of another virtual host. The server SHOULD verify that the client has permission to access the specified virtual host. The client can specify zero or more capability names, delimited by spaces. The server can use this string to how to process the client's connection request. In a configuration with multiple collaborating servers, the server may respond to a Connection.Open method with a Connection.Redirect. The insist option tells the server that the client is insisting on a connection to the specified server. When the client uses the insist option, the server MUST NOT respond with a Connection.Redirect method. If it cannot accept the client's connection request it should respond by closing the connection with a suitable reply code. This method signals to the client that the connection is ready for use. This method redirects the client to another server, based on the requested virtual host and/or capabilities. When getting the Connection.Redirect method, the client SHOULD reconnect to the host specified, and if that host is not present, to any of the hosts specified in the known-hosts list. Specifies the server to connect to. This is an IP address or a DNS name, optionally followed by a colon and a port number. If no port number is specified, the client should use the default port number for the protocol. This method indicates that the sender wants to close the connection. This may be due to internal conditions (e.g. a forced shut-down) or due to an error handling a specific method, i.e. an exception. When a close is due to an exception, the sender provides the class and method id of the method which caused the exception. After sending this method any received method except the Close-OK method MUST be discarded. When the close is provoked by a method exception, this is the class of the method. When the close is provoked by a method exception, this is the ID of the method. This method confirms a Connection.Close method and tells the recipient that it is safe to release resources for the connection and close the socket. A peer that detects a socket closure without having received a Close-Ok handshake method SHOULD log the error. The session class provides methods for a client to establish a session with a server and for both peers to operate the session thereafter. session = open-session *use-session close-session open-session = C:OPEN S:ATTACHED / C:RESUME S:ATTACHED use-session = C:FLOW S:FLOW-OK / S:FLOW C:FLOW-OK / S:PING / C:PONG / C:PING / S:PONG close-session = C:SUSPEND S:DETACHED / C:CLOSE S:CLOSED / S:CLOSED / S:CLOSE C:CLOSED / C:CLOSED This method opens a session with the server. When the responding peer creates the session, it MUST create a new, appropriately-unique name for the session and return this to the creator with the rest of the session details. Note that the timer controlling a session's automatic expiry, if any, counts down immediately from the moment of its creation, unless simultaneously with that moment a channel (or equivalent) is attached to the session. For this reason, it is recommended that network protocol mappings create sessions simultaneously with the creation and attachment of their channel-equivalents, since a zero lease time is perfectly valid and indicates that the session should be destroyed as soon as it first finds itself inactive. During the period that a channel (or equivalent) is attached to a session, the session has no deletion timer. Every time a channel is detached from a session such that the session is left without any attached network-level entities, the timer is created, set to its declared value and started. Note that if the peer decides that the requested detached-lifetime timeout is too long, either because the replying peer does not support sessions with non-zero requested timeouts, or because the requested timeout exceeds some peer-specific limitation, it may substitute an acceptable value for the detached-lifetime parameter in its reply to the creation request. An exception is not required. Whether the detachment is explicit or implicit, as a result of application action or of application error, the channel (or equivalent) is detached from its session and the session timer MUST start counting down as defined in session.open. The client MUST NOT send session.open on a channel that is already associated with a session. A "channel busy" connection exception will occur if the channel down which the open request was sent was already attached to a session. Client sends session.open twice down the same channel. The number of seconds the session's state is retained during periods when no channel (or equivalent) is attached to the session. This method signals to the client that the session is ready for use. Once a session.attached is received by the client, everything is in place for normal transmission of frames. However, depending on the network protocol mapping in use, the frame-id be undefined until certain control frames have been sent. Please see the specific details for each protocol mapping. If the attached session was freshly created, the session-id here will be a freshly-generated UUID. Note that the actual session detached-lifetime value, as decided by the peer, is returned using this method. The value returned may not be the same as that requested in the corresponding session creation request. In particular, a request for an unbounded detached-lifetime of may be fulfilled by creation of a session with a bounded actual lifetime parameter. The requesting peer SHOULD take the lifetime value returned as authoritative for its own session-related record-keeping. The session identifier (a UUID) used to identify this session. The number of seconds the session's state is retained during periods when no channel (or equivalent) is attached to the session. This method asks the peer to pause or restart the flow of content data. This is a simple flow-control mechanism that a peer can use to avoid overflowing its queues or otherwise finding itself receiving more messages than it can process. Note that this method is not intended for window control. The peer that receives a disable flow method should finish sending the current content frame, if any, then pause. When a new session is opened, it is active (flow is active). Some applications assume that sessions are inactive until started. To emulate this behaviour a client MAY open the session, then pause it. When sending content frames, a peer SHOULD monitor the session for incoming methods and respond to a Session.Flow as rapidly as possible. A peer MAY use the Session.Flow method to throttle incoming content data for internal reasons, for example, when exchanging data over a slower connection. The peer that requests a Session.Flow method MAY disconnect and/or ban a peer that does not respect the request. This is to prevent badly-behaved clients from overwhelming a broker. If true (1), the peer starts sending content frames. If false (0), the peer stops sending content frames. Confirms to the peer that a flow command was received and processed. Confirms the setting of the processed flow method: true (1) means the peer will start sending or continue to send content frames; false (0) means it will not. Requests that the receiving peer destroy a session, implicitly detaching any attached channels or channel-equivalents. Note that the reply, session.closed, is also used for asynchronous exception notifications. For normal closure, such as in response to a session.close request, reason code 200 ("ok") is to be used. Notifies the receiver that not only has the current channel been detached from its underlying session, but that the session itself has been destroyed. This method confirms a session.close method and tells the recipient that it is safe to release resources for the channel. Note also that for normal closure, reason code 200 ("ok") is to be used. The numeric reply code. The localised reply text. Attaches to an already-existing session. A "session busy" exception is returned if the session exists, but is not in a condition where it can accept the requested attachment. Peers receiving this exception may wish to retain their session state and retry the session.resume operation after a delay. The session identifier (a UUID) used to identify this session. Indicates the sending peer wishes to detach from this session, but not necessarily to destroy it. Signal detachment from the session. Signals receipt of all frames such that frame-id <= cumulative-seen-mark, or frame-id is in the set defined by seen-frame-set. This can be sent spontaneously, or in response to either session.solicit-ack or session.high-water-mark. Note that an encoded acknowledgement frame carried over the TCP network mapping (in the absence of cross-protocol use of a session) will never have any entries in its seen-frame-set. In order to ensure a canonical wire representation, the value cumulative-seen-mark + 1 must not be covered by the seen-frame-set. The low-water mark for seen frame-ids. All ids below this mark have been seen; above this mark, there are gaps containing unseen ids (i.e. discontinuous). By definition, the first frame-id above this mark (if it exists) is an unseen id. This set contains a sequence of discontinuous seen-frame-ids above the low-water mark (i.e. above the first gap of unseen ids). In some transports where out-of-order delivery is not possible (such as TCP), this set will always be empty. Carries information about the highest (most recent) frame-id number that the sending peer has sent through this session so far. The receiver should issue a session.ack at the earliest possible opportunity. Highest frame-id sent by the sending peer through this session so far. Requests a session.ack from the peer. The peer should issue one at the earliest possible opportunity. The protocol control access to server resources using access tickets. A client must explicitly request access tickets before doing work. An access ticket grants a client the right to use a specific set of resources - called a "realm" - in specific ways. access = C:REQUEST S:REQUEST-OK This method requests an access ticket for an access realm. The server responds by granting the access ticket. If the client does not have access rights to the requested realm this causes a connection exception. Access tickets are a per-session resource. Specifies the name of the realm to which the client is requesting access. The realm is a configured server-side object that collects a set of resources (exchanges, queues, etc.). If the session has already requested an access ticket onto this realm, the previous ticket is destroyed and a new ticket is created with the requested access rights, if allowed. The client MUST specify a realm that is known to the server. The server makes an identical response for undefined realms as it does for realms that are defined but inaccessible to this client. Client specifies an undefined realm. Request exclusive access to the realm, meaning that this will be the only session that uses the realm's resources. The client MUST NOT request exclusive access to a realm that has active access tickets, unless the same session already had the only access ticket onto that realm. Client opens two sessions and requests exclusive access to the same realm. Request message passive access to the specified access realm. Passive access lets a client get information about resources in the realm but not to make any changes to them. Request message active access to the specified access realm. Active access lets a client get create and delete resources in the realm. Request write access to the specified access realm. Write access lets a client publish messages to all exchanges in the realm. Request read access to the specified access realm. Read access lets a client consume messages from queues in the realm. This method provides the client with an access ticket. The access ticket is valid within the current session and for the lifespan of the session. The client MUST NOT use access tickets except within the same session as originally granted. Client opens two sessions, requests a ticket on one session and then tries to use that ticket in a second session. A valid access ticket to be used for gaining access to the server. Exchanges match and distribute messages across queues. Exchanges can be configured in the server or created at runtime. exchange = C:DECLARE / C:DELETE The server MUST implement these standard exchange types: fanout, direct. Client attempts to declare an exchange with each of these standard types. The server SHOULD implement these standard exchange types: topic, headers. Client attempts to declare an exchange with each of these standard types. The server MUST, in each virtual host, pre-declare an exchange instance for each standard exchange type that it implements, where the name of the exchange instance, if defined, is "amq." followed by the exchange type name. The server MUST, in each virtual host, pre-declare at least two direct exchange instances: one named "amq.direct", the other with no public name that serves as a default exchange for publish methods (such as message.transfer). Client creates a temporary queue and attempts to bind to each required exchange instance ("amq.fanout", "amq.direct", "amq.topic", and "amq.headers" if those types are defined). The server MUST pre-declare a direct exchange with no public name to act as the default exchange for content publish methods (such as message.transfer) and for default queue bindings. Client checks that the default exchange is active by publishing a message with a suitable routing key but without specifying the exchange name, then ensuring that the message arrives in the queue correctly. The default exchange MUST NOT be accessible to the client except by specifying an empty exchange name in a content publish method (such as message.transfer). That is, the server must not let clients explicitly bind, unbind, delete, or make any other reference to this exchange. The server MAY implement other exchange types as wanted. This method creates an exchange if it does not already exist, and if the exchange exists, verifies that it is of the correct and expected class. The server SHOULD support a minimum of 16 exchanges per virtual host and ideally, impose no limit except as defined by available resources. The client creates as many exchanges as it can until the server reports an error; the number of exchanges successfully created must be at least sixteen. When a client defines a new exchange, this belongs to the access realm of the ticket used. All further work done with that exchange must be done with an access ticket for the same realm. The client MUST provide a valid access ticket giving "active" access to the realm in which the exchange exists or will be created, or "passive" access if the if-exists flag is set. Client creates access ticket with wrong access rights and attempts to use in this method. Exchange names starting with "amq." are reserved for pre-declared and standardised exchanges. The client MUST NOT attempt to create an exchange starting with "amq.". The name of the exchange MUST NOT be a blank or empty string. Each exchange belongs to one of a set of exchange types implemented by the server. The exchange types define the functionality of the exchange - i.e. how messages are routed through it. It is not valid or meaningful to attempt to change the type of an existing exchange. Exchanges cannot be redeclared with different types. The client MUST not attempt to redeclare an existing exchange with a different type than used in the original Exchange.Declare method. The client MUST NOT attempt to create an exchange with a type that the server does not support. In the event that a message cannot be routed, this is the name of the exchange to which the message will be sent. If alternate-exchange is not set (its name is an empty string), unroutable messages MUST be dropped silently. If the alternate-exchange is not empty and if the exchange already exists with a different alternate-exchange, then the declaration MUST result in a channel error. A message which is being routed to a alternate exchange, MUST NOT be re-routed to a secondary alternate exchange if it fails to route in the primary alternate exchange. After such a failure, the message MUST be dropped. This prevents looping. If set, the server will not create the exchange. The client can use this to check whether an exchange exists without modifying the server state. If set, and the exchange does not already exist, the server MUST raise a channel exception with reply code 404 (not found). If set when creating a new exchange, the exchange will be marked as durable. Durable exchanges remain active when a server restarts. Non-durable exchanges (transient exchanges) are purged if/when a server restarts. The server MUST support both durable and transient exchanges. The server MUST ignore the durable field if the exchange already exists. If set, the exchange is deleted when all queues have finished using it. The server MUST ignore the auto-delete field if the exchange already exists. A set of arguments for the declaration. The syntax and semantics of these arguments depends on the server implementation. This field is ignored if passive is 1. This method deletes an exchange. When an exchange is deleted all queue bindings on the exchange are cancelled. The client MUST provide a valid access ticket giving "active" access rights to the exchange's access realm. Client creates access ticket with wrong access rights and attempts to use in this method. The client MUST NOT attempt to delete an exchange that does not exist. The name of the exchange MUST NOT be a blank or empty string. If set, the server will only delete the exchange if it has no queue bindings. If the exchange has queue bindings the server does not delete it but raises a channel exception instead. This method is used to request information on a particular exchange. The client MUST provide a valid access ticket giving "passive" access rights to the exchange's access realm. The name of the exchange for which information is requested. If not specified explicitly the default exchange is implied. This is sent in response to a query request and conveys information on a particular exchange. The type of the exchange. Will be empty if the exchange is not found. The durability of the exchange, i.e. if set the exchange is durable. Will not be set if the exchange is not found. If set, the exchange for which information was requested is not known. A set of properties of the exchange whose syntax and semantics depends on the server implementation. Will be empty if the exchange is not found. Queues store and forward messages. Queues can be configured in the server or created at runtime. Queues must be attached to at least one exchange in order to receive messages from publishers. queue = C:DECLARE / C:BIND / C:PURGE / C:DELETE / C:QUERY / C:UNBIND A server MUST allow any content class to be sent to any queue, in any mix, and queue and deliver these content classes independently. Note that all methods that fetch content off queues are specific to a given content class. Client creates an exchange of each standard type and several queues that it binds to each exchange. It must then successfully send each of the standard content types to each of the available queues. This method creates or checks a queue. When creating a new queue the client can specify various properties that control the durability of the queue and its contents, and the level of sharing for the queue. The server MUST create a default binding for a newly-created queue to the default exchange, which is an exchange of type 'direct' and use the queue name as the routing key. Client creates a new queue, and then without explicitly binding it to an exchange, attempts to send a message through the default exchange binding, i.e. publish a message to the empty exchange, with the queue name as routing key. The server SHOULD support a minimum of 256 queues per virtual host and ideally, impose no limit except as defined by available resources. Client attempts to create as many queues as it can until the server reports an error. The resulting count must at least be 256. When a client defines a new queue, this belongs to the access realm of the ticket used. All further work done with that queue must be done with an access ticket for the same realm. The client MUST provide a valid access ticket giving "active" access to the realm in which the queue exists or will be created. Client creates access ticket with wrong access rights and attempts to use in this method. Queue names starting with "amq." are reserved for pre-declared and standardised server queues. A client MUST NOT attempt to declare a queue with a name that starts with "amq." and the passive option set to zero. A client attempts to create a queue with a name starting with "amq." and with the passive option set to zero. If a message is rejected by a queue, then it is sent to the alternate-exchange. A message may be rejected by a queue for the following reasons: 1. The queue is deleted when it is not empty; 2. Immediate delivery of a message is requested, but there are no consumers connected to the queue. If alternate-exchange is not set (its name is an empty string), rejected messages MUST be dropped silently. If the alternate-exchange is not empty and if the queue already exists with a different alternate-exchange, then the declaration MUST result in a channel error. The alternate-exchange MUST NOT be deleted while a queue bound to it still exists. Such an attempt MUST result in a channel exception. If set, the server will not create the queue. This field allows the client to assert the presence of a queue without modifying the server state. The client MAY ask the server to assert that a queue exists without creating the queue if not. If the queue does not exist, the server treats this as a failure. Client declares an existing queue with the passive option and expects the command to succeed. Client then attempts to declare a non-existent queue with the passive option, and the server must close the channel with the correct reply-code. If set when creating a new queue, the queue will be marked as durable. Durable queues remain active when a server restarts. Non-durable queues (transient queues) are purged if/when a server restarts. Note that durable queues do not necessarily hold persistent messages, although it does not make sense to send persistent messages to a transient queue. The server MUST recreate the durable queue after a restart. Client creates a durable queue; server is then restarted. Client then attempts to send message to the queue. The message should be successfully delivered. The server MUST support both durable and transient queues. A client creates two named queues, one durable and one transient. The server MUST ignore the durable field if the queue already exists. A client creates two named queues, one durable and one transient. The client then attempts to declare the two queues using the same names again, but reversing the value of the durable flag in each case. Verify that the queues still exist with the original durable flag values. Exclusive queues can only be used from one connection at a time. Once a connection declares an exclusive queue, that queue cannot be used by any other connections until the declaring connection closes. The server MUST support both exclusive (private) and non-exclusive (shared) queues. A client creates two named queues, one exclusive and one non-exclusive. If the server receives a declare, bind, consume or get request for a queue that has been declared as exclusive by an existing client connection, it MUST raise a channel exception. A client declares an exclusive named queue. A second client on a different connection attempts to declare a queue of the same name. If this field is set and the exclusive field is also set, then the queue MUST be deleted when the connection closes. If this field is set and the exclusive field is not set the queue is deleted when all the consumers have finished using it. Last consumer can be cancelled either explicitly or because its channel is closed. If there was no consumer ever on the queue, it won't be deleted. The server MUST ignore the auto-delete field if the queue already exists. A client creates two named queues, one as auto-delete and one explicit-delete. The client then attempts to declare the two queues using the same names again, but reversing the value of the auto-delete field in each case. Verify that the queues still exist with the original auto-delete flag values. A set of arguments for the declaration. The syntax and semantics of these arguments depends on the server implementation. This field is ignored if passive is 1. This method binds a queue to an exchange. Until a queue is bound it will not receive any messages. In a classic messaging model, store-and-forward queues are bound to a direct exchange and subscription queues are bound to a topic exchange. A server MUST allow ignore duplicate bindings - that is, two or more bind methods for a specific queue, with identical arguments - without treating these as an error. A client binds a named queue to an exchange. The client then repeats the bind (with identical arguments). If a bind fails, the server MUST raise a connection exception. The server MUST NOT allow a durable queue to bind to a transient exchange. A client creates a transient exchange. The client then declares a named durable queue and then attempts to bind the transient exchange to the durable queue. Bindings for durable queues are automatically durable and the server SHOULD restore such bindings after a server restart. A server creates a named durable queue and binds it to a durable exchange. The server is restarted. The client then attempts to use the queue/exchange combination. If the client attempts to bind to an exchange that was declared as internal, the server MUST raise a connection exception with reply code 530 (not allowed). A client attempts to bind a named queue to an internal exchange. The server SHOULD support at least 4 bindings per queue, and ideally, impose no limit except as defined by available resources. A client creates a named queue and attempts to bind it to 4 different non-internal exchanges. Where more than one binding exists between a particular exchange instance and a particular queue instance any given message published to that exchange should be delivered to that queue at most once, regardless of how many distinct bindings match. A client creates a named queue and binds it to the same topic exchange at least three times using intersecting routing keys (for example, "animals.*", "animals.dogs.*", "animal.dogs.chihuahua"). Verify that a message matching all the bindings (using previous example, routing key = "animal.dogs.chihuahua") is delivered once only. The client provides a valid access ticket giving "active" access rights to the queue's access realm. Specifies the name of the queue to bind. If the queue name is empty, refers to the current queue for the session, which is the last declared queue. A client MUST NOT be allowed to bind a non-existent and unnamed queue (i.e. empty queue name) to an exchange. A client attempts to bind with an unnamed (empty) queue name to an exchange. A client MUST NOT be allowed to bind a non-existent queue (i.e. not previously declared) to an exchange. A client attempts to bind an undeclared queue name to an exchange. A client MUST NOT be allowed to bind a queue to a non-existent exchange. A client attempts to bind a named queue to a undeclared exchange. The name of the exchange MUST NOT be a blank or empty string. Specifies the routing key for the binding. The routing key is used for routing messages depending on the exchange configuration. Not all exchanges use a routing key - refer to the specific exchange documentation. If the queue name is empty, the server uses the last queue declared on the session. If the routing key is also empty, the server uses this queue name for the routing key as well. If the queue name is provided but the routing key is empty, the server does the binding with that empty routing key. The meaning of empty routing keys depends on the exchange implementation. If a message queue binds to a direct exchange using routing key K and a publisher sends the exchange a message with routing key R, then the message MUST be passed to the message queue if K = R. A set of arguments for the binding. The syntax and semantics of these arguments depends on the exchange class. This method unbinds a queue from an exchange. If a unbind fails, the server MUST raise a connection exception. The client provides a valid access ticket giving "active" access rights to the queue's access realm. Specifies the name of the queue to unbind. If the queue does not exist the server MUST raise a channel exception with reply code 404 (not found). The name of the exchange to unbind from. If the exchange does not exist the server MUST raise a channel exception with reply code 404 (not found). The name of the exchange MUST NOT be a blank or empty string. Specifies the routing key of the binding to unbind. Specifies the arguments of the binding to unbind. This method removes all messages from a queue. It does not cancel consumers. Purged messages are deleted without any formal "undo" mechanism. A call to purge MUST result in an empty queue. On transacted sessions the server MUST not purge messages that have already been sent to a client but not yet acknowledged. The server MAY implement a purge queue or log that allows system administrators to recover accidentally-purged messages. The server SHOULD NOT keep purged messages in the same storage spaces as the live messages since the volumes of purged messages may get very large. The client MUST provide a valid access ticket giving "read" access rights to the queue's access realm. Note that purging a queue is equivalent to reading all messages and discarding them. Specifies the name of the queue to purge. If the queue name is empty, refers to the current queue for the session, which is the last declared queue. If the client did not previously declare a queue, and the queue name in this method is empty, the server MUST raise a connection exception with reply code 530 (not allowed). The queue MUST exist. Attempting to purge a non-existing queue MUST cause a channel exception with reply code 404 (not found). This method deletes a queue. When a queue is deleted any pending messages are sent to a dead-letter queue if this is defined in the server configuration, and all consumers on the queue are cancelled. The server SHOULD use a dead-letter queue to hold messages that were pending on a deleted queue, and MAY provide facilities for a system administrator to move these messages back to an active queue. The client provides a valid access ticket giving "active" access rights to the queue's access realm. Specifies the name of the queue to delete. If the queue name is empty, refers to the current queue for the session, which is the last declared queue. If the client did not previously declare a queue, and the queue name in this method is empty, the server MUST raise a connection exception with reply code 530 (not allowed). The queue must exist. If the client attempts to delete a non-existing queue the server MUST raise a channel exception with reply code 404 (not found). If set, the server will only delete the queue if it has no consumers. If the queue has consumers the server does does not delete it but raises a channel exception instead. The server MUST respect the if-unused flag when deleting a queue. If set, the server will only delete the queue if it has no messages. If the queue is not empty the server MUST raise a channel exception with reply code 406 (precondition failed). This method requests information about a queue. This is sent in response to queue.query, and conveys the requested information about a queue. Reports the name of the queue. Reports the number of messages in the queue. Reports the number of active consumers for the queue. Note that consumers can suspend activity (Session.Flow) in which case they do not appear in this count. [DEPRECATED: replaced by message class.] The Basic class provides methods that support an industry-standard messaging model. basic = C:QOS / C:CONSUME S:CONSUME-OK / C:CANCEL / C:PUBLISH content / S:RETURN content / S:DELIVER content / C:GET ( S:GET-OK content / S:GET-EMPTY ) / C:ACK / C:REJECT The server SHOULD respect the persistent property of basic messages and SHOULD make a best-effort to hold persistent basic messages on a reliable storage mechanism. Send a persistent message to queue, stop server, restart server and then verify whether message is still present. Assumes that queues are durable. Persistence without durable queues makes no sense. The server MUST NOT discard a persistent basic message in case of a queue overflow. Create a queue overflow situation with persistent messages and verify that messages do not get lost (presumably the server will write them to disk). The server MAY use the Session.Flow method to slow or stop a basic message publisher when necessary. Create a queue overflow situation with non-persistent messages and verify whether the server responds with Session.Flow or not. Repeat with persistent messages. The server MAY overflow non-persistent basic messages to persistent storage. The server MAY discard or dead-letter non-persistent basic messages on a priority basis if the queue size exceeds some configured limit. The server MUST implement at least 2 priority levels for basic messages, where priorities 0-4 and 5-9 are treated as two distinct levels. Send a number of priority 0 messages to a queue. Send one priority 9 message. Consume messages from the queue and verify that the first message received was priority 9. The server MAY implement up to 10 priority levels. Send a number of messages with mixed priorities to a queue, so that all priority values from 0 to 9 are exercised. A good scenario would be ten messages in low-to-high priority. Consume from queue and verify how many priority levels emerge. The server MUST deliver messages of the same priority in order irrespective of their individual persistence. Send a set of messages with the same priority but different persistence settings to a queue. Consume and verify that messages arrive in same order as originally published. The server MUST support automatic acknowledgements on Basic content, i.e. consumers with the no-ack field set to FALSE. Create a queue and a consumer using automatic acknowledgements. Publish a set of messages to the queue. Consume the messages and verify that all messages are received. The server MUST support explicit acknowledgements on Basic content, i.e. consumers with the no-ack field set to TRUE. Create a queue and a consumer using explicit acknowledgements. Publish a set of messages to the queue. Consume the messages but acknowledge only half of them. Disconnect and reconnect, and consume from the queue. Verify that the remaining messages are received. [DEPRECATED: Basic replaced by message class.] This method requests a specific quality of service. The QoS can be specified for the current session or for all sessions on the connection. The particular properties and semantics of a qos method always depend on the content class semantics. Though the qos method could in principle apply to both peers, it is currently meaningful only for the server. The client can request that messages be sent in advance so that when the client finishes processing a message, the following message is already held locally, rather than needing to be sent within the session. Prefetching gives a performance improvement. This field specifies the prefetch window size in octets. The server will send a message in advance if it is equal to or smaller in size than the available prefetch size (and also falls into other prefetch limits). May be set to zero, meaning "no specific limit", although other prefetch limits may still apply. The prefetch-size is ignored if the no-ack option is set. The server MUST ignore this setting when the client is not processing any messages - i.e. the prefetch size does not limit the transfer of single messages to a client, only the sending in advance of more messages while the client still has one or more unacknowledged messages. Define a QoS prefetch-size limit and send a single message that exceeds that limit. Verify that the message arrives correctly. Specifies a prefetch window in terms of whole messages. This field may be used in combination with the prefetch-size field; a message will only be sent in advance if both prefetch windows (and those at the session and connection level) allow it. The prefetch-count is ignored if the no-ack option is set. The server may send less data in advance than allowed by the client's specified prefetch windows but it MUST NOT send more. Define a QoS prefetch-size limit and a prefetch-count limit greater than one. Send multiple messages that exceed the prefetch size. Verify that no more than one message arrives at once. By default the QoS settings apply to the current session only. If this field is set, they are applied to the entire connection. [DEPRECATED: Basic replaced by message class.] This method asks the server to start a "consumer", which is a transient request for messages from a specific queue. Consumers last as long as the session they were created on, or until the client cancels them. The server SHOULD support at least 16 consumers per queue, and ideally, impose no limit except as defined by available resources. Create a queue and create consumers on that queue until the server closes the connection. Verify that the number of consumers created was at least sixteen and report the total number. The client MUST provide a valid access ticket giving "read" access rights to the realm for the queue from which the message will be consumed. Attempt to create a consumer with an invalid (non-zero) access ticket. Specifies the name of the queue to consume from. If the queue name is null, refers to the current queue for the session, which is the last declared queue. If the queue name is empty the client MUST have previously declared a queue using this session. Attempt to create a consumer with an empty queue name and no previously declared queue on the session. Specifies the identifier for the consumer. The consumer tag is local to a connection, so two clients can use the same consumer tags. If this field is empty the server will generate a unique tag. The client MUST NOT specify a tag that refers to an existing consumer. Attempt to create two consumers with the same non-empty tag. The consumer tag is valid only within the session from which the consumer was created. i.e. A client MUST NOT create a consumer in one session and then use it in another. Attempt to create a consumer in one session, then use in another session, in which consumers have also been created (to test that the server uses unique consumer tags). Request exclusive consumer access, meaning only this consumer can access the queue. The client MUST NOT gain exclusive access to a queue that already has active consumers. Open two connections to a server, and in one connection create a shared (non-exclusive) queue and then consume from the queue. In the second connection attempt to consume from the same queue using the exclusive option. If set, the server will not respond to the method. The client should not wait for a reply method. If the server could not complete the method it will raise a channel or connection exception. A set of arguments for the consume. The syntax and semantics of these arguments depends on the providers implementation. [DEPRECATED: Basic replaced by message class.] The server provides the client with a consumer tag, which is used by the client for methods called on the consumer at a later stage. Holds the consumer tag specified by the client or provided by the server. [DEPRECATED: Basic replaced by message class.] This method cancels a consumer. This does not affect already delivered messages, but it does mean the server will not send any more messages for that consumer. The client may receive an arbitrary number of messages in between sending the cancel method and receiving notification of the completion of the cancel command. If the queue does not exist the server MUST ignore the cancel method, so long as the consumer tag is valid for that session. [DEPRECATED: Basic replaced by message class.] This method publishes a message to a specific exchange. The message will be routed to queues as defined by the exchange configuration and distributed to any active consumers when the transaction, if any, is committed. The client MUST provide a valid access ticket giving "passive" access rights to the realm for the exchange and "write" access rights to the realm for the queue to which the message will be published. Specifies the name of the exchange to publish to. The exchange name can be empty, meaning the default exchange. If the exchange name is specified, and that exchange does not exist, the server will raise a channel exception. The server MUST accept a blank exchange name to mean the default exchange. If the exchange was declared as an internal exchange, the server MUST raise a channel exception with a reply code 403 (access refused). The exchange MAY refuse basic content in which case it MUST raise a channel exception with reply code 540 (not implemented). Specifies the routing key for the message. The routing key is used for routing messages depending on the exchange configuration. If the reject-unroutable flag is set, then at the time of publishing the broker determines if the message will be routed to any queues. If it will not be routed to any queue then the broker responds with a basic.reject. If this flag is set, and the resulting message is delivered to a queue with no consumers, the message will not be queued but will instead be routed to the alternate-exchange for that queue. If no such exchange is defined the message will be silently dropped. The server SHOULD implement the immediate flag. [DEPRECATED: Basic replaced by message class.] This method delivers a message to the client, via a consumer. In the asynchronous message delivery model, the client starts a consumer using the Consume method, then the server responds with Deliver methods as and when messages arrive for that consumer. The server SHOULD track the number of times a message has been delivered to clients and when a message is redelivered a certain number of times - e.g. 5 times - without being acknowledged, the server SHOULD consider the message to be unprocessable (possibly causing client applications to abort), and move the message to a dead letter queue. Specifies the name of the exchange that the message was originally published to. Specifies the routing key name specified when the message was published. [DEPRECATED: Basic replaced by message class.] This method provides a direct access to the messages in a queue using a synchronous dialogue that is designed for specific types of application where synchronous functionality is more important than performance. The client MUST provide a valid access ticket giving "read" access rights to the realm for the queue from which the message will be obtained. Specifies the name of the queue to consume from. If the queue name is null, refers to the current queue for the session, which is the last declared queue. If the client did not previously declare a queue, and the queue name in this method is empty, the server MUST raise a connection exception with reply code 530 (not allowed). [DEPRECATED: Basic replaced by message class.] This method delivers a message to the client following a get method. A message delivered by 'get-ok' must be acknowledged unless the no-ack option was set in the get method. Specifies the name of the exchange that the message was originally published to. If empty, the message was published to the default exchange. Specifies the routing key name specified when the message was published. This field reports the number of messages pending on the queue, excluding the message being delivered. Note that this figure is indicative, not reliable, and can change arbitrarily as messages are added to the queue and removed by other clients. [DEPRECATED: Basic replaced by message class.] This method tells the client that the queue has no messages available for the client. For use by cluster applications, should not be used by client applications. [DEPRECATED: Basic replaced by message class.] This method acknowledges one or more messages delivered via the Deliver or Get-Ok methods. The client can ask to confirm a single message or a set of messages up to and including a specific message. If set to 1, the delivery tag is treated as "up to and including", so that the client can acknowledge multiple messages with a single method. If set to zero, the delivery tag refers to a single message. If the multiple field is 1, and the delivery tag is zero, tells the server to acknowledge all outstanding messages. The server MUST validate that a non-zero delivery-tag refers to a delivered message, and raise a channel exception if this is not the case. [DEPRECATED: Basic replaced by message class.] This method allows a client to reject a message. It can be used to interrupt and cancel large incoming messages, or return untreatable messages to their original queue. The server SHOULD be capable of accepting and processing the Reject method while sending message content with a Deliver or Get-Ok method. i.e. The server should read and process incoming methods while sending output frames. To cancel a partially-send content, the server sends a content body frame of size 1 (i.e. with no data except the frame-end octet). The server SHOULD interpret this method as meaning that the client is unable to process the message at this time. A client MUST NOT use this method as a means of selecting messages to process. A rejected message MAY be discarded or dead-lettered, not necessarily passed to another client. If this field is zero, the message will be discarded. If this bit is 1, the server will attempt to requeue the message. The server MUST NOT deliver the message to the same client within the context of the current session. The recommended strategy is to attempt to deliver the message to an alternative consumer, and if that is not possible, to move the message to a dead-letter queue. The server MAY use more sophisticated tracking to hold the message on the queue and redeliver it to the same client at a later stage. [DEPRECATED: Basic replaced by message class.] This method asks the broker to redeliver all unacknowledged messages on a specified session. Zero or more messages may be redelivered. This method is only allowed on non-transacted sessions. The server MUST set the redelivered flag on all messages that are resent. The server MUST raise a channel exception if this is called on a transacted session. If this field is zero, the message will be redelivered to the original recipient. If this bit is 1, the server will attempt to requeue the message, potentially then delivering it to an alternative subscriber. The file class provides methods that support reliable file transfer. File messages have a specific set of properties that are required for interoperability with file transfer applications. File messages and acknowledgements are subject to session transactions. Note that the file class does not provide message browsing methods; these are not compatible with the staging model. Applications that need browsable file transfer should use Basic content and the Basic class. file = C:QOS S:QOS-OK / C:CONSUME S:CONSUME-OK / C:CANCEL / C:OPEN S:OPEN-OK C:STAGE content / S:OPEN C:OPEN-OK S:STAGE content / C:PUBLISH / S:DELIVER / S:RETURN / C:ACK / C:REJECT The server MUST make a best-effort to hold file messages on a reliable storage mechanism. The server MUST NOT discard a file message in case of a queue overflow. The server MUST use the Session.Flow method to slow or stop a file message publisher when necessary. The server MUST implement at least 2 priority levels for file messages, where priorities 0-4 and 5-9 are treated as two distinct levels. The server MAY implement up to 10 priority levels. The server MUST support both automatic and explicit acknowledgements on file content. This method requests a specific quality of service. The QoS can be specified for the current session or for all sessions on the connection. The particular properties and semantics of a qos method always depend on the content class semantics. Though the qos method could in principle apply to both peers, it is currently meaningful only for the server. The client can request that messages be sent in advance so that when the client finishes processing a message, the following message is already held locally, rather than needing to be sent within the session. Prefetching gives a performance improvement. This field specifies the prefetch window size in octets. May be set to zero, meaning "no specific limit". Note that other prefetch limits may still apply. The prefetch-size is ignored if the no-ack option is set. Specifies a prefetch window in terms of whole messages. This is compatible with some file API implementations. This field may be used in combination with the prefetch-size field; a message will only be sent in advance if both prefetch windows (and those at the session and connection level) allow it. The prefetch-count is ignored if the no-ack option is set. The server MAY send less data in advance than allowed by the client's specified prefetch windows but it MUST NOT send more. By default the QoS settings apply to the current session only. If this field is set, they are applied to the entire connection. This method tells the client that the requested QoS levels could be handled by the server. The requested QoS applies to all active consumers until a new QoS is defined. This method asks the server to start a "consumer", which is a transient request for messages from a specific queue. Consumers last as long as the session they were created on, or until the client cancels them. The server SHOULD support at least 16 consumers per queue, unless the queue was declared as private, and ideally, impose no limit except as defined by available resources. The client MUST provide a valid access ticket giving "read" access rights to the realm for the queue from which the message will be consumed. Specifies the name of the queue to consume from. If the queue name is null, refers to the current queue for the session, which is the last declared queue. If the client did not previously declare a queue, and the queue name in this method is empty, the server MUST raise a connection exception with reply code 530 (not allowed). Specifies the identifier for the consumer. The consumer tag is local to a connection, so two clients can use the same consumer tags. If this field is empty the server will generate a unique tag. The tag MUST NOT refer to an existing consumer. If the client attempts to create two consumers with the same non-empty tag the server MUST raise a connection exception with reply code 530 (not allowed). Request exclusive consumer access, meaning only this consumer can access the queue. If the server cannot grant exclusive access to the queue when asked, - because there are other consumers active - it MUST raise a channel exception with return code 405 (resource locked). If set, the server will not respond to the method. The client should not wait for a reply method. If the server could not complete the method it will raise a channel or connection exception. A set of filters for the consume. The syntax and semantics of these filters depends on the providers implementation. This method provides the client with a consumer tag which it MUST use in methods that work with the consumer. Holds the consumer tag specified by the client or provided by the server. This method cancels a consumer. This does not affect already delivered messages, but it does mean the server will not send any more messages for that consumer. This method requests permission to start staging a message. Staging means sending the message into a temporary area at the recipient end and then delivering the message by referring to this temporary area. Staging is how the protocol handles partial file transfers - if a message is partially staged and the connection breaks, the next time the sender starts to stage it, it can restart from where it left off. This is the staging identifier. This is an arbitrary string chosen by the sender. For staging to work correctly the sender must use the same staging identifier when staging the same message a second time after recovery from a failure. A good choice for the staging identifier would be the SHA1 hash of the message properties data (including the original filename, revised time, etc.). The size of the content in octets. The recipient may use this information to allocate or check available space in advance, to avoid "disk full" errors during staging of very large messages. The sender MUST accurately fill the content-size field. Zero-length content is permitted. This method confirms that the recipient is ready to accept staged data. If the message was already partially-staged at a previous time the recipient will report the number of octets already staged. The amount of previously-staged content in octets. For a new message this will be zero. The sender MUST start sending data from this octet offset in the message, counting from zero. The recipient MAY decide how long to hold partially-staged content and MAY implement staging by always discarding partially-staged content. However if it uses the file content type it MUST support the staging methods. This method stages the message, sending the message content to the recipient from the octet offset specified in the Open-Ok method. This method publishes a staged file message to a specific exchange. The file message will be routed to queues as defined by the exchange configuration and distributed to any active consumers when the transaction, if any, is committed. The client MUST provide a valid access ticket giving "passive" access rights to the realm for the exchange and "write" access rights to the realm for the queue to which the message will be published. Specifies the name of the exchange to publish to. The exchange name can be empty, meaning the default exchange. If the exchange name is specified, and that exchange does not exist, the server will raise a channel exception. The server MUST accept a blank exchange name to mean the default exchange. If the exchange was declared as an internal exchange, the server MUST respond with a reply code 403 (access refused) and raise a channel exception. The exchange MAY refuse file content in which case it MUST respond with a reply code 540 (not implemented) and raise a channel exception. Specifies the routing key for the message. The routing key is used for routing messages depending on the exchange configuration. This flag tells the server how to react if the message cannot be routed to a queue. If this flag is set, the server will return an unroutable message with a Return method. If this flag is zero, the server silently drops the message. The server SHOULD implement the mandatory flag. This flag tells the server how to react if the message cannot be routed to a queue consumer immediately. If this flag is set, the server will return an undeliverable message with a Return method. If this flag is zero, the server will queue the message, but with no guarantee that it will ever be consumed. The server SHOULD implement the immediate flag. This is the staging identifier of the message to publish. The message must have been staged. Note that a client can send the Publish method asynchronously without waiting for staging to finish. This method returns an undeliverable message that was published with the "immediate" flag set, or an unroutable message published with the "mandatory" flag set. The reply code and text provide information about the reason that the message was undeliverable. Specifies the name of the exchange that the message was originally published to. Specifies the routing key name specified when the message was published. This method delivers a staged file message to the client, via a consumer. In the asynchronous message delivery model, the client starts a consumer using the Consume method, then the server responds with Deliver methods as and when messages arrive for that consumer. The server SHOULD track the number of times a message has been delivered to clients and when a message is redelivered a certain number of times - e.g. 5 times - without being acknowledged, the server SHOULD consider the message to be unprocessable (possibly causing client applications to abort), and move the message to a dead letter queue. Specifies the name of the exchange that the message was originally published to. Specifies the routing key name specified when the message was published. This is the staging identifier of the message to deliver. The message must have been staged. Note that a server can send the Deliver method asynchronously without waiting for staging to finish. This method acknowledges one or more messages delivered via the Deliver method. The client can ask to confirm a single message or a set of messages up to and including a specific message. If set to 1, the delivery tag is treated as "up to and including", so that the client can acknowledge multiple messages with a single method. If set to zero, the delivery tag refers to a single message. If the multiple field is 1, and the delivery tag is zero, tells the server to acknowledge all outstanding messages. The server MUST validate that a non-zero delivery-tag refers to an delivered message, and raise a channel exception if this is not the case. This method allows a client to reject a message. It can be used to return untreatable messages to their original queue. Note that file content is staged before delivery, so the client will not use this method to interrupt delivery of a large message. The server SHOULD interpret this method as meaning that the client is unable to process the message at this time. A client MUST NOT use this method as a means of selecting messages to process. A rejected message MAY be discarded or dead-lettered, not necessarily passed to another client. If this field is zero, the message will be discarded. If this bit is 1, the server will attempt to requeue the message. The server MUST NOT deliver the message to the same client within the context of the current session. The recommended strategy is to attempt to deliver the message to an alternative consumer, and if that is not possible, to move the message to a dead-letter queue. The server MAY use more sophisticated tracking to hold the message on the queue and redeliver it to the same client at a later stage. The stream class provides methods that support multimedia streaming. The stream class uses the following semantics: one message is one packet of data; delivery is unacknowledged and unreliable; the consumer can specify quality of service parameters that the server can try to adhere to; lower-priority messages may be discarded in favour of high priority messages. stream = C:QOS S:QOS-OK / C:CONSUME S:CONSUME-OK / C:CANCEL / C:PUBLISH content / S:RETURN / S:DELIVER content The server SHOULD discard stream messages on a priority basis if the queue size exceeds some configured limit. The server MUST implement at least 2 priority levels for stream messages, where priorities 0-4 and 5-9 are treated as two distinct levels. The server MAY implement up to 10 priority levels. The server MUST implement automatic acknowledgements on stream content. That is, as soon as a message is delivered to a client via a Deliver method, the server must remove it from the queue. This method requests a specific quality of service. The QoS can be specified for the current session or for all sessions on the connection. The particular properties and semantics of a qos method always depend on the content class semantics. Though the qos method could in principle apply to both peers, it is currently meaningful only for the server. The client can request that messages be sent in advance so that when the client finishes processing a message, the following message is already held locally, rather than needing to be sent within the session. Prefetching gives a performance improvement. This field specifies the prefetch window size in octets. May be set to zero, meaning "no specific limit". Note that other prefetch limits may still apply. Specifies a prefetch window in terms of whole messages. This field may be used in combination with the prefetch-size field; a message will only be sent in advance if both prefetch windows (and those at the session and connection level) allow it. Specifies a desired transfer rate in octets per second. This is usually determined by the application that uses the streaming data. A value of zero means "no limit", i.e. as rapidly as possible. The server MAY ignore the prefetch values and consume rates, depending on the type of stream and the ability of the server to queue and/or reply it. The server MAY drop low-priority messages in favour of high-priority messages. By default the QoS settings apply to the current session only. If this field is set, they are applied to the entire connection. This method tells the client that the requested QoS levels could be handled by the server. The requested QoS applies to all active consumers until a new QoS is defined. This method asks the server to start a "consumer", which is a transient request for messages from a specific queue. Consumers last as long as the session they were created on, or until the client cancels them. The server SHOULD support at least 16 consumers per queue, unless the queue was declared as private, and ideally, impose no limit except as defined by available resources. Streaming applications SHOULD use different sessions to select different streaming resolutions. AMQP makes no provision for filtering and/or transforming streams except on the basis of priority-based selective delivery of individual messages. The client MUST provide a valid access ticket giving "read" access rights to the realm for the queue from which the message will be consumed. Specifies the name of the queue to consume from. If the queue name is null, refers to the current queue for the session, which is the last declared queue. If the client did not previously declare a queue, and the queue name in this method is empty, the server MUST raise a connection exception with reply code 530 (not allowed). Specifies the identifier for the consumer. The consumer tag is local to a connection, so two clients can use the same consumer tags. If this field is empty the server will generate a unique tag. The tag MUST NOT refer to an existing consumer. If the client attempts to create two consumers with the same non-empty tag the server MUST raise a connection exception with reply code 530 (not allowed). Request exclusive consumer access, meaning only this consumer can access the queue. If the server cannot grant exclusive access to the queue when asked, - because there are other consumers active - it MUST raise a channel exception with return code 405 (resource locked). If set, the server will not respond to the method. The client should not wait for a reply method. If the server could not complete the method it will raise a channel or connection exception. A set of filters for the consume. The syntax and semantics of these filters depends on the providers implementation. This method provides the client with a consumer tag which it may use in methods that work with the consumer. Holds the consumer tag specified by the client or provided by the server. This method cancels a consumer. Since message delivery is asynchronous the client may continue to receive messages for a short while after cancelling a consumer. It may process or discard these as appropriate. This method publishes a message to a specific exchange. The message will be routed to queues as defined by the exchange configuration and distributed to any active consumers as appropriate. The client MUST provide a valid access ticket giving "passive" access rights to the realm for the exchange and "write" access rights to the realm for the queue to which the message will be published. Specifies the name of the exchange to publish to. The exchange name can be empty, meaning the default exchange. If the exchange name is specified, and that exchange does not exist, the server will raise a channel exception. The server MUST accept a blank exchange name to mean the default exchange. If the exchange was declared as an internal exchange, the server MUST respond with a reply code 403 (access refused) and raise a channel exception. The exchange MAY refuse stream content in which case it MUST respond with a reply code 540 (not implemented) and raise a channel exception. Specifies the routing key for the message. The routing key is used for routing messages depending on the exchange configuration. This flag tells the server how to react if the message cannot be routed to a queue. If this flag is set, the server will return an unroutable message with a Return method. If this flag is zero, the server silently drops the message. The server SHOULD implement the mandatory flag. This flag tells the server how to react if the message cannot be routed to a queue consumer immediately. If this flag is set, the server will return an undeliverable message with a Return method. If this flag is zero, the server will queue the message, but with no guarantee that it will ever be consumed. The server SHOULD implement the immediate flag. This method returns an undeliverable message that was published with the "immediate" flag set, or an unroutable message published with the "mandatory" flag set. The reply code and text provide information about the reason that the message was undeliverable. Specifies the name of the exchange that the message was originally published to. Specifies the routing key name specified when the message was published. This method delivers a message to the client, via a consumer. In the asynchronous message delivery model, the client starts a consumer using the Consume method, then the server responds with Deliver methods as and when messages arrive for that consumer. Specifies the name of the exchange that the message was originally published to. Specifies the name of the queue that the message came from. Note that a single session can start many consumers on different queues. Standard transactions provide so-called "1.5 phase commit". We can ensure that work is never lost, but there is a chance of confirmations being lost, so that messages may be resent. Applications that use standard transactions must be able to detect and ignore duplicate messages. tx = C:SELECT / C:COMMIT / C:ROLLBACK An client using standard transactions SHOULD be able to track all messages received within a reasonable period, and thus detect and reject duplicates of the same message. It SHOULD NOT pass these to the application layer. This method sets the session to use standard transactions. The client must use this method at least once on a session before using the Commit or Rollback methods. This method commits all messages published and acknowledged in the current transaction. A new transaction starts immediately after a commit. This method abandons all messages published and acknowledged in the current transaction. A new transaction starts immediately after a rollback. This class is part of the X-Open XA distributed transaction protocol support. It allows a session to be selected for use with distributed transactions and the transactional boundaries for work on that session to be demarcated. dtx-demarcation = C:SELECT *demarcation demarcation = C:START C:END Access-tickets are propagated with XA association methods with the aim of restricting which users are allowed to control which transactions. The server MAY restrict transaction association to a particular identity. Enabling XA transaction support on a session implies that the server MUST manage transactions demarcated by start-end blocks. That is to say that on this XA-enabled session, work undergone within transactional blocks is performed on behalf a transaction branch whereas work performed outside of transactional blocks is NOT transactional. This method sets the session to use distributed transactions. The client must use this method at least once on a session before using XA demarcation operations. This method is called when messages should be produced and consumed on behalf a transaction branch identified by xid. If the method is invoked in an improper context (see class grammar) then the server MUST raise a channel exception with reply code 503 (command invalid) If neither join nor resume is specified is specified and the transaction branch specified by xid has previously been seen then the server MUST raise a channel exception with reply code 530 (not allowed). If join and resume are specified then the server MUST raise a channel exception with reply code 503 (command invalid). Access-ticket granted by the server for a specific realm. The client MUST provide a valid access ticket giving "active" access rights to all the realms touched by this transaction. Specifies the xid of the transaction branch to be started. If xid is already known by the broker then the server MUST raise a channel exception with reply code 530 (not allowed). Indicate whether this is joining an already associated xid. Indicate that the start applies to joining a transaction previously seen. If the broker does not support join the server MUST raise a channel exception with reply code 540 (not implemented). Indicate that the start applies to resuming a suspended transaction branch specified. This confirms to the client that the transaction branch is started or specify the error condition. The value of this field may be one of the following constants: xa-ok: Normal execution. xa-rbrollback: The broker marked the transaction branch rollback-only for an unspecified reason. xa-rbtimeout: The work represented by this transaction branch took too long. This method is called when the work done on behalf a transaction branch finishes or needs to be suspended. If the method is invoked in an improper context (see class grammar) then the server MUST raise a channel exception with reply code 503 (command invalid). If suspend and fail are specified then the server MUST raise a channel exception with reply code 503 (command invalid). If an error occurs in ending the transaction branch then the server MUST raise a channel exception with reply code 541 (internal error). If neither fail nor suspend are specified then the portion of work has completed successfully. When a session is closed then the currently associated transaction branches MUST be marked rollback-only. Access-ticket granted by the server for a specific realm. The client MUST provide a valid access ticket giving "active" access rights to all the realms touched by this transaction. Specifies the xid of the transaction branch to be ended. The channel MUST be currently associated with the given xid (through an earlier start call with the same xid). If set, indicates that this portion of work has failed; otherwise this portion of work has completed successfully. An implementation MAY elect to roll a transaction back if this failure notification is recieved. Should an implementation elect to implement this behaviour, and this bit is set, then then the transaction branch SHOULD be marked as rollback-only and the end result SHOULD have the xa-rbrollback status set. Indicates that the transaction branch is temporarily suspended in an incomplete state. The transaction context is in a suspended state and must be resumed via the start method with resume specified. This method confirms to the client that the transaction branch is ended or specify the error condition. The value of this field may be one of the following constants: xa-ok: Normal execution. xa-rbrollback: The broker marked the transaction branch rollback-only for an unspecified reason. If an implementation chooses to implement rollback-on-failure behaviour, then this value should be selected if the dtx-demarcation.end.fail bit was set. xa-rbtimeout: The work represented by this transaction branch took too long. This class is part of the X-Open XA distributed transaction protocol support. It allows the transaction manager to coordinate transaction outcomes. dtx-coordination = *coordination coordination = command / outcome / recovery command = C:SET-TIMEOUT / C:GET-TIMEOUT outcome = one-phase-commit / one-phase-rollback / two-phase-commit / two-phase-rollback one-phase-commit = C:COMMIT one-phase-rollback = C:ROLLBACK two-phase-commit = C:PREPARE C:COMMIT two-phase-rollback = C:PREPARE C:ROLLBACK recovery = C:RECOVER *recovery-outcome recovery-outcome = one-phase-commit / one-phase-rollback / C:FORGET Access-tickets are propagated with XA demarcation methods with the aim of restricting which users are allowed to control which transactions. The server MAY restrict transaction coordination to a particular identity. Commit the work done on behalf a transaction branch. This method commits the work associated with xid. Any produced messages are made available and any consumed messages are discarded. If an error occurs in committing the transaction branch then the server MUST raise a channel exception with reply code 541 (internal error) If the method is invoked in an improper context (see class grammar) then the server MUST raise a channel exception with reply code 503 (command invalid) Access-ticket granted by the server for a specific realm. The client MUST provide a valid access ticket giving "active" access rights to all the realms touched by this transaction. Specifies the xid of the transaction branch to be committed. If xid is unknown (the transaction branch has not been started or has already been ended) then the server MUST raise a channel exception with reply code 404 (not found). If this method is called when xid is still associated with a session then the server MUST raise a channel exception with reply code 503 (command invalid) When set then one-phase commit optimization is used. This bit MUST be set if a commit is sent without a preceding prepare. This bit MUST NOT be set if a preceding prepare has been sent. This confirms to the client that the transaction branch is committed or specify the error condition. The value of this field may be one of the following constants: xa-ok: Normal execution xa-heurhaz: Due to some failure, the work done on behalf of the specified transaction branch may have been heuristically completed. xa-heurcom: Due to a heuristic decision, the work done on behalf of the specified transaction branch was committed. xa-heurrb: Due to a heuristic decision, the work done on behalf of the specified transaction branch was rolled back. xa-heurmix: Due to a heuristic decision, the work done on behalf of the specified transaction branch was partially committed and partially rolled back. xa-rbrollback: The broker marked the transaction branch rollback-only for an unspecified reason. xa-rbtimeout: The work represented by this transaction branch took too long. This method is called to forget about a heuristically completed transaction branch. If an error occurs in forgetting the transaction branch then the server MUST raise a channel exception with reply code 541 (internal error) If the method is invoked in an improper context (see class grammar) then the server MUST raise a channel exception with reply code 503 (command invalid) Access-ticket granted by the server for a specific realm. The client MUST provide a valid access ticket giving "active" access rights to all the realms touched by this transaction. Specifies the xid of the transaction branch to be forgotten. If xid is unknown (the transaction branch has not been started or has already been ended) then the server MUST raise a channel exception with reply code 404 (not found). If this method is called when xid is still associated with a session then the server MUST raise a channel exception with reply code 503 (command invalid). This method obtains the current transaction timeout value in seconds. If set-timeout was not used prior to invoking this method, the return value is the default timeout; otherwise, the value used in the previous set-timeout call is returned. If an error occurs in setting the transaction timeout then the server MUST raise a channel exception with reply code 541 (internal error). Specifies the xid of the transaction branch for getting the timeout. If xid is unknown (the transaction branch has not been started or has already been ended) then the server MUST raise a channel exception with reply code 404 (not found). Returns the value of the timeout last specified through set-timeout. The current transaction timeout value in seconds. This method prepares for commitment any message produced or consumed on behalf of xid. If an error occurs in preparing the transaction branch then the server MUST raise a channel exception with reply code 541 (internal error). The specified xid may or may not have been prepared. If the method is invoked in an improper context (see class grammar) then the server MUST raise a channel exception with reply code 503 (command invalid) Once this method successfully returns it is guaranteed that the transaction branch may be either committed or rolled back regardless of failures. The knowledge of xid cannot be erased before commit or rollback complete the branch. Access-ticket granted by the server for a specific realm. The client MUST provide a valid access ticket giving "active" access rights to all the realms touched by this transaction. Specifies the xid of the transaction branch that can be prepared. If xid is unknown (the transaction branch has not been started or has already been ended) then the server MUST raise a channel exception with reply code 404 (not found). If this method is called when xid is still associated with a session then the server MUST raise a channel exception with reply code 503 (command invalid) This method confirms to the client that the transaction branch is prepared or specify the error condition. The value of this field may be one of the following constants: xa-ok: Normal execution. xa-rdonly: The transaction branch was read-only and has been committed. xa-rbrollback: The broker marked the transaction branch rollback-only for an unspecified reason. xa-rbtimeout: The work represented by this transaction branch took too long. This method is called to obtain a list of transaction branches that are in a prepared or heuristically completed state. If an error occurs in recovering then the server MUST raise a channel exception with reply code 541 (internal error) If this endscan is used in conjunction with startscan then a single call starts and then ends a scan. If none of endscan and startscan are set then a recovery scan must already be started otherwise the server MUST raise a channel exception with reply code 503 (command invalid) Access-ticket granted by the server for a specific realm. The client MUST provide a valid access ticket giving "active" access rights to all the realms touched by this transaction. Indicates that recovery scan should start. If a recovery scan is already open, the effect is as if the recovery scan were ended and then restarted. Indicates that the recovery scan should end after returning the xids. Returns to the client a table with single item that is a sequence of transaction xids that are in a prepared or heuristically completed state. xids to be recovered (xids that are in a prepared or heuristically completed state). This method rolls back the work associated with xid. Any produced messages are discarded and any consumed messages are re-enqueued. If an error occurs in rolling back the transaction branch then the server MUST raise a channel exception with reply code 541 (internal error) If the method is invoked in an improper context (see class grammar) then the server MUST raise a channel exception with reply code 503 (command invalid) Access-ticket granted by the server for a specific realm. The client MUST provide a valid access ticket giving "active" access rights to all the realms touched by this transaction. Specifies the xid of the transaction branch that can be rolled back. If xid is unknown (the transaction branch has not been started or has already been ended) then the server MUST raise a channel exception with reply code 404 (not found). If this method is called when xid is still associated with a session then the server MUST raise a channel exception with reply code 503 (command invalid) This method confirms to the client that the transaction branch is rolled back or specify the error condition. The value of this field may be one of the following constants: xa-ok: Normal execution xa-heurhaz: Due to some failure, the work done on behalf of the specified transaction branch may have been heuristically completed. xa-heurcom: Due to a heuristic decision, the work done on behalf of the specified transaction branch was committed. xa-heurrb: Due to a heuristic decision, the work done on behalf of the specified transaction branch was rolled back. xa-heurmix: Due to a heuristic decision, the work done on behalf of the specified transaction branch was partially committed and partially rolled back. xa-rbrollback: The broker marked the transaction branch rollback-only for an unspecified reason. xa-rbtimeout: The work represented by this transaction branch took too long. Sets the specified transaction branch timeout value in seconds. If an error occurs in setting the transaction timeout then the server MUST raise a channel exception with reply code 541 (internal error) Once set, this timeout value is effective until this method is reinvoked with a different value. A value of zero resets the timeout value to the default value. Access-ticket granted by the server for a specific realm. The client MUST provide a valid access ticket giving "active" access rights to all the realms touched by this transaction. Specifies the xid of the transaction branch for setting the timeout. If xid is unknown (the transaction branch has not been started or has already been ended) then the server MUST raise a channel exception with reply code 404 (not found). The transaction timeout value in seconds. The tunnel methods are used to send blocks of binary data - which can be serialised AMQP methods or other protocol frames - between AMQP peers. tunnel = C:REQUEST / S:REQUEST This method tunnels a block of binary data, which can be an encoded AMQP method or other data. The binary data is sent as the content for the Tunnel.Request method. This field table holds arbitrary meta-data that the sender needs to pass to the recipient. The message class provides methods that support an industry-standard messaging model. message = C:QOS / C:CONSUME / C:CANCEL / C:TRANSFER [ S:REJECT ] / S:TRANSFER [ C:REJECT ] / C:GET [ S:EMPTY ] / C:RECOVER / C:OPEN / S:OPEN / C:APPEND / S:APPEND / C:CLOSE / S:CLOSE / C:CHECKPOINT / S:CHECKPOINT / C:RESUME S:OFFSET / S:RESUME C:OFFSET The server SHOULD respect the persistent property of messages and SHOULD make a best-effort to hold persistent mess ages on a reliable storage mechanism. Send a persistent message to queue, stop server, restart server and then verify whether message is still present. Assumes that queues are durable. Persistence without durable queues makes no sense. The server MUST NOT discard a persistent message in case of a queue overflow. Create a queue overflow situation with persistent messages and verify that messages do not get lost (presumably the server will write them to disk). The server MAY use the Session.Flow method to slow or stop a message publisher when necessary. Create a queue overflow situation with non-persistent messages and verify whether the server responds with Session.Flow or not. Repeat with persistent messages. The server MAY overflow non-persistent messages to persistent storage. The server MAY discard or dead-letter non-persistent messages on a priority basis if the queue size exceeds some configured limit. The server MUST implement at least 2 priority levels for messages, where priorities 0-4 and 5-9 are treated as two distinct levels. Send a number of priority 0 messages to a queue. Send one priority 9 message. Consume messages from the queue and verify that the first message received was priority 9. The server MAY implement up to 10 priority levels. Send a number of messages with mixed priorities to a queue, so that all priority values from 0 to 9 are exercised. A good scenario would be ten messages in low-to-high priority. Consume from queue and verify how many priority levels emerge. The server MUST deliver messages of the same priority in order irrespective of their individual persistence. Send a set of messages with the same priority but different persistence settings to a queue. Consume and verify that messages arrive in same order as originally published. The server MUST support automatic acknowledgements on messages, i.e. consumers with the no-ack field set to FALSE. Create a queue and a consumer using automatic acknowledgements. Publish a set of messages to the queue. Consume the messages and verify that all messages are received. The server MUST support explicit acknowledgements on messages, i.e. consumers with the no-ack field set to TRUE. Create a queue and a consumer using explicit acknowledgements. Publish a set of messages to the queue. Consume the messages but acknowledge only half of them. Disconnect and reconnect, and consume from the queue. Verify that the remaining messages are received. This method transfers a message between two peers. When a client uses this method to publish a message to a broker, the destination identifies a specific exchange. The message will then be routed to queues as defined by the exchange configuration and distributed to any active subscriptions when the transaction, if any, is committed. The client may initiate transfers from the broker by starting a subscription using the subscribe method and passing in a destination, then the broker responds with transfer methods to the specified destination as and when messages arrive in the subscribed queue. The client MUST provide a valid access ticket giving "passive" access rights to the realm for the exchange and "write" access rights to the realm for the queue to which the message will be published. Specifies the destination to which the message is to be transferred. The destination can be empty, meaning the default exchange or subscription. If the destination is specified, and that exchange or subscription does not exist, the peer must raise a channel exception. The server MUST accept a blank destination to mean the default exchange. If the destination refers to an internal exchange, the server MUST raise a channel exception with a reply code 403 (access refused). A destination MAY refuse message content in which case it MUST raise a channel exception with reply code 540 (not implemented). Indicates that the message transfers are un-processable in some way. A message may be rejected for a number of reasons. A server may reject a message if it is unroutable. A client may reject a message if it is invalid. When a client rejects a message, the server MUST deliver that message to the alternate-exchange on the queue from which it was delivered. If no alternate-exchange is defined for that queue the broker MAY discard the message. The recipient MUST have acquired a message in order to reject it. If the message is not acquired any reject MUST be ignored. Acquires previously transferred messages for consumption. The acquired ids (if any) are sent via message.acquired. One of: - any (0): acquire any available messages for consumption - all (1): only acquire messages if all are available for consumption Identifies a set of previously transferred messages now available for consumption. Release previously transferred messages that have been acquired for consumption (whether implicitly or explicitly). Released messages will be available for acquisition by other consumers. The order of released messages may be lost. This method asks the server to start a "subscription", which is a transient request for messages from a specific queue. Subscriptions last as long as the session they were created on, or until the client cancels them. The server SHOULD support at least 16 subscriptions per queue, and ideally, impose no limit except as defined by available resources. Create a queue and create subscriptions on that queue until the server closes the connection. Verify that the number of subscriptions created was at least sixteen and report the total number. The client MUST provide a valid access ticket giving "read" access rights to the realm for the subscribed queue. Attempt to create a subscription with an invalid (non-zero) access ticket. Specifies the name of the subscribed queue. Specifies the destination for the subscription. The destination is local to a connection, so two clients can use the same destination. The client MUST NOT specify a destination that refers to an existing subscription. Attempt to create two subscriptions with the same non-empty destination. The destination is valid only within the session from which the subscription was created. i.e. A client MUST NOT create a subscription in one session and then use it in another. Attempt to create a subscription in one session, then use in another session, in which subscriptions have also been created (to test that the server uses unique destinations). If the no-local field is set the server will not send messages to the connection that published them. The default confirm-mode for this subscription. The default acquire-mode for this subscription. Request exclusive subscription access, meaning only this subscription can access the queue. The client MUST NOT gain exclusive access to a queue that already has active subscriptions. Open two connections to a server, and in one connection create a shared (non-exclusive) queue and then subscribe to the queue. In the second connection attempt to subscribe to the same queue using the exclusive option. A set of filters for the subscription. The syntax and semantics of these filters depends on the providers implementation. This method cancels a consumer. This does not affect already delivered messages, but it does mean the server will not send any more messages for that consumer. The client may receive an arbitrary number of messages in between sending the cancel method and receiving the notification of completion of the cancel command. If the queue does not exist the server MUST ignore the cancel method, so long as the consumer tag is valid for that session. This method provides a direct access to the messages in a queue using a synchronous dialogue that is designed for specific types of application where synchronous functionality is more important than performance. The client MUST provide a valid access ticket giving "read" access rights to the realm for the queue from which the message will be consumed. Specifies the name of the queue to consume from. If the queue name is null, refers to the current queue for the session, which is the last declared queue. If the client did not previously declare a queue, and the queue name in this method is empty, the server MUST raise a connection exception with reply code 530 (not allowed). On normal completion of the get request (i.e. a response of ok). A message will be transferred to the supplied destination. This method asks the broker to redeliver all unacknowledged messages on a specified session. Zero or more messages may be redelivered. This method is only allowed on non-transacted sessions. The server MUST set the redelivered flag on all messages that are resent. The server MUST raise a channel exception if this is called on a transacted session. If this field is zero, the message will be redelivered to the original recipient. If this bit is 1, the server will attempt to requeue the message, potentially then delivering it to an alternative subscriber. This method creates a reference. A references provides a means to send a message body into a temporary area at the recipient end and then deliver the message by referring to this temporary area. This is how the protocol handles large message transfers. The scope of a ref is defined to be between calls to open (or resume) and close. Between these points it is valid for a ref to be used from any content data type, and so the receiver must hold onto its contents. Should the session be closed when a ref is still in scope, the receiver may discard its contents (unless it is checkpointed). A ref that is in scope is considered open. The recipient MUST generate an error if the reference is currently open (in scope). This method signals the recipient that no more data will be appended to the reference. A recipient MUST NOT acknowledge a message until its reference is closed (not in scope). The recipient MUST generate an error if the reference was not previously open (in scope). This method appends data to a reference. The recipient MUST generate an error if the reference is not open (not in scope). This method provides a means to checkpoint large message transfer. The sender may ask the recipient to checkpoint the contents of a reference using the supplied identifier. The sender may then resume the transfer at a later point. It is at the discretion of the recipient how much data to save with the checkpoint, and the sender MUST honour the offset returned by the resume method. The recipient MUST generate an error if the reference is not open (not in scope). This is the checkpoint identifier. This is an arbitrary string chosen by the sender. For checkpointing to work correctly the sender must use the same checkpoint identifier when resuming the message. A good choice for the checkpoint identifier would be the SHA1 hash of the message properties data (including the original filename, revised time, etc.). This method resumes a reference from the last checkpoint. A reference is considered to be open (in scope) after a resume even though it will not have been opened via the open method during this session. The recipient MUST generate an error if the reference is currently open (in scope). This method requests a specific quality of service. The QoS can be specified for the current session or for all sessions on the connection. The particular properties and semantics of a qos method always depend on the content class semantics. Though the qos method could in principle apply to both peers, it is currently meaningful only for the server. The client can request that messages be sent in advance so that when the client finishes processing a message, the following message is already held locally, rather than needing to be sent within the session. Prefetching gives a performance improvement. This field specifies the prefetch window size in octets. The server will send a message in advance if it is equal to or smaller in size than the available prefetch size (and also falls into other prefetch limits). May be set to zero, meaning "no specific limit", although other prefetch limits may still apply. The prefetch-size is ignored if the no-ack option is set. The server MUST ignore this setting when the client is not processing any messages - i.e. the prefetch size does not limit the transfer of single messages to a client, only the sending in advance of more messages while the client still has one or more unacknowledged messages. Define a QoS prefetch-size limit and send a single message that exceeds that limit. Verify that the message arrives correctly. Specifies a prefetch window in terms of whole messages. This field may be used in combination with the prefetch-size field; a message will only be sent in advance if both prefetch windows (and those at the session and connection level) allow it. The prefetch-count is ignored if the no-ack option is set. The server may send less data in advance than allowed by the client's specified prefetch windows but it MUST NOT send more. Define a QoS prefetch-size limit and a prefetch-count limit greater than one. Send multiple messages that exceed the prefetch size. Verify that no more than one message arrives at once. By default the QoS settings apply to the current session only. If this field is set, they are applied to the entire connection. Sets the mode of flow control used for a given destination. With credit based flow control, the sender of messages continually maintains its current credit balance with the recipient. The credit balance consists of two values, a message count, and a byte count. Whenever message data is sent, both counts must be decremented. If either value reaches zero, the flow of message data must stop. Additional credit is received via the message.flow method. The sender MUST NOT send partial framesets. This means that if there is not enough byte credit available to send a complete message, the sender must either wait or use chunked transfer to send the first part of the message data in a complete frameset. Window based flow control is identical to credit based flow control, however message acknowledgment implicitly grants a single unit of message credit, and the size of the message in byte credits for each acknowledged message. The byte count is decremented by the payload size of each transmitted frame with segment type header or body appearing within a message.transfer command. Note that the payload size is the frame size less the frame header size (frame-size - 12). Mode switching may only occur if both outstanding credit balances are zero. There are three ways for a recipient of messages to be sure that the sender 's credit balance is zero: 1) The recipient may send a message.stop command to the sender. When the recipient receives confirmation of completion for the message.stop command, it knows that the sender's credit is zero. 2) The recipient may perform the same steps described in (1) with the message.flush command substituted for the message.stop command. 3) Immediately after receiving a message.consume, the credit for that destination defaults to zero. One of: - credit (0): choose credit based flow control - window (1): choose window based flow control This method controls the flow of message data to a given destination. It is used by the recipient of messages to dynamically match the incoming rate of message flow to its processing or forwarding capacity. Upon receipt of this method, the sender must add "value" number of the specified unit to the available credit balance for the specified destination. A value of (0xFFFFFFFF) indicates an infinite amount of credit. This disables any limit for the given unit until the credit balance is zeroed with message.stop or message.flush. Specifies the unit of credit balance. One of: - message (0) - byte (1) A value of (0xFFFFFFFF) indicates an infinite amount of credit. Forces the sender to exhaust his credit supply. The sender's credit will always be zero when this method completes. The message does not complete until all the message transfers occur. On receipt of this method, a producer of messages MUST set his credit to zero for the given destination. This obeys the generic semantics of command completion, i.e. when confirmation is issued credit MUST be zero and no further messages will be sent until such a time as further credit is received. Signals that a queue does not contain any messages; usually sent in response to the get method. Returns the data offset into a reference body; usually sent in response to resume method. Offset in bytes into message body data. This is a utility class for querying and exchange about its bindings to queues. This method is used to request information on the bindings to a particular exchange. The client MUST provide a valid access ticket giving "passive" access rights to the exchange's access realm. The name of the exchange for which binding information is being requested. If not specified explicitly the default exchange is implied. If populated then determine whether the given queue is bound to the exchange. If populated defines the routing key of the binding of interest, if not populated the request will ignore the routing key on bindings when searching for a match. If populated defines the arguments of the binding of interest if not populated the request will ignore the arguments on bindings when searching for a match This method is used in response to a query and conveys information on the bindings to a particular exchange. If set, the exchange for which information was requested is not known. If set, the queue specified is not known. A bit which if set indicates that no binding was found from the specified exchange to the specified queue. A bit which if set indicates that no binding was found from the specified exchange with the specified routing key. A bit which if set indicates that no binding was found from the specified exchange with the specified arguments. This class allows for efficiently communicating information about completion of processing. Requests notification of all currently complete commands. The server should issue an execution.complete at the earliest possible opportunity. Signals completion of all commands such that command-id <= cumulative-execution-mark, or command-id is in the set defined by ranged-execution-set. This can be sent spontaneously, in response to a execution.flush, or as requested by use of the sync bit. In order to ensure a canonical wire representation, the value cumulative-execution-mark + 1 must not be covered by the ranged-execution-set. The low-water mark for executed command-ids. All ids below this mark have been executed; above this mark, there are gaps containing unexecuted command ids (i.e. discontinuous). By definition, the first id above this mark (if it exists) is an unexecuted command-id. This set contains a sequence of discontinuous executed command-ids above the low-water mark (i.e. above the first gap of unexecuted command ids). This command may be used when it is desirable to send a command that has no effect. This situation can occur after issuing a number of commands with sync=False. If, after issuing the commands, a peer wishes to receive confirmation of completion, the peer can do so by sending an execution.noop command with sync=True. This method carries data resulting from the execution of a command. Requests notification (via execution.complete) when all commands issued prior to the sync control are complete. If the recipient of this control has already notified the sender that said commands are complete, it may safely ignore the control.