Overview : About AWIPS
AWIPS (formerly know as AWIPS II or AWIPS2) is a weather forecasting display and analysis package developed by the National Weather Service and Raytheon. AWIPS is a Java application consisting of a data-rendering client (CAVE, which runs on Red Hat/CentOS Linux and Mac OS X) and a backend data server (EDEX, which runs only on 64-bit CentOS or RedHat)
AWIPS takes a unified approach to data ingest, and most data types follow a standard path through the system, starting with an LDM client requesting data from Unidata’s IDD, which are then decoded and stored as HDF5 and PostgreSQL/PostGIS metadata. Unidata supports two visualization frameworks for rendering AWIPS data: 1) CAVE, 2) the Python Data Access Framework (python-awips).
License
Unidata AWIPS source code and binaries (RPMs) are considered to be in the public domain, meaning there are no restrictions on any download, modification, or distribution in any form (original or modified). Unidata AWIPS contains no proprietery content and is therefore not subject to export controls as stated in the Master Rights licensing file.
Software Components
The primary AWIPS application for data ingest, processing, and storage is the Environmental Data EXchange (EDEX) server; the primary AWIPS application for visualization/data manipulation is the Common AWIPS Visualization Environment (CAVE) client, which is typically installed on a workstation separate from other AWIPS components.
In addition to programs developed specifically for AWIPS, AWIPS uses several commercial off-the-shelf (COTS) and Free or Open Source software (FOSS) products to assist in its operation. The following components, working together and communicating, compose the entire AWIPS system.
EDEX
The main server for AWIPS. Qpid sends alerts to EDEX when data stored by the LDM is ready for processing. These Qpid messages include file header information which allows EDEX to determine the appropriate data decoder to use. The default ingest server (simply named ingest) handles all data ingest other than grib messages, which are processed by a separate ingestGrib server. After decoding, EDEX writes metadata to the database via Postgres and saves the processed data in HDF5 via PyPIES. A third EDEX server, request, feeds requested data to CAVE clients. EDEX ingest and request servers are started and stopped with the commands edex start and edex stop, which runs the system script /etc/rc.d/init.d/edex_camel
CAVE
Common AWIPS Visualization Environment. The data rendering and visualization tool for AWIPS. CAVE contains of a number of different data display configurations called perspectives. Perspectives used in operational forecasting environments include D2D (Display Two-Dimensional), GFE (Graphical Forecast Editor), and NCP (National Centers Perspective). CAVE is started with the command /awips2/cave/cave.sh or cave.sh
Alertviz
Alertviz is a modernized version of an AWIPS I application, designed to present various notifications, error messages, and alarms to the user (forecaster). AlertViz can be executed either independently or from CAVE itself. In the Unidata CAVE client, Alertviz is run within CAVE and is not required to be run separately. The toolbar is also hidden from view and is accessed by right-click on the desktop taskbar icon.
LDM
http://www.unidata.ucar.edu/software/ldm/
The LDM (Local Data Manager), developed and supported by Unidata, is a suite of client and server programs designed for data distribution, and is the fundamental component comprising the Unidata Internet Data Distribution (IDD) system. In AWIPS, the LDM provides data feeds for grids, surface observations, upper-air profiles, satellite and radar imagery and various other meteorological datasets. The LDM writes data directly to file and alerts EDEX via Qpid when a file is available for processing. The LDM is started and stopped with the commands edex start and edex stop, which runs the commands service edex_ldm start and service edex_ldm stop
edexBridge
edexBridge, invoked in the LDM configuration file /awips2/ldm/etc/ldmd.conf, is used by the LDM to post “data available” messaged to Qpid, which alerts the EDEX Ingest server that a file is ready for processing.
Qpid
Apache Qpid, the Queue Processor Interface Daemon, is the messaging system used by AWIPS to facilitate communication between services. When the LDM receives a data file to be processed, it employs edexBridge to send EDEX ingest servers a message via Qpid. When EDEX has finished decoding the file, it sends CAVE a message via Qpid that data are available for display or further processing. Qpid is started and stopped by edex start and edex stop, and is controlled by the system script /etc/rc.d/init.d/qpidd
PostgreSQL
PostgreSQL, known simply as Postgres, is a relational database management system (DBMS) which handles the storage and retrieval of metadata, database tables and some decoded data. The storage and reading of EDEX metadata is handled by the Postgres DBMS. Users may query the metadata tables by using the termainal-based front-end for Postgres called psql. Postgres is started and stopped by edex start and edex stop, and is controlled by the system script /etc/rc.d/init.d/edex_postgres
HDF5
Hierarchical Data Format (v.5) is the primary data storage format used by AWIPS for processed grids, satellite and radar imagery and other products. Similar to netCDF, developed and supported by Unidata, HDF5 supports multiple types of data within a single file. For example, a single HDF5 file of radar data may contain multiple volume scans of base reflectivity and base velocity as well as derived products such as composite reflectivity. The file may also contain data from multiple radars. HDF5 is stored in /awips2/edex/data/hdf5/
PyPIES (httpd-pypies)
PyPIES, Python Process Isolated Enhanced Storage, was created for AWIPS to isolate the management of HDF5 Processed Data Storage from the EDEX processes. PyPIES manages access, i.e., reads and writes, of data in the HDF5 files. In a sense, PyPIES provides functionality similar to a DBMS (i.e PostgreSQL for metadata); all data being written to an HDF5 file is sent to PyPIES, and requests for data stored in HDF5 are processed by PyPIES.
PyPIES is implemented in two parts: 1. The PyPIES manager is a Python application that runs as part of an Apache HTTP server, and handles requests to store and retrieve data. 2. The PyPIES logger is a Python process that coordinates logging. PyPIES is started and stopped by edex start and edex stop, and is controlled by the system script /etc/rc.d/init.d/https-pypies