Using JavaTM Technology and XML for Astronomical Instrument Control
Using JavaTM Technology and XML for Astronomical Instrument Control
From: http://industry.java.sun.com/javaone/99/event/0,1768,530,00.html"
See also: http://industry.java.sun.com/javaone/99/
Session Information:
Using JavaTM Technology and XML
for Astronomical Instrument
Control
Speakers
Troy J. Ames
Senior Software Engineer
NASA Goddard Space Flight Center
Lisa Koons
Project Leader
AppNet, Inc.
Craig E. Warsaw
Senior Systems Architect
AppNet, Inc.
Abstract
NASA Goddard Space Flight Center and
AppNet, Inc. have developed an astronomical
instrument remote control architecture that
combines the platform-independent
processing capabilities of the JavaTM
platform with the power of Extensible
Markup Language (XML) to express
hierarchical data in an equally
platform-independent, as well as human
readable manner. This architecture is
implemented using a variety of XML support
tools and APIs written in the Java
programming language.
By creating our own Instrument Markup
Language (IML), we have expressed an
instrument's control commands and
responses, data streams, message formats,
communication mechanisms, and
documentation in an extremely flexible XML
format. Sun's XML Library and the Simple
API for XML (SAX) parse the XML files. Java
programming language objects are
instantiated corresponding to chunks of XML
markup (elements). Code generation and
(where real-time constraints permit)
interpretation enable developers and
hardware engineers to make last-minute
changes to IML text files which are then
automatically reflected in the application.
Project Swing GUI components are
automatically instantiated based on
information in the instrument description
files. Viewers based on the JTree and JTable
components enable traversing and editing
the complex instrument description files.
IML is based on a custom Document Type
Definition (DTD) which enables the parser to
validate the input XML files, thereby
guaranteeing the instrument description is
complete and correct according to the rules
we have defined. The IML DTD can be
extended to cover new instruments or to
accommodate changing constraints of
existing instruments, often without
requiring changes to previously written
instrument descriptions.
Our initial implementation is targeted for an
airborne observatory aboard a Boeing 747, to
be commissioned in 2001. Although our
architecture and implementation is focused
on infrared astronomy, most of the
techniques employed have much wider
applicability. Our approach defines a
flexible methodology by which a complex
Java technology-based application is created
and modified primarily by textual
descriptions (XML documents). Future work
includes the development of other XML
dialects including (1) PAML (Pipeline
Algorithm Markup Language) for data
manipulation and (2) IGS (Instrument GUI
Stylesheet, based on XSL) for customizing
GUI components and GUI layout
For more information refer to NASA Goddard
Instrument Markup Language web site:
http://pioneer.gsfc.nasa.gov/public/iml/
Schedule
Wednesday - June 16th
12:15 pm - 1:15 pm
Ballroom
The Sheraton Palace Hotel