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8 Tool Interoperability

TOPCAT makes use of a tool interoperability protocol called PLASTIC (PLatform for AStronomical InterConnection). This can be used to exchange messages between TOPCAT and other PLASTIC-aware tools such as Aladin, VisIVO and STILTS. The messages which are relevant to TOPCAT are things like "load this table" or "highlight this set of rows".

The communication works by all tools communicating with a central 'hub' process, so a hub must be running in order for the messaging to operate. If a hub is running when TOPCAT starts, it will connect to it automatically, listening for messages sent by other tools. If not, you can start a hub from the Interop menu in the Control Window or start one externally and then connect to it using that menu. Other tools will have their own policy for connecting to the hub, but in general it's best to start a hub first before starting up the tools which you want to talk to it. Currently, the usual way to run a hub is to start up the AstroGrid Workbench which provides a hub service. You can run Workbench using Java WebStart from http://software.astrogrid.org/userdocs/workbench.html.

The interoperability has two aspects to it: on the one hand TOPCAT can send messages to other applications which cause them to do things, and on the other hand TOPCAT can receive and act on such messages sent by other applications. These are described separately in the subsections below. There is also a section on the Interop menu in the Control Window used to control hub operations.

The PLASTIC protocol itself is still under development and may undergo changes in the future. It is therefore possible that there may be version compatibility issues which arise between TOPCAT and other PLASTIC-compliant tools and services, so these facilities should probably be regarded as experimental at present.


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TOPCAT - Tool for OPerations on Catalogues And Tables
Starlink User Note 253
TOPCAT web page: http://www.starlink.ac.uk/topcat/
Author email: m.b.taylor@bristol.ac.uk