Slicer3:Launcher

Requirements

One of the projects at the 2007 AHM was a review of the Slicer3 launcher.

A summary of the conclusions is:

• for the shared library plugins to work the application needs to be built in shared mode (not static)
• this means that shared library paths must be set before the application is started
• a launcher can do this -- it is a small program that does not have shared library dependencies that sets paths and then executes the main application

Some other nice things the launcher can do:

• since the launcher starts quickly, it can put up a splash screen for user feedback while the main program is loading
• the launcher can catch abnormal termination conditions of the main program and provide user feedback
• the launcher can run arbitrary programs with the exact environment used by the main application (for example, you can run a debugger on Slicer3-real with all the shared libraries resolved, or you can run a shell from which you can run ldd to see the dependencies for a library).

Implementation

The group decided to adopt the approach used by slicer2, which is based on the starkit/starpack technology for building small, stand alone programs that include a full tcl/tk interpreter.

The code and documentation are in Slicer3/Utilities/Launcher. The actual startup script is Slicer3/launch.tcl.in, which gets configured by cmake into Slicer3-build/lib/launch.tcl.

Usage for the launcher is:

Slicer3 [--launch <program>] [Options...]
where:
  <program> is a program that should be run using the environment settings defined by the launcher (defaults to Slicer3-real)
  [Options...] are any options to send to <program>