yargh, hooks

One of the goals of the CORE project is hackability. In that spirit, you can now define hooks under the experiment menu. Hooks are optional shell scripts that run at the specified session state. (If you previously used the global experiment script, this is the same thing; the experiment script now becomes a runtime hook.) The hook script runs on the host as root, is not associated with any particular node, and is saved in the imn file.

 Below the hook configuration dialog is shown. You select the session state from a drop-down menu.

Here are the session states and their meanings:

1. Definition - used by the GUI to tell the backend to clear any state.
2. Configuration - when the user presses the Start button, node, link, and other configuration data is sent to the backend.
3. Instantiation - after configuration data has been sent, just before the nodes are created.
4. Runtime - all nodes and networks have been built and are running.
5. Datacollect - the user has pressed the Stop button; a good time to collect log files before nodes are shut down.
6. Shutdown - all nodes and networks have been shut down and destroyed.

Another related feature that has been added is a /tmp/pycore.nnnnn/state file. As a session changes states, it will write the current state number and name into this file. This would enable an external program or script to monitor that file.