JupyterServer: opening content in other extensions

[oliver-sanders]

The Cylc UI Server allows browsing workflows, cycles, tasks and whatnot.

We can open log files, but, the Cylc app lacks tooling to inspect and analyse task output. This is where tools like Jupyter Lab come into it.

We should make it easier to open resources associated with Cylc (e.g. data created by tasks) in other server extensions (e.g. Jupyter Lab).

E.G. We could have a button which opens a task's work directory in Jupyter Lab.

This is actually kinda possible, Jupyter Lab has a URL argument to open the server at a specific location, however, because this is done in the URL you get a new Lab instance every time you follow the link. Ideally we would like the ability to open tabs in an existing Lab session from within Cylc.

There are two ways to go about this problem:

1. Send the message down into the server, and from the server back up to the Lab app.
2. Use LocalStorage to send the message sideways to active Lap app sessions.

Ideally Jupyter Server would provide an interface for doing this so that all extensions can communicate in this way. Have a chat with the Jupyter folks and see what they think.