Allow a session to persist beyond its kernel's lifetime.

[jasongrout]

This allows sessions to persist beyond a kernel’s lifetime, allowing us to have a more persistent reference to shared kernel that can die, be restarted, and be changed.

This is somewhat still a work-in-progress. I'm still experimenting with a frontend that can take advantage of such persistent sessions.

[kevin-bates]

Hi @jasongrout - these server-side changes look consistent with what you were describing at last week's open studio. I'll be happy to review once ready.

[vidartf]

Just for reference, what will we be able to do after this change, that isn't currently possible (or, what will become easier)?

[jasongrout]

Just for reference, what will we be able to do after this change, that isn't currently possible (or, what will become easier)?

It will mean that a session can exist independent of its kernel, i.e., if a kernel is shut down, the session still lives. Another consequence should be that a session can be created without a kernel, and then a kernel started later, though I haven't tried that yet.