Support saving and restoring of terminal state

Hi everyone,

With xterm.js maturing, I think a great feature to expand the range of applications xterm.js could be useful for would be the formalization of a headless mode. What do I mean? Well basically, for the ability to:

1. Run a client without a renderer.
2. Communicate to a client with a renderer the state of a headless client and vice versa.

Right now, the only way to reliably “set” the state of a client is to replay the set of all commands that produced that editor’s state (at least via the public API). However, you could easily imagine wanting to do things like:

• scrubbing back and forth through a terminal’s history
• running a terminal in the cloud that you intermittently connect to via the client
• (my use case) having multiple users have literally the same terminal with the ability to come and go

A lot of this is basically almost already possible if you just serialize term.rows and assorted state flags, but the adoption of a formal API would help a lot. It may also help improve the testability and robustness of the core library, too!

Thoughts? Vincent

[ebertmi]

Any updates on this one? I am also having a similar use case.

[Tyriar]

Some more things we probably want to serialize:

• All the options
• The alt buffer

@parisk I was thinking a getState or serialize function would perform the serialization at that point, we could put everything into some json object and return the json pretty easily. All the state you’re mentioning may not be owned by the Terminal object, for example the buffer lives in CircularList. It would make more sense to tell the CircularList to serialize itself on a call to the function. Something like this:

Terminal.prototype.getState() {
  const state = {};
  // this.serializableComponents is an ISerializable[] which ensures they
  // have componentKey/getState()
  this.serializableComponents.forEach(c => {
    state[c.componentKey] = c.getState();
  });
  // TODO: Add anything owned by Terminal to state
  // ...
  return state;
}

// Restore using something like this which would do the reverse
Terminal.prototype.restoreState(state: Object): void;

// A static method that returns a Terminal might be better:
Terminal.restoreTerminal(state: Object): Terminal;