multicore ideas

Core terms:

Try not to re-use terms that are used in Automerge in Metamerge, as it just gets confusing.

Automerge terms:

• Document - a set of changes by a number of actors that has been merged together
• Actor - an owner of a sequence of changes
• Change - a mutation owned by an actor, with dependencies on prior changes
• Sequence - a stream of changes by an actor

Metamerge terms:

• View - defined by a set of cursors, which identify changes to apply to generate a document
• Discoverable View - an advertised view that people can join to either watch, collaborate on, or fork
• Non-discoverable View - a non-advertised view, useful for storing snapshots, viewing history, triaging changes, etc. in the user interface
• Collaborator - the person controlling an actor in the set of cursors used to define a view
• Fork - a new discoverable view based on a previous discoverable view with a set of forked cursors
• Cursor - identifies a position in sequence of changes by an actor. A cursor can be set to "follow" the latest changes as they arrive, or be set to a specific sequence number (for use in snapshots and forks).
• "Ghost" cursor - when a fork happens, we may want to hold a reference (cursor) to a previous change by an actor in the old discoverable view before that collaborator has created any new changes in the forked discoverable view. When the collaborator creates a change (eg. creates a new actor) in the new discoverable view, the "ghost" cursor can be replaced with a new cursor that points to the new change that has a dependency on the old change

Proposed operations:

• Create a discoverable view
• Create an actor
• Create a cursor
• Add a cursor to a discoverable view
• Add a change to an actor's sequence
• Tell a cursor to follow the latest change in an actor's sequence
• Pin a cursor at a specific change in an actor's sequence
• Create a non-discoverable view
• Get the document for a view
• Be notified when the document for a view changes
• Fork a view to create a new view (with ghost cursors)
• Collaborator writes a new change to a forked view with a ghost cursor and a new actor and cursor is created

Questions:

• Should non-owner collaborators be allowed to modify the cursors on a discoverable view?