Modularize Persist

[kirangadhave]

Persist has separation for core and output modules. However, the API is not defined, and the separation is not completely clean.

We should do this first so individual modules can be created independently and new features can be added.

The basic idea is:

• Output adapter converts interaction to JSON.
• Core module saves/loads provenance graph with the JSON
• Core module updates dataframe with provenance graph
  The output adapter uses a dataframe to update output.

Core

The core is a widget with four components:
- Toolbar
- Trrack Graph
- Dataframe manager
- <slot>

Define a set of standard data operations we want to support

• selections
• filters
• columns
• etc.

execute() - will apply operations and update df
update() - notify the updated df to output adapter
save() - will save the latest graph
load() - will load the latest graph

Output Adapter

Output adapter is a widget that renders in the <slot>.

• Should output one of the defined operations in JSON format to respond to interactions. Can compose multiple in one for complex interactions.
• Take the updated dataframe (any other info?) and update the view if needed.