Repository: flutter
Issue: Should have finer grained linkability
Labels: framework,f: routes,P3,team-framework,triaged-framework

Ideas from earlier:
# Linkability

This file has ideas only, so far. Comments welcome.
## Scenarios
- soduku app:
  - want to share the board layout, but not my progress so far
  - want to transfer my progress to another device
- a wikipedia-like app:
  - follow links to other topics
  - have links from other apps (e.g. search) to a specific subsection of a topic
- an instant-messenger app:
  - bookmark specific group conversations
- a social network app:
  - link to specific posts
  - link to social network constructs like user lists (twitter), communities (g+), walls (fb), users…
- an IDE
  - want to save a particular state of open windows, maybe to share with other developers
- Navigation app
  - want to link to different modes of the app: nav mode, search page, personal profile, settings, etc
  - want to link to specific points of interest, either public (restaurant) or private (home, work, saved locations)
  - want to link to a specific map location, zoom level, direction, angle, time of day (for shadows), route (for navigation)
  - want to link to a destination in nav mode (without a route)
- Podcast app
  - want to link to a specific view (e.g. in doggcatcher, feeds, audio, video, news...)
  - want to link to a specific podcast (maybe independently of the app)
  - want to link to a specific time in a specific episode of a specific podcast
  - save ui state (e.g. size of ui area vs podcast list in doggcatcher, scroll position in a list, specific settings window being on top of specific tab at a specific scroll position, etc)
- News app
  - categories
  - articles
  - sets of categories
  - sets of categories + a selected category + a scroll position
  - app sections (e.g. Newsstand’s Explore vs Read Now vs My Library)
  - specific settings in the settings section of the app
- Code Review Tools
  - a specific code review
  - a specific file in a specific code review
  - code review plus scroll position
  - specific comment
  - the state of the UI, such as which changes are visible, which comments are expanded, sort settings, filter settings, etc; whether the settings window is open, what tab it’s open to, what field is focused…
## UI
- Sharing current state to another device using NFC: just put the phones together, the active app(s?) serialise their state to a “URL” and that is sent to the other device
- App exposes a “permalink” or “get link” UI that exposes a string you can Share (a la Android’s Share intent) or copy and paste.
- An accessibility tree should expose the URL of each part of the app so that a user with an accessibility tool can bookmark a particular location in the app to jump to it later.
## Thoughts
- Seems like you link to three kinds of things:
  - different in-app concepts, which might be shared across apps
    - specific posts in a social network
    - users
    - particular game board starting configurations, game levels
    - wikipedia topics
    - search results
    - POIs in a map
    - videos on Vimeo, YouTube, etc
    - a code review / CL / pull request
    - a comment on a code review
    - a file in a code review
    - a comment in a blog post
    - telephone numbers
    - lat/long coordinates
    - podcasts
  - different top-level parts of the app (shallow state)
    - e.g. in Facebook, linking to the stream; in G+, linking to the communities landing page, etc
    - in a maps app, the mode (satellite, navigation, etc)
  - deep state
    - the current state of a particular game board, e.g. all the piece positions in chess, all the current choices in soduku...
    - what windows are open, what field is focused, what widgets are expanded, the precise view of a 3D map, etc
    - subsection of a topic in wikipedia (scroll position)
- Since almost every app is going to have app-specific items, we need to make the item space trivially extensible (no registry, no fixed vocabulary). This means that common items (e.g. lat/long coordinates, podcasts) will probably evolve conventions organically within communities rather than in a centralised fashion
- We don’t have to use URLs as they are known today, but doing so would leverage the existing infrastructure which might be valuable
## Ideas
- Two kinds of URLs: application state, and “things”.
- Application state URLs consist of an identifier for the app, plus a blob of data for how to open the app
- Thing URLs identify a thing, either by string name, opaque identifier, or more structured data (e.g. two comma-separated floating point numbers for lat/long).
- Thing URLs have a label saying what they are, e.g. “poi” or “geo” or “cl-comment” or something.
- Maybe “apps” are just things, and going to an app is like picking that app thing from the system app, the same way you’d pick a post from a social network app.