Concept component hiding (http) networking stack

[pocmo]

Currently our component code uses HttpUrlConnection - mostly because that is offered by the Android System and doesn't require any third-party dependency.

However HttpUrlConnection has its issues:

• The API doesn't really separate requests/responses and makes it unpredictable at what point it actually performs a request. It's not pleasant to use.
• It only has a synchronous API so you almost always want to wrap it
• It may have different underlying implementations based on Android version / flavor.

Other options are:

• OkHttp is the de-facto standard used in Android apps. A bunch of other libraries use it internally. HttpUrlConnection is actually backed by it on newer versions of Android.
• Necko - There has been an ongoing discussion on whether Necko can/should/will be turned into something that can live outside of Firefox. This was mostly interesting for Rust components. However with a nice Kotlin layer on top that this would be interesting for app code as well.
• WebExecutor API in GeckoView: The GeckoView team is working on an API that allows apps using GV to send arbitrary http requests.

The reality is:

• Apps may have different requirements.
  • An app already using GV may want to send (some) http requests through it as well (Favicons?).
  • An app already using okHttp may want to do that for component code too (because it allows them to use debugging tools like stetho).
  • An app optimized for size may want to continue using HttpUrlConnection (e.g. Rocket)
  • Apps not using GV definitely do not want to add it just for the http client.
• Android Components do not want to force any (third-party) dependencies on apps if not absolutely necessary.

So should we:

• Add a concept component with the necessary interfaces for doing http requests (something like fetch; concept-fetch?)

• Provide components implementing the concept component. At least HttpUrlConnection and GeckoView?

• Modify components doing http requests to depend on the concept component and let apps inject a dependency implementing it.

┆Issue is synchronized with this Jira Task

[pocmo]

@ncalexan You mentioned that you are working on something similar in the Rust world. You also mentioned that it may be worthwhile to put things together in a way that Rust and Kotlin code uses the same http client implementation.

[pocmo]

Components that do some kind of http request or require a client:

• service-glean: Ping upload
• service-telemetry: Ping upload
• service-fretboard: Configuration download (Kinto)
• browser-search: search suggestions