A proposal regarding over-complicated connection API.

[serzero2007]

For now Connection API is a ES6 class with a lot of methods, used inconsistently along the codebase. I have experimented for some time with a different ways how to change the design, and would like to share my findings.

1. Treat connections as a generic objects without defining a class.
2. From the typescript point of view these objects should provide Duplex Stream interface and Peer Info interface (have properties peerInfo and a method getObservedAddrs).
3. Creating new connection objects using factories and transformation functions.

Why this approach is interesting? Well, see:

1. Factory

function attachPeerInfo (stream: Duplex, peerInfo: PeerInfo): Connection {
  stream.peerInfo = peerInfo
  if (stream.observer) stream.observer(stream, peerInfo, 'new', 'peerInfo')
  return stream // Actually a connection
}

2. Attaching the observer to the connection, so that observer function is called for each message:

import { tap } from 'pull-tap'

export function observeDuplexStream (stream, observer) {
  stream.observer = observer

  // This will allow to easely get stream.peerInfo
  let _out = tap(msg => stream.observer(stream, stream.peerInfo, 'out', msg))
  let _in  = tap(msg => stream.observer(stream, stream.peerInfo, 'in',  msg))

  // Monkey-patching the underlying streams
  stream.source = pull(stream.source, _out)
  stream.sink   = pull(_in, stream.sink)

  return stream
}

That's all. There is no need to define a complex interaction on the data. Observer will see the peerInfo on the stream when it appears.
3) The proxy stream with an observer and a different peerInfo attached:

const { duplex } = require('pull-defer')

function createProxyConnection (swarm): Connection {
  let proxy = duplex()
  // Basically a mixins that define the connection behaviour
  observeDuplexStream(proxy, swarm.observer)
  attachPeerInfo(proxy, swarm.peerInfo)
  // it's created! 
  return proxy
}

What do you think?

Also this would allow to add any number of annotations. ES6 Symbols can be used to get rid of name collision problems.

[serzero2007]

Also I have found this https://github.com/stampit-org/stamp that could simplify a lot dealing with a prototypical inheritance.

[jacobheun]

The API has changed to an async iterators based api, and has significantly changed. Closing this as it no longer applies to the current API.