SwarmClient re-connection to WebSocket

[aquiladev]

I use @erebos/swarm-browser package in order to communicate with swarm in my app.

const client = new SwarmClient({ws: '...'});

When I restart swarm, erebos package throws an error Connection failed and it is not possible to continue work with app, in order to fix it I need to refresh the app.

Do you have any ideas how to implement automatic re-connection of SwarmClient

[PaulLeCam]

I'm guessing you're using the ws config in order to use PSS, so for a bit of context, the ws config is used by the @mainframe/rpc-ws-browser module, that itself is using the @mainframe/rpc-stream module over @mainframe/transport-ws-browser.

This transport is simply using RxJS' WebSocketSubject, that can be provided an openObserver and a closeObserver, so by creating the WebSocketSubject instance in your app, you could keep track of the connection state and reconnect accordingly.
I think the setup would look like:

import { SwarmClient } from '@erebos/swarm-browser'
import PssAPI from '@erebos/api-pss'
import StreamRPC from '@mainframe/rpc-stream'
import { WebSocketSubject } from 'rxjs'

const transport = new WebSocketSubject({
  // Config with url, openObserver and closeObserver
})
const rpc = new StreamRPC(transport)
const pss = new PssAPI(rpc)
const client = new SwarmClient({ pss })

Then it would be part of your application logic to recreate the client as needed.
I opened an issue in the relevant repository with some ideas regarding how this could be implemented as a separate package, and this article might provide some useful pointers.

[aquiladev]

@PaulLeCam thanks for advice, I try it later today

[aquiladev]

It took a while to implement it, coz it was a bit more complicated.

I didn't use PssAPI, coz it caused errors. I pas rpc directly in SwarmClient constructor.

I took reference implementation of WebSocketSubject wrapper https://gearheart.io/blog/auto-websocket-reconnection-with-rxjs-with-example
It works in both cases, when no connection and when connection lost.

Here is my implementation okamilab/nebula@881470f

[PaulLeCam]

Nice, thanks for sharing!

What errors did you get using PssAPI please? Any issue that should get fixed in Erebos?

[aquiladev]

this.subject = new RxWebSocketSubject(ws);
const rpc = new StreamRPC(this.subject.socket);
const pss = new PssAPI(rpc);
this.client = new SwarmClient({ pss });

leads to an error on application startup

erebos.production.js:6105 
Uncaught Error: Invalid RPC instance provided: must support subscriptions
    at new t (erebos.production.js:6105)
    at _o (erebos.production.js:6635)
    at new t (erebos.production.js:6646)
    at new ClientResolver (client.js:14)
    at configureStore (redux.js:23)
    at Module../src/index.js (index.js:14)
    at __webpack_require__ (bootstrap:781)
    at fn (bootstrap:149)
    at Object.0 (reducer.js:22)
    at __webpack_require__ (bootstrap:781)
    at checkDeferredModules (bootstrap:45)
    at Array.webpackJsonpCallback [as push] (bootstrap:32)
    at main.chunk.js:1

[PaulLeCam]

Thanks for the details!