Library should support the websocket rpc API

[simolus3]

Library should support the websocket rpc API

[liuyuejiang]

Thank you Simon, how's it going?

[simolus3]

Was fixing the coverage tooling yesterday because it didn't work with Dart 2.3. Will take a look at this today. There is a dart library which implements jsonrpc over websockets, so hopefully it should be straightforward to implement.

[simolus3]

It's working on development now and can be used like this:

web3dart/example/contracts.dart

Lines 58 to 60 in bec10fd

	final client = Web3Client(rpcUrl, Client(), socketConnector: () {
	return IOWebSocketChannel.connect(wsUrl).cast<String>();
	});

You'll need to add a dependency on web_socket_channel: ^1.0.0 in your pubspec.yaml and import 'package:web_socket_channel/io.dart'. There are errors with ganache when unsubscribing from a stream which I still need to fix, but otherwise everything seems to work.

Also, when using websockets in a Flutter app, you should call dispose() on the client when the app goes into background and then create a new Web3Dart client when it's resumed. The OS might close the websocket (and therefore, the event streams), so it's better to make that explicit and restore them when the app comes back into foreground.

[simolus3]

Got it working, I'll merge it into master and release a new version soon. The previous comment still holds, especially the remarks about dispose(). When using infura, be aware that your wsUrl is wss://<NETWORK>.infura.io/ws/v3/YOUR-PROJECT-ID (note the /ws/).