[Stream]Multiple NettyStreamingService error and (re)connection handling

Right now, I can’t implement

class GeminiStreamingExchange { @Override public Observable<Throwable> reconnectFailure() { return streamingService.subscribeReconnectFailure(); } @Override public Observable<Object> connectionSuccess() { return streamingService.subscribeConnectionSuccess(); } }

Because Gemini is using several GeminiProductStreamingService (which derives from [Json]NettyStreamingService) instead of a single JsonNettyStreamingService private Map<CurrencyPair, GeminiProductStreamingService> productStreamingServices;

This also applies to other services which have two JsonNettyStreamingService instances (one for market data one for private data).

Any thoughts, on how we can aggregate these events across multiple instances?

_Originally posted by @mdvx in https://github.com/knowm/XChange/pull/3533#issuecomment-633318275_

[mdvx]

And maybe add READY, once client re-initialize after connect has been complete?

enum StreamState { DISCONNECTED, PARTIALLY_CONNECTED, CONNECTED, READY }

[mdvx]

I like the way this is going. Can we now extend this cover re-connections?

T	A	B	Result
0	Connecting		DISCONNECTED
1	Connected		CONNECTED
2	Connected	Connecting	PARTIALLY_CONNECTED
3	Connected	Connected	CONNECTED
4	Disconnected	Connected	PARTIALLY_CONNECTED
5	Disconnected	Disconnected	DISCONNECTED
6	Connecting	Disconnected	DISCONNECTED
7	Connected	Disconnected	PARTIALLY_CONNECTED