Can i make the reconnection manually?

#1

I find that Theia Frontend keeps reconnecting to the Backend after the Backend has shut down, as a result, once the Backend restart, the Frontend can connect to it.

But i want to make the reconnection manually. For example, only if the user move the mouse over the offline page, its Frontend sends a reconnection message to the Backend.

Can i do that? Please help.

#2

We currently use ReconnectingWebSocket. See https://github.com/eclipse-theia/theia/blob/e95311d16baa865e50a356dc108e1bd800952a33/packages/core/src/browser/messaging/ws-connection-provider.ts#L91

You might be able to rebind this through Inversify to use your own mechanism instead?

Note that you need to provide an instance mimicking a real WebSocket but that never closes. The current connection status depends on traffic going in/out, not on actual disconnections. See https://github.com/eclipse-theia/theia/blob/1ca3ec37c079a6b316278cf292609653e57b8151/packages/core/src/browser/connection-status-service.ts#L152

#3

Yes i see. Once i call ReconnectingWebsockets.close(), the Frontend will not automatically reconnect to the Backend any more. And if i want to reconnect, calling ReconnectingWebsockets.reconnect() is well.

#4

But it really confuses me that by doing the following steps, the Frontend can reconnect to the Backend:

  1. call ReconnectingWebsockets.close() in Frontend.
  2. shut down the Backend manually.
  3. restart the Backend. (the Frontend will not reconnect to the Backend)
  4. call ReconnectingWebsockets.reconnect() manually in the Frontend.

However, if i shut down the Backend first,

  1. shut down the Backend manually.
  2. call ReconnectingWebsockets.close() in Frontend.
  3. restart the Backend. (the Frontend will not reconnect to the Backend)
  4. call ReconnectingWebsockets.reconnect() manually in the Frontend.
    the Frontend can never reconnect to the Backend, unless i refresh the page.

I really do not known why.

#5

I find it is because calling ReconnectingWebsockets.close() sets _closeCalled to be true, then _connectLock can not be set to false, which reaults in ReconnectingWebsockets.reconnect() returns immediately.