Apollo-android: SubscriptionHeartbeat no "pong" message in sealed class OperationClientMessage

[KirillDemchenko]

I need to implement heartbeat to Apollo client, like server says: {"type":"ka"}, client: {"type":"pong"}
But there is no option in sealed class OperationClientMessage{}.
I cant override it and add option for "pong" response cause its sealed.

sealed class OperationClientMessage {
  @Deprecated("This method is deprecated. Use an OperationMessageSerializer instead.")
  fun toJsonString(): String =
      try {
        val buffer = Buffer()
        ApolloOperationMessageSerializer.writeClientMessage(this, buffer)
        buffer.readUtf8()
      } catch (e: IOException) {
        throw RuntimeException("Failed to serialize to json", e)
      }

  @Suppress("DeprecatedCallableAddReplaceWith")
  @Throws(IOException::class)
  @Deprecated("This method is deprecated. Use an OperationMessageSerializer instead.")
  fun writeToJson(writer: JsonWriter) {
    with(ApolloOperationMessageSerializer) { writeContentsTo(writer) }
  }

  class Init(@JvmField val connectionParams: Map<String, Any?>) : OperationClientMessage() {
    companion object {
      internal const val TYPE = "connection_init"
    }
  }

  class Start(
      @JvmField
      val subscriptionId: String,
      @JvmField
      val subscription: Subscription<*, *, *>,
      @JvmField
      val scalarTypeAdapters: ScalarTypeAdapters,
      @JvmField
      val autoPersistSubscription: Boolean,
      @JvmField
      val sendSubscriptionDocument: Boolean
  ) : OperationClientMessage() {
    companion object {
      internal const val TYPE = "start"
    }
  }

  class Stop(@JvmField val subscriptionId: String) : OperationClientMessage() {
    companion object {
      internal const val TYPE = "stop"
    }
  }

  class Terminate : OperationClientMessage() {
    companion object {
      internal const val TYPE = "connection_terminate"
    }
  }
}

Am i need to send pull request for heartbeat "pong" response to server, or am i missunderstand something and there is easier way to send "pong" to "ka"?
Thanks for answer

[martinbonnin]

Are you using apollo-server ? If yes, I don't think it requires a pong message.

If you're using another server with a different transport, you will most likely have to implement your own WebSocketSubscriptionTransport.

[KirillDemchenko]

Yes i'm using apollo-server go-lang, but it requires a pong message to not disconnect a connection.
Now socket flow is :

1. connect
2. server send a "ka" message
3. client dont send "pong"
4. server disconnected
5. client catch disconnect error and reconnect

[martinbonnin]

Ah, that's interesting! Looks like something we should add upstream. Do you want to do a pull request?

[KirillDemchenko]

I just found out that we use https://github.com/99designs/gqlgen in backend - really dont know does socket realization different than in https://github.com/graphql-go/graphql , but in any case would be nice to have option of "pong" response for server with a different transport. For example - flag in Builder. Yes i want to do a pull request

[martinbonnin]

Got it 👍 .

I thought you might be using https://www.apollographql.com/docs/apollo-server/ but graphql-go is another story, I'm not sure what the protocol is there.

I'm a bit reluctant to adding more flags/parameters to WebSocketSubscriptionTransport as we can't account for each and every different transport but it would be nice to offer alternate WebSocketSubscriptionTransport that we could package in a separate maven artifact or repo. In that case, maybe something like GraphQLGoSubscriptionTransport?

[KirillDemchenko]

Okay, got it, i could try GraphQLGoSubscriptionTransport