I'm trying to slowly migrate an android app to mul...

# apollo-kotlin

[Sean Proctor]

I'm trying to slowly migrate an android app to multiplatform. It seems that addHttpInterceptor doesn't affect WS connections. Is that intentional? Is there an alternative to using an OkHttpClient with an interceptor for web sockets?

[mbonnin]

WS is different from HTTP as it's not request/response but more bidirectional communication

[mbonnin]

Does okhttp has interceptors for Websockets?

[Sean Proctor]

Yes, adding an interceptor to the okhttp client works for both http and ws.

[mbonnin]

Wait but a WebSocket may return multiple payloads messages

[mbonnin]

Found this: https://github.com/square/okhttp/issues/4192

[mbonnin]

And this https://stackoverflow.com/a/48856490/752630

[mbonnin]

What am I missing?

[Sean Proctor]

In my case, I need to send the authentication token. Adding the interceptor to the okhttp client works for me.

[mbonnin]

Looks like it's used for the initial handshake 👀

[mbonnin]

Let me check how to do this on iOS

[Sean Proctor]

I'm really not a websockets expert. I did plenty of reading and experimenting a year ago to get this working. It's super late here, so I'm a bit useless currently, sorry.

[mbonnin]

No worries at all!

[mbonnin]

Turns out the WebSocket initial handshake is actually a HTTP request

[mbonnin]

I guess this is why the OkHttp interceptor is working for WebSockets

[Sean Proctor]

Well, that's good news, I think.

[mbonnin]

Making a multiplatform version of this is going to be challenging though as the APIs are wildly different on iOS and Android

[mbonnin]

We could make the initial headers configurable relatively easily though here : https://github.com/apollographql/apollo-kotlin/blob/330b695abb6868555c54197070f50a[…]m/apollographql/apollo3/network/ws/WebSocketNetworkTransport.kt

[mbonnin]

It'd have to be a lambda for the token to be updated on reconnect

[mbonnin]

Out of curiosity, is there any chance you could send your token in the initial "connection_init" message?

[Sean Proctor]

That would work for me. I guess you can't just use the http interceptor in there.

[Sean Proctor]

Pretty sure I could.

[mbonnin]

I guess you can't just use the http interceptor in there.

Not really. HttpInterceptor uses a different API that iOS/OkHttp don't understand

[Sean Proctor]

It's a hasura server, so if they accept it, certainly. Any idea how I'd do that?

[mbonnin]

Pretty sure I could.

If you can, that's the easiest route, SubscriptionWsProtocol has a connectionPayload parameter

[mbonnin]

Something like

val apolloClient = ApolloClient.Builder()
        .httpServerUrl("<http://localhost:8080/graphql>")
        .webSocketServerUrl("<http://localhost:8080/subscriptions>")
        .wsProtocol(
            SubscriptionWsProtocol.Factory(
                connectionPayload = {
                  mapOf("authorization" to myToken)
                }
            )
        )

[mbonnin]

According to this page , hasura is expecting headers though, not a connection payload

[Sean Proctor]

Give me one minute and I'll test it.

[mbonnin]

Exposing a function to customize headers wouldn't harm in all cases. Let me know if you want to open a pull request. If not, I'll try to get this in next version

[Sean Proctor]

Finished testing. No luck.

[Sean Proctor]

I guess there's no rush on it. I'm going to be traveling the next few days. I might find some time in there or when I get back. If you don't mind the wait, I'll try to make a pull request.

[mbonnin]

Nice ! Not sure when we'll do the next version, maybe end of next week or so. Sounds like something that'd be a nice addition