&gt; <If an engine supports HTTP/2, you can enable...

# ktor

[S.]

If an engine supports HTTP/2, you can enable it in the engine's configuration

how do I enable that for the Js or Okhttp client for example? I can't find any option like protocolVersion in the engine config

[Aleksei Tirman [JB]]

You can configure the protocols for the OkHttp engine by configuring the underlying client:

val client = HttpClient(OkHttp) {
    engine {
        preconfigured = OkHttpClient.Builder()
            .protocols(listOf(Protocol.HTTP_2))
            .build()
    }
}

You can't configure protocols for the Js engine because the undelying implementation doesn't allow that.

[S.]

I see. thanks

[S.]

HttpClient(Darwin) {
    engine {
        configureSession {
            setProtocolClasses(listOf(HttpProtocolVersion.HTTP_2_0))
        }
    }
}

is that correct for Darwin? setProtocolClasses accepts List<*> so not sure what it actually expects

[Aleksei Tirman [JB]]

Can you please explain your use case? Do you need to disable some protocols? The description of the protocolClasses can be found here.

[S.]

I just want to make sure it's using http2. the ktor docs I linked above sound like you need to enable it manually

[Aleksei Tirman [JB]]

If the client supports HTTP/2 and the server decides to upgrade to that version, then HTTP/2 will be used for the communication. With the OkHttp engine, you can use the Protocol.H2_PRIOR_KNOWLEDGE object to avoid a round trip for the upgrade.