Filterable streams with service subjects.

[hanselke]

I want to create a 'chat' service, and also use the service's subject as a persistant store to pull message history on a per user level.

// Setup the service
    let service = nc.service_builder()
        .description("Chat Service")
        .start("chat", "0.0.1")
        .await?;

    // Setup the service group and endpoint
    let chat_group = service.group("service");
    let mut chat_endpoint = chat_group.endpoint("chat").await?;
    
    // create stream to store messages
    let js = jetstream::new(nc.clone());
    let stream_name = "CHAT";
    let mut chat_stream = match js.get_stream(stream_name).await {
        Ok(existing_stream) => {
            println!("Stream {} already exists", stream_name);
            existing_stream
        }
        Err(_) => {
            println!("Creating stream: {}", stream_name);
            js.create_stream(jetstream::stream::Config {
                name: stream_name.to_string(),
                subjects: vec!["service.chat".to_string()],
                ..Default::default()
            }).await?
        }
    };

Dont see a way to make users request to service.chat.user_pk , so i cant filter the stream for the user's messages.
Subject mapping doesnt seem to allow me to pull in the user_pk (which is available via an _INBOX prefix i've set for the user client).

Is there a way to do this other then republishing to a stream?

[Jarema]

Service API is just for Core NATS request/reply pattern.
We have some plans for the that in the future.