Setting headers for SSE-response

[staklau]

Setting headers for SSE-response

[daviddenton]

So this currently isn't possible without digging down into the guts and changing the definition of SSE. Looking at it, I think it is probably required. What you can do is to change the SSE handler at the server level (but that isn't a great solution TBH)

[daviddenton]

We've got an idea, and looking at what to do to make sure it's testable. It's going to be a breaking change whatever happens if we want to support it. For the time being, if you need to rewrite the underlying server-level handler that's the only way. Stay tuned :)

[staklau]

@daviddenton Thank you for the fast response.
What does it mean to rewrite the underlying server-level handler, exactly?

[daviddenton]

Well, assuming you are using Jetty, it would involve creating your own version of the server-backend and explicitly: JettyEventStreamHandler. This is pretty horrid TBH and would only work if you really want to set a standard set of headers for every SSE request

[daviddenton]

We think we have an idea of the type of change that might be required - we'll keep you posted

[staklau]

@daviddenton Then I'll stay put for now :)

[daviddenton]

We've managed to fix this and are releasing the changes as a part of 5.1.0.0 :)

[staklau]

@daviddenton Great, thanks! :)

[staklau]

@daviddenton Hi! I thought this was solved but when I'm trying to create a CORS-filter with the SseFilter I'm not allowed to set any headers for the response, ref:

  val corsFilter = SseFilter { next ->
    { request ->
      val response = next(request)
      response.header("Access-Control-Allow-Origin", "*") <-- the .header method does not exist
      response
    }
  }

Let me know If I'm missing something.

[staklau]

@daviddenton Ah nevermind I forgot about the copy method, ref:
response.copy(headers = listOf("Access-Control-Allow-Origin" to "*"))