Introduce a way to set headers and status code for streaming response

[geoand]

Relates to: #33130
Closes: #26523

[geoand]

@cescoffier WDYT?

[cescoffier]

Just made a small comment.

[github-actions]

🙈 The PR is closed and the preview is expired.

[geoand]

@cescoffier I pushed a second commit which makes this feature even more usable, you might want to have a look as I needed to introduce a custom Multi (the implementation was copied pretty much verbatim from existing Mutiny code)

[quarkus-bot]

Failing Jobs - Building 0e313b6

Status	Name	Step	Failures	Logs	Raw logs
✔️	JVM Tests - JDK 11
✔️	JVM Tests - JDK 17
✖	JVM Tests - JDK 17 Windows	Build	Failures	Logs	Raw logs
✔️	JVM Tests - JDK 19

Full information is available in the Build summary check run.

Failures

⚙️ JVM Tests - JDK 17 Windows #

- Failing: integration-tests/mongodb-panache 

📦 integration-tests/mongodb-panache

✖ io.quarkus.it.mongodb.panache.reactive.ReactiveMongodbPanacheResourceTest.testMoreRepositoryFunctionalities line 351 - More details - Source on GitHub

java.lang.AssertionError: 
1 expectation failed.
Expected status code <200> but was <500>.

[scrocquesel]

Works for my use case as well. Thanks.

I'm just wondering if a builder pattern could improve API discoverability. It may not be a good idea, but generally, RestResponse is a well-known starting point to create a response builder for specific use cases. Having fromUni and fromMulti would help discover those supported use cases while keeping the builder pattern. The return type of the builder will also help the user determine what to use as the return type for its resource method.

For example:

return RestResponse.fromUni(Uni.createFrom().item(new MyObject()))
     .onItem()
        .header(Map.of("Content-Disposition", "attachment;filename=" + outerParam)) // header (String, String), for header known before the Uni returned
        .header("Content-Type", object -> object.contentType()) // header (String, Function<T, String>), when only the value vary
        .header(object -> Map.of("Content-Length", List.of(object.length()))) // header (Function<T, Map<String, List<String>>>), for total control
        .transformToMulti(object -> Multi.createFrom().publisher(object.getPublisher()))
        .build();

Also, it feels bad that because we're doing things reactively, we lose the strongly typed helper method of ResponseBuilder to set headers. That way, new methods may be added later to the builder to fill the gap.

[geoand]

Thanks for the suggestion.

The problem is that the RestResponse models a very specific thing - a single HTTP response.

When you are streaming data back however, that model doesn't work - you need something that represents the fact that you can only specify the headers once and then have a payload of multiple chunks.

[geoand]

I should also mention that RestResponse works perfectly with Uni (you don't loose it's usefulness in the Reactive world).

The problem as I mentioned above is the mismatch with the data streaming paradigm

[k-wilmeth]

Hello! I have not yet upgraded to Quarkus 3 in my application yet. Is there a RestMulti equivalent for Quarkus 2 that could be used to stream bytes? Thank you.

[geoand]

Hi,

No, there is not really

[k-wilmeth]

Huh... okay. Maybe it's time I look to upgrade then.
I was trying to get it to work with Multi<Buffer> but it doesn't seem to work.