feat: add configurable Alt-Svc handler for HTTP/3 alternative service discovery

[Harshal96]

Motivation:

Adds a new AltSvcHandler and AltSvcOptions API for advertising HTTP Alternative Services from Vert.x Web routes.

This enables applications to declaratively send Alt-Svc response headers for configured origins, which is useful for HTTP/3 discovery. For example:

router.route().handler(
  AltSvcHandler.create(
    new AltSvcOptions()
      .addOrigin("http://localhost:8080", "h3:localhost:8443")
  )
);

Fixes #2847

[vietj]

@Harshal96 thanks for the contribution, the code is missing the support of HTTP/2 that works differently than with a HTTP header, I recommend you read the ALT-SVC RFC to learn more about this. For that matter you should look at HttpServerResponse#writeAltSvc method which has been added for this purpose.

[Harshal96]

@vietj done, can you please take a look now?

[Harshal96]

@vietj is this good for another review?

[vietj]

we actually don't need JsonGen annotation here, there is no interested in having a converter for this

[Harshal96]

done

[vietj]

I think we cannot reasonnably maintain such a map because it will never be cleaned from stale connections, so we need to find a way to do that properly.

[Harshal96]

updated to remove stale connections

[vietj]

I think for this we would rather need to develop an HTTP connection local storage instead of relying on the close handler, or actually have a close future for the connection

[Harshal96]

done

[vietj]

actually I meant I would add a map like structure on vertx internal HTTP connection object in vertx-core which would solve the issue more directly

[Harshal96]

oh, do you want me to support this in https://github.com/eclipse-vertx/vert.x/tree/master/vertx-core before this can be merged?

[vietj]

yes in HttpConnectionInternal interface contract

…

On Wed, Jul 8, 2026 at 6:22 PM Harshal Parekh ***@***.***> wrote: ***@***.**** commented on this pull request. ------------------------------ In vertx-web/src/main/java/io/vertx/ext/web/impl/HttpConnectionLocal.java <#2910 (comment)>: > + * + * You may elect to redistribute this code under either of these licenses. + */ + +package io.vertx.ext.web.impl; + +import io.vertx.core.http.HttpConnection; + +import java.util.Map; +import java.util.WeakHashMap; +import java.util.function.Supplier; + +/** + * Storage scoped to the lifetime of an ***@***.*** HttpConnection}, without retaining connections after they become unreachable. + */ +public class HttpConnectionLocal<T> { oh, do you want me to support this in https://github.com/eclipse-vertx/vert.x/tree/master/vertx-core before this can be merged? — Reply to this email directly, view it on GitHub <#2910?email_source=notifications&email_token=AABXDCROSZJFHMBWUP3WN3T5DZYKVA5CNFSNUABKM5UWIORPF5TWS5BNNB2WEL2QOVWGYUTFOF2WK43UKJSXM2LFO4XTINRVGYYDIMBSGE22M4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJLDGN5XXIZLSL5RWY2LDNM#discussion_r3545605797>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABXDCSMJK5CB66IRMKRCI35DZYKVAVCNFSNUABEKJSXA33TNF2G64TZHMZDMNRSHA4TKNB3JFZXG5LFHM2DKNZUGMZDMNRZGWQXMAQ> . You are receiving this because you were mentioned.Message ID: ***@***.***>