JAX-RS AsyncResponse.resume() with Location header - rest

Question

UPDATE
Some more digging showed that thrown Exceptions were dropped and the actual problem is that an injected UriInfo could not be resolved in the AsyncResponse's thread!
Accessing #Context UriInfo uriInfo; during AsyncResponse.resume() gives the following LoggableFailure's message:
Unable to find contextual data of type: javax.ws.rs.core.UriInfo
ORIGINAL
According to RFC 7231 HTTP/1.1 Semantics and Control, a POSTshould return 201 CREATED and supply the new resource's location in the header:
the origin server
SHOULD send a 201 (Created) response containing a Location header
field that provides an identifier for the primary resource created
(Section 7.1.2) and a representation that describes the status of the
request while referring to the new resource(s).
When writing a synchronous REST Server, the javax.ws.rs.core.Responseoffers the Response.created() shorthand which does exactly that.
I would save the new entity, build an URI and return
return Response.created(createURL(created)).build();
However, when I switch to an asynchronous approach utilizing a
#Suspended javax.ws.rs.container.AsyncResponse
the HTTP request on the client will hang infinitely:
#POST
public void createUser(#Valid User user, #Suspended AsyncResponse asyncResponse) {
executorService.submit(() -> {
User created = userService.create(user);
asyncResponse.resume(
Response.created(createURL(created)).build()
);
});
}
Through trial-and-error I found out that the modified location header is responsible.
If I return my entity and set the 201 Created, without touching the header, the request will eventually resolve:
#POST
public void createUser(#Valid User user, #Suspended AsyncResponse asyncResponse) {
executorService.submit(() -> {
User created = userService.create(user);
asyncResponse.resume(
Response.status(Status.CREATED).entity(created).build() //this works
//Response.created(createURL(created)).build()
);
});
}
So what's the problem? Am I misunderstanding the concepts?
I am running RestEasy on GlassFish4.1
If you need more information, please comment!
edit
As soon as I change any link or the header, the request will hang.

Answer 1

In case anyone ever has the same problem:
The problem was that I created the location header through an injected #Context UriInfo uriInfo using its .getAbsolutePathBuilder().
The approach was working in a synchronous server because the thread which accessed the UriInfo still had the same Request context.
However, when I switched to an async approach, the underlying Runnable which eventually had to access uriInfo.getAbsolutePathBuilder() was NOT within any context - thus throwing an exception which halted further execution.
The workaround:
In any async method which should return a location header, I .getAbsolutePathBuilder() while still within the context. The UriBuilder implemantion can then be used within the async run:
#POST
public void createUser(#Valid User user, #Suspended AsyncResponse asyncResponse) {
UriBuilder ub = uriInfo.getAbsolutePathBuilder();
executorService.submit(() -> {
User created = userService.create(user);
asyncResponse.resume(
Response.created(createURL(ub, created)).build()
);
});
}
private URI createURL(UriBuilder builder, ApiRepresentation entity) {
return builder.path(entity.getId().toString()).build();
}