How to use CXF, JAX-RS and HTTP Caching

Question

The CXF documentation mentions caching as Advanced HTTP:

CXF JAXRS provides support for a number of advanced HTTP features by handling If-Match, If-Modified-Since and ETags headers. JAXRS Request context object can be used to check the preconditions. Vary, CacheControl, Cookies and Set-Cookies are also supported.

I'm really interested in using (or at least exploring) these features. However, while "provides support" sounds really interesting, it isn't particularly helpful in implementing such features. Any help or pointers on how to use If-Modified-Since, CacheControl or ETags?

Answer 1

Actually, the answer isn't specific to CXF - it's pure JAX-RS:

// IPersonService.java
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.Request;
import javax.ws.rs.core.Response;

@GET
@Path("/person/{id}")
Response getPerson(@PathParam("id") String id, @Context Request request);


// PersonServiceImpl.java
import javax.ws.rs.core.CacheControl;
import javax.ws.rs.core.EntityTag;
import javax.ws.rs.core.Request;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.Response.ResponseBuilder;

public Response getPerson(String name, Request request) {
  Person person = _dao.getPerson(name);

  if (person == null) {
    return Response.noContent().build();
  }

  EntityTag eTag = new EntityTag(person.getUUID() + "-" + person.getVersion());

  CacheControl cc = new CacheControl();
  cc.setMaxAge(600);

  ResponseBuilder builder = request.evaluatePreconditions(person.getUpdated(), eTag);

  if (builder == null) {
    builder = Response.ok(person);
  }

  return builder.cacheControl(cc).lastModified(person.getUpdated()).build();
}

Answer 2

With the forthcoming JAX-RS 2.0 it will be possible to apply Cache-Control declaratively, as explained in http://jalg.net/2012/09/declarative-cache-control-with-jax-rs-2-0/

You can already test this at least with Jersey. Not sure about CXF and RESTEasy though.