Scaling JAX-RS Applications - RESTful Java with JAX-RS 2.0 - page 166

public public void void setNoStore ( boolean boolean noStore ) {...}

public public Map < String , String > getCacheExtension () {...}

}

The ResponseBuilder class has a method called cacheControl() that can accept a
CacheControl object:

@Path ( "/customers" )
public

public class class CustomerResource CustomerResource {

@Path ( "{id}" )
@GET
@Produces ( "application/xml" )
public public Response getCustomer ( @PathParam ( "id" ) int int id ) {

Customer cust = findCustomer ( id );

CacheControl cc = new CacheControl ();
cc . setMaxAge ( 300 );
cc . setPrivate ( true );
cc . setNoStore ( true );
ResponseBuilder builder = Response . ok ( cust , "application/xml" );
builder . cacheControl ( cc );
return return builder . build ();

}

In this example, we initialize a CacheControl object and pass it to the ResponseBuild-
er.cacheControl() method to set the Cache-Control header of the response. Unfortu-
nately, JAX-RS doesn't yet have any nice annotations to do this for you automatically.

Revalidation and Conditional GETs
One interesting aspect of the caching protocol is that when the cache is stale, the cacher can
ask the server if the data it is holding is still valid. This is called revalidation . To be able to
perform revalidation, the client needs some extra information from the server about the re-
source it is caching. The server will send back a Last-Modified and/or an ETag header with
its initial response to the client.

Last-Modified

The Last-Modified header represents a timestamp of the data sent by the server. Here's an
example response:

HTTP / 1.1 200 OK
Content - Type: application / xml
Cache - Control: max - age = 1000