Ok, I know that the session concept is not a Rest style approach and It may
not be a best practice, however I believe Jersey is not just the reference
implementation of JAXRS. I know many people using it as a general purpose
web framework including me. When you start using it as a web framework your
resource classes become more like services and you try to consume these
services from other services as much as you can. Imagine a method which
returns an Entity/Resource which requires an Id which will be looked up from
the session. The two alternative implementations would be like follows:
@GET
public A getA(@Context HttpServletRequest request) {
HttpSession session = request.getSession();
session.getAttribute("keyForA");
/// return A
}
or
@GET
public A getA(@SessionAttribute("keyForA") String key) {
/// return A
}
I believe the second method is much more efficient in terms of reusability.
You can't simply create a HttpServletRequest object to call the first
method.
I think even if it is not supported as a built-in feature, these kind of
extra utilities can be bundled in an external jar.
Erdinc
On Mon, Jan 25, 2010 at 4:53 PM, Marc Hadley <Marc.Hadley_at_sun.com> wrote:
> See #6 at:
>
> http://www.prescod.net/rest/mistakes/
>
> While its possible to use sessions via an injected HttpServletRequest, we
> don't want to make it too easy to do the wrong thing.
>
> Marc.
>
> On Jan 25, 2010, at 11:40 AM, Erdinc Yilmazel wrote:
>
> > Sorry if I am mistaken, but I wonder why there isn't a built-in
> annotation for injecting session attributes in Jersey? I know you can inject
> HttpServletRequest and access session attributes using it, but that is a lot
> of typing.
> >
> > Writing a @SessionAttribute annotation is achievable by just implementing
> three classes...
> >
> > @Target({ElementType.PARAMETER, ElementType.METHOD, ElementType.FIELD})
> > @Retention(RetentionPolicy.RUNTIME)
> > @Documented
> > public @interface SessionAttribute {
> > String value();
> > }
> >
> > ------------------
> >
> > @Provider
> > public class SessionParamProvider implements
> InjectableProvider<SessionAttribute, Type> {
> >
> > @Override
> > public ComponentScope getScope() {
> > return ComponentScope.PerRequest;
> > }
> >
> > @Context
> > HttpServletRequest requestProxy;
> >
> > @Override
> > public Injectable<Object> getInjectable(ComponentContext ic,
> SessionAttribute a, Type type) {
> > return new SessionAttributeInjectable(a.value(), requestProxy);
> > }
> > }
> >
> > -------------------
> > public class SessionAttributeInjectable implements Injectable<Object> {
> > String attributeName;
> >
> > public SessionAttributeInjectable(String attributeName,
> HttpServletRequest requestProxy) {
> > this.attributeName = attributeName;
> > this.request = requestProxy;
> > }
> >
> > HttpServletRequest request;
> >
> > @Override
> > public Object getValue() {
> > HttpSession session = request.getSession(true);
> > return session.getAttribute(attributeName);
> > }
> > }
> >
> >
> > Erdinc
>
>
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