RE: Representation<T> and Entity<T>

From: Jerome Louvel <>
Date: Thu, 12 Apr 2007 10:23:28 +0200

Hi Dhanji,

> Because you can issue a redirection without returning an output
> representation.
> Right, this is why I doubled back on my suggestion and was
> wondering if Representation<T> is the correct artifact for
> getRedirectLocation().

Ok, also agree that Representation<T> should contain a "contentLocation" or
"redirectLocation" property. I suggest that this is added as a property of a
new Context (or RWSContext) class (unifying existing HttpContext,
HttpRequestContext and HttpResponseContext interfaces as well as the
HttpResponse class).

> > This seems to indicate that the response content is to be
> > ignored, which makes me wonder if Representation<T> is the
> > correct artifact to be supporting "Location." Just
> wondering...
> Even if I think redirects won't have output
> representation in most cases,
> I'm not sure that the spec prevents that.
> What would the alternative be? A second wrapper? or a
> derivative of Representation<T> (ugh)?

The suggested Context class with a "redirectRef" property or similar should
do it.

> In the current api--it looks like this is done via the
> HttpResponse object, added as a keyed string to the header
> map. Im not hot on this approach either.

Agreed. I also suggested to have shortcut methods like:

        // Redirection methods
        void redirectPermanent(uri);
        void redirectSeeOther(uri);
        void redirectTemporary(uri);

They would set both the "redirectRef" and the status at the same time.

> In one of our web frameworks, we have an event handler on a
> page (which handles hyperlink clicks for instance) that
> returns either the target page (equivalent of content) or a
> client-side redirect (interpreted and executed as
> response.sendRedirect(..) by the framework--i.e. the
> "location" header). In this case, I use a transparent wrapper
> with a static utility:
> @OnEvent
> public Object nextPage() {
> return NextPage; //standard case
> }
> @OnEvent
> public Object nextPage() {
> return"http://...."); //redirect case
> }
> The downsides here are the use of the static utility and the
> ugly (Object) return type. But it is certainly superior to
> throwing an exception.

I'm not too fond either of the idea to use exceptions to express
redirections. Hopefully the Context class, with potentially some
complimentary redirection annotations will be a better solution.

Best regards,