Re: How to create URIs?

From: Marc Hadley <Marc.Hadley_at_Sun.COM>
Date: Tue, 17 Jul 2007 09:02:36 -0400

Paul and I have been thinking along similar lines but there's nothing
in the API yet. We were thinking of adding some additional methods to
the existing UriInfo interface so you could write code like:

URI uri = uriInfo.buildAbsoluteUri(Widget.class, widgetId)

where Widget is an annotated resource class and widgetId is the value
of a uri template parameter. I'll try to put together a more detailed
proposal and circulate it soon.


On Jul 17, 2007, at 6:35 AM, Stefan Tilkov wrote:

> One of the key constraints - if not *the* key constraint - of REST
> is hypermedia. While playing around with the current implementation
> during my vacation, I noticed that I find something missing -
> namely, a decent way to create links in my representations. The
> mapping from URIs to the appropriate class and method, based on the
> annotations, works fine - but how do we get back?
> The Rails framework offers URI-to-code mapping in both directions.
> Here's an example route configuration:
> ActionController::Routing::Routes.draw do |map|
> map.customers 'customers/', :controller => 'Customer', :action =>
> 'index'
> map.customer 'customers/:name', :controller =>
> 'Customer', :action => 'show'
> end
> This creates two "named routes" (called "customer" and
> "customers"). One effect is that if I run my application on http://
> localhost:3000, a GET on a URL like
> http://localhost:3000/customer/whatever
> will create a "CustomerController" object and invoke its "show"
> method, passing "whatever" as the value for the name parameter.
> This is similar to what can be achieved with the current JSR RI
> (although personally, I prefer the centralized, rule-based approach
> Rails takes).
> But Rails also creates a number helper methods, specifically
> customer_url(<name>) and
> customer_path(<name>)
> When invoked as customer_url("whatever") and customer_path
> ("whatever"), these will yield "http://localhost:3000/customers/
> whatever" and "/customers/whatever", respectively. With these
> methods I can write a collection resource representation (in ERB
> syntax, very similar to JSPs) like this:
> <h1>Index</h1>
> <ul>
> <% @customers.each do |name| %>
> <li>Link to <a href="<%= customer_path(name) %>"><%= name %></
> a></li>
> <% end %>
> </ul>
> In contrast, the only way to build links to be included in a
> representation using our current API seems to be string
> concatenation, duplicating much of the knowledge included in the
> annotations.
> In other words: I suggest we extend the API to provide a way to
> build a URI based on the resource class and method to be invoked.
> For more info on Rails routing, see
> classes/ActionController/Routing.html and http://
> Stefan
> --
> Stefan Tilkov,
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Marc Hadley <marc.hadley at>
CTO Office, Sun Microsystems.