Give every “thing” and/or resource an “ID”

Everything that should be identifiable should obviously get an ID — on the Web, there is a unified concept for IDs: The URI. URIs make up a global namespace, and using URIs to identify our key resources means they get a unique, global ID.

The main benefit of a consistent naming scheme for things is that you don’t have to come up with your own scheme — you can rely on one that has already been defined, works pretty well on global scale and is understood by practically anybody.

Here are some examples of URIs you might come up with:

To summarize the first principle: Use URIs to identify everything that merits being identifiable, specifically, all of the “high-level” resources that one’s application provides, whether they represent individual items, collections of items, virtual and physical objects, or computation results.

<span style="color: blue">&lt;</span><span style="color: #a31515">order </span><span style="color: red">self</span><span style="color: blue">='http://example.com/customers/1234' &gt; 
   &lt;</span><span style="color: #a31515">amount</span><span style="color: blue">&gt;</span>23<span style="color: blue">&lt;/</span><span style="color: #a31515">amount</span><span style="color: blue">&gt; 
   &lt;</span><span style="color: #a31515">product </span><span style="color: red">ref</span><span style="color: blue">='http://example.com/products/4554' /&gt; 
   &lt;</span><span style="color: #a31515">customer </span><span style="color: red">ref</span><span style="color: blue">='http://example.com/customers/1234' /&gt; 
&lt;/</span><span style="color: #a31515">order</span><span style="color: blue">&gt; </span>

Link things together

Links are something we’re all familiar with from HTML, but they are in no way restricted to human consumption.

<span class="lnum">   1:  </span>&lt;order self=<span class="str">'http://example.com/customers/1234'</span> &gt;

<span class="lnum">   2:  </span>     &lt;amount&gt;23&lt;/amount&gt; 

<span class="lnum">   3:  </span>     &lt;product <span class="kwrd">ref</span>=<span class="str">'http://example.com/products/4554'</span> /&gt; 

<span class="lnum">   4:  </span>     &lt;customer <span class="kwrd">ref</span>=<span class="str">'http://example.com/customers/1234'</span> /&gt; 

<span class="lnum">   5:  </span>&lt;/order&gt;

If we look at the product and customer links in this document, we can easily imagine how an application that has retrieved it can “follow” the links to retrieve more information. Of course, this would be the case if there were a simple “id” attribute adhering to some application-specific naming scheme, too — but only within the application’s context. The beauty of the link approach using URIs is that the links can point to resources that are provided by a different application, a different server, or even a different company on another continent — because the naming scheme is a global standard, all of the resources that make up the Web can be linked to each other.

To summarize this principles: Use links to refer to identifiable things (resources) wherever possible. Hyperlinking is what makes the Web the Web.

Use standard methods

<span class="lnum">   1:  </span><span class="kwrd">class</span> Resource 

<span class="lnum">   2:  </span>{    

<span class="lnum">   3:  </span>    Resource(URI u);

<span class="lnum">   4:  </span>    Response get();    

<span class="lnum">   5:  </span>    Response post(Request r);     

<span class="lnum">   6:  </span>    Response put(Request r);

<span class="lnum">   7:  </span>    Response delete();

<span class="lnum">   8:  </span>}