title: REST get calculated view of resource
body: <p>I'm interested in the correct convention to use when requesting a calculation on an entity from the server. That is - a specific entity is involved, but its data is not returned. Instead, a calculation based on the entity is returned.</p>
  
  <p>Take for example a site that stores multiple clocks, each with a different offset/timezone value. The purpose of the site is to present images of analog clocks with hands pointing in the appropriate direction.</p>
  
  <p>Using good convention I would expect to be able to do this:</p>
  
  <pre><code>POST /clocks
  {
      "offsetHours": 5
  }
  </code></pre>
  
  <p>And I would receive this response:</p>
  
  <pre><code>201 (Created)
  {
      "id": "fe884d5e",
      "offsetHours": 5
  }
  </code></pre>
  
  <p>Now I would expect to be able to retrieve that clock object:</p>
  
  <pre><code>GET /clocks/fe884d5e
  </code></pre>
  
  <p>Which responds:</p>
  
  <pre><code>200 (OK)
  {
      "id": "fe884d5e",
      "offsetHours": 5
  }
  </code></pre>
  
  <p>This is all fine so far. But there are two other endpoints I would expect to have access to. The first one would return the current time calculated for a clock's offset. The second one would return image data displaying an analog clock based on the clock's current time.</p>
  
  <p>My question is: what does convention dictate the GET requests for these data items should look like? Or is convention loose when it comes to dealing with calculated views of entities?</p>