title: Create ABAP REST Class to query multiple entities
body: <p>I don't have Gateway available in my landscape and I want to use the ABAP REST library to expose web services: <a href="https://help.sap.com/viewer/753088fc00704d0a80e7fbd6803c8adb/7.52.3/en-US/0f5fb77942744afe94afafa78df57b70.html" rel="nofollow noreferrer">SAP Library - REST Programming Tutorial</a></p>
  
  <p>With a very simple example, I successfully created a class to read a single domain list of values, the GET call is quite simple:</p>
  
  <p><code>http://mydomain/domainvalues/XFELD</code></p>
  
  <p>And the GET implementation is in my class ZCL_REST_DOMAIN_VALUES extending from CL_REST_RESOURCE implementing IF_REST_RESOURCE~GET method.</p>
  
  <p>Now I want to make it possible to read or query multiple domains. I'm not an expert in REST but I've seen two options searching around, one using the same URI as the single entity and one with special URI for queries.</p>
  
  <ul>
  <li><code>http://mydomain/domainvalues?Id=XFELD,WERKS_D</code></li>
  <li><code>http://mydomain/query/domainvalues?Id=XFELD,WERKS_D</code></li>
  </ul>
  
  <p>In the backend, should I use the second approach and create a class only for this call named for instance ZCL_REST_DOMAIN_VALUES_QUERY implementing the GET method again?</p>
  
  <p>Or maybe should I use POST method to send the list of IDs to fetch in the body?</p>