title: Schema extension for SCIM 2.0
body: <p>We have an Identity Provider User registry, and a SOAP Web Service for applications to read/write user profiles. Now we plan to add a SCIM interface as well.</p>
  
  <p>We find that Core User schema covers the basic set of attributes, however our existing system has a different naming convention for the same attributes.</p>
  
  <p>For example, say USERTELEPHONENUMBER, USERSTREETADDR1 and so on.</p>
  
  <p>Considering large number of applications already using this naming convention, we would like to continue the same with SCIM 2.0.</p>
  
  <p>Given that we can extend the Core User schema, </p>
  
  <p>1) Can we opt not using any attributes from Core schema ? If the payload includes these attributes, can we simply ignore them on the server side, and process only custom schema attributes ?</p>
  
  <p>An example User document - </p>
  
  <pre><code>    {
          "schemas":    [ "urn:scim:schemas:core:2.0:User",
                       urn:scim:schemas:extension:customattrs:2.0:User"], 
          "id": "2819c223-7f76-453a-919d-413861904646",
  
          "urn:scim:schemas:extension:customattrs:2.0:User": {
              "USERFIRSTNAME": "fname",
              "USERLASTNAME": "lname",
           "USERTELEPHONENUMBER": "1231231234
       }
      }
  </code></pre>
  
  <p>2) We can define a new resource itself and define a new core schema. </p>
  
  <p>Which of these options would be a cleaner way ? </p>