Determine if Metadata has Changed Using Jscript or C# in Microsoft Dynamics CRM 2011 Using RetrieveTimestampRequest

This illustration shows how to programmatically determine if there have been changes in Metadata  in Microsoft Dynamics CRM 2011 in code using jscript and also C#  with the RetrieveTimestampRequest.   This example will be given in SOAP (JScript) and in C# (.NET).

IMPORTANT NOTE: The time stamp retrieved is actually not a time stamp at all.  It's really a hash computed on the metadata in CRM.   This means that you must have a previous time stamp value to compare against to be able to determine if a change has occurred or not.

Ok, here is what the code look like!

First in C#:

RetrieveTimestampRequest req = new RetrieveTimestampRequest();
RetrieveTimestampResponse resp = (RetrieveTimestampResponse)slos.Execute(req);

If you need help instantiating a service object in .NET within a plugin check out this post:
http://mileyja.blogspot.com/2011/04/instantiating-service-object-within.html

Now here is the Jscript nicely formatted by the CRM 2011 SOAP formatter. Available at: http://crm2011soap.codeplex.com/

Now in Jscript


This is example is asynchronous, if you want to learn how to make JScript SOAP calls synchronously please visit this post: http://mileyja.blogspot.com/2011/07/using-jscript-to-access-soap-web.html

if (typeof (SDK) == "undefined")
   { SDK = { __namespace: true }; }
       //This will establish a more unique namespace for functions in this library. This will reduce the 
       // potential for functions to be overwritten due to a duplicate name when the library is loaded.
       SDK.SAMPLES = {
           _getServerUrl: function () {
               ///<summary>
               /// Returns the URL for the SOAP endpoint using the context information available in the form
               /// or HTML Web resource.
               ///</summary>
               var ServicePath = "/XRMServices/2011/Organization.svc/web";
               var serverUrl = "";
               if (typeof GetGlobalContext == "function") {
                   var context = GetGlobalContext();
                   serverUrl = context.getServerUrl();
               }
               else {
                   if (typeof Xrm.Page.context == "object") {
                         serverUrl = Xrm.Page.context.getServerUrl();
                   }
                   else
                   { throw new Error("Unable to access the server URL"); }
                   }
                  if (serverUrl.match(/\/$/)) {
                       serverUrl = serverUrl.substring(0, serverUrl.length - 1);
                   } 
                   return serverUrl + ServicePath;
               }, 
           RetrieveTimestampRequest: function () {
               var requestMain = ""
               requestMain += "<s:Envelope xmlns:s=\"http://schemas.xmlsoap.org/soap/envelope/\">";
               requestMain += "  <s:Body>";
               requestMain += "    <Execute xmlns=\"http://schemas.microsoft.com/xrm/2011/Contracts/Services\" xmlns:i=\"http://www.w3.org/2001/XMLSchema-instance\">";
               requestMain += "      <request i:type=\"a:RetrieveTimestampRequest\" xmlns:a=\"http://schemas.microsoft.com/xrm/2011/Contracts\">";
               requestMain += "        <a:Parameters xmlns:b=\"http://schemas.datacontract.org/2004/07/System.Collections.Generic\" />";
               requestMain += "        <a:RequestId i:nil=\"true\" />";
               requestMain += "        <a:RequestName>RetrieveTimestamp</a:RequestName>";
               requestMain += "      </request>";
               requestMain += "    </Execute>";
               requestMain += "  </s:Body>";
               requestMain += "</s:Envelope>";
               var req = new XMLHttpRequest();
               req.open("POST", SDK.SAMPLES._getServerUrl(), true)
               req.setRequestHeader("Accept", "application/xml, text/xml, */*");
               req.setRequestHeader("Content-Type", "text/xml; charset=utf-8");
               req.setRequestHeader("SOAPAction", "http://schemas.microsoft.com/xrm/2011/Contracts/Services/IOrganizationService/Execute");
               var successCallback = null;
               var errorCallback = null;
               req.onreadystatechange = function () { SDK.SAMPLES.RetrieveTimestampResponse(req, successCallback, errorCallback); };
               req.send(requestMain);
           },
       RetrieveTimestampResponse: function (req, successCallback, errorCallback) {
               ///<summary>
               /// Recieves the assign response
               ///</summary>
               ///<param name="req" Type="XMLHttpRequest">
               /// The XMLHttpRequest response
               ///</param>
               ///<param name="successCallback" Type="Function">
               /// The function to perform when an successfult response is returned.
               /// For this message no data is returned so a success callback is not really necessary.
               ///</param>
               ///<param name="errorCallback" Type="Function">
               /// The function to perform when an error is returned.
               /// This function accepts a JScript error returned by the _getError function
               ///</param>
               if (req.readyState == 4) {
               if (req.status == 200) {
               if (successCallback != null)
               { successCallback(); }
               }
               else {
                   errorCallback(SDK.SAMPLES._getError(req.responseXML));
               }
           }
       },
       _getError: function (faultXml) {
           ///<summary>
           /// Parses the WCF fault returned in the event of an error.
           ///</summary>
           ///<param name="faultXml" Type="XML">
           /// The responseXML property of the XMLHttpRequest response.
           ///</param>
           var errorMessage = "Unknown Error (Unable to parse the fault)";
           if (typeof faultXml == "object") {
               try {
                   var bodyNode = faultXml.firstChild.firstChild;
                   //Retrieve the fault node
                   for (var i = 0; i < bodyNode.childNodes.length; i++) {
                       var node = bodyNode.childNodes[i];
                       //NOTE: This comparison does not handle the case where the XML namespace changes
                       if ("s:Fault" == node.nodeName) {
                       for (var j = 0; j < node.childNodes.length; j++) {
                           var faultStringNode = node.childNodes[j];
                           if ("faultstring" == faultStringNode.nodeName) {
                               errorMessage = faultStringNode.text;
                               break;
                           }
                       }
                       break;
                   }
               }
           }
           catch (e) { };
        }
        return new Error(errorMessage);
     },
 __namespace: true
};

To understand how to parse the response please review my post on using the DOM parser.

http://mileyja.blogspot.com/2011/03/microsoft-dynamics-crm-2011-parsing.html

Now you can call the SDK.SAMPLES.RetrieveTimestampRequest function from your form jscript handler.

Thats all there is to it!

I hope this helps!