When you perform an action on a human task of a BPM, Case Model, or any other source, validations can be performed before and after the specific action is done. For instance, you may want to restrict a user from claiming more than one task at a time. To do that, you can provide your logic in the OnBeforeClaim hook, which is called when a task or the Case activity is claimed and verifies if the user has already claimed it. If it is found to be claimed already, the user is restricted from claiming this task or the Case activity.
To do this, you must write a Web library as described in the Sample Validations Library. Refer to the table below for a complete list of available validations and refer to Creating a Web Library Definition for creating a Web library in CWS.

After creating the Web library, you must call the action validations defined in this Web library as follows:

1. Update the entry in the XML Store Key /Cordys/notification/task/taskoperationlibraries.xml. If this entry is not present, you can create an XML Store definition from CWS.
2. Add the custom validations library for your model as provided in the sample code snippet below:

   <TaskOperationsLibrary>
       <!--You can provide as many model elements as required.-->
       <model fqn="CasesAndBPMs/Sales">
           <libraryurl>cpc.nsinbox.utils.SalesTasksEventHandler</libraryurl>
       </model>
   </TaskOperationsLibrary>
   

   Note: You can add multiple model nodes in the same XML Store definition entry and specify validation libraries for multiple models.

3. Provide the model names and the relative URLs as many as required in the format provided in the sample code snippet above.

Validations on task action. The following table describes various validations that can be performed on the task actions:

 //In the prototype OnAfterComplete, add the following logic to override the default behavior.
ActivityHookLib.prototype.OnAfterCommit = function(dataObject, callBackFunction)
{
  Workflow.taskView.openTask(sTaskId);
  dataObject.dontOpenNextActivity = true;
  callBackFunction(dataObject);
}

//In the prototype OnAfterComplete add the following code to open Case instance view.
ActivityHookLib.prototype.OnAfterCommit = function(dataObject, callBackFunction)
{
  dataObject.openCaseInstanceView = true;
  callBackFunction(dataObject);
}

 //In the prototype OnAfterSkip add the following logic to override the default behavior.
ActivityHookLib.prototype.OnAfterSkip = function(dataObject, callBackFunction)
{
  Workflow.taskView.openTask(sTaskId);
  dataObject.dontOpenNextActivity = true;
  callBackFunction(dataObject);
}

//In the prototype OnAfterSkip, add the following code to open the Case instance view.
ActivityHookLib.prototype.OnAfterSkip = function(dataObject, callBackFunction)
{
  dataObject.openCaseInstanceView = true;
  callBackFunction(dataObject);
}

//In the prototype OnAfterOpen add the following code, so that the data or UI in the Case Overview tab will not be refreshed while switching between the activities of the same Case model.
ActivityHookLib.prototype.OnAfterOpen = function(dataObject, callBackFunction)
{
  dataObject.isCaseOverviewRefreshRequired = false;
  callBackFunction(dataObject);
}