Microsoft Dynamics CRM 2013 Unleashed

When to Use a Plug-In

Use a plug-in when you need to integrate Microsoft Dynamics CRM with a legacy system or when you want to extend or customize the original functionality or behaviors of Microsoft Dynamics CRM.

Plug-ins are the best choice to enforce the business rules of your business. You could use JavaScript events or Business Rules to add validation on the rules you want to enforce; however, those types of validations will work only when CRM is used through the native interfaces (such as the web or Outlook client). If we remember that other applications can be interacting with the CRM system through the web services, service endpoints, and so on, the validations and rules enforcement will work always if we put them on plug-ins. Plug-ins ...