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In a previous article Top 10 Best Practices Using VMware VI and vSphere SDK, I mentioned synchronous versus asynchronous calls in the second best practice “Choose Right APIs.” But no detail was provided there. In this article, which is based on my book VMware VI and vSphere SDK , I discuss all the details.

Some methods defined on managed objects in vSphere API are asynchronous, meaning they return right away whether the operations are done successfully or not. That makes sense for long-running operations; you don’t want to block your current thread by waiting for the return of the call, and you might want to cancel it before it’s done.

For these asynchronous methods, the VI SDK provides a way to track the progress and results after the invocation is returned. As a naming convention, a long-running asynchronous method has _Task as a suffix in the method name, and it returns MOR to a Task. With MOR pointing to the Task object, you can track the progress and even get the result of the operation. For example, the cloneVM_Task() method defined in VirtualMachine is a long-running method that returns MOR pointing to a Task managed object.  Read more... (484 words, estimated 1:56 mins reading time)