Thanks in advance for your time and answers.

* I have multiple, say 3 AWS EC2 windows instances.
* I have .NET executables A, B and C in each of the 3 windows instances. (I could also have java programs in the mix)
* They need to be run, one after the other, in a workflow like fashion, depending on the outcome of the previous executable. i.e B should run after A has succeeded; C should run after B has succeeded etc. In short, I am looking to
achieve a work flow.
* Being in the AWS, I looked at Amazon Simple Workflow; however to me
to use that, I need to weave in the AWS SWS SDK in the .NET code. But
unfortunately I only have the executable and am not allowed to
rebuild that.
* I also have the Amazon Simple Queue Service and notification service in
mind. 

**But is there a better and preferred way to achieve this ?**