I am developing a solution in .Net utilising the VMWare Web Service API to create new isolated virtualised development environments.

The front end will be web based. Requestors input details for the specific environment which will be persisted to SQL. So I need to write an engine of some sort to pull the data from SQL and work on the long running task of creating resource pools, switch port groups and cloning existing VM templates etc. As work progresses, events will be raised to write logs and update info back to SQL. This allows requestors to pull data back into a webpage to see how it's progressing or if it's completed.

The thing I am struggling with is how to engineer the engine which will exec the long running task of creating the environment. I cannot write a windows service (which I would like) as we work in a very secure environment and it's not possible (group policy etc). I could write a web service to execute the tasks, extending the httpRuntime executionTimeout to allow the task to complete. But I'm keen to hear what you guys think may be a better solution to use (based on .Net 3.5). The solution needs to be service oriented as we may be using it on other projects within our org. What about WWF, WCF? I have not used any of the newer technologies available since .Net 2.0 as we've only just been approved to move up from .Net 2.0.