Question

We are developing a web application in ASP.Net and C#. The requirement here is to interact with a third party exe which is developed in Fortran77. This third party exe produces an output file after being provided with some inputs and shuts down.In windows desktop single user application this is easily possible by using System.Diagnostics.Process and the events provided therein. But in web there will be multi-user environment, and many calls will be made to this exe. What are the best possible ways to handle such an exe in web application?

1. Is it fine if we invoke exe on each user request as the exe shuts down after generating output file? Or
2. Is it possible to use windows service? Or
3. Any other approach?

Thanks in advance.
-Prasad

Answer 1

Typically, invoking a different process to do some job (for a request) does not scale well when your number of requests start growing. Said that, if the process invocation is not going to happen frequently then you should be OK. The number of concurrent requests and through-put etc will really depend on your server hardware and the best bet would be to load test the server. As such you should use Process class to launch the process to get the work done.

Yet another issue that is possible that your legacy executable does not support multiple instance. It’s unlikely but there are quite a few desktop windows application that check for existing instance. So in such, you cannot launch process concurrently and only way would be to create a queuing logic – you can create a in-process queue (in your web application) or create a external application (such as windows service) that will do queuing.

There can be alternate approach for this solution that is useful when the time taken for process to complete is large (so that you cannot block your web requests till the job is complete) and/or you need to scale your app to support more load. Essentially idea is use producer-consumer pattern where your web server will add requests to a persisted (e.g. table in database) queue and then you have multiple machines/servers running a job/windows service that would read from this queue and run the process to generate file.