Hi,
Let me see if I understand the problem.
You have many extract files that arrive at various points in times. These files are to be processed, sometimes in specified order.For example if FileA has to be processed before FileB can be processed, then, if FileB arrives first, it must not be processed.
The tool that you are creating should wait until FileA arrives and is processed successfully.
This is essentially a workflow problem. Many vendors provide software solutions for these types of situations.
If you are developing in-house solutions, then the process that runs FileB must check if FileA has been processed before starting work on FileB.
In a Unix environment, you could create a shell script that does this. In a loop, it could check if FileA has been processed. If yes, process FileB. If not, "sleep" for some time and then repeat until FileA has been processed.
More complicated situations can be handled in a similar manner. Alternatively, you could use your database management system's scheduler to accomplish the same task.
Was that what you were looking for? Or did I misunderstand your problem?
Ravi