服务代理对话的最佳实践：我可以打开多少个，打开多长时间？

Question

I'm designing a system that will issue commands (via service broker) that a user may wish to undo. My thinking was that I could use a pattern like this:

1. Create a conversation
2. Send the "do command" message on the newly created conversation
3. Keep the conversation open..
4. If user wishes to undo, send the undo message on the conversation
5. Close conversation

This keeps messages in order (the undo command cannot appear before the initial command it must "undo"), I recognize that this may keep many conversations open indefinitely as users for the most part will not wish to perform an undo. Would this be a performance problem? Is there an alternative using service broker?

Answer 1

You can hold them open for as long as you like, but you probably don't want them to live forever on the system. Is there a period of time after which you can reasonably infer that you are not going to get an undo? An hour perhaps or by the end of the business day?

You can give conversations a maximum lifetime so you can clear them down once you're satisfied that they are logically committed.