RESTful web services and delta updates

I'm writing client code (desktop/mobile a开发者_如何学编程pps) that interact with RESTful web services for a while. I wonder that such services don't allow you to get delta updates.

I currently write an app that notifies you about new issues added to your Redmine. So I need to download all issues again and then compare them with that I downloaded before. That's very bad solution sir, since there may be dozens of issues.

I'd like to know why RESTful web services don't give you an option to download delta updates. Does it contradict the basic idea of RESTful? Or probably the solution is too obvious to document it?

Too domain-specific to document. Any RESTful application would not find it hard to add new resources that you can GET to see deltas, if only they knew that's what their clients wanted. Have you asked the Redmine group for this feature?