This post expands on the handling of hit determination and merging server and local changes of cache pattern, which’s design pattern for building an offline-capable web application. It’s implemented to make Gmail for Mobile tolerant of flaky wireless connections but the approach is generally applicable. Here's how it works. Consider a typical AJAX application. As shown in the diagram, we have a web application with a local model, view and controllers. The user interacts with theapplication and the controller dispatches XmlHttpRequests (XHRs for short) to the server. The server sends asynchronous requests to the application which it inserts into the model.

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