Programming Android, 2nd Edition

Chapter 13. A Content Provider as a Facade for a RESTful Web Service

In Chapter 6, we saw that user interfaces that need to interact with remote services face interesting challenges, such as not tying up the UI thread with long-running tasks. We also noted in Chapter 3 that the Android content provider API shares symmetry with REST-style web services. Content provider data operations map straight onto REST data operations, and now we’ll show you how to translate content provider URIs to request network data. We suggest taking advantage of this symmetry by writing content providers to operate as an asynchronous buffer between the domain or unique aspects of your application, and the network requests that acquire the data on which your application operates. Writing your application in this way will simplify your application, and will solve common UI and network programming errors encountered in Android and other types of Java programming.

Historically, Java UI programmers, both enterprise and mobile, have written mobile and desktop-based applications in a rather brittle way, and sometimes did run network requests directly on the UI thread, often without caching data obtained from those requests. In most applications, showing anything in a UI would require accessing the network every time a user requested the display of data. Believe it or not, Unix workstations from the 1980s and 1990s would frequently lock up when access to remotely mounted filesystems became unavailable. If applications ...