Over the past few years, people have become increasingly accustomed to the “always on” Internet, and we expect our devices to be connected all (or at least most) of the time. You should be able to pop open a browser any time you like and have access to information anywhere in the world. You also need email applications to fetch new mail for you whenever it is available, without you having to manually log on somewhere to get it. Other applications, such as RSS feed readers, instant messaging clients, and so on also get information from the Internet in the same way. These are examples of using web services to communicate with other applications that exist somewhere on the Internet.

Figure 8-1 shows the sort of connections you can expect from a Windows Phone 7 application. The application connects to a web service, which can connect to a number of other web services and data sources. The application “consumes” this service and all the functionality it provides, and users of the application might not be aware that this process is occurring.

Web services allow you to send and receive information. For example, you might access a web service for high scores that enables games that you write to send a user's best score to an online database that's available to other users.

It's important to bear in mind that a device's Internet connection may not always be available, and you need to take this into account in your applications. You don't, for example, want a user's hard-fought ...

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