Chapter 10
Networking
WHAT YOU WILL LEARN IN THIS CHAPTER
- How to connect to the web using HTTP
- How to consume XML web services
- How to consume JSON web services
- How to connect to a Socket server
In Chapter 8, you learned about how your application can talk to the outside world through the use of SMS messaging and e-mails. Another way to communicate with the outside world is through the wireless network available on your Android device. Therefore, in this chapter you will learn how to use the HTTP protocol to talk to web servers so that you can download text and binary data. You will also learn how to parse XML files to extract the relevant parts of an XML document — a technique that is useful if you are accessing web services. Besides XML web services, this chapter also covers JSON (JavaScript Object Notation), which is a lightweight alternative to XML. You will make use of the classes available in the Android SDK to manipulate JSON content.
Finally, this chapter also demonstrates how to write an Android application to connect to servers using TCP sockets. Using sockets programming, you can write sophisticated, interesting networked applications.
CONSUMING WEB SERVICES USING HTTP
One common way to communicate with the outside world is through HTTP. HTTP is no stranger to most people; it is the protocol that drives much of the web’s success. Using the HTTP protocol, you can perform a wide variety of tasks, such as downloading web pages from a web server, downloading binary data, ...
