Web services are built using a number of industry-standard protocols. Although covering these in detail is beyond the scope of this book, the following overview will help you understand the architecture of web services.
A protocol is a set of rules that describe the transmission and receipt of data between two or more computing devices. For example, Transmission Control Protocol/Internet Protocol (TCP/IP) governs the low-level transport of packets of data on the Internet.
Hypertext Transfer Protocol (HTTP) is used to enable servers and browsers on the Web to communicate. It is primarily used to establish connections between servers and browsers and to transmit data, such as HTML pages or images, to the client browser.
The client sends an HTTP request to the server, which then processes the request. The server typically returns HTML pages to be rendered by the client browser. HTTP requests start with a verb. The typical verbs used by browsers are GET and POST (web servers also support PUT for creating new resources, DELETE for deleting them, HEAD for getting the metadata for a resource, and others). In a typical HTML form page, GET is used to access the HTML that shows the form and POST is used to process it (for more information visit http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html).
Since the verbs could technically be used interchangeably, there are guidelines for when to use GET and when to use POST. You should use a GET ...