Learn Java for Web Development

40 CHAPTER 1: Introducing Java Web Development

Note JSON Processing is defined as the Java API for JSON Processing in JSR 353; see Table 1-3.

Two Java APIs facilitate web services:

   JAX-WS: This is based on the Simple Object Access Protocol (SOAP),^29 which

is an XML-based protocol that allows web services and clients to communicate,

even if the client and the web service are written in different languages.

   JAX-RS: This uses Representational State Transfer (REST), which is a network

architecture that uses the Web’s traditional request-response mechanisms such

as GET and POST requests.

Simple Object Access Protocol

The Simple Object Access Protocol (SOAP) is a platform-independent protocol that uses XML to
interact with web services, typically over HTTP. Each request and response is packaged in a SOAP
message, which is XML markup containing the information that a web service requires to process
the message. A SOAP web service works as follows:

1. When a method of a SOAP web service is invoked, the request is packaged
   in a SOAP message enclosed in a SOAP envelope and sent to the server on
   which the web service resides.


2. When the SOAP )web service receives this message, it parses the XML
   representing the message and then processes the message’s contents.


3. Then, the web service, after processing the request, sends the response to
   the client in another SOAP message.


4. The client parses the response.

Representational State Transfer

The term representational state transfer (REST) was introduced and defined in 2000 by Roy Fielding
in his doctoral dissertation^30 at UC Irvine. REST refers to an architectural style for implementing
web services called RESTful web services. Each method in a RESTful web service is identified by a
unique URL.

Note RESTful web services are defined as JSR 339, as shown in Table 1-3.

(^29) http://www.w3.org/TR/soap/
(^30) http://www.ics.uci.edu/~fielding/pubs/dissertation/rest_arch_style.htm