Alternatives to SOAP

Though SOAP is considered as the standard protocol for web services communication, it is not the only possible transport protocol which is used. SOAP was designed to be extensible so that the other standards could be integrated into it. The WS-* extensions such as WS-Security, WS-Addressing, and WS-ReliableMessaging are associated with SOAP messaging due to this extensible nature. In addition to the platform and language agnosticism, SOAP messages can be transmitted over various transports such as HTTP, HTTPS, JMS, and SMTP among others. However, there are a few drawbacks associated with SOAP messaging. The performance degradations due to heavy XML processing and the complexities associated with the usage of various WS-* specifications are two of the most common disadvantages of the SOAP messaging model. Because of these concerns, we can identify some alternative approaches to SOAP.

REST

Due to the complexities accompanied with the SOAP model, Representational State Transfer (REST) architecture has emerged as a result. RESTful web services can be considered as a lightweight alternative to the bulky and complex SOAP based web service standards. In RESTful web services, the emphasis is on point-to-point communication over HTTP, primarily using plain old XML (POX) messages. We will discuss RESTful web services in detail in Chapter 8, Getting started with REST Testing.

Java Script Object Notation

Java Script Object Notation (JSON) is a lightweight data exchange format similar to XML. It is based on a subset of JavaScript language. JSON uses key value pairs to represent data which are carried inside the message. The following example shows how the XML payload of a SOAP message can be represented in JSON:

The corresponding JSON format of the preceding XML payload is represented by:

You may refer to http://www.json.org for more details about JSON.