SOAP XML and its features

Simple Object Access Protocol (SOAP) is a protocol that can be used for accessing the Web pages. SOAP or Simple Object Access Protocol is an XML based Object invocation Protocol. SOAP was developed for distributed applications to communicate through HTTP and firewalls. SOAP is platform independent and it uses XML and HTTP to access services, servers and objects.

SOAP consists of 3 parts:

* SOAP ENVELOPE: Defines a framework for expressing what is in a message and who should handle it. The SOAP envelope namespace defines header and body element names and the encoding style.

* SOAP ENCODING RULES: Defines a mechanism for exchanging instances of application defined data types. An encoding rule means an encoding style to know how it is applied to a specific data.

* SOAP RPC: Defines a method to represent Remote Procedure Calls and responses. Soap RPC uses a request/response model for message exchanges. The request that is sent to the end point is the call and the response it sends represents the result of the call sent.

SOAP has the following features:

* PROTOCOL independence
* LANGUAGE independence
* PLATFORM AND OS independence

SOAP is a way by which programs communicate with other programs using XML.SOAP uses XML to encapsulate data that needs to be sent to a remote subroutine. In more simple terms SOAP is a way by which Java objects and COM objects communicate with each other. A SOAP client is a program that creates an XML document that contains information required to invoke a method remotely in a distributed system.

A SOAP server is a code that listens to the SOAP messages and acts as a distributor and an interpreter. SOAP defines encoding rules called Base level codings. The encodings can be either

* SIMPLE ENCODINGS
* COMPOUND ENCODINGS

SIMPLE ENCODINGS are simple types like ints, floats, strings or user defined data types. These include data types such as arrays of bytes and Enumerations.

COMPOUND ENCODINGS include data types such as arrays and structures.

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