SOAP Introduction

SOAP is a simple XML-based protocol that lets applications exchange information over HTTP.

Or more simply: SOAP is a protocol for accessing web services.

Prerequisites

Before proceeding, you should have a basic understanding of the following:

• XML
• XML Namespaces

If you wish to learn these topics first, please visit our XML Tutorial.

What is SOAP?

• SOAP stands for Simple Object Access Protocol
• SOAP is a communication protocol
• SOAP is for communication between applications
• SOAP is a format for sending messages
• SOAP is designed to communicate over the Internet
• SOAP is platform-independent
• SOAP is language-independent
• SOAP is based on XML
• SOAP is simple and extensible
• SOAP allows you to bypass firewalls
• SOAP will be developed as a W3C standard

Why Use SOAP?

For application development, it is important for programs to communicate over the Internet.

Current applications communicate using Remote Procedure Call (RPC) between objects such as DCOM and CORBA, but HTTP was not designed for this purpose. RPC can create compatibility and security issues; firewalls and proxy servers often block such traffic.

Communicating between applications over HTTP is a better approach, as HTTP is supported by all Internet browsers and servers. SOAP was created to fulfill this task.

SOAP provides a standard method that allows applications running on different operating systems and using different technologies and programming languages to communicate with each other.

Microsoft and SOAP

SOAP is a key element in Microsoft's .NET architecture for future Internet application development.

SOAP 1.1 Submitted to W3C

In May 2000, UserLand, Ariba, Commerce One, Compaq, Developmentor, HP, IBM, IONA, Lotus, Microsoft, and SAP submitted the SOAP Internet protocol to W3C. These companies expected the protocol to revolutionize application development by connecting graphical user interface desktop applications to powerful Internet servers using Internet standards (HTTP and XML).

W3C Developing SOAP 1.2

The first public working draft on SOAP was released by W3C in December 2001. To read more about SOAP activities at W3C, please visit our W3C Tutorial.