Stands for "Simple Object Access Protocol," and can do more than just get your hands clean. SOAP is a method of transferring messages, or small amounts of information, over the Internet. SOAP messages are formatted in XML and are typically sent using HTTP (hypertext transfer protocol). Both are widely supported data transmission standards. HTTP, which is the protocol that Web pages are sent over, has the additional advantage of avoiding most network firewalls. Since firewalls usually do not block port 80 (HTTP) traffic, most SOAP messages can pass through without any problems.
Each SOAP message is contained in an "envelope" that includes a header and a body. The header may include the message ID and date the message was sent, while the body contains the actual message. Because SOAP messages all use the same format, they are compatible with many different operating systems and protocols. For example, a user can send a SOAP message from a Windows XP machine to a Unix-based Web server without worrying about the message being altered. The Unix machine can then redirect the message to the appropriate location or open the file using a program on the system. While most SOAP messages are sent over the Web via HTTP, they can also be sent via e-mail, using SMTP.