Web Services Protocols

SOAP

Simple Object Access Protocol (SOAP) is a standard for exchanging structured information, and in IBM web services, it uses XML format over HTTPS. SOAP requires a WSDL (Web Services Description Language) file to describe the payload for XML messages.

SOAP defines three parts to every message:

• Envelope
• Encoding rules
• Communication styles

The SOAP envelope defines a framework for describing what is in a message and how to process it. A SOAP message is an envelope containing zero or more headers and exactly one body. The envelope is the top element of the XML document, providing a container for control information, the address of a message, and the message itself. Headers transport any control information such as quality-of-service attributes. The body contains the message identification and its parameters. Both the headers and the body are child elements of the envelope.

SOAP envelopes of version 1.1 or 1.2 are supported.

HTTPS

Hypertext Transfer Protocol Secure (HTTPS) is a widely-used communications protocol for secure communication. Technically, it is not a protocol in itself; rather, it is the result of layering the Hypertext Transfer Protocol (HTTP) on top of the Secure Sockets Layer (SSL)/Transport Layer Security (TLS) protocol, thus adding the security capabilities of SSL/TLS to standard HTTP communications. For IBM web services, HTTPS is a non-standard protocol, with SOAP being the standard protocol.

HTTPS is typically used for XML-based messages, but can be used for binary or flat files as well.