Posted: Sep. 23, 2002

GXA is a layered architecture built upon baseline Web service specifications (bottom), such as Simple Object Access Protocol (SOAP), Universal Data Discovery Interface (UDDI), and Web Services Description Language (WSDL).

The GXA protocols above the baseline can be divided into two layers. The first layer (middle) is SOAP modules, such as WS-Security and WS-Attachments. These protocols are primarily concerned with the content and structure of an individual message. For example, the Security specification describes (among other things) how security information, such as a Kerberos ticket, is embedded in a SOAP message.

The second layer (top) is composed of infrastructure protocols such as Transaction and reliable messaging. Infrastructure protocols describe how sequences of a message are put together to solve business problems. The Transaction specification, for example, describes the flow of a SOAP message sent between a set of Web services that need to work together to coordinate a series of database updates.

Some of the GXA protocols are already defined or even partially implemented (such as WS-Security and WS-Transaction) while others, most notably reliable messaging, have yet to be specified.