W3C

The W3C Web Services Workshop, led by IBM and Microsoft, has agreed that the architecture stack consists of three components:
Wire, Description, and Discovery.
Wire Stack
The following table shows what layers constitute the Wire Stack.





As you will notice, this Wire Stack has extensions to two layers: SOAP and XML. This means whenever the SOAP is used
as the envelope for the XML messages, they must be attached, secure, reliable, and routed to the intended service requester
or provider. In the stacks of other organizations, SOAP and XML are not treated as "extensions." IBM, for instance, refers
to SOAP as a tool for its stack layer, "XML-Based Messaging."
Description Stack
The Description Stack, the most important component, consists of five layers:




This stack starts with orchestration of business processes from which the messages are sequenced, depending on how service
capabilities are configured. Whatever comes out of the proposal on combining WSFL and MS XLANG that IBM and
Microsoft submitted to the W3C last year will be the tool for the Business Process Orchestration Layer. What needs to be
resolved is to consider what parts of WSFL and MS XLANG are more open than the other: transition-based versus blockstructured
based control flow, and extending versus complementing WSDL among others.
The Service Capabilities Layer is similar to IBM's WSEL as mentioned in IBM WSCA 1.0 and WSFL 1.0 (http://www-
4.ibm.com/software/solutions/Webservices/pdf/WSFL.pdf). Like IBM, the W3C uses WSDL to describe service interface
and service implementation, neither of which is explicitly highlighted in other stacks. WSDL may use a hefty chuck of XML
Schema and takes advantage of SOAP/HTTP bindings to WSDL. SMTP, Reliable HTTP (HTTPR), and HTTP Get are
other possible bindings that could be used.
Discovery Stack
As the name implies, the Discovery Stack involves the use of UDDI, allowing businesses and trading partners to find, discover,
and inspect one another in a directory over the Internet, as follows:







The Inspection Layer refers to WSIL (Web Services Inspection Language) and WS-Inspection specifications. Please refer
to the Microsoft section below for more information on WSIL.
Putting all three stack-components together, we have the Architecture Stack.