Web Service Protocol Stack in a Nutshell
The Web service protocol stack is mainly comprised of four areas:
- Service Transport: It is responsible for transporting messages between network applications and includes protocols such as HTTP, SMTP, FTP, as well as the more recent Blocks Extensible Exchange Protocol (BEEP).
- XML Messaging: It is responsible for encoding messages in a common XML format so that messages can be understood at either end of the network connection. Currently, this area includes such protocols as XML-RPC and SOAP.
- Service Description: It is used for describing the public interface to a specific web service. The WSDL protocol is typically used for this purpose.
- Service Discovery: It centralizes services into a common registry such that network web services can publish their location and description, and makes it easy to discover what services are available on the network. At present, the UDDI protocol is normally used for service discovery.
XML: All data to be exchanged is formatted with XML tags. This encoding can be performed by SOAP or XML-RPC (note: industry standards for security, interoperability, etc. are based on SOAP).
Common protocols: XML data can be transported between applications using common protocols such as HTTP, FTP, SMTP and XMPP.
WSDL: The public interface to the web service is described by Web Services Description Language, or WSDL. This is an XML-based service description on how to communicate using the web service.