One of the key attributes of Internet standards is that they focus on protocols and not on implementations. The Internet is composed of heterogeneous technologies that successfully interoperate through shared protocols. This prevents individual vendors from imposing a standard on the Internet. Open Source software development plays a crucial role in preserving the interoperability of vendor implementations of standards.
The following standards play key roles in Web services: Universal Description, Discovery and Integration (UDDI), Web Services Description Language (WSDL), and Simple Open Access Protocol (SOAP). The relationship between these standards is described in Figure 2.
The UDDI specification defines open, platform-independent standards that enable businesses to share information in a global business registry, discover services on the registry, and define how they interact over the Internet. For more information on UDDI refer to www.uddi.org
WSDL is an XML-based open specification that describes the interfaces to and instances of Web services on the network. It is extensible, so endpoints can be described regardless of the message formats or network protocols that are used to communicate. Businesses can publish the WSDL documents for their Web services to UDDI and discover the WSDL documents for other Web services in UDDI.. WSDL is described as a separate topic in this documentation. For more information on WSDL, refer to www.w3.org/TR/wsdl
SOAP is an XML-based standard for messaging over HTTP and other Internet protocols. It is a lightweight protocol for the exchange of information in a decentralized, distributed environment. It is based on XML and consists of three parts:
SOAP enables the binding and usage of discovered Web services by defining a message path for routing messages. SOAP is used to query UDDI for Web services. For more information on SOAP, refer to www.w3.org/TR/SOAP