Web Services - Enabling Semantic Web Services: The Web Service Modeling Ontology - page 45

UDDI provides a data model for services and business entities. More con-
cretely, it provides three categories of information: white, yellow, and green
pages. This model provides related information to a service such as the name,
address, telephone number, and other contact information of a given appli-
cation; basically, any information that categorizes applications, and technical
information about the Web services provided by a given application.
Initially, big vendors such as Microsoft and SAP operated public UDDI
services and connected them to an UDDI Business Registry (UBR) as a single
entry point for service searches. However, UDDI has not been successful in
the area of public Web services. UBR has been discontinued, and only smaller
providers such as XMethods still provide an UDDI interface as an additional
means for accessing their service repository.
The continued development of the UDDI product, however, indicates that
the technology is still relevant for intranet and extranet usage. We shall briefly
take a more detailed look at what information can be advertised:

• Application information. This is contained in a business entity object,

which in turn contains information about services, categories, contacts,
URLs, and other things necessary to interact with a given application.

• Service information. This describes a group of Web services. These are

contained in a business service object.

• Binding information. The technical details necessary to invoke a Web ser-

vice. This includes URLs, information about method names, argument
types, and so on. The binding template object represents this data.

• Service specification detail. This is metadata about the various specifica-

tions implemented by a given Web service. These are called tModels in the
UDDI specification.

To illustrate the categorization information in UDDI we have browsed the
XMethods UDDI repository using the Web Service Explorer 7 and depicted
the information for the GlobalWeather service used in the previous subsec-
tion (Listing 4.3). Using key value pairs, one can assign a service to specific
categories, similar to using a geographical code or a standard product classi-
fication such as UNSPC. 8
An interesting remark on the annotation can be made here: the key value
pairs in the annotation provide good hints about what the service does; how-
ever, just reusing standard taxonomies and not making the context explicit
does leave some questions open. For example, the geo taxonomy unambigu-
ously describes a location; however, by just placing it in the context of a
service interface the intended meaning remains unspecified. In this case the

7 The Web Service Explorer is a client that can browse and edit UDDI entries as
part of the Eclipse Web Tools Platform (WTP) project; see http://www.eclipse.
org/webtools .
8 To illustrate the annotation, we have manually added this information to the
service, since the original public service has only minimal information.