INTRODUCING UDDI

The world of business communication and integration is rapidly changing.
In the past, different methods were used to connect businesses and their
applications to one another. Implementing changes to these connections
and integrations was often slow and tedious, however. As a result, a new
architecture based on services rather than applications or technology has
emerged. This service-based architecture allows organizations to reduce
the time required to integrate complex systems and to more efficiently
respond to changes. One of the cornerstones of this service-based
architecture is a new technology called Universal Description, Discovery and
Integration (UDDI), a protocol that will change the way businesses and their
services communicate.

OVERVIEW

UDDI is more than just a protocol; it's also a paradigm and architecture
for implementing service-based integration. Developed and maintained by
a global community of organizations (including Microsoft, IBM, and
Fujitsu), the goal of UDDI is to assist in locating businesses and services and
to provide a common method for loosely integrating with these services.

UDDI is based on common Web standards, such as eXtensible Markup
Language (XML), Simple Object Access Protocol (SOAP), and Hypertext Transfer
Protocol (HTTP). Similar to Domain Name System (DNS), UDDI is based on the
registration of Web services using various registry operators. The
registry is accessed via SOAP, while the particular Web services in the registry
are accessed through one of several protocols (such as ebXML, CORBA, or
Java RMI). Services in the registry are described using methods such as
Web Services Definition Language (WSDL) or Web Services Conversation
Language (WSCL).

UNIVERSAL REGISTRIES

One of the key components of the UDDI protocol is the registry. A UDDI
registry is a collection of Web service descriptions. Companies that
provide Web services enter their information into the registry for discovery
by other companies. Services are registered using a WSDL document or some
other description method.

Companies discover services by searching the registry. Each company can
classify itself and its services in a number of ways. A user or
application can search the registry for companies using one of several methods: by
company name, by their Dunn and Bradstreet (DUNS) number, by industry
code (e.g., SIC or NAICS), etc.

SERVICE DESCRIPTIONS

Services are described in a variety of ways in the UDDI registry. Many
services are described using the WSDL. This XML grammar provides the
technology to describe Web services; multiple services can be described in a
single WSDL document. Each service is broken down into one or more
operations. Each operation is described by what it does, as well as the input
and output parameters and their associated protocol bindings.

SERVICE DISCOVERY

Service discovery is based on a search of the UDDI registry. Services
are located by looking up a business name, location, URL, NAICS code, SIC
code, UN/SPSC code, ISO 3166 Geographic Taxonomy code, RealNames keyword,
or some other identifier. Once a business is located, its services can be
discovered. Services are found by retrieving the XML document pointed to
by the business' discovery URL. The discovery URL XML document contains
information about the business, as well as its registered services.

A unique string, called a service key, identifies each business service.
The service also contains a name, description, and access information.
Some services are accessed by simple HTTP requests, while others use SOAP
or CORBA.

INTEGRATION

Integrating services described by UDDI involves all of the components
discussed above. By using a registry to house the service descriptions, it
is easy to adapt to variations in service protocols. For example, new
services can be discovered as soon as they're available, and existing
services can respond to parameter modifications.

Because the integration is only loosely coupled with the service
descriptions, services can be changed to incorporate new behavior without
crashing running systems. UDDI also offers a somewhat standard approach to
integrating business-to-business (B2B) services. Companies and organizations
that adopt UDDI as a part of their integration strategy will be able to
easily expose their services to their business partners.

SUMMARY

UDDI is a new approach to the old problem of integrating business
services. By providing a reliable registry service and a common method of
discovery and description, UDDI offers a standardized solution to implementing
a service-based architecture that can integrate beyond the enterprise.

Brian Schaffner is a senior consultant for DMR Consulting, a Fujitsu
company. He provides architecture, design, and development support for DMR's
Telcom360 group.

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