Universal Description, Discovery and Integration (UDDI) protocol is one of the major building blocks required for successful Web services. UDDI creates a standard interoperable platform that enables companies and applications to quickly, easily, and dynamically find and use Web services over the Internet (or Intranet). UDDI is a technology for publishing, querying, finding, and invoking Web services using a registry that provides data, metadata, and pointers to these services.
Universal Description Discovery and Integration (UDDI) is a standard sponsored by OASIS (Organization for the Advancement of Structured Information Standards). Often described as the yellow pages of Web services, UDDI is a specification for creating an XML-based registry that lists information about businesses and the Web services they offer.
UDDI provides businesses a uniform way of listing their services and discovering services offered by other organizations. Though implementations vary, UDDI often describes services using WSDL and communicates via SOAP messaging. Registering a Web service in a UDDI registry is an optional step, and UDDI registries can be public or private (i.e. isolated behind a corporate firewall). To search for a Web service, a developer can query a UDDI registry to obtain the WSDL for the service he/she wishes to utilize. Developers can also design their Web services clients to receive automatic updates about any changes to a service from the UDDI registry.
If a web service is to be used, the information about how to access it must be published. Universal Description, Discovery, and Integration (UDDI) allow a web service’s access information, like location, WSDL, and owner, to be published. The main purpose of UDDI is to provide an API for publishing and discovering information about a web service. UDDI specifies a framework that “will enable businesses to:
- Discover each other
- Define how they interact over the Internet
- Share information in a global registry that will more rapidly accelerate the global adoption of B2B e-Commerce .”
Universal Description, Discovery, and Integration (UDDI) provides the definition of a set of services supporting the description and discovery of (1) businesses, organizations, and other Web Services providers, (2) the Web Services they make available, and (3) the technical interfaces which may be used to access those services. The idea is to “discover” organizations and the services that organizations offer, much like using a phone book or dialing information. UDDI is based on a common set of industry standards, including HTTP, XML, XML Schema, and SOAP. It provides an infrastructure for a Web Services-based software environment for both publicly available services and services only exposed internally within an organization. The UDDI Business Registry system consists of three directories:
- UDDI white pages: basic information such as a company name, address, and phone numbers, as well as other standard business identifiers like Dun & Bradstreet and tax numbers.
- UDDI yellow pages: detailed business data, organized by relevant business classifications. The UDDI version of the yellow pages classifies businesses according to the newer NAICS (North American Industry Classification System) codes, as opposed to the SIC (Standard Industrial Classification) codes.
- UDDI green pages: information about a company’s key business processes, such as operating platform, supported programs, purchasing methods, shipping and billing requirements, and other higher-level business protocols.
The UDDI technology “is a layer on top of standards-based technologies such as TCP/IP, HTTP, XML, and SOAP to form a uniform service description format and service discovery protocol.” See figure 1 for the relationship between UDDI and these other technologies.
Figure 1: UDDI Technology Overview
 Sean MacRoibeaird, Universal description, discovery & integration (UDDI), an executive summary, XML at Sun: Developer Connection, December 2003.
 “Service Architecture: Universal Description, Discovery, and Integration (UDDI)”, https://www.service-architecture.com/articles/web-services/universal_description_discovery_and_integration_uddi.html
 “Chapter 1. Universal Description, Discovery and Integration (UDDI)”, https://juddi.apache.org/docs/3.2/juddi-guide/html/ch01.html