An XML-based registry for businesses worldwide to list themselves on the internet. Its primary purpose is to serve as a directory for Web Services, allowing companies to discover one another and define how they interact online.
The Three Pillars of UDDI
A UDDI registration consists of three specific component types that help a client find exactly what they need:
- White Pages: Contains basic contact information (business name, address, and unique identifiers).
- Yellow Pages: Categorizes businesses by industry standards (e.g., NAICS codes or geographic locations).
- Green Pages: Provides technical information about the services offered, including references to the service’s WSDL files and technical specifications.
UDDI in the Web Services Stack
UDDI is one of the three foundational technologies that enable Service-Oriented Architecture (SOA). It works in a specific lifecycle:
- Publish: A service provider registers its business and technical interface in the UDDI directory.
- Find: A service consumer searches the UDDI registry for a service that meets their criteria.
- Bind: Once found, the consumer uses the technical details (from the Green Pages) to connect to and use the service.
UDDI Characteristics
| Feature | Description |
| Format | XML-based data model. |
| Communication | Uses SOAP to query and update the registry. |
| Visibility | Can be Public (global business directory) or Private (internal to a large corporation). |
| Primary Goal | Interoperability and dynamic discovery of web services. |
Current Usage
While UDDI was a core part of the original Web Services vision, public UDDI registries (like those once hosted by Microsoft and IBM) have largely been shut down. Today, UDDI is primarily used in private enterprise environments to manage internal catalogs of APIs and services, while RESTful ecosystems typically use more modern Service Discovery tools.