UDDI – Overview

UDDI is an XML-based standard for describing, publishing, and finding web services.

• UDDI stands for Universal Description, Discovery, and Integration.

• UDDI is a specification for a distributed registry of web services.

• UDDI is a platform-independent, open framework.

• UDDI can communicate via SOAP, CORBA, Java RMI Protocol.

• UDDI uses Web Service Definition Language(WSDL) to describe interfaces to web services.

• UDDI is seen with SOAP and WSDL as one of the three foundation standards of web services.

• UDDI is an open industry initiative, enabling businesses to discover each other and define how they interact over the Internet.

UDDI has two sections −

• A registry of all web service”s metadata, including a pointer to the WSDL description of a service.

• A set of WSDL port type definitions for manipulating and searching that registry.

History of UDDI

• UDDI 1.0 was originally announced by Microsoft, IBM, and Ariba in September 2000.

• Since the initial announcement, the UDDI initiative has grown to include more than 300 companies including Dell, Fujitsu, HP, Hitachi, IBM, Intel, Microsoft, Oracle, SAP, and Sun.

• In May 2001, Microsoft and IBM launched the first UDDI operator sites and turned the UDDI registry live.

• In June 2001, UDDI announced Version 2.0.

• As the time of writing this tutorial, Microsoft and IBM sites had implemented the 1.0 specification and were planning 2.0 support in the near future.

• Currently UDDI is sponsored by OASIS.

Partner Interface Processes

Partner Interface Processes (PIPs) are XML based interfaces that enable two trading partners to exchange data. Dozens of PIPs already exist. Some of them are listed here −

• PIP2A2 − Enables a partner to query another for product information.

• PIP3A2 − Enables a partner to query the price and availability of specific products.

• PIP3A4 − Enables a partner to submit an electronic purchase order and receive acknowledgment of the order.

• PIP3A3 − Enables a partner to transfer the contents of an electronic shopping cart.

• PIP3B4 − Enables a partner to query the status of a specific shipment.

Private UDDI Registries

As an alternative to using the public federated network of UDDI registries available on the Internet, companies or industry groups may choose to implement their own private UDDI registries.

These exclusive services are designed for the sole purpose of allowing members of the company or of the industry group to share and advertise services amongst themselves.

Regardless of whether the UDDI registry is a part of the global federated network or a privately owned and operated registry, the one thing that ties them all together is a common web services API for publishing and locating businesses and services advertised within the UDDI registry.

UDDI – Elements

A business or a company can register three types of information into a UDDI registry. This information is contained in three elements of UDDI.

These three elements are −

• White Pages,
• Yellow Pages, and
• Green Pages.

White Pages

White pages contain −

• Basic information about the company and its business.

• Basic contact information including business name, address, contact phone number, etc.

• A Unique identifiers for the company tax IDs. This information allows others to discover your web service based upon your business identification.

Yellow Pages

• Yellow pages contain more details about the company. They include descriptions of the kind of electronic capabilities the company can offer to anyone who wants to do business with it.

• Yellow pages uses commonly accepted industrial categorization schemes, industry codes, product codes, business identification codes and the like to make it easier for companies to search through the listings and find exactly what they want.

Green Pages

Green pages contains technical information about a web service. A green page allows someone to bind to a Web service after it”s been found. It includes −

• The various interfaces
• The URL locations
• Discovery information and similar data required to find and run the Web service.

NOTE − UDDI is not restricted to describing web services based on SOAP. Rather, UDDI can be used to describe any service, from a single webpage or email address all the way up to SOAP, CORBA, and Java RMI services.

UDDI – Technical Architecture

The UDDI technical architecture consists of three parts −

UDDI Data Model

UDDI Data Model is an XML Schema for describing businesses and web services. The data model is described in detail in the “UDDI Data Model” chapter.

UDDI API Specification

It is a specification of API for searching and publishing UDDI data.

UDDI Cloud Services

These are operator sites that provide implementations of the UDDI specification and synchronize all data on a scheduled basis.

The UDDI Business Registry (UBR), also known as the Public Cloud, is a conceptually single system built from multiple nodes having their data synchronized through replication.

The current cloud services provide a logically centralized, but physically distributed, directory. It means the data submitted to one root node will automatically be replicated across all the other root nodes. Currently, data replication occurs every 24 hours.

UDDI cloud services are currently provided by Microsoft and IBM. Ariba had originally planned to offer an operator as well, but has since backed away from the commitment. Additional operators from other companies, including Hewlett-Packard, are planned for the near future.

It is also possible to set up private UDDI registries. For example, a large company may set up its own private UDDI registry for registering all internal web services. As these registries are not automatically synchronized with the root UDDI nodes, they are not considered as a part of the UDDI cloud.

UDDI – Data Model

UDDI includes an XML Schema that describes the following data structures −

• businessEntity
• businessService
• bindingTemplate
• tModel
• publisherAssertion

businessEntity Data Structure

The business entity structure represents the provider of web services. Within the UDDI registry, this structure contains information about the company itself, including contact information, industry categories, business identifiers, and a list of services provided.

Here is an example of a fictitious business”s UDDI registry entry −

<businessEntity businessKey = "uuid:C0E6D5A8-C446-4f01-99DA-70E212685A40"
   operator = "http://www.ibm.com" authorizedName = "John Doe">
   <name>Acme Company</name>
   <description>
      We create cool Web services
   </description>
	
   <contacts>	
      <contact useType = "general info">
         <description>General Information</description>
         <personName>John Doe</personName>
         <phone>(123) 123-1234</phone>
         <email>[email protected]</email>
      </contact>		
   </contacts>
	
   <businessServices>
      ...
   </businessServices>
   <identifierBag>	
      <keyedReference tModelKey = "UUID:8609C81E-EE1F-4D5A-B202-3EB13AD01823" 
         name = "D-U-N-S" value = "123456789" />
   </identifierBag>
	
   <categoryBag>	
      <keyedReference tModelKey = "UUID:C0B9FE13-179F-413D-8A5B-5004DB8E5BB2" 
         name = "NAICS" value = "111336" />			
   </categoryBag>		
</businessEntity>

businessService Data Structure

The business service structure represents an individual web service provided by the business entity. Its description includes information on how to bind to the web service, what type of web service it is, and what taxonomical categories it belongs to.

Here is an example of a business service structure for the Hello World web service.

<businessService serviceKey = "uuid:D6F1B765-BDB3-4837-828D-8284301E5A2A"
   businessKey = "uuid:C0E6D5A8-C446-4f01-99DA-70E212685A40">
   <name>Hello World Web Service</name>
   <description>A friendly Web service</description>
   <bindingTemplates>
      ...
   </bindingTemplates>
   <categoryBag />
</businessService>

Notice the use of the Universally Unique Identifiers (UUIDs) in the businessKey and serviceKey attributes. Every business entity and business service is uniquely identified in all the UDDI registries through the UUID assigned by the registry when the information is first entered.

bindingTemplate Data Structure

Binding templates are the technical descriptions of the web services represented by the business service structure. A single business service may have multiple binding templates. The binding template represents the actual implementation of the web service.

Here is an example of a binding template for Hello World.

<bindingTemplate serviceKey = "uuid:D6F1B765-BDB3-4837-828D-8284301E5A2A"
   bindingKey = "uuid:C0E6D5A8-C446-4f01-99DA-70E212685A40">
   <description>Hello World SOAP Binding</description>
   <accessPoint URLType = "http">http://localhost:8080</accessPoint>
   
   <tModelInstanceDetails>
      <tModelInstanceInfo tModelKey = "uuid:EB1B645F-CF2F-491f-811A-4868705F5904">
         <instanceDetails>
            <overviewDoc>
               <description>
                  references the description of the WSDL service definition
               </description>
               
               <overviewURL>
                  http://localhost/helloworld.wsdl
               </overviewURL>
            </overviewDoc>
         </instanceDetails>
      </tModelInstanceInfo>
   </tModelInstanceDetails>
</bindingTemplate>

As a business service may have multiple binding templates, the service may specify different implementations of the same service, each bound to a different set of protocols or a different network address.

tModel Data Structure

tModel is the last core data type, but potentially the most difficult to grasp. tModel stands for technical model.

tModel is a way of describing the various business, service, and template structures stored within the UDDI registry. Any abstract concept can be registered within the UDDI as a tModel. For instance, if you define a new WSDL port type, you can define a tModel that represents that port type within the UDDI. Then, you can specify that a given business service implements that port type by associating the tModel with one of that business service”s binding templates.

Here is an example of a tModel representing the Hello World Interface port type.

<tModel tModelKey = "uuid:xyz987..." operator = "http://www.ibm.com" 
   authorizedName = "John Doe">
   <name>HelloWorldInterface Port Type</name>
   <description>
      An interface for a friendly Web service
   </description>
	
   <overviewDoc>
      <overviewURL>
         http://localhost/helloworld.wsdl
      </overviewURL>
   </overviewDoc>
</tModel>

publisherAssertion Data Structure

This is a relationship structure putting into association two or more businessEntity structures according to a specific type of relationship, such as subsidiary or department.

The publisherAssertion structure consists of the three elements: fromKey (the first businessKey), toKey (the second businessKey), and keyedReference.

The keyedReference designates the asserted relationship type in terms of a keyName keyValue pair within a tModel, uniquely referenced by a tModelKey.

<element name = "publisherAssertion" type = "uddi:publisherAssertion" />
<complexType name = "publisherAssertion">
   <sequence>
      <element ref = "uddi:fromKey" />
      <element ref = "uddi:toKey" />
      <element ref = "uddi:keyedReference" />
   </sequence>
</complexType>

UDDI – Interfaces

A registry is of no use without some way to access it. The UDDI standard version 2.0 specifies two interfaces for service consumers and service providers to interact with the registry.

Service consumers use Inquiry Interface to find a service, and service providers use Publisher Interface to list a service.

The core of the UDDI interface is the UDDI XML Schema definitions. These define the fundamental UDDI data types through which all the information flows.

The Publisher Interface

The Publisher Interface defines sixteen operations for a service provider managing its entries in the UDDI registry −

• get_authToken − Retrieves an authorization token. All of the Publisher interface operations require that a valid authorization token be submitted with the request.

• discard_authToken − Tells the UDDI registry to no longer accept a given authorization token. This step is equivalent to logging out of the system.

• save_business − Creates or updates a business entity”s information contained in the UDDI registry.

• save_service − Creates or updates information about the web services that a business entity provides.

• save_binding − Creates or updates the technical information about a web service”s implementation.

• save_tModel − Creates or updates the registration of abstract concepts managed by the UDDI registry.

• delete_business − Removes the given business entities from the UDDI registry completely.

• delete_service − Removes the given web services from the UDDI registry completely.

• delete_binding − Removes the given web services technical details from the UDDI registry.

• delete_tModel − Removes the specified tModels from the UDDI registry.

• get_registeredInfo − Returns a summary of everything the UDDI registry is currently keeping track of for the user, including all businesses, all services, and all tModels.

• set_publisherAssertions − Manages all of the tracked relationship assertions associated with an individual publisher account.

• add_publisherAssertions − Causes one or more publisherAssertions to be added to an individual publisher”s assertion collection.

• delete_publisherAssertions − Causes one or more publisherAssertion elements to be removed from a publisher”s assertion collection.

• get_assertionStatusReport − Provides administrative support for determining the status of current and outstanding publisher assertions that involve any of the business registrations managed by the individual publisher account.

• get_publisherAssertions − Obtains the full set of publisher assertions that is associated with an individual publisher account.

The Inquiry Interface

The inquiry interface defines ten operations for searching the UDDI registry and retrieving details about specific registrations −

• find_binding − Returns a list of web services that match a particular set of criteria based on the technical binding information.

• find_business − Returns a list of business entities that match a particular set of criteria.

• find_ltservice − Returns a list of web services that match a particular set of criteria.

• find_tModel − Returns a list of tModels that match a particular set of criteria.

• get_bindingDetail − Returns the complete registration information for a particular web service binding template.

• get_businessDetail − Returns the registration information for a business entity, including all services that entity provides.

• get_businessDetailExt − Returns the complete registration information for a business entity.

• get_serviceDetail − Returns the complete registration information for a web service.

• get_tModelDetail − Returns the complete registration information for a tModel.

• find_relatedBusinesses − Discovers businesses that have been related via the uddi-org:relationships model.

UDDI – Usage Example

Consider a company XYZ wants to register its contact information, service description, and online service access information with UDDI. The following steps are necessary −

• Choose an operator with which to work. Each operator has different terms and conditions for authorizing access to its replica of the registry.

• Build or otherwise obtain a UDDI client, such as those provided by the operators.

• Obtain an authentication token from the operator.

• Register information about the business. Include as much information as might be helpful to those searching for matches.

• Release the authentication token.

• Use the inquiry APIs to test the retrieval of the information, including binding template information, to ensure that someone who obtains it can use it successfully to interact with your service.

• Fill in the tModel information in case someone wants to search for a given service and find your business as one of the service providers.

• Update the information as necessary to reflect the changing business contact information and new service details, obtaining and releasing a new authentication token from the operator each time. Whenever you need to update or modify the data you”ve registered, you have to go back to the operator with which you have entered the data.

The following examples will show how the XYZ Company would register its information and how a distributor interested in carrying the XYZ”s product line might find information about how to contact the company and place an order, using the XYZ.com Web services.

Creating Registry

After obtaining an authentication token from one of the operators Microsoft, for example the XYZ.com developers decide what information to publish to the registry and use one of the UDDI tools provided by Microsoft. If necessary, the developers can also write a Java, C#, or VB.NET program to generate the appropriate SOAP messages. Here is an example.

POST /save_business HTTP/1.1
Host: www.XYZ.com
Content-Type: text/xml; charset = "utf-8"
Content-Length: nnnn
SOAPAction: "save_business"

<?xml version = "1.0" encoding = "UTF-8" ?>
<Envelope xmlns = "http://schemas/xmlsoap.org/soap/envelope/">
   <Body>
      <save_business generic = "2.0" xmlns = "urn:uddi-org:api_v2">
         <businessKey = "">
         </businessKey>
         
         <name>
            XYZ, Pvt Ltd.
         </name>
         
         <description>
            Company is involved in giving Stat-of-the-art....
         </description>
         
         <identifierBag> ... </identifierBag>
         ...
      </save_business>
   </Body>
</Envelope>

This example illustrates a SOAP message requesting to register a UDDI business entity for XYZ Company. The key element is blank, because the operator automatically generates the UUID key for the data structure. Most fields are omitted for the sake of showing a simple example.

Company XYZ can always execute another save_business operation to add to the basic information required to create a business entity.

Retrieving Information

After XYZ Company has updated its UDDI entry with the relevant information, companies that want to become XYZ distributors can look up contact information in the UDDI registry and obtain the service descriptions and the access points for the two Web services that XYZ.com publishes for online order entry: preseason bulk orders and in-season restocking orders.

This example illustrates a sample SOAP request to obtain business detail information about the XYZ Company. Once you know the UUID, or key, for the specific business that”s been registered, you can use it in the get_businessDetail API to return specific information about that business.

POST /get_businessDetail HTTP/1.1
Host: www.XYZ.com
Content-Type: text/xml; charset = "utf-8"
Content-Length: nnnn
SOAPAction: "get_businessDetail"

<?xml version = "1.0" encoding = "UTF-8" ?>
<Envelope xmlns = "http://schemas/xmlsoap.org/soap/envelope/">
   <Body>
      <get_businessDetail generic = "2.0" xmlns = "urn:uddi-org:api_v2">
         <businessKey = "C90D731D-772HSH-4130-9DE3-5303371170C2">
         </businessKey>
      </get_businessDetail>
   </Body>
</Envelope>

UDDI With WSDL

The UDDI data model defines a generic structure for storing information about a business and the web services it publishes. The UDDI data model is completely extensible, including several repeating sequence structures of information.

However, WSDL is used to describe the interface of a web service. WSDL is fairly straightforward to use with UDDI.

• WSDL is represented in UDDI using a combination of businessService, bindingTemplate, and tModel information.

• As with any service registered in UDDI, generic information about the service is stored in the businessService data structure, and information specific to how and where the service is accessed is stored in one or more associated bindingTemplate structures. Each bindingTemplate structure includes an element that contains the network address of the service and has associated with it one or more tModel structures that describe and uniquely identify the service.

• When UDDI is used to store WSDL information, or pointers to WSDL files, the tModel should be referred to by convention as type wsdlSpec, meaning that the overviewDoc element is clearly identified as pointing to a WSDL service interface definition.

• For UDDI, WSDL contents are split into two major elements the interface file and the implementation file.

The Hertz reservation system web service provides a concrete example of how UDDI and WSDL works together. Here is the <tModel> for this web service −

<tModel authorizedName = "..." operator = "..." tModelKey = "...">
   <name>HertzReserveService</name>
   <description xml:lang = "en">
      WSDL description of the Hertz reservation service interface
   </description>
	
   <overviewDoc>
      <description xml:lang = "en">
         WSDL source document.
      </description>
      <overviewURL>
         http://mach3.ebphost.net/wsdl/hertz_reserve.wsdl
      </overviewURL>
   </overviewDoc>
   
   <categoryBag>
      <keyedReference tModelKey = "uuid:C1ACF26D-9672-4404-9D70-39B756E62AB4"
         keyName = "uddi-org:types" keyValue = "wsdlSpec"/>
   </categoryBag>	
</tModel>

The key points are −

• The overviewURL element gives the URL to where the service interface definition WSDL file can be found. This allows humans and UDDI/WSDL aware tools to locate the service interface definition.

• The purpose of the keyedReference element in the categoryBag is to make sure that this tModel is categorized as a WSDL specification document.

UDDI – Implementations

A number of UDDI implementations are currently available. These implementations make it easier to search or publish UDDI data, without getting mired in the complexities of the UDDI API. Here is a brief synopsis of the main UDDI implementations available.

Java Implementations

There are two UDDI implementations for Java.

• UDDI4J (UDDI for Java) − UDDI4J was originally created by IBM. In January 2001, IBM turned over the code to its own open source site. UDDI4J is a Java class library that provides an API to interact with a UDDI.

• jUDDI − jUDDI is an open source Java implementation of a UDDI registry and a toolkit for accessing UDDI services.

Perl Implementation

• UDDI::Lite − It provides a basic UDDI client for inquiry and publishing.

Ruby Implementation

• UDDI4r − It provides a basic UDDI client for inquiry and publishing.

Python Implementation

• UDDI4Py − UDDI4Py is a Python package that allows the sending of requests to, and processing of responses from the UDDI Version 2 APIs.

UDDI – Specifications

The UDDI project also defines a set of XML Schema definitions that describe the data formats used by the various specification APIs. These documents are all available for download at www.uddi.org. The current version of all specification groups is Version 2.0.

The specifications include the following −

• UDDI Replication,
• UDDI Operators,
• UDDI Programmer”s API, and
• UDDI Data Structures

UDDI Replication

This document describes the data replication processes and interfaces to which a registry operator must conform to achieve data replication between sites. This specification is not a programmer”s API; it defines the replication mechanism used among UBR nodes.

UDDI Operators

This document outlines the behavior and operational parameters required by the UDDI node operators. This specification defines data management requirements to which operators must adhere.

UDDI Programmer”s API

This specification defines a set of functions that all UDDI registries support for inquiring about services hosted in a registry and for publishing information about a business or a service to a registry. This specification defines a series of SOAP messages containing XML documents that a UDDI registry accepts, parses, and responds to. This specification, along with the UDDI XML API schema and the UDDI Data Structure specification, makes up a complete programming interface to a UDDI registry.

UDDI Data Structures

This specification covers the specifics of the XML structures contained within the SOAP messages defined by the UDDI Programmer”s API. This specification defines five core data structures and their relationships with one another.

The UDDI XML API schema is not contained in a specification; rather, it is stored as an XML Schema document that defines the structure and datatypes of the UDDI data structures.

UDDI – Summary

UDDI and its elements in this tutorial and have also seen the complete architecture and the data model of UDDI.

We have learned about the two UDDI interfaces: Publisher”s Interface and Enquiry Interface. We have also learned how to register and search for web services with UDDI.

What”s Next?

The next step is to learn about SOAP, WSDL, and Web Services.

SOAP

SOAP is a simple XML-based protocol that allows applications to exchange information over HTTP.

If you want to learn more about SOAP, please visit our SOAP tutorial.

WSDL

WSDL is the standard format for describing a web service in XML format.

WSDL is an integral part of UDDI.

If you want to learn more about WSDL, please visit our WSDL Tutorial.

Web Services

Web services can convert your applications into web-applications.

If you want to learn more about web services, please visit our Web Services tutorial.

UDDI – API Quick References

Here is the complete reference of the UDDI Enquiry APIs and the UDDI Publishing APIs.

The UDDI Inquiry APIs

The UDDI Publishing APIs

Error Code Reference

A complete reference of error codes returned by UDDI APIs is as given −

Error Codes