UDDI and WS-Inspection

We describe the Universal Description, Discovery, and Integration project. This talk is based on:

• James Snell, Doug Tidwell, and Pavel Kulchenko. Programming Web Services with SOAP [1]. 2002. Chapter 6
• Tyler Jewell and Dave Chappell UDDI: Universal Description, Discovery, and Integration Part 1 [2]

• Once everyone posts the WSDL description of their service, how do you find the service you need?
• The Universal Description, Discovery, and Integration of Business for the Web [3] project is an industry effort to define a registry where users can automatically discover the services they need (and rent them).
• They publish the official UDDI Specification [4].
• UDDI has two parts
  • A registry of all the web service's metadata.
  • A set of WSDL port type definition for manipulating and searching the registry.

• Allows a business to publicly list a description of itself and the services it provides.
• Customers will go to it and locate what they want based on taxonomical information.
  • e.g. who provides weather reports for offshore vessels?
• The registry itself is defined as a hierarchy of business, service, and binding descriptions expressed in XML.

• The business entity structure represents the provider of web services.
• It contains information about the company itself: contact information, industry categories, business identifiers, and a list of services provided.

<businessEntity 
                businessKey="uuid:dkeieie-sdfsdf-sdfs-3343334342234"
                operator="http://www.ibm.com"
                authorizedName="John Palms">
  <name>Acme Company</name>
  <description>
    We make things that go wrong.
  </description>
  <contacts>  
    <contact useType="general info">
      <description>General Information</description>
      <personName>John Doe</personname>
      <phone>(803) 777-0234</phone>
      <email>jdoe@acme.com</email>
    </contact>
  </contacts>
  <businessServices>
    ...
  </businessservices>
  <identifierBag>
    <keyedReference
                    TModelKey="UUID:8989df-09df0df9-eede"
                    name="D-U-N-S"
                    value="123456"/>
  </identifierbag>
  <categoryBag>
    <keyedReference
                    TModelKey="UUID:eer90-erere99-9898e-ee3"
                    name="NAICS"
                    value="12334455"/>
  </categorybag>
</businessEntity>

• It contains information such as the name, description, contacts, categories, and business keys.

• Includes information about how to bind to the web service, what type of web service it is, and what taxonomical categories it belongs to.
• The Universally Unique Identifiers (UUID) are assigned by the registry when the information is first entered.

<businessService serviceKey="uuid:udjeei-ded3-d33343"
                 businessKey="uuid:ccdkjd898-98cd9-cddd">
  <name>Hello World Web Service</name>
  <description>A basic web service</description>
  <bindingTemplates>
    ....
  </bindingtemplates>
  <categoryBag/>
</businessService>

• Technical descriptions of the web services represented by the business service structure.
• One service might have multiple binding templates.
• The binding template represents the implementation of the web service, i.e., what protocol, network address, etc. it uses.

<bindingTemplate serviceKey="uudi:123"
                 bindingKey="uuid:abd45">
  <description>Hellow World SOAP binding.</description>
  <accessPoint URLType="http">
    http://localhost:8080
  </accesspoint>
  <TModelInstanceDetails>
    <TmodelInstanceInfo
                        TModelKey="uuid:abfdg">
      <instanceDetails>
        <overviewDoc>
          <description>
            references the description of the WSDL
            service definition.
          </description>
          <overviewURL>
            http://localhost/helloworld.wsdl
          </overviewURL>
        </overviewDoc>
      </instanceDetails>
    </TModelInstanceInfo>
</bindingTemplate>

• A TModel is a way of describing the various business, service, and template structures stored within the UDDI registry.
• For example, you can define a TModel to represent a WSDL port type then associate the TModel with one of the business service's binding templates.

<TModel TModelKey="uuid:asdf34"
        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>

• UDDI is built of a number of linked registries, all of which implement the same interface.
• These can provide distributed search capability.
  • Not hierarchical like DNS.
  • A producer might only register with some registries.
• Another option is to deploy your own private UDDI registry.
• If you later want to open its services, its a simple matter since it already implements all the interfaces.

• The UDDI standard provides two SOAP interfaces:
• InquireSOAP is used by service consumers to find a service.
• PublishSOAP is used by providers to list a service.
• The services are described with WSDL.

• It defines 16 operations:
• get_authToken
• discard_authToken
• save_business: creates or updates a business' information.
• save_service: creates or updates information about the web services that a business provides.
• save_binding
• save_TModel
• delete_business
• delete_service
• delete_binding
• delete_TModel
• get_registeredInfo

• It defines the following operations:
• find_binding
• find_business
• find_TModel
• get_bindingDetail
• get_businessDetail
• get_businessDetailExt
• get_serviceDetail
• get_TModelDetail

• There is some overlap between them in the way they describe services.
• The coalition has a document describing the best practices to follow when using a WSDL description to generate a UDDI registration.

1. Divide the WSDL description into two files.
   • One file includes the data types, messages, portTypes, and bindings. It is known as the interface description.
   • The other file includes just the service definition. It is known as the implementation description. Use wsdl:import to import the first one.
2. Register the interface description as a UDDI TModel and mark the TModel as one that represents a WSDL interface description (whose WSDL file must be available in a website).
3. Specify that the service is an instance of this TModel.
4. Provide a link to the WSDL implementation description, which must also be available in a website.
5. Initialize the proxy and call the save_service operation to register the service.

• For example, IBM's Emerging Technologies Toolkit [5] allows you to easily find a service with UDDI and invoke it via a dynamically configured WSDL-based proxy.

• UDDI has a lot of features. It might be overkill for a small (in-house) application.
• IBM and Microsoft got together and came up with the Web Services Inspection Language [6].
• It can be used to create a simple index of service descriptions.
• An example of two services. The first provides stock quotes with a HTTP-accessible WSDL file and UDDI-accessible. The second provides a calculator with an FTP-accessible WSDL file.

<?xml version="1.0"?>
<inspection xmlns="http://schemas.xmlsoap.org/ws/2001/10/inspection/"
            xmlns:wsiluddi="http://schemas.xmlsoap.org/ws/2001/10/inspection/uddi/">
  <service>
    <abstract>A stock quote service with two descriptions</abstract>
    <description referencedNamespace="http://schemas.xmlsoap.org/wsdl/"
                 location="http://example.com/stockquote.wsdl"/>
    <description referencedNamespace="urn:uddi-org:api">
      <wsiluddi:serviceDescription location="http://www.example.com/uddi/inquiryapi">
        <wsiluddi:serviceKey>4FA28580-5C39-11D5-9FCF-BB3200333F79</wsiluddi:serviceKey>
      </wsiluddi:serviceDescription>
    </description>
  </service>
  <service>
    <description referencedNamespace="http://schemas.xmlsoap.org/wsdl/"
                 location="ftp://anotherexample.com/tools/calculator.wsdl"/>
  </service>
  <link referencedNamespace="http://schemas.xmlsoap.org/ws/2001/10/inspection/"
        location="http://example.com/moreservices.wsil"/>
</inspection>

• These documents should be placed in a website which must also have a http://host/inspection.wsil file that lists the services.
• UDDI is useful when you don't know who provides the service you want. WS-Inspection can only be used if you know who you want to use.