Brief

WS-Inspection is an XML format for assisting in the inspection of a site for available services. It is also a collection of rules for how inspection-related information should be made available for consumption. A WS-Inspection document provides a means for aggregating references to pre-existing service description documents that have been authored in any number of formats. These inspection documents are then made available at the point-of-offering of the services as well as through references, which may be placed within a content medium such as HTML.

Specification

WS-Inspection

Schemas

WS-Inspection/
WSDL/
UDDI
UDDI v.2

Sample

Download WSISetup.msi.

Status

WS-Inspection was published jointly by IBM and Microsoft as a public specification on November 1, 2001.

ApNote

Overview

WS-Inspection is the Web Service Inspection Language. It defines both a packaging model described by a schema, and a querying model to retrieve a list of service offerings at the point of offering.

What Is Inspection?

Inspection is the process of querying a server to find out what services it offers and knows about. This allows an application to dynamically find new services that it may be interested in.

WS-Inspection relies on a completely distributed model for providing service-related information; the service descriptions may be stored at any location, and requests to retrieve the information are generally made directly to the entities that offer the services. The WS-Inspection specification does not stipulate any particular format for the service information; it relies upon other standards, including WSDL and UDDI, to define the description formats. The WS-Inspection specification also relies on existing Web technologies and infrastructure to provide mechanisms for publishing and retrieving its documents.

In terms of the personal information discovery context described in the introduction, the WS-Inspection mechanism most closely resembles business cards and other simple information aggregation documents. As is the case with those other mechanisms, WS-Inspection documents are very lightweight, easy to construct, and easy to maintain. By providing the ability to disseminate service-related information through existing protocols directly from the point at which the service is being offered, the WS-Inspection mechanism enables focused discovery to be performed on a single target. Due to its decentralized nature, however, the WS-Inspection specification does not provide for a good mechanism on which to execute focused discovery if the communication partner is unknown. In cases such as this, UDDI would be a better alternative. As is the case with other simple aggregation supporting discovery mechanisms, there is little cost associated with creating and maintaining the aggregations.

Example of Inspection Result

<?xml version="1.0"?>
<inspection xmlns="http://schemas.xmlsoap.org/wsil/"
            xmlns:wsiluddi="http://schemas.xmlsoap.org/wsil/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/wsil/"
        location="http://example.com/moreservices.wsil"/>
</inspection>

This example shows that WS-Inspection can not only return a list of links to services, but also return meta-information about those services. The WS-Inspection specification defines an extensibility point at the description element. It also defines specific extensions for WSDL and UDDI.