Despite Web-services delivery limitations, T-Mobile, headquartered in Bonn, Germany, bet on Web services two years ago as the foundation for delivery of data to mobile workers and consumers. The company has middleware built on 50 to 60 Web services that integrate T-Mobile services such as identity, personalization and billing, with mobile content delivery services for consumers, which 250 partners provide. Also, the company has spent $30 million to develop its Service Integration Platform, a middleware that uses Web services to hook mobile workers into their corporate applications.On the consumer side, Web services help T-Mobile integrate with content providers to give users features such as single sign-on and itemized billing. For example, a content provider incorporates T-Mobile's identity and billing Web services into its Web applications using a SOAP interface. When a T-Mobile user accesses a content provider application through their phone, the application makes a SOAP call to T-Mobile to access identity information on the user. The application uses that information to provide personalized services and also to link into the billing Web service. Web services also are used to integrate the platforms that T-Mobile divisions in different countries use, so, T-Mobile can offer single billing, currency conversion and taxation Web services."There is obviously a support drag on our organization to keep content providers integrated and tested," says Mike Glendinning, a consultant at T-Mobile. "The fact that Web services are simple and technically neutral means we actually have a fighting chance of supporting those guys." He says content providers need only modify their applications with WSDL and SOAP, which is a couple of lines of code that T-Mobile generates using tools from Systinet.On the corporate side, T-Mobile used .Net to create its Service Integration Platform middleware, which takes in XML data from a corporate customer's application and transcodes it for delivery to a mobile worker's device or laptop over any channel, including wireless and fixed lines. The service is available in Germany with plans for worldwide rollout over the next few years."We really don't care if the systems are Microsoft, Unix or mainframes on the corporate side, as long as the output is in XML and is using SOAP and our extensions for mobility," says Hossein Mooin, chief architect and director of technology for T-Mobile international data services. He says Web services gives corporations the flexibility to change their back-end systems and front-end clients independent of one another."This was not possible before," Mooin says. He saysT-Mobile only needed to modify its network architecture to provide access points for users because T-Mobile re-uses the routing and monitoring of its Web infrastructure."Web services do offer you one thing that we had great difficulty with in the past with things such as [Common Object Request Broker Architecture] or Object Request Brokers, and that is having this notion of components that serve each other as opposed to monolithic architectures," Mooin says.He says the benefit of Web services clearly is simplification: "Sometimes you go in and you recall how long it took you to do things in the old days. You say, 'Wow.'"Tracking elk in ColoradoBuilding a foundationThe concept of Web services today is built around four XML-based standards. Other standards under development address such needs as security, workflow ond provisioning.Existing StandardsDescriptionXML (Extensible Markup Language)A markup language that provides data about data.SOAP (Simple Object Access Protocol)A message transport that rides on HTTP.WSDL (Web Services Description Language) A file that describes the properties of a Web service including the protocols and formats it uses. Can be stored in UDDI directory (see below).UDDI (Universal Description, Discovery and Integration)A sort of yellow pages listing of available Web services.Emerging StandardsDescription WS-SecurityBlueprint for integrating security sysems such as Kerberos and PKI.SAML (Security Assertion Markup Language)A way to exchange authentication and authorization credentials between systems.WSCI (Web Service Choreography Interface); BPELWS (Business Process Execution Language for Web Services) Workflow specifications.XACML (Extensible Access Control Markup Language)For expressing policies for access.