Tools based on WSDL allow the creation of proxies that can communicate and use Web services and implementation skeletons or templates for implementing a Web service within a specific programming model. These proxies and skeletons/templates offer a simple familiar programming model to use Web services and do not require any knowledge or manipulation of the raw SOAP or XML messages. Using XML and message models for communication allows message broker products (for example, IBM WebSphere MQ Integrator) to observe in-flight messages and perform transparent addition of capability. Some examples are message transformations, content-based routing, publish/ subscribe models, and automatic warehousing of messages. UDDI. UDDI is both a standard and a set of public implementations hosted by companies such as IBM and Microsoft. These public UDDI implementations can be used by any Internet-connected business to publish, search for, and locate businesses and services. Businesses can be organized and categorized according to their industry. Each service is assigned a unique identifier called a tModel, which allows users of UDDI to search for particular services across businesses. UDDI can also be implemented within a closed user group, or within a closed network to provide details of businesses or organizations where the public UDDI is not appropriate. This usage is called Private UDDI, though a private UDDI server might still be accessible by anyone on the Internet. WSIL. The Web Services Inspection Language complements the discovery features of UDDI (see www-106.ibm.com/developerworks/webservices/library/ws-wsilspec.html). UDDI provides for a global or wide-scale directory of services. Analogous to large-scale Web-content directories such as the Open Directory Project (see dmoz.org), UDDI is key to finding and identifying services. However, it is also important to be able to understand which local services are available on a particular site. The Inspection standard offers this ability to query a given site or server and retrieve a list of available services. The list of services includes pointers to either WSDL documents or UDDI service entries. WSIL is a useful lightweight way of accessing a service description without requiring access to a UDDI server. Most person-facing Web sites provide a site map to help guide users; WSIL is a similar function for programs that wish to explore a site. |
The Services aspect has the following attributes:
All of these benefits are important to the Web services vision, especially when connecting disparate systems across the Web. However, many companies have invested heavily in existing integration mechanisms, such as message-oriented middleware and CORBA. As we talk to such companies, we often hear they are tempted by the simplicity and power of the Web services vision, but they want to use existing tried and trusted infrastructure in conjunction with the service-oriented architecture. One other powerful aspect of the Web services vision is that it unifies two styles of integration: request-response and messaging. Typically, many integration approaches have selected either tightly coupled request-response approach, or the loosely coupled one-way messaging. Each approach has different strengths, and as companies have become involved in more complex Web integration, they have often discovered that a well-built user experience requires both styles. Both SOAP and WSDL offer support for using and describing one-way and request-response style interactions. |
We can see from this analysis that CICS transactions offer a few of the services attributes, but significantly lack the description, independence of technology, and open protocols. Here, we describe two approaches to making enterprise systems into enterprise services. The first approach is SOAP-enabling the transaction; the second approach is creating a service infrastructure for enterprise systems. In fact both approaches are likely to be used together.
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There are also a number of issues with the model that can be addressed to take the architecture onward:
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