You can use XML Web services in a composite manner to integrate a seemingly disparate group of existing applications. The wide adoption of custom software throughout virtually every department of most companies has resulted in a vast array of useful but isolated islands of data and business logic. Due to the varied circumstances under which each was developed, and the ever-evolving nature of technology, it is a daunting task to create a functional grouping from these applications.
With XML Web services, it is possible to expose the functionality and data of each existing application as an XML Web service. You can then create a composite application that uses this collection of XML Web services to enable interoperability between the constituent applications.