Web services: -A web service provides a service interface enabling clients to interact with servers in a more general way than web browsers do. -Clients access the operations in the interface of a web service by means of requests and replies formatted in XML and usually transmitted over HTTP ie marshalling of messages exchanged between clients and web service is done in XML -The web services provide an infrastructure for maintaining a richer and more structured form of interoperablity between clients and servers than a simple HTTP request reply protocol -The provision of web servies as an addition to web servers is based on the ability to use an HTTP request to cause the execution of a program. -Web services and applications may be built on top of other web services -A web service may be managed by a web server along with web pages; or it may be a totally separate service. -The operations in a web service may be provided by a variety of different resources, for example, programs, objects or databses
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-A web service deploys service descriptions to specify the interface and other aspects of the service for the benefit of potential clients
-Another need in middleware is for naming or directory service to allow clients to find out about services, but frequently manage without directory services, for ex, often find out about services from information on a web page.
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