Semantic Web Service Is Automatically Called

A Web service is a software system identified by a URI whose public interface and bindings are defined and described by XML. Its definition can be discovered by other software systems. These systems may then interact with the Web service in a manner prescribed by Internet protocols.A Semantic Web service is a Web service whose description is in a language that has well-defined semantics. It is unambiguously computer interpretable, and facilitates maximal automation and dynamism in Web service discovery, selection, composition, negotiation, invocation, monitoring, management, recovery and compensation.The problem of composing Web services can be reduced to three fundamental problems:1.Make a plan that describes how Web services interact and how the functionality they offer can be integrated to provide a solution of the problem.2. Discovery of the Web services that perform the tasks required in the plan.3.Then we can manage the interaction among those Web services and achieve automated invocation.The service composition orders atomic processes in the right sequence; the interaction is complete only when the processes are invoked/executed. Invocation involves gathering the correct data to be provided as input to each service.The AutoInvoke algorithm takes the plan generated by web services composer as the input and has access to user information stored as facts in the userKB and the outputs received from earlier execution of services stored as facts in the outputKB: both these reside in Jess. The plan has n levels, with the head of the plan corresponding to level 0 and the tail of the plan corresponding to level n. We pick the service at level 0 and check if all preconditions associated with them hold TRUE. We then query userKB and the ouputKB to find a match for their inputs. If a match is found for all the inputs, we execute the service and store the ouputs received in the outputKB. We then move on and pick operators from the next level. If all inputs are not found (QueryAndMatch returns NIL), we try to diagnose the cause of error using the Diagnose routine. If all the services in allthe levels are executed successfully, then plan execution succeeds.The algorithm we present for automatic invocation using two types of queries : ExactQuery and PartQuery. At any stage, if invocation fails, our algorithm tries to diagnose the likely cause of failure, which may be either the faulty execution of a service or incorrect/incomplete information provided by the user.