Information Technology Reference
In-Depth Information
underlying the architecture. End user tools represent those tools that draw
together application services according to a particular problem domain. A
sketch of these tools will be given in Chapter 11. Next, we shall discuss a par-
ticularity of WSMX, which is not obvious from this sketch of the components.
For the components to interact properly, a “glue” is needed that regulates the
interplay of them: execution management.
Execution Management
Execution management has the role of coordinating the execution of the ap-
plication services in a meaningful scenario. Such scenarios are called execution
semantics, and they can be seen as low-level projections of the requirements
of the application layer. The execution semantics define the way the appli-
cation services have to work together to complete a useful scenario. Having
the execution semantics as a separate concept in the architecture is the first
step towards a highly decoupled system. That is, given a set of application
services, when new execution semantics to be executed are defined, the whole
architecture basically changes the way it offers a certain functionality, or even
the functionality itself. As such, WSMX is a packaged environment capable
of completing a “round trip” starting from accepting a user's goal, and then
performing discovery and selection, finding the most suitable Web service, me-
diating when necessary, invoking the service, and returning the results. But
also, by using different execution semantics, WSMX can simply discover and
return the services found to the user, allowing the requester itself to perform
selection.
In WSMX, much of the process of finding and using Web services can be
automated. Automatic discovery offers a great advancement over the current
situation, allowing users to find services that can fulfill their requirements
without spending large amounts of resources. Mediation and invocation also
reduce the effort of manually interpreting interfaces, inputs, and outputs of
Web services and switching data formats to fit the formats required by those
Web services.
10.3.2 The Internet Reasoning Service IRS-III
IRS-III [33] is a framework and an implemented platform that acts as a broker
mediating between the goals of a user or client and the available deployed
Web services. Thus IRS is not a framework on its own, but uses WSMO as
its ontology and follows the WSMO design principles. The conceptual model
of IRS-III is based on five design principles:
Support capability based invocation. IRS-III enables clients (human users
or application programs) to invoke a Web service by simply specifying a
concrete desired capability. IRS acts as a broker that finds, composes, and
invokes appropriate Web services in order to fulfill the request.
Search WWH ::




Custom Search