Information Technology Reference
In-Depth Information
enterprise that requires certain functions to be satisfied. From an architec-
tural perspective, this is the application that is looking for, and subsequently
invoking, the service.
The Web Services requestor searches the service registry for the desired
Web Services and using the information in the description to bind to the
service. Two different kinds of Web Services requestors exist. The requestor
role can be played either by another Web Service as part of an application
(i.e., without a user interface) or a browser driven by an end user.
15.3.3 Layers in an SOA
On the basis of their requirements, enterprises may use SOA for the following:
•
Implementing end-to-end collaborative business processes
:
The term
end-
to-end business process
signifies that a succession of automated busi-
ness processes and
information systems in different enterprises
(which are typically involved in intercompany
business transactions)
are successfully integrated. The aim is to provide
seamless interop-
eration and interactive links between all the relevant members in
an extended enterprise—ranging from product designers, suppliers,
trading partners,
and logistics providers to end customers. At this
stage, an organization moves
into the highest strategic level of SOA
implementation. Deployment of services
becomes ubiquitous, and
federated services collaborate across enterprise boundaries
to create
complex products and services. Individual services in this extended
enterprise may originate from many providers, irrespective of
company-specific
systems or applications.
•
Implementing enterprise service orchestrations
: This basic SOA entry
point focuses on a typical implementation within a department
or between a small number of departments and enterprise assets
and comprises two steps: The first step is transforming enterprise
assets and applications into an SOA implementation. This can start
by service enabling existing individual applications or creating
new applications using Web Services technology. This can begin by
specifying a Web Service interface into an individual application or
application element (including legacy systems). The next step after
this basic Web Service implementation is implementing service
orchestrations out of the service-enabled assets or newly created
service applications.
•
Service enabling the entire enterprise
: The next stage in the SOA
entry point hierarchy is when an enterprise seeks to provide a set
of common services based on SOA components that can be used
across the entire organization. Enterprise-wide service integration is
achieved on the basis of commonly accepted standards. This results
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