Database Reference
In-Depth Information
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Web Services will enable independent Software Vendors (ISVs) to bring products to market
more quickly and respond to competitive threats with more flexibility.
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Web Services will enable enterprises to reuse existing legacy application functionality with
the latest applications and technologies.
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Web Services will obviate the need of porting applications to different hardware platforms
and operating systems at great expense.
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Web Services enable applications to communicate irrespective of platform or operating
system.
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Web Services will have the effect of leveling the playing field because it will enable even spe-
cialized boutique application firms to compete easily with well-established and resourceful
Original Equipment Manufacturers (OEMs).
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Web Services will enable only those OEMs to flourish that focus on providing comprehen-
sive implementations and highly productive application development environments for Web
Services.
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Web Services will enable applications to be packaged not only as licenses but also as services;
this would give a big fillip to ASP services (as discussed in the earlier section) that would
consequently expand the overall market size tremendously.
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Web Services will enable value-added resellers (VARs) to rapidly add new functionality to
current product offerings or to customize existing applications of customers.
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Web Services will enable enterprises to adopt better to the changing market conditions or
competitive threats.
Though Web Services may seem just another component model, they differ in the following
important ways:
1.
Granularity
: Refers to the complexity of the description of a service. A simple UNIX call
has a very fine level of granularity, but a Purchase Order (PO) has a very coarse level of
granularity.
2.
Coupling
: Refers to the nature of the interface between the producer of the service and the
consumer of the service. It is concerned with the impact on the consumer of the service, in
case the implementation changes.
While components are very good at doing tightly coupled and fine-grained things, Web Services
are very good at doing loosely coupled and coarse-grained kind of things. For instance, while com-
ponents are capable of interoperating only with other components designed using the same APIs
or object model, Web Services are designed to interact with any other component, irrespective of
its origin, as long as it is encapsulated in a self-describing wrapper.
10.3.1.1 Describing Web Services: Web Services
Description Language (WSDL)
The Web Services Description Language is an XML-based language used to describe the goods
and services that an organization offers and provides a way to access those services electronically.
WSDL is an XML vocabulary that provides a standard way of describing service IDLs. WSDL
is the resulting artifact of a convergence of activities between NASSL (IBM) and SDL (Microsoft).
It provides a simple way for service providers to describe the format of requests and response
Messages for Remote Method Invocations (RMIs). WSDL addresses this topic of service IDLs
