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interface, as well as a method for organizing the full directory of web services.
Web services use XML in many ways. Though the messaging protocol is not
mandated, the common implementations today use Simple Object Access
Protocol ( SOAP ), an XML -based standard messaging protocol. The message
content is, of course, in XML , and the definition language for services is an
XML derivative.
The web services architecture, and the open standards that form its foun-
dation, is based on standards that are simple, adequate for the task, and flexi-
ble. Table 7.1 describes the benefits of web services.
Table 7.1 By allowing us to describe our interface as a service that clients can register and
bind, web services provide significant benefits.
Loose coupling
Reduced maintenance and integration cost.
Late binding
Improved flexibility in business process and
A comprehensive, open standard
One widely available and deployed standard addresses
service encapsulation, binding, invocation, distribution,
and description.
Dynamic and robust technologies
Improved flexibility of implementation.
Platform and language neutrality
Improved flexibility of deployment, wider vendor support,
and wider market penetration.
Mini-antipatterns for XML misuse
We have seen that XML can loosen the coupling between two systems, provid-
ing better insulation to change and more independence between the client
and service provider. The key to effective XML interfaces is a good, flexible
schema. Clean XML documents describing a service lead to smoother, more
flexible connections.
XML is perhaps the most powerful new standard related to the Internet.
Although previous standards provided open implementations for communica-
tion, messaging, presentation, and applications, the missing link was a stan-
dard language that provided structure and meaning to data . However, keep in
mind that XML is subject to misuse. Next up, we'll look at some antipatterns
related to XML .
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