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Chapter 3 • Enterprise Systems Architecture 77

•Security system needs to be sophisticated
• Costs can be high because services need to be junked very often

According to Gregor Hohpe, enterprise integration practice leader at Chicago-based
7
ThoughtWorks, Inc., and coauthor of the book Enterprise Integration Patterns, “the SOA
architecture is a different approach to distributed services. It provides simple messaging-based
interactions. Messages are more self-contained, lack object-oriented complexities, and better
accommodate asynchronous communications.”

SOA and Web Services
Web services play an important role in the SOA approach. That is because Web services precede
SOA. While the concepts are associated in some form, they’re also quite different. Web services
basically are interfaces that allow different software applications and components to be operated
together. Web services are necessary because different applications operate in dissimilar ways.
One special feature of Web services is that the IT industry reached a consensus on certain
standards concerning the communication of applications to other applications. These standards
are passed down from organizations like W3C and OASIS. Thanks to these standards, different
applications can interact with each other without concern for communication problems.
There are several important characteristics of Web services to consider. First, the only
method of interaction by Web services is by receiving and sending messages. Because of the na-
ture of Web services, the programs that activate them can simply be changed without worrying
about interference with their communication ability. Second, these services are developed using
open standards. Such standards include, but are not limited to, WSDL (Web Services Description
Language), UDDI (Universal Description, Discovery, and Integration), and SOAP (Simple
Object Access Protocol). Finally, the protocols used in Web services are XML based. The
behavior of the respective Web services is documented in what is known as a contract. These
contracts describe the interaction between services and the applications that invoke them.

Enterprise Content Management and SOA
Enterprise content management deals with enterprise software products. These products usually
store, preserve, manage, and deliver any documents or content that is connected to business
processes. Meanwhile, enterprise content management strategies and tools mainly concentrate on
managing any unstructured information that exists in an organization. Nevertheless, enterprise
content management is also about supporting business goals, not just managing content itself.
Until recently, enterprise content management solutions were supplied by vertical
applications. The problem with that is it made developing new applications for content
management a process that is more expensive, longer, and more complicated. The business
would have to deal with integrations that were problematic to maintain and develop.
Integrating Web services to enterprise applications were made quite simple. However, they
lack efficiency.
Now due to SOA, the software market for enterprise content management is being
overhauled. Vendors have come to an understanding that content management takes advantage of
technology and information assets across the business and is no longer application specific.
Where enterprise content management is concerned, utilizing the SOA approach consists of

7 Hohpe, G., and Woolf, B. (2003). Enterprise Integration Patterns. Boston, MA: Addison-Wesley.