measured with respect to the number of program language bindings
available, as a proxy for maturity. In comparison, Web service clients
can be a JavaServer Page (JSP), servlet, or Java application, or an
executable written in languages such as C++, Perl, Visual Basic, or
_javascript_. With respect to Web services in an SOA, a real sense of
when and where a true Web service needs to be deployed and the
appropriate modeling artifacts and specification approaches needs to
be further refined. However, in general, I find most organizations
have limited tolerance for protracted analysis and system design
lifecycle phases; even though meta-data and model-driven programming
are the wave of the future, whether the implementation is a Spring Web
Flow service or a standard Web service.
Mission important but not necessarily critical
The article mentioned above discusses exposing an EGL program (a 4GL
for J2EE used by for non-Java programmers) that integrates with
MQSeries as a Web service. What the article doesn't discuss is when
this type of architecture is appropriate.
Web services are, for the most part, an improvement in B2B
technologies and standards for the Internet, including XML. An SOA
doesn't necessarily mean you must expose all services as Web services,
but there's a strong case for implementing B2B functionality as a Web
service. So, during the discovery phase of an SOA project, a good
candidate for a Web services is B2B functionality. Conversely, the
technology does not have to be limited to B2B. It does represent a
solid bridge technology for communicating between disparate
environments; however, the SOA model, which uses Web service as its
enabling technology, really addresses a more complex problem set.
Yet another methodology
The purpose of this article was to develop a unique philosophy and
position regarding implementing an SOA. The resulting approach and
artifacts overtime could develop into a methodology, which could be
used in a project plan where SOA is a partial requirement or the focus
of the project. In contrast, RUP (Rational Unified Process), a
methodology for designing and building Object-oriented systems
developed overtime and represented the "unification" of many OO
methodologies.
An SOA methodology represents a set of tasks and associated artifacts
that are focused on creating and maintaining a SOA. Some of these
tasks would be represented in any forward engineering development
project, but some of them are unique to SOA. In general, SOA projects
have some of the features of a portal project and some of the features
of integration projects and some of the features of application
reengineering projects. Indeed, an enterprise-wide SOA will span
legacy as well as new technology. Some analysts refer to this approach
as "legacy abstraction" services -- services built on top of existing
services, including technology, such as COBOL and CICS on mainframes.
The concept is to externalize these older internal processes as
services and surface them as modern Web services.
One artifact that seems to be emerging as the de facto initiation of
an SOA project is to perform an SOA assessment. Both BEA and IBM have
SOA assessment models. I highly recommend taking those assessments.
But beware - they appear to be setting the stage for creating the need
for their Enterprise Service Bus (ESB) technologies. In the March 16,
2006 issue of Network Computing BEA's AquaLogic Service Bus was the
Editor's Choice during a vendor lab test of eight ESB suites with
Oracle being the runner-up.
A [Nascent] SOA project methodology
During a more rigorous SOA assessment, the SOA team would harvest
existing artifacts as well as create new ones. It is recommended that
the following subjects be discussed and factored into appropriate
tasks for the assessment. Artifacts collected or completed during an
SOA assessment should be revisited during a full lifecycle SOA project.>>
You can read this in full at:
http://www.theserverside.com/articles/article.tss?l=WantedSOA
Gervas
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