8 Geac System21 commerce.connect: Implementation on the iSeries Server
2.1 The need for an architecture
Why is an architecture necessary? Can’t we simply write programs that deliver the function
that is required? The reasons for having an architecture are:
Ever increasing demands are placed on systems in terms of security and availability.
The need to extend the system to both customers and suppliers across the Internet is
growing rapidly. Applications need to have this capability “architected in”.
The need to reduce the product development life-cycle, while delivering more complex
systems at the same time, means that Geac simply cannot develop its systems from
scratch or the infrastructure required.
There is a need to connect different systems (both Geac and external systems) to provide
a viable, reliable, and robust solution.
To meet these requirements, Geac has to rely more and more on infrastructure or middleware
to provide these services. In turn, this means that Geac should clearly architect, develop, and
deploy its software to maximize the benefits that the chosen middleware offers.
Over two years ago, as part of the strategic alliance with IBM, Geac chose to base its new
e-business enterprise applications around WebSphere.
The WebSphere suite of products enables Geac to develop, deploy, and integrate
next-generation e-business applications. This includes such applications for
business-to-business e-commerce. Geac also supports business applications from simple
Web publishing through enterprise-scale transaction processing, extending applications to
incorporate mobile devices, etc.
The entire WebSphere philosophy allows Geac, as an Enterprise Application Developer, to
build, integrate, and deliver solutions more timely to market using WebSphere. WebSphere is
the cornerstone of IBM’s enterprise development strategy. There is little functional or time
availability differences between the release of WebSphere on the iSeries server and
WebSphere on Windows 2000. This allows Geac to deploy its J2EE applications on the
platform that is best suited to the particular customer.
Many of the middleware services provided by WebSphere form part of IBM’s implementation
of the J2EE specification. J2EE defines the standard for developing multi-tier enterprise
applications. J2EE simplifies enterprise applications by basing them on standardized,
modular components, providing a complete set of services to those components, and
handling many details of application behavior automatically, without complex programming.
However, it is true (from practical experience) that both the EJB specification and WebSphere
do not completely remove or absolve the implementor of the responsibility of using the above
services appropriately. Performance needs to be “designed” into the application. Key
architectural decisions still need to be made within the constraints and goals of the project
and these decisions need to be well documented and understood by everyone involved in the
project. This ensures a consistent and high quality approach when designing and
implementing a large-scale project.
2.1.1 Key Enterprise JavaBeans and WebSphere Application Server benefits
The Architectural Specification Geac follows is Enterprise JavaBeans 1.0 (EJB 1.0). As
discussed, the Application Server that Geac uses to implement this specification is IBM’s
WebSphere Application Server Advanced Edition. If the applications that Geac were
implementing were entirely PC-based, WebSphere Advanced Edition would not be
necessary, but this is not the case.
