SYSOA, PCs and web-based systems

By Andrew Clifford

System-oriented architecture gives clarity and discipline to the management of PCs and web-based systems.

I have been exploring the idea of structuring IT into strictly independent systems, which I call system-oriented architecture (SYSOA).

For back-end, server-based systems, SYSOA provides clear rules for ownership and separation that can make management easier and more effective. But what about PC systems and systems with a browser front end?

Let's start with the simplest case. A server-based application with a browser front end can be considered and managed as a single system. The browser, and the PC on which it runs, are just a generic capability - an appliance - that is not managed as part of the system.

PC software itself can be managed in one of two ways.

Standard PC software, which everyone needs in the same way, can be managed as part of the PC appliance. More specialised PC software that has a specific business purpose needs to be managed as a system in its own right.

This distinction allows the IT organisation to focus on providing a relatively simple, standard PC platform. Specialised PC-based business applications require additional ownership, control, resources and management. The PC support team are not just dumped with the integration, support and management of every piece of PC software. They provide a standard platform and rules for how other systems can use that platform.

SYSOA clarifies client/server systems. The client (PC application) and the server are separate systems. There is no special relationship between client and server. Composite applications, where clients use the services of many different systems, are the norm. Client/server is not a special and difficult category of architecture, but a normal interaction of independent systems.

PC-based software that combines components from many different applications undermines system independence. To be compatible with SYSOA, either:

• The applications that are combined must be managed together as a single system.
• Each application must run independently and use well-defined interface methods, not just in-memory calls and data sharing.

This isn't really a restriction. It's a response to the problem of "dll hell", where different bits of PC software use conflicting components. The disciplines of SYSOA ensure that PC-based business systems are well-behaved and do not cause conflicts.

Not all composite applications are PC-based. Some server-based systems (such as "portals" and "mash-ups") allow new user interfaces to be built from the components of other systems. SYSOA clarifies that these are just standard interactions between independent systems, not a special category of architecture.

To summarise, SYSOA provides clear guidance in many areas of PCs and web-based systems:

• SYSOA makes a clear distinction between managing a standard PC platform and managing specialised PC-based business systems that need more business ownership, control and resources.
• SYSOA encourages better management of PC applications to avoid "dll hell".
• SYSOA encourages the standardisation of client/server connectivity, and the enablement of composite applications, both PC-based and server-based.
• SYSOA provides a management structure that can be applied consistently across PC systems, web-based systems and server-based systems.

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