Taming the SOA Beast – Part 1

Certainly, I admit to not being a programmer or a techie expert (not to use somewhat derogatory words like “geek” or “nerd”) per se. Still, my engineering background and years of experience as a functional consultant should suffice for understanding the advantages and possible perils of service oriented architecture (SOA).

On one hand, SOA’s advantages of flexibility (agility), components’ reusability and standards-based interoperability have been well publicized. On the other hand, these benefits come at a price: the difficulty of governing and managing all these mushrooming “software components without borders”, as they stem from different origins and yet are able to “talk to each other” and exchange data and process steps, while being constantly updated by their respective originators (authors, owners, etc.).

At least one good (or comforting) fact about the traditional approach to application development was that old monolithic applications would have a defined beginning and end, and there was always clear control over the source code.

Instead, a new SOA paradigm entails composite applications assembled from diverse Web services (components) that can be written in different languages, and whose source code is hardly ever accessible by the consuming parties (other services). In fact, each component exposes itself only in terms what data and processes it needs as an input and what it will return as an output, but what goes “under the hood” remains largely a “black box” or someone’s educated guess at best.

Consequently, SOA causes radical changes in the well-established borders (if not their complete blurring) of software testing, since runtime (production) issues are melding with design-time (coding) issues, and the traditional silos between developers, software architects and their quality assurance (QA) peers appear to be diminishing when it comes to Web services.

Transparency is therefore crucial to eliminate the potential chaos and complexity of SOA. Otherwise, the introduction of SOA will have simply moved the problem area from a low level (coding) to a higher level (cross-enterprise processes), without a reduction in problems. In fact, the problems should only abound in a distributed, heterogeneous multi-enterprise environment.

Then and Now

Back to the traditional practices and mindset: the software world considers design as development-centric (i.e., a “sandbox” scenario), and runtime as operation-centric (i.e., a part of a real-life customer scenario). But with SOA that distinction blurs, since Web services are being updated on an ongoing basis, thus magnifying the issues of recurring operations testing and management.

Namely, companies still have to do component-based software testing (to ascertain whether the code is behaving as expected) at the micro (individual component) level, but there is also application development at the macro (business process) level, since composite applications are, well, composed of many disparate Web services. In other words, programmers are still doing traditional development work, but now that development work becomes involved in infrastructure issues too.

For instance, what if a Web service (e.g., obtaining exchange rates, weather information, street maps information, air flight information, corporate credit rating information, transportation carrier rates, etc.), which is part of a long chain (composite application), gets significantly modified or even goes out of commission? To that end, companies should have the option of restricting the service’s possibly negative influence in the chain (process) until a signaling mechanism is in place, which can highlight changes that may compromise the ultimate composite application.