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Sunday 22 April 2007

Built To Last

There’s an interesting interview with Niall McCullough, architect, yesterday in the Irish Times weekend magazine, about the new version of his book “Dublin: An Urban History” (unfortunately the Irish Times online is only premium paid-for content so I can only give you this url to the article). There’s also an interesting web site, giving additional histories of Dublin and the patterns which have shaped it at

One of the things which I had not realized about Georgian Dublin is that the buildings, which of course are a part of our heritage, were apparently in general not built to last! The article says: “Based on a land-lease system, the terraces and squares were designed to stand for the lifetime of the lease, usually between 40 and 100 years, whereupon they would be torn down and built again.” Perhaps this is one reason why the Georgian Society has had so many challenges in trying to preserve the best of Georgian Dublin for us and for future generations.

Earlier in the last week, I was in Liaoning province in north east China, for Sli Siar, for discussions relating to the “Five Points, One Line” strategy to re-invigorate one of the old industrial parts of China. As you probably know, Chinese government policy (until recently) is that land is only available for lease, and is owned by the State. The lengths of leases are set by national law, and vary between 40 and 70 years, depending on the land use: residential, commercial, industrial etc. In fact, China has been through various land reform policy changes: the 1946 reform in which land was expropriated from the landlords and equitably distributed to individual households in rural villages; the collectivisation period during the Great Leap Forward in the 1950s in which land was grouped into shared communes; and the current system introduced in the late1970s during Deng Xiaoping’s reforms. I say “the current system”, because in fact just last month, the National People’s Congress passed a new property law, after many years of deliberations, which recognizes the status of private property including land. In my own experience, urban planners and developers today in modern China in general expect their buildings and developments to survive the length of leases of the land on which they are built.

Then on Friday, having traveled back to Europe the previous day, I was with some folks from IONA, visiting one of our customers in the financial services sector, in Zurich. The meeting was with their senior architect – let me call him Tom. Tom is responsible for their group-wide, global IT architecture, and the meeting was to discuss SOA strategy. One of the very interesting points he and I discussed was that there is a sense in the enterprise IT industry, that at long last, we collectively in the enterprise software industry are “building to last”.

As an aside, I do wonder whether “architect” is the appropriate title for somebody like Tom. I tend to think of civil architects as professionals who design buildings. Rather somebody like Tom is really an “urban planner” – he presides over the current and future infrastructure of an entire software city, on which individual applications – buildings – are built.

Anyway. With previous middleware technologies – DCE, DCOM, CORBA, J2EE, etc – and with all due respect to those thousands of technologists world-wide who worked to create these technologies, I think there was always an expectation amongst senior architects (urban planners ?) and IT visionaries, that each of these technologies would fade in time. Sure, each might be strong enough to last for a decade or so, but business logic and applications that were built to exploit any one of these technologies were constructed in the expectation that a more modern, better middleware technology, would emerge within at most a decade. It was perhaps like the relatively short land leases of Georgian Dublin I mentioned above: build your artifacts in the expectation of re-building them a few years later. And so the middleware world proved to be,

Tom postulated that, at long last, enterprise software architects (urban planners ?) can be like the Victorians of over a century ago: laying down infrastructure – whether it be urban water supply, underground and metro train networks, or even sewage pipe networks (what is the best analogy for middleware ? – I leave it to your personal prejudice!) – that will last for a hundred years or so. Is SOA the end of middleware as we know it ? Isn’t SOA good enough to give us a stable infrastructure for at least a hundred years ?

Well, my view is yes, I agree that it is but with one proviso: one has to construct a SOA based (urban-like, city) environment in the expectation that middleware technologies will in fact continue to evolve and change. SOA may mark the end of middleware as we know it, yes Tom, but its chief contribution in this context is its meta-level. In the same way that metadata in a database allows one to reason and manipulate the underlying data, so should a SOA system enable one to reason and manipulate the underlying middleware.

SOA capabilities in frameworks like Artix and its open source companion Celtix allow a de-coupling between business logic and services, and the underlying middleware. In particular, future middleware technologies can be inserted into such frameworks. The meta-level capabilities enable dynamic re-configuration, including for example interface versioning, data versioning, retooling and end-point guardianship.

With SOA, we have indeed reached the end of middleware as we know it, and can now enable enterprise applications which can be built to last.

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