By Allard, on April 6th, 2009
As many other developers, I’ve been used to the fat service layer and the anemic domain model of the transaction script pattern. In that programming model, immutability is pretty much as rare as a Dodo. However, I have been investigating the rich domain model pattern lately (as you can read in my previous post) and more importantly, a good migration path for “transaction script” developers to get acquainted with the rich Domain Model, a design pattern that has been heavily underrated (and misunderstood) by many.
In this post, I will explain some of the advantages that immutable domain objects bring us, while showing that some of the seemingly problematic side effects aren’t really that problematic.
Continue reading The power of immutability in a Rich Domain Model
By Allard, on October 30th, 2008
Applications have to run in high-consequence environments. They have to serve hundreds of thousands of users 24 / 7. Our clients spend millions in hard- and software and highly depend on the revenue generated by these applications. Unnecessary outage of these application is fatal.
Software Architects play an important role in setting up an architecture that can cope with these high demands. At the JAOO, Michael Nygard‘ had a talk, “Failure comes in Flavors“, that gave very good insight in the risks and opportunities of today’s application. The talk was was divided into two sessions. The first session covered the bad news: the stability threats. He discussed several situations that pose a threat to the long and happy life of an application. The second session was a happier one. It covered the patterns that should be applied to the application architecture to prevent these threats.
In this post, I will elaborate on some of the stability threats and pick one specific pattern to resolve them: the circuit breaker.
Continue reading Bring some stability to your architecture
By Ben, on August 6th, 2008
Does the name dihydromonoxide sound in any way familiar to you? It should (really, it should). Try googling it (here, I’ll make it easy for you). If and when you do google it, you will be informed by all sorts of sites of the various properties and dangers of this chemical compound. This one, for instance, covers all the dangers of dihydromonoxide (or DHMO) in great and completely accurate detail.
Of course dihydromonoxide and the many warnings against it are all based on a clever use of words. Seen in that light dihydromonoxide is a wonderful example of something I was taught by a professor of mine at university (and reminded of a couple of times today): Shakespeare may have prattled on about roses by any other name, but in reality notation is absolutely everything in our business.
Continue reading Dihydromonoxide: what’s in a name?
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