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Peter Holditch

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Top Stories by Peter Holditch

In most large-scale "mission critical" systems, high on the list of requirements is resistance to failure. With the world living in fear of violent destruction post 9/11, it is more common for the definition of "failure" in this context to be the loss of a whole data-processing facility. Taking the provision of a full failover site into consideration provides some good food for thought in terms of the best way to architect a solution. Having decided to split data processing over two sites, it then needs to be determined whether the sites operate in a dual-running mode, whereby both share the transaction load during normal operation or in a master/backup configuration where the processing all occurs on the "master" site, and entirely fails over to a backup site should disaster strike. In these parsimonious times, it is usual to want dual operation to cut down on the ... (more)

Four Legs Good, Two Legs Bad?

The buzz in the industry these days is all about service-oriented architecture. One of the key benefits that this brings is loose coupling between systems, which in turn improves the agility of the overall architecture - if systems are unaware of each other's implementation details, then as things change over time the function of the IT infrastructure as a whole can be preserved without constantly having to revisit and tweak hundreds of touch points between systems, which has been a bugbear of composite systems in the past. I have started to hear of people who, having heard the ... (more)

Transactions, Suspension, and the Ticking Clock

This month's article is again inspired by a posting on the weblogic.developer.interest.transaction newsgroup. The question (excerpted from the posting) was: Does the 10 in weblogic-ejb-jar.xml apply to transactions that are in a suspended state? I have EJB1 (Container Managed/Required) that starts transaction T1 and does some work, then calls another EJB, EJB2 (Container Managed/NotSupported), which makes an interdomain T3 call. Since EJB2 is configured with NotSupported transaction attribute, transaction T1 is suspended for the tim... (more)

Application Environments, Migration, and Transactions

No, don't worry, it's not a a floor-wax/dessert-topping/toothpaste article this month; it's simply a look at how multilanguage application environments might be used together in highly distributed systems. Interested? Well, don't worry, somebody has to beS Swallow your pride and read on, MacDuff! Looking at the IT systems of most large organizations is often closely akin to going on a fossil hunt. You dig through the J2EE surface to find a strata of C++ code in the supporting layers. Dig a little deeper and you start finding relics of a bygone age when C and Unix ruled the world. ... (more)

Transactions: How Distributed Are Yours?

Another discussion based on a weblogic.developer.interest.transaction posting this month. It's a newsgroup that always proves to be a good source of information for the world at large when it comes to transactional behavior (and a good source of inspiration for me when the article time of the month rolls around again). This particular posting is a great illustration of how an apparently simple assumption can pitch you into the bowels of the infrastructure, if you're not carefully guided by the architecture you're building against, and the possibilities it offers. The original po... (more)