Saturday, June 21, 2003

Service Oriented Architecture for e-Government

I have done a lot of work over the last eighteen months with Reach - the Irish Government Agency with responsibility for the Public Services Broker initiative.
A large part of my involvement has been the creation of an architectural model for e-Government with particular emphasis on the integration challenges encountered.
It is (to my definitions at least!) an example of a Service Oriented Architecture.
The architectural model can be found here(PDF) 270k.

Friday, June 20, 2003

Error messages, source code envy, utter frustration and how did we survive before the Web?

I have problems. Error messages. Java apps using Sun MQ. I have error numbers. Here are a few - C4055, B2009, B4006.
Normally, I'm a mere google away from information once I have the error numbers. Not in this case. Yes, I have tried Sun Forums. No joy. Boy is this frustrating!
Just in case some JMS guru is reading this blog...
I have three apps reading/writing MQ queues. Given just the right time ordering of activity, I can provoke a "B4006 - unable to attach to queue . A primary queue is already active.".
All doco I can find is silent on what a "primary queue is" and the circumstances that can lead to not being able to attach to them.
The good news is that the Singapore Noodles from the local takeway are cheering me up this Friday evening.

Illusion of interoperability

Kendall Clark, in a piece on xml.com about WS-Arch, says:

    The web services architecture is concerned with making sure that all of the relevant standards are conceptually coherent, so that actually existing, deployed web services may work together. If the relevant standards cohere with each other, and if deployed services comply with those standards, interoperability may be a more likely outcome.

    I state this conclusion in a very weak form because it's not clear that coherence and compliance are sufficient or necessary conditions of interoperability. I don't have space here to argue for that claim; email me privately if you're curious about it.

Kendall hits on a very, very important point. Remember DOS? Remember Int 21H? It appears to me that the WS-Arch uses the term "interoperablity" to mean that a programmer can write against a software interrupt spec. without regard to who provided the software interrupt "stack". This gains you very, very, little and is often at odds with what WS vendors tell you are getting.
API interoperability has basically nothing to do with data interoperability.
The big irony here is that if you look at the problem the other way round and focus on data interoperability *first*, we would be a lot further on in terms of real business level interoperability.

Wednesday, June 18, 2003

Generate Java object models from Relax schemas

Relaxer. Another reason not to use Relax NG bites the dust.

Picturing a Service Oriented Architecture

How would you draw and SOA? I am very opinionated on this point. I think you can tell a lot about where any proponent of SOA's is coming from by looking at how they draw it. This is an interesting list. No, I wouldn't draw an SOA like any of those. The diversity is very interesting I think. Compare Three tiered architecture.

FoneBlog

O2 Ireland offering phone blogs on 30 day free trials.

Interesting looking XML conference

Gotta love this description of a paper at the upcoming Applied XML Conference, 2003, West

    SOAP, it wasn't Simple, we didn't Access Objects and its not really a Protocol
    David Ing, Meridian Project Systems
    Writing a business critical enterprise product from scratch using new programming languages, run-time and a new team just wasn't hard enough - so we added SOAP web services to the mix. This talk describes the XML adventures of the last two years using web services to bring a new product to market. Some of the real-world experiences discussed will contradict the current thinking of the use of WSDL, ASP.NET and XML Schema, so please be prepared for some awkward silences. It describes the design patterns that emerged from a service-orientated architecture and what lessons are still being learnt at every daily build. If you're contemplating starting your shiny new web services based product soon, then use this talk to save yourself some time, money and heartache. Warning: This talk contains explicit references to OO heresy - flaming torch / pitchfork not supplied.

I hope someone blogs the conference. Actually, thats pretty much guaranteed looking at the other speakers. Sam Ruby, Dave Winer, Patrick Logan etc.

Using XPath to query Jython objects

Patrick Logan shows how to tee up a Jython class so that it can be acessed with XPath expressions.

The good, the bad and the DOM

ERH on the wonderous, towering, monument to complexity that is the Document Object Model.

Tuesday, June 17, 2003

Jython is just too useful

Joey Gibson shares the delights of interactive Jython.

Googling M.C, Escher

I love today's Google logo. I first came across Escher at a Usenix conference in London some time in the late Eighties. A bunch of AT&T luminaries were in the front row. I think it was Rob Pike (or what is Ken Thompson?) who had a Escher T-Shirt. Someone else from AT&T pushing the benefits of TCP/IP had a T-Shirt that said something like "ISO Seven Layered Model - same day response in a nanosecond world". Or words to that effect.

Monday, June 16, 2003

Dan Gillmor ponders Mobile Cameras and the nature of snapshots

Mobile cameras and the nature of snapshots. How many moblog entries as-they-happened do you think this photo represents. What if the photo was take again this time next year? My hunch is that every phone will have a blog. A perfect place to put your photos which, unlike your SMS messages, need to live beyond the moment.

Python stuff on microsoft.com

Via Todd Ogasawara, eGovernment Team Leader for the State of Hawaii Information & Communications Services Division. There is lots of Python stuff to be found on microsoft.com. This article is about getting Python set up for scripting inside IIS.