18 december 2008

Devoxx 2008 - afterthought

The annual Devoxx conference is already "recent history". I posted my last comments on conference talks. This is the right time to do a small recap of the conference.

The university days: not an overall success for me, at least not for all the talks I attended. Luckily I didn't have to choose between university and conference (I chose for the full conference). There were better conference talks of which a combination could have been a good replacement for university talks. Highlights for me are Ivar jacobsen's talk, the university talk on Websockets, the different conference talks on REST, including the talk on Spring 3.0 and the talk on workload estimation. A colleague of mine will probably add the "french fries" to this list :-).

The daily Parlays magazine offered extra background information for a number of sessions; in case you were still in doubt what to choose, these articles could help make up your mind. It was nice to see my blog quoted in 2 Parlays issues (on Thursday about WebSockets and on Friday about this year's buzzword). To me this means that the Devoxx-people think I have something interesting to tell... :-)

Overall the conference was a big success. Apart from the known "issues" (catering, wireless connection during the first days and hardly usable browser clients in the cyber café), this was, again, a great conference, an excellent opportunity to keep up with the evolution. This was my 6th time; I'll be looking forward to the 7th.

The effort of 8 months preparation for this conference is definitely worthwile. I certainly hope Stephan drove home on Friday afternoon with a big smile on his face.

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17 december 2008

Devoxx 2008 - day 5: XML persistence

The last talk of this year's Devoxx conference that I attended was at bit in the extent of the previous talk: it was about XML persistence. The speaker seems to be a regular "conference closer", because I remember his talk of the last day of last year's Javapolis conference on ESB's and messaging, with a main focus on the finance and banking business.

This talk was related to his talk of last year: how to persist XML messages. I was very interested in this talk, because I have been involved in projects where we had to persist XML messages of dealing room activities. According to his "that was acquired by Oracle" (referring to both TopLink and Tangosol) and "see your license fee doubled", he didn't seem to be very fond of the O-company. He adviced not to opt for vendor specific solutions regarding to XML persistence, but stick to open standards as much as possible.

You don't want to dissect an XML document inito its composing entities and create tables for them. This would lead to a far too scattered relational database model, with joins that fill an entire page and take ages to execute. Relational databases just aren't meant for this purpose. They haven't even evolved with today's needs. To illustrate his statement, he showed a hierarchic representation of a simple swap (dealing room product) modeled in FPML (Financial Products Markup language).  The best way to represent an XML document, is an object. The best way to query XML-documents, is XPath.

His conclusion was a bit surprising, but, given the current technological situation, not such a bad idea: keep everything in memory as much as possible and only persist for archiving purposes. Why? Memory is cheap. A server nowadays comes with at least 32 GB of memory. You can have a cluster of servers, say 20 servers (= 640 GB of RAM, minus the memory required for running applications), keeping all data in memory. Apparently there is an investment bank that keeps all XML messages of dealing room activities of 1 day in memory and only persists the data at the end of the day.

I guess that these servers should somehow be setup redundantly, so that the crash or power failure of a server doesn't lead to a disaster (compare it to RAID-configured disks).

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Devoxx 2008 - day 5: Java & XSLT 2.0

The last day was one without interruptions: all talks were held the one after the other. For the second talk I didn't even have to change rooms. This talk was about XSLT and more specifically XSLT 2.0 and Java.

Per default the Java runtime comes with a Xalan XSLT-processor. However, this processor only supports XSLT 1.0. If you want to make full usage of the new features of XSLT 2.0, you have to point the processor factory to a XSLT 2.0 aware processor, e.g. Saxon.

This presentation gave a nice overview of the XSLT 2.0 capabilities (like e.g. language specific collation), how to invoke them from within Java and how to extend XSLT with your own functions. The presentation also dealt with nice eye-candy features, like generating an SVG pie chart based numbers in an XML document and generating a PDF document using XSL-FO.

In a world driven by annotations, RESTful web services and stuff, it is good to see that XML isn't dead yet but that the focus is more on "data", rather than on configuration or RPC protocol.

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Devoxx 2008 - day 5: agile in the enterprise

This talk was about the way Scrum in combination with XP was introduced in the Belgian Postal services. It was an interesting story, touching upon all the growing pains of the rollout of an agile approach.

But the "enterprise" in this case is still located in 1 single building. This makes it still possible to colocate all team members, including the business. But things are all different once your company is divided over different buidlings, even over different city's and worse, different countries. The colocation becomes really hard... to say the least. This postal guy probably has no clue, but Erich Gamma, lead developer of Eclipse, knows all about it!

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16 december 2008

Devoxx 2008 - day 4: JEE6

This was a recap of the presentation of last year, given by the same speaker. I've looked up my blog post of last year again and apparently there was not much difference in the talk of this year, compared with the talk of last year. The idea of profiles was already mentioned last year, but the only profile that is concrete today, is the web profile (this was already mentioned last year, but the building block of this profile are more or less fixed now). Things like EJB 3.1 light (only session beans) and the single class/no interface approach of EJB's were new.

The difference with last year? Last year Q3 2008 was meant as the milestone for completing the entire JEE6 spec; most sub-specs are in their final review stage, but the beta reference implementation was meant for Q4. That will be hard to meet...

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Devoxx 2008 - day 4: JAX-RS

After all the "theoretical" presentations about REST (now that I finally got the picture clear after the talk of Stefan Tilkov), it was time to see how this was all implemented in Java. Because to be honest, the first day's university talk "REST (in peace) with Java)" was NOT what I expected of a presentation on REST and Java; it even made it all more fuzzy to me. The JAX-RS talk however made it all bright and shiny again: it's all in the annotations :-)

All previous talks that mentioned REST talked about resources and URI's and also HTTP operations and statuses, but how on earth could you define an URI? This talk showed how it could be done using Jersey.

For me this was like the icing on the cake, after all the conceptual talks on REST. Not that I know how to do it myself, but now at least I know where to start looking for more information once I may need to do an implementation of a RESTful web service. This talk, preceeded by Stefan Tilkov's talk, would have been a great replacement for the REST in peace talk of the first day.

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Devoxx 2008 - day 4: how do we test this stuff?

This talk focussed on the challenge of testing AJAX and/or web service based applications and the tools that can be used for it. The speaker started building his own testing tools after his request for ordering the Mercury toolset got denied. This resulted in the PushToTest toolset, which integrates with other tools, like Selenium, soapUI and the likes.

However, he didn't do a commercial talk, presenting his toolset. He focussed on the distinct test cases and how a unit test can be promoted to/reused as a functional test or even a stress and load test or a service availability test (for monitoring purposes), how htmlUnit can emulate the role of a user operated browser an can be launched in parallel (multiple threads) for stress testing purposes.

This was an interesting presentation. To me it was a teaser to take a closer look at the tools that were mentioned in this presentation, including the TestMaker bundle of PushToTest.

Links:

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