http://www.hietavirta.net/blog/ J2EE software engineer writing about working abroad, cultures and insights en-us Nucleus CMS v3.32 © Weblog http://backend.userland.com/rss http://www.hietavirta.net/blog//nucleus/nucleus2.gif http://www.hietavirta.net/blog/ http://feedproxy.google.com/~r/hietavirta/ptHE/~3/OJa88A11nsI/index.php
I also had bad luck with cash ISA (tax free savings account) as I applied for higher rate account but First Direct introduced new lower rates while they were processing my application. I did not like that so I cancelled the opening - luckily I did not send transfer order before that.

But at least now GBP seems to get stronger against Euro. That is good because our trip to Finland is approaching... holiday I say!]]> General http://www.hietavirta.net/blog/index.php?itemid=321 Mon, 15 Jun 2009 17:42:05 +0300 http://www.hietavirta.net/blog/index.php?itemid=321 http://www.hietavirta.net/blog/index.php?itemid=321 http://feedproxy.google.com/~r/hietavirta/ptHE/~3/iwkYSzsqGuo/index.php Apache HTTP for proxying and load balancing.

I started up JBoss on both machines with -c all. This setup has clustering turned on as a default so instances found each other and established JGroup communication channels. Then I deployed the .ear file directly to the deploy directory on each server as the farm deployment did not look too promising. The Apache proxy and balancer were already correctly configured so cookies and sticky sessions worked fine.

The big question is naturally how the performance improved. First I ran a load test without second level caching or query caching in order to have a baseline for comparisons. Then I turned Hibernate second level cache on and executed the same load test. The results were showing around twofold throughput as the average response times halved. I also tried turning on query caching but I did not experience any significant difference with it. Maybe I did not have proper configurations.

I also learned that it is not a good idea to modify data on the DB used by the cluster with Hibernate second level caching on. The nodes communicate sending invalidate messages to each other when data is changed and needs to be refreshed. Modifications outside the cluster mean that the cached data is stale but nodes do not know about it and resulting various errors...]]> Bits and Bytes http://www.hietavirta.net/blog/index.php?itemid=320 Thu, 28 May 2009 21:49:11 +0300 http://www.hietavirta.net/blog/index.php?itemid=320 http://www.hietavirta.net/blog/index.php?itemid=320 http://feedproxy.google.com/~r/hietavirta/ptHE/~3/dNMifji0qKI/index.php
Our persistence layer is using Hibernate so the next step in caching was to enable Hibernate's second level cache. There are various options but in our clustered environment JBoss Cache was the choice. But getting started with it took some time.

The easiest way is to use 'all' server setup from the JBoss 5 and enable second level cache in Hibernate settings. The JBoss community wiki page provides an example for the setup. Also your JPA entity annotations or mappings need some changes as well because you need to define caching strategy for them.

Taking a look at the documentation of JBoss Cache reveals huge amount of configuration options. Luckily only some of them are relevant for Hiberante second level caching. Be aware that JBoss Cache has been around for some time so some of the older tutorials and blog posts are outdated. At the moment JBoss Cache version 3.x is the recommended one.

In case of caching it is very important to run proper load tests after each configuration modification to verify the performance gain or loss. At the moment I have my test setup running on Apache JMeter. It creates similar load to the server based on historical usage data. Another area of testing is to verify that cluster's caches are having their state updated properly.

I have been experimenting with JBoss Cache only for a day so it will take a bit more time before I can give my opinion or better advices. So, follow my RSS feed to learn more - hopefully soon there will be an update.]]> Bits and Bytes http://www.hietavirta.net/blog/index.php?itemid=319 Mon, 25 May 2009 22:00:38 +0300 http://www.hietavirta.net/blog/index.php?itemid=319 http://www.hietavirta.net/blog/index.php?itemid=319 http://feedproxy.google.com/~r/hietavirta/ptHE/~3/CO4GF-HtRiE/index.php
The sauna in the topic has nothing to do with helicopters. Instead, we found a nice gym in Kirkcaldy and it has a proper sauna. I would pay the membership fee almost just for sauna usage but being able to do some work out is a big plus.

]]> General http://www.hietavirta.net/blog/index.php?itemid=318 Tue, 19 May 2009 22:45:24 +0300 http://www.hietavirta.net/blog/index.php?itemid=318 http://www.hietavirta.net/blog/index.php?itemid=318 http://feedproxy.google.com/~r/hietavirta/ptHE/~3/qv-xBDhG7ls/index.php Scottish-Finnish Society in Edinburgh was a great way to meet up and taste excellent home made sima.

On the photography front I have taken plenty of photos but I have not spent fortunes on new camera gear. I think the current setup is decent enough and might need only couple minor things. A set of Kenko extension tubes is most likely next thing to get. Obviously the set is never complete, there is always a better lens or camera to buy.

At work it has been busy enough. The project has been progressing nicely and working with GWT/GXT has been a good experience. The most recent highlight was from today as I set up a soft RAID 1 for new hard drives in my Ubuntu dev box. Of course I did not figure out the setup myself, the instructions were clear enough.

Oh yea, I also ordered a new toy for myself. It is still on the way from Hong Kong so have not tried it out, yet...]]> General http://www.hietavirta.net/blog/index.php?itemid=317 Tue, 5 May 2009 23:13:32 +0300 http://www.hietavirta.net/blog/index.php?itemid=317 http://www.hietavirta.net/blog/index.php?itemid=317 http://feedproxy.google.com/~r/hietavirta/ptHE/~3/-DW6-lwLfRU/index.php
View Kirkcaldy-West Wemyss-Dysart in a larger map]]> General http://www.hietavirta.net/blog/index.php?itemid=316 Thu, 9 Apr 2009 00:10:10 +0300 http://www.hietavirta.net/blog/index.php?itemid=316 http://www.hietavirta.net/blog/index.php?itemid=316 http://feedproxy.google.com/~r/hietavirta/ptHE/~3/7OWfA5MNyRA/index.php This is the tool of the future. Well, and past as well...]]> Money and Economy http://www.hietavirta.net/blog/index.php?itemid=315 Wed, 8 Apr 2009 22:13:28 +0300 http://www.hietavirta.net/blog/index.php?itemid=315 http://www.hietavirta.net/blog/index.php?itemid=315 http://feedproxy.google.com/~r/hietavirta/ptHE/~3/xhOn9D8y3tM/index.php Social Innovation Camp. The idea sounds interesting and most likely I will try to attend because there will be a camp taking place in Glasgow. Now I just need a great idea or two...]]> General http://www.hietavirta.net/blog/index.php?itemid=314 Mon, 30 Mar 2009 21:46:01 +0300 http://www.hietavirta.net/blog/index.php?itemid=314 http://www.hietavirta.net/blog/index.php?itemid=314 http://feedproxy.google.com/~r/hietavirta/ptHE/~3/A1pCtSkSgd8/index.php Apertoire blog. Feel free to visit it and add it to your favorites.]]> General http://www.hietavirta.net/blog/index.php?itemid=313 Sun, 22 Mar 2009 20:33:20 +0200 http://www.hietavirta.net/blog/index.php?itemid=313 http://www.hietavirta.net/blog/index.php?itemid=313 http://feedproxy.google.com/~r/hietavirta/ptHE/~3/tTy9Sx-tsDw/index.php
User groups:
Java User Group Scotland
Scottish Developers
Agile Scotland
BCS Edinburgh Branch


Events:
Tech MeetUp
BarCamp Scotland
Developer Day Scotland
Scotland on Rails


There are much more outside this list - so submit your favorite computing related group or event by sending me email or through comments.]]> Culture http://www.hietavirta.net/blog/index.php?itemid=312 Mon, 16 Mar 2009 00:05:10 +0200 http://www.hietavirta.net/blog/index.php?itemid=312 http://www.hietavirta.net/blog/index.php?itemid=312