pcjuzer_en

Installing Firefox Java plugin on Ubuntu Linux for Dummies

2010-09-22T02:40:00.000-07:00

As a Windows user, I was amused how not easy to install Java on Ubuntu Linux (10.04) nor installing Java (1.6) plugin into Firefox (3.6). It's not nearly a download-next-next-finish task. Additionally, digging into forums I found a lot outdated solutions which I tried and soon realized that they doubtlessly aren't working. Here is the one which worked for me:

First, open a terminal window:

Applications menu -> Accessories -> Terminal.

Type the followings (you will be promted for admin password, because sudo prefix means you want to do something in the name of the super (or sytem) user):

sudo add-apt-repository "deb http://archive.canonical.com/ lucid partner"
sudo aptitude update
sudo aptitude install sun-java6-jdk

Then you have to select things with arrows and pressing enter.
Then Timothy says in the forum you have to type this, but I didn't need it:

sudo update-alternatives --config java

Now you can check if java is installed by typing java -version.

Installing Java plugin into Firefox is no more than making a symbolic link with the ln command. I had to go in the /usr/lib/mozilla/plugins directory, then make the symbolic link with this:

sudo ln -s /usr/lib/jvm/java-6-sun/jre/lib/i386/libnpjp2.so

Restart Firefox if it's running. Java may work.
Sorry for the laxity, I'm still a beginner Ubuntu user.

Web-based chart libraries

2010-08-16T05:14:00.000-07:00

Recently I was hunting for good web-based client-side chart-drawing libraries. I've found a number of blog entries or articles which enumerates some subset of existing frameworks and write sentences about them, like this: 'This is fancy, this is not so fancy but it's still good.' Those writings didn't help me a lot.
What I am interested in?

Presentation model: Can be Flash, HTML Canvas or any other magic. This influences interoperability and scalability of the charts.
Licensing model: Is it free, commercial or GPL.
Dependencies: Should I have to bring another dependencies with the chart-drawing facility?
Docs: quality of documentation.
Examples: quality of examples.
And finally, outlook of the charts and number of the options are also matters.

I've found 16 libraries up to now and made an overall matrix about them, regarding considerations above.

Check it out.

Brillien

2010-03-19T01:25:00.000-07:00

There were three presentation as usual at the 14th Java User Meeting at Budapest yesterday, but this time I'll write only about the first one.

Imre Fazekas had been invited from Debrecen to make a presentation about Brillien, their Java enterprise platform. It's an alternative way of modeling and implementing business logic in place of Java Enterprise (J2EE) Technology. It uses invasive programming model which means we have to extend classes from Brillien superclasses and we may use annotations. The whole system based on asynchronous XMPP communication and a set-context-flow concept. It's something like an application server, but uses a more logical and set-based approach. As the presenter said, it has very good speed and performance characteristics.

Currently there are no IDE or other tools for editing models because this is a very young project, however a Maven plugin and a Maven archetype is accessible on the homepage.

A very good introduction and tutorial can be also found on the homepage. The code can be downloaded as binary distribution and SVN repository is also accessible. As he said they are preparing to run it in production environment and they know about a few other users.

It seems very exciting. Unfortunately I dont't have time to check it out at the moment, however, it's in the queue.

Hacking Apache POI

2009-09-30T01:13:00.000-07:00

In the near future, presumably, I'll have to read and process complex xlsx documents containing a lots of formulas. Jexcelapi can't even open those kinds documents, so I turned to Apache POI. Unfortunately, POI also have problems with some formulas becase support of this field is not fully laboured.

[Update 2010.03.10: After some experimentations I found that Apache POI can read and process new Excel (xlsx) documents including calculating very complex formulas: Basically, cell.getStringCellValue() gives the evaluated outcome. This way, I didn't have to hack POI. That's great!]

I choosed to start two methods:

Knowing exact static structure of the Excel template document, I do problematic calculations in the reader program itself, eliminating POI's formula support.
I study Apache POI's internal structure and try to make up the missing functionality. Unfortunately, POI isn't amendable in a non-invasive way with registering components at certain extension points, so I had to dig in the source code in order to make modifications. Here are the basic experiences regarding setting up the POI sources locally:

Sources can be obtained from subversion http://svn.apache.org/repos/asf/poi/trunk/ or from direct download. There are some "how to build info" on the homepage but it may be useful to record my own experiences, because there are some tricks. Downloaded source has pdf and html docs, but SVN repo contains those in xml format which can be converted by running docs Ant target after installing Apache Forrest v0.5.1 (unzip & set FORREST_HOME system variable to the forrest's root directory). I had to edit forrest.build.xml at line 630, changing failonerror value to false, otherwise the build failed. Place of generated docs is written on the console after a successful build.

For running dist target, JDepend jar have to be on the classpath and setting -Xmx512m VM argument is needed. It completes in 7 minutes for me but no need to run it regularly, just to see if everything can go smoothly. Target jar completes in 45 seconds from scratch and makes all needed jars.

For building with an interactive IDE, add jars to the project from lib and ooxml-lib directories. Setting up JUnit3 may be also needed for running test cases. When running unit tests, add test-data directory to the classpath or specify POI.testdata.path system property.

Target maven-poms creates jar and POM files for Maven and a Unix shell script to install the artifacts in the build/dist directory. I created a DOS batch file with commands like this:
call mvn install:install-file -Dfile=poi-scratchpad-@VERSION@.jar -DpomFile=poi-scratchpad-@VERSION@.pom
I ommited date timestamp info from the artifacts' name. build.xml must have been modified in the jar target to ommit timestamp postfixes. maven-poms also must have been modified to copy the new maven-deploy batch file. version.id property may be modified in build.xml to flag the forked version.

Apache POI is now ready to be hacked.

Json-lib vs Hibernate

2009-07-30T03:09:00.000-07:00

Subtitle: java.util.Date vs java.sql.Timestamp

One of my projects has a data path where Hibernate entities are converted to Json objects by using json-lib. I have some special formatters, e.g. for Date objects for having an easy readable format instead of this:

{"date":1,"day":4,"hours":1,
"minutes":0,"month":0,"nanos":0,
"seconds":0,"time":0,"timezoneOffset":-60,"year":70}

A JsonConfig object can be suited by special formatters which later will be given to the fromObject method:

JsonConfig cfg = new JsonConfig();  
cfg.registerJsonValueProcessor(
  java.util.Date.class, new JsonValueProcessor() {
  private static final SimpleDateFormat SDF =
  new SimpleDateFormat("yyyy-MM-dd");
  public Object processArrayValue(Object value, JsonConfig c) {
    return format((Date)value);
  }
  public Object processObjectValue(
    String key, Object v, JsonConfig c) {
    return format((Date)v);
  }
  public static String format(Date date) {
    return SDF.format(date);
  }
});
JSONObject json = JSONObject.fromObject(objToConvert, cfg);

The problem is, that the code above sometimes doesn't work, because json-lib's default search mechanism regarding value formatters is based on exact class match, however, Hibernate sometimes replaces values for something else, say java.util.Date to java.sql.Timestamp.

It's no matter when using final classes, but we simply cannot apply substitution principle (LSP) generally when using getClass-match. In this case, fromObject won't convert descendants properly when we register a formatter for the superclass. An ugly solution is to register formatters for all descendant classes explicitly but this violates Open Closed Principle. When a new descendant appears, we must amend the code which registers the formatters.

Fortunately it's possible to replace the default search mechanisn too:

cfg.setJsonValueProcessorMatcher(
  new JsonValueProcessorMatcher() {
  public Object getMatch(Class target, Set set) {
    if( target != null && set != null) {
      for(Object obj : set) {
        Class c = (Class) obj;
        if(c.isAssignableFrom(target)) return c;
      }
    }
    return null;
  }
});

target is the runtime class type of the object to convert, set contains the registered formatters' keys. getMatch contract method returns the key for the appropriate formatter or null if no such one.

This solution still have drawbacks. Say, if I register java.util.Date and java.sql.Timestamp too, the matcher will randomly find them, based on the order of the keys in the set. So, some logic is missing which searches for closest match or something like that. But it's good for a demo code.

jxl.log

2009-06-20T11:18:00.000-07:00

In an intranet production environment we have running a Glassfish v2 appserver with several J2EE applications which all use JexcelApi, a.k.a JXL, which is an open source library for accessing, generating or manipulating Microsoft Excel documents. We use version 2.6.3 of JXL because it's the recent one in the Maven repository which we use, however, at the official JXL site there are newer versions. Additionally we have log4j and Java Commons Logging (JCL), ignoring Glassfish's JSR-47 Java Util Logging (JUL) facility.

Application #1 uses purely log4j and gets its log4j.xml config from a custom location.
Application #2 runs Java Commons Logging with no explicite configuration file given, so JCL uses the default JUL facility of the appserver.

Application #1 had been running for a long time without problems but when we installed #2 we realized that a jxl.log file had been created in the glassfish/domain/domain1/config directory and it's rapidly growing. As it happens, we realized that when the partition had been fulled and all enterprise applications had been badly crashed.

I looked into the JexcelApi source and saw that it has a log4.xml which set everything into debug mode and set up a file appender for file jxl.log. It was clear that it's a demo config file and because of the JCL configuration mechanism, the Log4 DOM Configurator gained control and did its job. As Andy Khan wrote "The sample log4j file included along with the distribution is only indicative" and as Kevin replied at the Yahoo JexcelApi group back in 2007: "I think the problem occurs when using jexcelapi in an environment that where multiple logging frameworks are used. Some libraries use log4j, some use commons logging and some use the jdk logging framework. The ones that use log4j or commons logging sometimes look for a log4j.xml on the classpath. When jexcelapi is jarred up, the log4j.xml gets stuck in the "root" of the jar and often gets picked up by log4j or commons logging. Since the default log4j config of jexcelapi is so broad, it ends up overwriting the policies of other libraries." Yes, I can confirm it's definitively a problem.

So, the narrower task was to fix this particular problem but the broader task was to prepare for those cases when a jar in a j2ee application contains a log4j config for any reasons.

It's a good fix to remove log4j.xml from the jar, but say when we talk about Maven build system, it's not a trivial task to dig into an artifact and change it. What's more, who want to care about changing third party dependencies even when using Ant? Fortunately, later versions of JXL don't contain this config file so it could be a good fix to use one of them. Conclusion for component builders to not to put log4j (and any) config into the root of the artifact.
However, it could happen that it's not enough to change the jar to a newer one, make a new build and deploy to the appserver, because the appserver may hold the configured loggers running and some jar files in a devious working directory and couldn't release them when undeploying. Additionally, when it restarts it may pick up again the old wrong jars. Particularly, we have had the old jar files in the application/j2ee-apps and the webapps' directory of the Glassfish's domain directory and couldn't delete it even by hand until the appserver had been stopped.
As Application #1 showed us, it may be a rough but useful practice to get the log4j config from a custom location by giving an absolute file name in an environment variable. (-D argument of the JVM.) But this defends only the particular application. And when we don't want to use log4j in that application we also have to give a log4j config just for hide the corrupted one, which is unacceptable.
A good practice according to me, to follow Andreas Shaefer's tip regarding set up log4j logging in Glassfish in his blog entry: To the hell with JDK logging II.. In our case it prevented Application #1 from corrupt logging by placing a log4j.xml to the very front of the classpath, however, it enabledApplication #2 to use its special config.

Otherwise, a correct and useful logging tip collection would be very handsome for J2EE environment, but not a one which says that every logger instance method invocation should be an EJB call.

JUM VIII. - IX. - X.

2009-05-30T10:23:00.000-07:00

In the recent months there were a few Java-related microconferences organized at Budapest.

At the eighth occassion of the Java User Meeting (JUM) in January we had a presentation about OSGi by local guys and about Flex by Cornel Creanga from the Romanian Adobe office. I've read his blog and I must say life of an evangelist can be very cool (if there's no wife or girlfriend:)). Visiting Java and Adobe user groups all around in Europe, it's great.

At the ninth occasion in March we had three presentations: introduction to the Maven build system, SOAP testing with SOAPui and various other components, and OLAP architectures. The latter was driven by the magnificant prezi presentation engine, which is a very young Hungarian startup project and which will be introduced soon at the Silicon Walley and I'm sure it will have a great success. Otherwise, I guess this time we beat down the highest participant number with about 40 attendees.

At the tenth occassion we had a presenter again from outside of the country: Corsin Decurtins from Switzerland came and talked about Rapid prototyping with object oriented databases. The discourse had also been presented at the Jazoon conference in 2007. He also talked about the conference itself which is organized in Zurich every summer. I think this time I skip it due to various domesticies. Other two discourses were about SOAP testing with Groovy and Amazon Web Services.

The next Java User Meeting will be held at the third wednesday of September. If you are an ardent evangelist or your company would appreciate if you would talk about their product, (and this product can be connected to Java somehow) contact with the JUM organizers. Budapest is still beautiful in September and we know the right pubs.

Budapest Newtech Meetup

2009-01-19T04:00:00.000-08:00

The originally planned programme of the January Budapest Newtech Meetup contained some interesting presentations like the smart 3D visualizer solution (3dForAll) from a young Hungarian inventor or the Google App Engine which is an alternative server-side solution for those who don't have own server facilities. It can be used mainly for OpenSocial applications which is actual nowadays because of leader social network of Hungary (Wiw: Who is Who) had been announced to support opensocial applications in the near future. Further live demo would had been the Surface which is a Microsoft hardware but it had been also cancelled.

The event had been organized this time in a small art movie near the Buda-side of the Margareth bridge. About 130 people were present, some of them couldn't fit into the room.

The first demo was about the Zoomery application which is built on Microsoft Silverlight technology and used for deep-zooming a set of pictures or documents. Several kinds of documents can be converted to this special image format which is highly zoomable, filterable and orderable with the application itself.

Next presentation was about the Sensenet, a unique open source .NET based Enterprise Content Management System. They have some working project with this CMS at some larger company or organization in Hungary and abroad. It can be a deliberate solution for those who adhere Microsoft technology. In Java world, Alfresco is a similar open source Enterprise CMS.

UStream is a web-based video streaming solution. The company have some Hungarian relations and not least most development happen at Budapest. We saw a video stream on the movie screen in a web browser which was being captured by a 3G phone in the room and was passed through a server placed in the US. Not the technology was the main point but the possibility to manage the stream as a service: embedding it into own webpage, placing own trademark on the stream, managing user-access. Afterall, it was a great demonstration.

Last presentation was about TurulMeme, which is a webpage based on sharing facilities of Google Reader. People can register their sharings into the TurulMeme and they appear on the page as tagged, commentable, filterable news with information on how many other users read it and something like this. It wasn't a big technological breakthrough according to me, there are many more similar services on the web, but the main difference that this site focuses mainly on Hungarian news sources. As the developer said it had been completed in days (MS techonology) and it's rather fun than a serious competitor of other link sharing services.

Afterall, it was a great event in a great place with many people and hot vine.

Client's transaction aborted

2008-12-19T05:42:00.000-08:00

I've met the above error message using a Wicket 1.2 / EJB3 intranet application under Glassfish v2.
Here is the more particular head of the stack trace:

javax.ejb.TransactionRolledbackLocalException: Client's transaction aborted
at com.sun.ejb.containers.BaseContainer.useClientTx(BaseContainer.java:3394)
at com.sun.ejb.containers.BaseContainer.preInvokeTx(BaseContainer.java:3274)
at com.sun.ejb.containers.BaseContainer.preInvoke(BaseContainer.java:1244)
at com.sun.ejb.containers.EJBLocalObjectInvocationHandler.invoke(EJBLocalObjectInvocationHandler.java:195)
at com.sun.ejb.containers.EJBLocalObjectInvocationHandlerDelegate.invoke(EJBLocalObjectInvocationHandlerDelegate.java:127)

This exception raised on the integration server sometimes, randomly, for simple page fetch operations. After pressing reload on the browser, the operation was usually successful. I couldn't reproduce the failure on the local machine where I regularly restart the app server and have run some tiny applications only beside the subject one.

After some hours code bugging I'd found a forum message which gave me an idea to play some rounds with the Glassfish's HTTP Service configuration. Maybe not my EJB logic is buggy or misconfigured but the client web application causes the error somehow. Unfortunately I couldn't quarry anything regarding this from the default server logs.

Finally I tried the following on the Glassfish admin console which solved the problem as a symptomatic treatment:
Configuration > HTTP Service > RequestProcessing > Thread Count (set a higher value, the default is 5. 10 is worked for me.)

It seems to be working now.

Eclipse DemoCamp Budapest

2008-12-10T05:34:00.000-08:00

This year I also couldn't get to any of the heavy European Java conferences, so I stayed at visiting some tiny local events intown. For example last week I attended on the Eclipse DemoCamp Budapest which was organized by the right engaging b2i local team at a pleasant (but not too silent) downtown pub.

Around 20 participant were present and there were two presentations, or rather demos planned. When people entered they were asked if they had some interesting subject to speak about, so the whole thing had an unconference style. FOT Testing Services guys actually had a notebook with a copy of their recent project so they took the opportunity to introduce it to the public.

First demo was about making a generic data model with EMF (Eclipse Modeling Framework) plugin and creating a model editor with Eclipse GMF (Graphical Modeling Framework) which is given by GEF (Graphical Editing Framework). The example model was a basic CD database.

With suitable experiences, it takes about 10-20 minutes to create a comfortable class diagram-like Eclipse-based graphical editor for a data model with the same complexity. b2i assembled a complex healthcare system model and editor in six months as they said. (I don't know how many people, I guess 2-4.) It's worth considering to use these tools in case of a similar proposition.

Second demo was about testing banking applications with Eclipse environment (FOT Testing Services) with their plugin set. There were green and red strikes, an imitation of the GUI of the banking application for testing, report generation tools and much more. People with

Third demo was about Eclipse tips and tricks. A guy showed a number of smart keyboard shortcuts and useful functions. Most of us know most funtions so I observed that the average knowledge was rather high.

After that, or rather during the last demo, the event slightly turned into a drinking party. Unfortunately I had to leave but I decided to be there at the next occassion, maybe in next Juny or so.

Cloud Computing

2008-08-07T07:03:00.000-07:00

Is it the ultimate innovation or is it the next buzzword managers and sales staff members must record into their notebooks?

After reading some material it doesn't mean more for me than a clustered client-server architecture where processing capacity and memory can be hired and clients are generally web browsers or other applications. It's not a big novelty form the developers' point of view so first of all we got a new phrase for the hot water.

Don't mix it with 'grid computing' where real math computations are running on a statically or dynamically built distributed network (SETI@home for an example) and clients are active participants of the process. Instead of this, with cloud computing, you connect to the service and use it. So I don't get again where is the magic. (Maybe the magic is in the ability of obtaining a large amount of personal data and money from the users.) I can imagine an architecture which discovers (sourceforge does this) or even deploys automatically service components geographically closer to the requester. So yes, there can be interesting aspects.

Anyway, we have to learn:

Internet, Server (deprecated, past)
Cloud Computing (trendy, future)

Setting up EJB3 default interceptor

2008-06-05T09:10:00.001-07:00

It wasn't easy to find out how to configure a default interceptor in EJB3 environment.
It's okay to make this snippet into the ejb-jar.xml:


  <assembly-descriptor>
      <interceptor-binding>
          <ejb-name>*</ejb-name>
          <interceptor-class>pkg.IC</interceptor-class>
      </interceptor-binding>
  </assembly-descriptor>

Maybe everybody forget to mention maybe it's a Glassfish V2 trick that I get this error message during deployment:

Interceptor binding contains an interceptor class name = pkg.IC that is not defined as an interceptor

...unless I register the interceptor class itself too with this:


 <interceptors>
      <interceptor>
          <interceptor-class>pkg.IC</interceptor-class>
          <around-invoke>
              <method-name>call</method-name>
          </around-invoke>
      </interceptor>
  </interceptors>

<interceptors> and <assembly-descriptor> are children of <ejb-jar> element in this order as it seems well in the xsd.

Survey

2008-05-06T06:53:00.000-07:00

Some months ago I read an article which said programmers usually do their hobby projects much better than their working projects. There are several reasons like time-pressure, predefined set of useless tools and pointless procedures, rubber specifications etc.

I've made a little survey about that. Do you feel sometimes it would be better to be a shepherd somewhere on a sympathetic highland in, say, Scotland and to forget all office crap? Or do you arrive at yor workplace every morning that you know you will change the world a little, of course in the right direction?

The survey is here at the right. Thank you for giving an answer if you did.

It would be nice to know the distribution of the answers by several categories like programming languages, destination environments, open source and commercial projects, speciality of the projects (banking, science, administration, telecommunications, entertainment, web/publishing), however, this simple survey is not capable for that.

But I have some opinions. It's apparent that open source projects are cooler than commercial ones. Scientific and academic projects must be also nice as they can have much more time for research and development than, let's say, outsourced banking projects where contracting party is generally absolutely disinterested in the question of nice, reusable and well-unit-tested code in contrast with delaying the payment for the software. I don't know what is the situation between programming languages but I think C or C++ programmers on embedded devices make a much more precise work than Java programmers at enterprise projects. Lower-level programming languages need more enthusiasm, higher-level ones are more popular which implies broader distribution in the level of knowledge of the programmers. But these are just thoughts...

Let's see the results at 1st of July.

AppServer Shootout

2008-04-02T03:22:00.000-07:00

Recently we organized an AppServer shootout (we call it deatmatch) on our local Java User Meeting. The three contestants would have been Sun's Glassfish v2, Redhat's JBoss and IBM's Geronimo. Unfortunately IBM guy couldn't attend on this event because of other business and JBoss presentation had technical difficulties so we had to do with Glassfish demo. Let's see the 8 tasks:

1. Deploying simple EJB3/JPA webapplication with pre-initialized DB. Checking WSDL as a bonus.

It was easy and elegant. We checked WSDL which was an ugly and large XML but it's been generated automatically. We did a test request by using the Glassfish's admin console. That means we filled an HTML form containing one of the webservice's method's parameters and submitted it.

2. Remote deploy from build script. (Usual development task.)

We did it from Netbeans using Ant and a special Glassfish deploy task. AFAIK hot deploy is also supported by Glassfish when appserver scans a pre-set directory and our task is to plump ear or war file into that place.

3. Changing logging config during runtime.

We did it by using the admin console and logs could be browsed by a fancy HTML table. Severity level of loggers could be set by logger instance as usual. The Test application was Glassfish-friendly because it used Java Util Logging and 'fortunately' Glassfish also supports that (and only that?) logger framework. I think log4j config could had been happened by editing log4j.xml by hand and we had to pass up the fancy HTML log table, nevertheless I would have been happy with that since I prefer anything else than java.util.logging.

4. Remote runtime-debugging of the application.

It was OK, however Glassfish must have been restarted each time before connecting debugger client. As I remember JBoss doesn't need restart when a certain JVM switch is set. Of course it needs when we want to change that switch. We used Netbeans as a debugger client but it would have been anything else, for example Eclipse.

5. Changing data-source.

We expected it won't work without restarting the application and of course it did (not). Other expectation could be against the appserver to not to totally crash down in this case. It didn't crash, just the application started to throw ugly excpetions with long-long stack traces. Changing datasource had been worked after restarting application.

6. Restarting appserver with the application. (How much time does it take?)

We restarted appserver, but unfortunately forgot to measure it with stopwatch. It could have been 10 seconds.

7. Integrating LDAP (if we have time)

Guys started to configure it but there were some technical difficulties. They said usually it can be done in 10 minutes. We wanted to see the stress test so we jumped.

8. Stress test with JMeter

That would have been exciting if we had the other contestant appservers running on the same hardware, unfortunately we had not. However, a plain dual-core notebook could serve 1700 requests per second without tuning, and 2200 with tuning.

Tuning tips we used.
Why didn't we use Apache Benchmark.
We used JMeter.

I'm looking forward to the next occassion where we'll have hopefully other competitors with sharpened environments.

Beyond this appserver stuff, we had a presentation about component models and a BlazeDS, Flex prototype app.

Challenge24 EC

2008-03-07T00:51:00.000-08:00

Challenge24 had been started as an internal competition at the local techincal university of Budapest. For now it became an international programming contest which is being organized 8th time this year. The contest itself usually happens in May when teams must be present personally but it's preceeded by a qualifying session (a.k.a Electronic Contest) which has been arranged on the last weekend of February and teams didn't have to be present personally, just to be online.

At Electronic Contest there are up to 8 combinatorical, geometrical, game theorical problems which have to be solved by sending the result files to the central server. Teams are free to choose platform and programming language.

More information including rules, list of teams and their scores, assignment of the Electronic Contest can be found on the homepage. The name is Challenge24, because the main contest in May lasts for 24 hours.

I didn't take part nor this year nor earlier but I usually download and solve some tasks from the Electronic Contest's problem set, just to keep my mind rolling. I need these screwed examples because at work I'm developing administration and web-based software components for business sector where capability of whoomping buzzwords and using the four elementary math operations is rather enough than real thinking and planning.

Sometimes I envy guys who are working on games, 3D engines, embedded devices where the iron is highly finite or anything else than administrative software.

And I'm curious how leader teams are preparing for the competition. I guess they need a very rich algorythm collection, they have to know perfectly the language and the IDE they are using, strong self-confidence is also a must in algorythms but I don't know how deep mathematical knowledge is required. How much counts the targeted knowledge, how much are exercies finger-practices for those who have targeted knowledge, let's say geometrical examples. It would be interesting to know what language and IDE do they use. Do they use mainstream production languages (Java, C#, C++) or use some functional or logic programming languages like Prolog? Do they use artificial intelligence modules?

Who are the leader teams at all? University students? Colleagues in a company? Talent freelancers? It's a pity that challenge24.org doesn't serve a short introduction of the teams. Hey! Write a comment if you know anything abut them. So I don't know anything but it seems something goes very well in Sweeden and Poland.

Congratulations!

JavaPosse Episode 157

2008-03-05T04:31:00.001-08:00

Why do I post these? I've been regularly listening these podcasts and sometimes I flag more interesting subjects in order to be able to re-listen them. It's just one step forward to flag *all* main subjects and make it public whether it's useful for others. This one was the latest Episode in 2007 or the first in 2008 depending on the point of view. With this, all tracklists of 2008-episodes are present up to now. Further ones are posted to the JavaPosse Google Group. Henceforward, I plan to write real posts here. :)

Original shownotes and the audible mp3 of the podcast can be found here.
More tracklists can be found here.

00:10 Metal theme, intro
03:40 Announcing JavaPosse Roundup
09:35 'Smart Drink Coasters - Digital Pub' / Is java slow?
14:00 Is java loosing place? Reflecting for weird articles.
21:55 What did you give for Christmas?
31:55 Favourite aspect or moments of the year
33:10 JavaPosse Google Group
41:40 Last year predictions
45:50 Predictions for next year
47:30 Special guests :)
50:10 Winners or loosers
52:20 Happy New Year

JavaPosse Episode 158

2008-02-24T23:45:00.000-08:00

This is a tracklist of a JavaPosse Episode.
Original shownotes and the audible mp3 can be found here.
More tracklists can be found here.

Newcast for January 9th 2008

00:25 Intro (T-shirt is available)
01:44 Roundup - only days left for the early bird price
02:35 Bruce Eckel: should we simply stop adding new features to Java?
17:40 Apple has released an updated developer preview version of Java 6
22:50 Two Professors from NYU have slammed Java as a teaching language
33:20 Scala Roundup
38:00 Library of the week - PDF Renderer
40:30 Up and coming Project of the Week - Mighty Box

Quick News Items

44:00 JSR 271 - The Mobile Information Device Profile 3 (better known as MIDP 3)
44:23 Chris Adamson has issued a call for comments on how java.net might be improved in 2008
44:48 Is Rails a Ghetto?
45:51 Apache Wicket 1.3 has been released
46:09 Motorola has released a new version of the ROKR music playing phone
46:15 JSR 286 - the Java Portlet Specification 2.0
46:33 JSR 255 - JMX (the Java Management Extensions) version 2.0
46:45 JSR 279 - Service Connection API for Java ME
47:12 JSR 235 - Service Data Objects - has been stalled for about 3 years
48:20 Apache Jakarta have released a new version Commons configuration
48:43 There is a new preview version of Oracle JDeveloper 11g available
49:05 Using Erlang (a functional language) and Java together
49:30 Pearson Education held a four day GWT conference in San Francisco
49:50 The NetBeans source code is being moved to Mercurial
50:18 Django is getting very close to running on top of Jython
50:35 NetBeans has once again kicked off it's world tour
51:00 The Java 2 Fifth Edition Complete Reference is now available for free as a PDF download
51:19 Groovy 1.5.1 has been released
51:34 The JDIC project have updated their netbeans plugin for NetBeans 6
51:47 Infoworld reckons that Sun Microsystems is back in the game
52:16 Nominations for the 2008 Eclipse Community Awards are now being accepted
52:43 Jason LaPier has put together a NetBeans cheat sheet for Ruby and Rails development
53:00 Grizzly 1.7 is out
53:20 On a related note, Glassfish v2 update release 1 is also now available
53:30 Metro versions 1.0.1 and 1.1 have been released
53:46 A new version of Excelsior JET is now available
54:09 JRuby 1.1RC1 released

54:20 BluRay Wins?

JavaPosse Episode 163

2008-02-14T00:28:00.001-08:00

This is a tracklist of a JavaPosse Episode.
Original shownotes and the audible mp3 can be found Shownotes.
More tracklists can be found More Tracklists.

00:30 Intro -couple of guests in studio, club feeling, somebody is speaking from the cupboard. Roundup, Sun / MySQL, etc.
17:28 Grails 1.0 released
21:10 Registration for JavaOne is now open
30:25 Closures
38:50 JSF has passed Swing as the number one GUI component model for job demand
42:20 JavaFX update N, reinventing client Java
49:40 Nymbus Look and Feel
52:10 Font rendering

Quick News
64:00 A NetBeans Innovators Grants program has been introduced by Sun
64:50 How to write a full application that uses JSF, Seam 2.0 and JPA together, Carol McDonald's blog
65:26 Duke's Choice Award (deadline is 14th March)
65:40 Opera Mobile
69:37 TheServerSide.com has an introduction to using MapReduce in Java applications
69:58 Sun has released a new version of their Solaris Express Developer Edition
70:57 Sun has also posted a proposed final draft of JSR 293 - Location API 2.0
71:20 Thanks

JavaPosse Episode 162

2008-02-13T07:39:00.000-08:00

This is a tracklist of a JavaPosse Episode.
Original shownotes and the audible mp3 can be found here.
More tracklists can be found here.

Interview with Dalibor Topic about Open JDK, the JCP, Kaffe, Iced Tea and more

00:40 Intro
01:44 About Kaffe project
05:28 What's the current state of Kaffe now?
07:35 Are annotations and generics supported by Kaffe now?
09:15 What were the trade-offs between those two licenses and why did you end up picking the GPL side of the two?
10:45 How difficult is it to hit a moving target like the Java Language Specification in a project like Kaffe?
12:26 What do you think is the future for Kaffe?
14:25 ... Are you seeing now that OpenJDK is open sourced or at least mostly open sourced that it's definitely being picked up from those kind of distributions? (Java in Linux)
16:25 Any other project you are involved? (GNU classpath)
17:20 Dalibor's relationship with OpenJDK.
20:33 The OpenJDK was released under the GPLv2 with the classpath exception. Do you think it was a good choice?
22:10 About Interim Governance Board
24:47 How does this Governance Board relate to the JCP?
26:37 What will happen once the temporary governance board is finished with its work?
28:50 Are you personally interested in serving on the next GB for the OpenJDK meeting ...?
29:45 How much of the current binary ... the Java is carrying can be replaced by stuff out of projects like Iced Tea and do you think that's likely to happen?
31:20 Do you think that JCP is too slow?
32:15 Do you think maybe they should have a little bit more development going on before JSR-s are formed from the ideas?
34:50 Do you think that JCP is dominated by Sun?
40:20 Superpackages vs OSGi (JSR277,JSR294 vs JSR291)
47:50 Thanks

JavaPosse Episode 161

2008-02-11T01:34:00.000-08:00

This is a tracklist of a JavaPosse Episode.
Original shownotes and the audible mp3 can be found here.
More tracklists can be found here.

Open JavaME and JavaSE interviews

00:30 Intro : About roundup signups, skiing, next episode (will be a listener feedback session), etc
05:00 About interview at Sun Java Mobile and Embedded Developer Days
06:10 Sun aquiring MySQL
12:52 Oracle acquiring BEA
17:25 Is the Geronimo in trouble?
20:00 Applet of the Week: Sea Level applets
21:05 Project of the week - LoboBrowser

Quick News
23:43 JDK6u4
24:00 CommunityOne 2008 call for participation
24:38 JavaZone 2008 call for presentations
25:17 Jazoon 08
25:50 EclipseCon
26:21 Artifactory, Maven
26:34 Chris Richardson's blog entry
27:04 JSR 323 - Strong Mobility for Java
27:41 Bill Venners has released a new testing tool - ScalaTest ('JUnit for Scala')
28:06 The Developer.com product awards for 2008 have been announced
28:32 JackRabbit 1.4
28:49 Apache Jakarta Commons Pool 1.4
29:10 Neal Gafter: Java is dead
29:32 Posse listeners in Pune, India
30:02 Apache Lenya 2.0 (Content Management System)
30:26 Sun is holding another Second Life virtual meeting
30:36 Sun's JavaFX tools to interop with Adobe

31:38 An easy-going interview with Roger and Terrence at Sun Java Mobile and Embedded Developer day
32:16 Are You gonna have this scene next year?
35:50 Why hasn't there been an event like this already?
42:40 ...Google's Android is a reflection that so many things in the industry went wrong...
43:00 Some announcements
45:15 One of the big goals of the community...
45:45 Vodafone r&d
46:50 Squack (?) virtual machine is open source
49:10 When the Sun spot blend? (?)
56:10 Thanx

56:45 Outro

JavaPosse Episode 159

2008-02-06T11:01:00.000-08:00

This is a tracklist of a JavaPosse Episode.
Original shownotes and the audible mp3 can be found here.
More tracklists can be found here.

Open source ME and SE interviews

00:30 Intro, background

01:16 Interview with Terence Barr, introduction
02:11 What happened since the announcement of open sourcing JavaME?
03:21 What were the reasons for applying GPLv2 without the classpath exception? Has it turned out to be a good choice in retrospect?
05:53 Had commercial licensees react to the open sourcing of JavaME?
07:42 What the deal is with JavaME CLDC and JavaME CDC? It was reported earlier that CLDC was being killed. What's going on here?
10:02 Have you seen any unusual or unexpected port JavaME since it was open sourced?
12:52 Do you think JavaME development has accelerated as a result of its open sourcing?
14:06 How will the JavaFX script work in JavaME? When will we see FX script running on mobile devices any time soon?
15:45 What's the story with device availability? Are there any devices running CDC yet?
17:16 When we gonna see some MobileFX or JavaFX mobile stuff comeout?
18:15 Why isn't there a mobility pack for Mac OS 10 yet?
20:14 Are there any regrets inside of Sun about open sourcing JavaME?
22:35 Are you still confident we'll see JavaME for Apple iPhone?
24:30 About Java Mobile and Embedded Developer Days.
26:27 Thx

26:43 Interview with Mark Reinhold about state of open source Java and OpenJDK
26:55 Introduction
27:53 A quick update on the state of open sourcing the JDK.
28:41 What is the work remained to be done?
30:11 Do you have any non-Sun regular contributors?
31:10 About moving to Mercurial.
32:10 About governance (?) board.
34:57 Ice Tea project of RedHat
38:25 GPLv2, questions about licesing.
41:08 Have OpenJDK a positive effect on improving the language (Java7)?
43:00 Do you have any personal favourite JSR?
46:40 Are there any regrets inside of Sun from the open sourcing the JDK?
47:20 How do you feel the community building is going around the OpenJDK?
48:45 Are there any other tools for helping the community development efforts?
49:55 Are people each other helping ...
51:50 Thx

53:30 outro

JavaPosse Episode 155

2008-02-06T10:57:00.000-08:00

This is a tracklist of a JavaPosse Episode.
Original shownotes and the audible mp3 can be found here.
More tracklists can be found here.

00:25 Prologue
00:50 Introducing Martin Odersky
05:14 How long have you been working on Scala?
06:35 Do you think Scala can be a general purpose language?
08:58 Why Scala is a much more practical approach to functional
programming than something like Miranda is?
11:37 What are monets? (?)
13:42 What do you suggest for Java programmers to get started in
Scala? (First steps to Scala)
17:16 Earliest real world examples of Scala usage
20:00 What other applications do you see as perfect fits for Scala?
22:00 Why immutability is kind of that important in functional
languages or Scala?
24:10 About XML 'efficiency' in Java
26:00 What do you think about closures in Java?
28:28 Embedding XML in Scala
30:52 What's your strategy about (backward) compatibility?
34:00 ending

JavaPosse Episode 153

2008-02-05T23:55:00.000-08:00

This is a tracklist of a JavaPosse Episode.
Original shownotes and the audible mp3 can be found here.
More tracklists can be found here.

Newscast for Dec 6th 2007

02:55 NetBeans 6.0 GWT plugin, Scala plugin(s)
09:05 Spring 2.5 has been released
11:25 Applets of the Week: Maths, Physics and Engineering applets
14:30 Android news: Robert Cooper's article
15:20 Carlos Bazarella from Polipus, ME4Android
15:40 OHA member Ascender announced 'Droid Fonts'
16:52 Starting with android. Article from John Lombardo
17:12 AndroidPort - new Google Group
17:22 Karl Pauls of Luminis has managed, to get Apache Felix to work on Android
Quick New Items
17:44 TheServerSide article about RestFaces
18:45 Mark Reinhold, Governance Board
20:00 Think Record Storage
20:30 Atlassian Software has released version 1.2 of Crowd
20:50 The Apache project has released version 1.1 Final of Continuum
21:00 JBoss has released a JSF unit testing tool: JSFUnit
21:46 Project Mojarra
23:46 JSR321 - Trusted Computing API for Java
24:10 Roberto Chinnici blogs that he has got GlassFish v2 running on SoyLatte on Tiger
24:30 DeveloperLife has started a series of tutorials about developing with GWT
25:12 Microsoft released GWT like API
26:10 The third season of Lost on Blu-Ray...
26:55 Sun has announced a new program to compensate Open Source developers for their coding efforts
28:30 JavaRanch has an article about James Gosling's recent "State of the Java Universe" talk
30:06 Kelly O'Hair blogs about JDK 7...

32:10 Listener Feedback
33:04 'return this'
36:20 'instance initializers in anonymous inner classes'
38:40 Closures
41:38 Ryan Dewsbury's new GWT book
43:28 Java ME OS 10
45:30 Delegation vs Inheritance
49:10 NetBeans6 syntax coloring glitch
50:20 JUG popularity
52:55 JavaPosse T-shirts
55:50 Javapolis

JavaPosse Episode 160

2008-02-04T09:20:00.000-08:00

This is a tracklist of a JavaPosse Episode.
Original shownotes and the audible mp3 can be found here.
More tracklists can be found here.

Interview with Bob Lee about Guice
(Guice is an IoC framework.)

00:30 Intro
00:47 What is Guice?
03:56 What was the reason to start a new framework?
10:23 Have you seen people use it for really small things?
12:51 What's coming up?
22:50 Some things about Google Collections API
23:55 Differences between weak and soft references
26:15 Interesting combinations of strong and weak references in practice
28:18 What are the other things that you think are coming in the future for Google Collections?
30:30 Anything else, goodbye, outro...

Nav N Go @ CES Las Vegas

2008-01-13T04:22:00.000-08:00

It always inflates me with pride when I see a Hungarian company at a famouns international exhibition. Many tiny software companies in Hungary are usually forming for optimizing income and for supplying ordinary software demands of other tiny companies which have not too much aim beside optimizing income and supplying some ordinary human demands. No creative ideas, just for hunting contracts and tenders on more or less fair ways.

After reading their story I guess Nav N Go absolutely doesn't belong to this gang. They deal with car navigation systems and as I far I know they are market leader in the European region.

JUnit 3.8 JUnit 4.x

2007-12-30T06:37:00.000-08:00

Recently I looked through some JUnit 3.8 - JUnit 4 stuffs. Here are two useful readings in the subject: First is at IBM, other is on DevX. JUnit 4.X is basically direct improvement of JUnit 3.X with exploiting new features of JDK5. Current version is 4.4 and it can be downloaded from www.junit.org. What have been changed?

It needs (surprisingly) at least Java 5.
Package has been changed from junit.framework to org.junit.
Using @Test annotations instead of naming conventions. Methods must be public with void return type and they shouldn't have parameters. If we don't comply with these we would expect the following runtime exceptions:
java.lang.Exception: Method xxx should have no parameters java.lang.Exception: Method xxx should be void
Using static import: import static org.junit.Assert.assertEquals; We can write instead of Assert.assertEquals(...); a sorter assertEquals(...);. (Of course we can use static import with JUnit 3.8 if we have Java 5.)
Extending TestCase isn't necessary anymore, so it becames possible to test protected methods by extending the subject class with the class which has the tests.
Instead of method setUp() we use @Before annotation, even more than one. Order of executing these methods is theoretically random.
tearDown()'s annotation pair is @After, which we can have also more than one.
In super classes we haven't have to invoke explicite setUp()==@Before and tearDown()==@After methods because their invocation is automatic: First @Before-s of the super class are invoked, then ones in descendant classes. Order of invoking @After is reversed. First the descendant classes, then super classes.
A @Before and @After is invoked before and after every test method as setUp() and tearDown() does. We have the possibility to concede @BeforeClass and @AfterClass which will be invoked before and after all test methods in the given class. There is no such feature in JUnit 3.X. (It has TestSuite class which ensures similar functionality.)
If a class doesn't have any @Test annotation, we will get an error.
In JUnit 3.X we could check exceptions by writing an assert into the catch block. In JUnit 4 we can define expected exceptions in annotation: @Test(expected=ArithmeticException.class). If exception isn't thrown or different exception has been thrown the test will fail. If more checks needed about parameters and message of the thrown exceptions we must follow the well-known try-catch practice.
If we don't want to run some test methods for some reason it's possible to ignore it by using @Ignore. (@Test needn't have to be removed. @Ignore can follow or precede it.) It can have a String-type parameter with the reason why is the test ignored. Test won't run and the runner will sign the fact that it was ignored. We can say @Ignore for the whole class but it's slightly differs from ignoring each test methods one by one, because @AfterClass and @BeforeClass will run in the latter case.
Highly appreciated feature to be able to give timeout for the test cases: @Test(timeout=500) Millisec.
There is a new assert which compares object arrays, however many (12) assert method removed because of the autoboxing feature. assertXXX(Object, Object) is used instead of them. More precisely DevX writes this happened but oddly I can use these old asserts in the TestCase class.
assert keyword of Java1.4 can also be used, however -ea JVM switch must be given at running the tests, otherwise asserts won't be evaluated. When using native asserts, instead of the JUnit's assertException, the general java.lang.AssertionError will raise in certain cases.

In JUnit4 there is no suite() method. We can create an empty class which has the runnable classes in annotation:

@RunWith(Suite.class)
@Suite.SuiteClasses({My1Test.class, My2Test.class, My2Test.class})
public class AllTests {
}

By using @RunWith class annotation we can define own runner for the test cases. For an example, the org.junit.runners.Parameterized, which drives the test by a set of parameters we defined previously. A public static method with @Parameters annotation is needed which returns a Collection and a public constructor is needed which can accept elements of the previous Collection. If the Collection contains integer pairs, constructor must have two integer parameters. The runner walks through on the Collection, calls the constructor and the test methods for every element of the Collection. DevX article has a good example about this on the third page. (Listing 2.)
Giving @RunWith(TestClassRunner.class) doesn't make any difference than giving anything because the TestClassRunner is the default runner.
JUnit4 doesn't make difference between expected failures and wrongly written test cases. This is a stepback. One testcase can have (passed/error/failure) in JUnit 3.8. In JUnit 4 it can have (passed/failure/(ignored)) only.
Test can be runned by java –ea org.junit.runner.JUnitCore. It can run 3.8 tests according to the DevX article. Practically 3.8 must have a small modification:
```
public static junit.framework.Test suite() {
   return new JUnit4TestAdapter(MyTestClass.class);
```
4.0 tests certainly won't run on 3.8. When having both old and new JUnit on the classpath they may impact. It least I had securityException.
I've heard about a so called assertThat method. Theoretically 4.4 have this but I didn't see it in the current javadoc on junit.org.
Eclipse 3.3 has JUnit4.4 and JUnit3.8 support.

If you need this in Hungarian, click here.

Logger frameworks

2007-12-01T08:58:00.000-08:00

Let's have a look round in the world of logging.
There is a glorious article in the Wikipedia about fundamental concepts of logging.

Two (or rather three) competitors are log4j, java logging API == java.util.logging == JUL == JSR47 and Java Commons Logging == JCL. The latter is not a real logging framework, just an adapter which quests for the available framework in runtime and uses it. It can be helpful when we don't want to wrap some modul to log4j, JUL or anything, however, it has disadvantages regarding efficiency and functionality. See this article about it: Think again before adopting the commons-logging API

Here is an opinion about differences between log4j and JUL. I've read it a long time ago and deeply agree with it with the supplement, that because of the continuous inconveniences I hate Java Logging API.

(The author of the former article, Ceki Gülcü is the founder of log4j. He has a blog where he writes engaging things. For an example, mentions presentation of Linus Torvalds about GIT vs SVN. Well, I also didn't like that style not to say about this.)

Nowadays it seems that he (Ceki Gülcü) walks differents ways from Apache group, because he is working on the possible posteriors of log4j and JCL, namely LogBack and SLF4J. (Wikipedia article doesn't mentions these.) Theoretically, SLF4J will have log4j support. I don't know how much will be SLF4J efficient but I guess they started to implement a new framework because they wanted to make something better.

log4j exists since Java 1.1, JUL was invented in 1.4. By exploring homepage of log4j it turns out soon that there's no version which exploits advantages of Java 5.0. Log4j 2.0 would have been the one which fulfils this task, but there are not too much (any) visible activity in this subject.

However, LogBack and SLF4J are going to be in a useable shape soon. LogBack has version 0.9.X nowadays. On our Hungarian forum there was a flame about logBack and using isDebugEnabled. First important consequence was for me, that people do log in many different styles and it depends on the developed application. Somebody can use toString often, somebody doesn't have this possibility. Secondly, isDebugEnabled condition can't be dropped out in every cases, just when there are no expressions in the parameter list. (For sample, explicit high-cost function calls.) By the way, using varargs instead of String evaluation can be rather beneficial during logging.

Which one would I choose? In conservative software modules, when embedding environment may not be log4j-based I would choose JCL. Otherwise I would use log4j. At newly started projects I would use LogBack or SLF4J, although I would get a line if there are existing appenders which I should use. Regarding log4j, (as it is an old professional in the scene) there are a lot of appenders.

(This was a translation again. See original here in Hungarian.)

Wicket vs JSF

2007-11-09T05:05:00.000-08:00

This post is the translation of the writing (Hungarian) from my other blog with the identical title.

In the recent months I had the pleasure to get acquainted with Wicket and JSF which are both servlet-based web technology frameworks with identical position and purpose. A Wicket presentation was also organized by Hungarian Javafórum guys at the summer, but unfortunately, I couldn't attend on it.

JSF is part of the J2EE standard, Wicket is a Sourceforge-project which has joined to the Apache Foundation some months ago. Wicket means the implementation itself, while JSF is just a specification with a reference implementation and some real implementations. I met Tomahawk among real implementations, which is also related to Apache.

Wicket uses HTML markup with wicket tags which are replaced to real HTML components in rendering time on the server-side. (Similar to Dojo with the difference, that Dojo replaces components on the client side.) JSF is taglib-based.

We used Facelets with JSF which helps modularization of pages. We also used standard tag library where we could. Instead of writing a long discourse, I've chosen some criterias and here I compare the two competitors:

HTML element set: What kinds of prefabricated elements are present.
Wicket: In the core API, there are just the most basical form components. There aren't sortable table or tree, however a bunch of cool components can be found here: Wicket extensions
JSF: Reference implementation is rather poor, however, there are some more opportunities in Tomahawk. Theoretically, it's possible to mix more implementations by getting the appropriate components even from commercial implementations. There's much room for improvement in Tomahawk JSF components. I've met tree2 which doesn't support default expanded nodes (when showing the tree for the first time, some nodes couldn't be expanded by default without attaching a workaround logic). Generally, a lot of workaround code was needed for creating really usable components, which was very time-consuming and rankling, considering we should spend that time for polishing the application's business logic.

DHTML support: Is it possible to inject javascript into the page or to components and is it possible to refer components?
Wicket: It's okay, but sometimes it's tricky to inject javascript into the pages.
JSF: Referencing components is problematic with the base implementation because it shares identifiers itself. With using "forceId" in Tomahawk, we can specify identifiers, which is basically enough for javascripting.

Logic extensibility: How much can we affect or modify the framework's workflow logic?
Wicket: It's quite possible even to change the code of the framework itself if needed, however, in most cases it's enough to inject logic by implementing and applying specified interfaces.
JSF: It's not easy to intercept, because the JSF engine is outside of the competency of the application. Additionally, JSF page life-cycle is very strict and not too much applicable for some cases. Validation, model update and page render stages have their own unchangeable places. We usually stuck to the problem for a long time when we use more complex validation logic, not to say about multiple forms on a page.

AJAX: They are coming from the pre-Ajaxian era, so Ajax-support is an added feature in each of them. However, supposedly JSF has Ajax-based implementations. (Maybe commercial ones.) Wicket fans say that embedded Ajax support is absolutely good. Practically, it's possible to make nice dynamic functions without writing any line of javascript. In the comment-conversation of the original post I described that I called an application really cool dynamic and "Ajaxified" if it had the same functionality as the Google Calendar. I don't think a JSF or Wicket application could convey this.

Data-model presentation bridge: Model must be pumped into the HTML elements.
Wicket: It happens in Java which is highly comfortable and makes easy to find errors. Hierarchy of the markup must be followed by the Java behind-code, e.g. if a text input is inside a frame stack, the model must contain these frame elements too. Generally, a lots of anonymous inner class must be used for describing the Wicket data-model. It's relatively easy to build in pieces of validation logic.
JSF: Bindigs between the page and the JavaBean-based model is described in XML. So-created model can be detached from the presentation somewhat easier but it needs more boilerplate XML code and JSF can cause further problems. If we manage to create XML without errors and there are no special demands, assembled parts may work in a surprisingly little while. When we want dynamic play, e.g. validation rules of a field depend on another field's value, we might expect problems.

Bugs:
Wicket: It logs quite detailed error messages and stack traces. It's straightforward to find the roots of the error messages in the java code. It's harder to make errors because a lot of potential error is filtered out by the used modern IDEs. Many errors come from mistyping hierarchy between the java behind-code and the HTML markup. It has to be mentioned again, that Wicket pages are simple HTMLs which can be displayed in a simple browser without any server.
JSF: Generally error messages are indirect or even there aren't error messages but anomalies can be seen on the page. Control is empty or it's falled apart. Searching for the missing comma or the mistyped name in the JSF and the XMLs is a 'great fun'. Using some static analyzer for developing JSF application is highly recommended.

Modularity, reusability: Reusability of HTML page fragments.
Wicket: The embedded "fragment" mechanisum can be used. I'd expect much more, however, Wicket fans are delighted with it.
JSF: Facelet support is an amazing hit, nevertheless, it's not direct part of the JSF spec.

Graphic design:
Wicket: As the markup is plain X(HTML), it can be designed by any HTML tool. Images and CSS can be used.
JSF: It isn't plain HTML, but there are more and more WYSWYG JSF editors to be used. Some of them are integrated into graphical IDE-s. (Netbeans, Eclipse, Idea) With these tools I managed to construct simple pages only. Images and CSS can be used too.

I18n: Certainly each of them supports internationalization.

Flow control on pages: Iterations, controlling components' visibility and other properties
Wicket: Doesn't support because it's a base principle that pages don't contain business logic. (But what's about presentation logic-related flow control?) 'Fragment' and 'iterator' mechanism can be used instead of writing direct flow control into the markup. Particular conditions of the iterations and if-else statements are located in the java code behind the page markup. You can switch some component properties also in the java code.
JSF: Supports flow control at more levels by certain tags of the standard taglibs, JSF tags and facelets. However, these mixed technologies don't always cooperate well, which can tremendously increase suck factor.

Server loading: I feel they are in the same level in this question. wicket needs more memory because it must store information about component hierarchy in user sessions. JSF rebuilds server-side representation of component structure upon every HTTP request, which needs increased amount of processing and theoretically settles for less memory. Be aware of serialization when using Wicket, because misconfigured members can easily pull up some megs into the session. Also take care of inactive clients and their sessions. Each of JSF and wicket can be clustered (as I know).

Documentation:
Wicket: it has good docs according to me. People who used more deeply say that it could be better.
JSF: every kind of writings can be found. Tomahawk has a Wiki wich contains mainly descriptions of problems among some useful posts. J2EE specification also has a JSF section.

Which of them would I use in the next web-project?
JSF, although it's somewhat more cumbersome, has more opportunities because it has more implementations. Before choosing JSF I'm sure I would look after a good one. However, if there would be less dynamic form-styled content I would use Wicket because it stands closer to the plain HTML, it's easier to design it, it's easier to code it. For those who are not familiar with JSP-s and taglibs I also would highly recommend Wicket. If there would be more logic, reused and nested model and form elements I would choose JSF. However, it would be too early to forget other web-frameworks. If I would have to make a really dynamic AJAX web-application I would presumably choose another framework beyond these two ones.

Here is another argumentation on the subject. It also contains a Wicket vs JSF opinion strongly on the Wicket-side.

post[0]

2007-10-27T12:04:00.000-07:00

I have been writing a blog about Java programming and software technology since 2005. Originally, main purpose of these postings was to ingrain my own thoughts and experiences for myself, but recently I realized that 5 to 10 readers visit these pages per day. Some of these hits come from static links and the more from Google search result pages. Unfortunately, that blog is in Hungarian which is my mother language, so, as I guess, some people finally don't get what they are looking for.

So, I start another one in English to be able to share thoughts with more people, and not least, to improve my English composition skills. :)