Lies, damned lies, and statistics: EE edition

I came across some figures regarding downloads of Glassfish and JBoss AS that really puzzled me. Basically Glassfish was downloaded 700.000 times a month (end of '08) while JBoss AS was only downloaded around 115.000 times a month at the same. My first reaction was "Well done to you, Sun!" and then I realized that the gap was too good to be true. Let's have a look at these numbers.

For JBoss AS, the Sun team has only counted the direct number of downloads out of SourceForge. That's public knowledge by the way, go there for the JBoss stats.

For Glassfish (according to this), downloads numbers (not public BTW) come from:

• JDK bundles
• Java EE SDK
• NetBeans Bundles (when downloading NetBeans, apparently you automatically get GF bundled)

Surprisingly, no stats on the direct number of downloads from the Glassfish project page. Let's analyze that a bit.

JDK bundles is the thing downloaded even by my grand'ma by accident. I can tell you right there, she has never ever used Glassfish ( nor JBoss ;) ). How many times, did I download the whole enchilada while I just wanted the plain old JDK!

Java EE SDK. This one is hard. Of course, people interested in EE will go download this package. Are they interested in GF? Hard to say. On the other hand providing a SDK without runtime will do no good.

NetBeans. I'm surprised at the popularity of NB, but there it is. Are all NB users actually GF users? BTW NB also comes with a JDK bundle but I don't know if this bundle also bundle GF :)

Let's call this strategy the Russian doll statistic generation strategy. Frankly, that's not very honest for your users and customers to use this strategy and then compare apple to oranges with your competition. When someone downloads JBoss AS, for sure he did not do it by accident (thanks to SourceForce's sense of UI :) )

So we have two strategies here, JBoss could start playing the Russian doll statistics generation strategy and we can be pretty good at it:

• include JBoss AS in Fedora and count it
• include JBoss AS in RHEL and count it (Dell, IBM and the like are pretty good at delivering RHEL on their hardware)
• include JBoss AS in IcedTea and count it
• include JBoss AS in JBoss Tools and count it
• include JBoss AS Core in JBoss ESB, Portal etc etc and count it
  
• include the number of downloads from our maven repository (with the number of times you have to nuke your local repo that will be a big hit :) )
• I've only added a few ideas but for sure our marketing guys can be more productive

Of course we won't do that. An alternative strategy would be for the Glassfish team to only display their direct download numbers (the one they fail to display) and stop using bogus charts in their public and private slides.

On a side note, I find it disappointing that open source projects don't keep their stats open and preferably via a third party provider like SourceForge. Granted the SF stats are somewhat flaky but it keeps everyone honest with their own (lack of) success.

Disclaimer: I am not saying Glassfish is not a success, I am quite happy to have them as coopetitors on the server market in general and Java EE in particular.

Having problems with Adium and Yahoo IM?

Yahoo has changed its login protocol, breaking a number of third party IM clients including Adium.

The Adium team has released 1.3.5.rc1 which solves the issue. Check it out. If you use Adium 1.4 beta, upgrade to beta7.

Hope this will save you some time.

Java generics end of mystery

Remember my puzzlement in front of http://blog.emmanuelbernard.com/2009/04/java-generics-mystery.html?

I usually try to make sense of the unknown type by looking at what should be allowed when two incompatible types are used as the unknown type, and then using the generic type using the unknown type as a reference to a known type to see what incorrect things can be done through the reference. If the assignment your questioning was allowed, you would be able to add two incompatible ConstraintValidators to the validatedAddresses as in:

class Address {}
class Person {}

// A set of ConstraintValidator for Address
Set<ConstraintValidator<Address>> validatedAddresses =
    new HashSet<ConstraintValidator<Address>>();

// A set of ConstraintValidator of a single unknown type (*)
Set<ConstraintValidator<?>> validatedThings = validatedAddresses;

ConstraintValidator<Address> a;
ConstraintValidator<Person> p;

// A ConstraintValidator of unknown type, ? = Address
ConstraintValidator<?> thingA = a;

// A ConstraintValidator of unknown type, ? = Person
ConstraintValidator<?> thingP = p;

// This would be allowed if (*) was a valid assignment, which puts a ConstraintValidator<Person> in a set of ConstraintValidator<Address>

validatedThings.add(thingP);

What I missed initially is that I cannot add new (and potentially heterogeneous) elements in Set<?> or Set<? extends X>, but I am free to add elements in Set<X<?>>:

Set<A<?>> c1 = new HashSet<A<?>>();
c1.add( new A<B>() );
c1.add( new A<C>() );

Set<? extends A<?>> c1 = new HashSet<A<?>>();
c1.add( new A<B>() ); <-- compilation error
c1.add( new A<C>() ); <-- compilation error

While the first example compiles, the second does not.

So to answer my initial mystery, I need to use the <? extends X<?>> approach (thanks Vivien for pointing that out).

Set<? extends ConstraintValidator<?>> valiatedThings = ...;

Java generics mystery

Here is a puzzle for Generics gurus.

Can somebody explain why

Set<Address> addresses = new HashSet<Address>();
Set<?> things = addresses;

compiles but

Set<ConstraintValidator<Address>> validatedAddresses = 
    new HashSet<ConstraintValidator<Address>>();
Set<ConstraintValidator<?>> validatedThings =
    validatedAddresses;

does not compile?

More specifically, the assignment on the second line breaks.

Oracle is buying Sun: best quotes of the day

Alex Miller: "Next version of Java will be Java SE 7.0.0.0.17832"

Emmanuel Bernard: "The day an Oracle swallows the Sun and in front the Business Machine. No kidding it's a Titans fight."

Max Andersen: Thinking when Orsun will introduce a String in Java that says null == ""

Alexis MP: "Checking my blog posts tagged with "oracle". No need to MarcF' them ;)"

Bruno Georges: "yes, this came out of the Blue :-)"

Stomp Rasta: "There'll have Java SE 7 Lite (300 MB) and Java SE 7 Full (600 MB). And we'll have to pay for each VM installed."

Add your own...

Les Cast Codeurs Podcast is born

I have just started a new podcast with a few French open source activists. All about Java, all in French. If you know French, read on ; otherwise, well... learn :)

Les Cast Codeurs Podcast est dans les bacs!

Le podcast en français dans le code sur Java par Emmanuel Bernard (JBoss, Hibernate), Guillaume Laforge (SpringSource, Groovy), Antonio Goncalves (freelance, auteur), Vincent Massol (XWiki, Maven).

Restez informés sur les sujets brûlants de l'industrie Java. Plongez sur un sujet précis avec l'interview de l'épisode. Supportez les radotages de vos hôtes.

Ecoutez-nous et faites passer le message autour de vous !

web: http://lescastcodeurs.com
itunes: http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewPodcast?id=312239675
podcast syndication: http://lescastcodeurs.com/podcast-rss
blog feed: http://lescastcodeurs.com/feed/
feedback: commentaire@lescastcodeurs.com

Podcast on Bean Validation lastest PFD

I have recently been interviewed by Kenneth Rimple for the Chariot TechCast.

In this podcast, we speak to JBoss's Emmanuel Bernard on the future of validation using JSR-303, the Bean Validation framework. JSR-303 aims to provide an annotation-driven mechanism to mark plain old java beans with annotations, such as @NotNull, @Min, @Max, and can support custom validation annotations as well.

JSR-303 is part of the Java EE 6 suite of JSRs and will be used automatically out of the box by frameworks such as JSF 2.0. Emmanuel also goes into some detail about the current state of Hibernate Search.

You can listen to it here or register to iTunes.