Moving away from Kenai

As is commonly known, Oracle have finally taken over Sun and yesterday they announced what they are intending to do with the various services provided by Sun.

Unfortunately one of those announcements was that they were withdrawing the Kenai project from public use at some point in the near future. This is a pity because the Kenai project was becoming one of the more useful forges out there.

During today there’s been a lot of forum activity on the kenai site from a lot of project owners about what to do in migrating away, including myself.

So, after a good year of being hosted on kenai I’m now faced with moving to yet another forge – but where to go and what’s going to be involved?

Well the steps needed are (in order of importance):

  1. Move the source repositories
  2. Move the maven repository
  3. Move the jira issues
  4. Change all links to the new location(s).

As an initial measure I’ve mirrored the mercurial repositories on bitbucket so at least they are mirrored elsewhere. One of mercurial’s features is being distributed so that was relatively painless.

The next two are tricky so I’m still researching them, but they all depend on what forge to use. I’ve used sourceforge in the distant past so I don’t want to go back to them, and although bitbucket does have wiki and a tracker – it’s not jira.

Anyhow here’s the new repo information for the bitbucket mirrors:

  • https://username@bitbucket.org/petermount/reteptools/
  • https://username@bitbucket.org/petermount/retepmicrokernel/
  • https://username@bitbucket.org/petermount/retepxmpp/
  • https://username@bitbucket.org/petermount/retepjavadoc/

As soon as I’ll have more information I’ll make another post here, on twitter and on identi.ca

    Binding custom objects to attributes in JAXB

    When generating Java sources from an XML Schema with JAXB, the type of field used to represent an attribute is determined by it’s type in the schema.

    For example, a snippet from jabber-client.xsd:

    <xs:element name="message">
      <xs:complextype>
        <xs:attribute name="from" type="xs:string" use="optional">
          <xs:attribute name="to" type="xs:string" use="optional">
        </xs:complextype>
      </xs:sequence>
    </xs:element>
    

    By default, JAXB would create the object (Message in this case) with two String properties. To change this to another object (say JID) we would add a simple binding changing these to use JID and define two static methods who’s job it is to convert between a String and a JID.

    So the bindings would be something like:

    <bindings schemalocation="jabber-client.xsd">
      <bindings node="/xsd:schema/xsd:element[@name='message']/xsd:complexType">
        <bindings node="xsd:attribute[@name='from']">
          <property>
            <baseType>
              <javaType name="uk.org.retep.xmpp.JID"
                parseMethod="uk.org.retep.xmpp.jaxb.adaptor.XMPPDatatypeConverter.parseJID"
                printMethod="uk.org.retep.xmpp.jaxb.adaptor.XMPPDatatypeConverter.printJID"
              />
            </baseType>
          </property>
        </bindings>
      </bindings>
    </bindings>
    

    Now for mose usecases this is fine and works pretty well. The problem is when you have a large number of custom bindings.

    What JAXB does for each binding is that it generates an anonymous Adapter class. In that adaper class are two methods which call the two methods declared in the binding – in the case of binding to a Double you would get the following:

    public class Adapter1
        extends XmlAdapter<String, Double>
    {
    
        public Double unmarshal(String value) {
            return (javax.xml.bind.DatatypeConverter.parseDouble(value));
        }
    
        public String marshal(Double value) {
            if (value == null) {
                return null;
            }
            return (javax.xml.bind.DatatypeConverter.printDouble(value));
        }
    
    }
    

    The problem here is that JAXB generates one of these for every instance, so you can end up having multiple Adapter classes present, all doing the same thing. In one instance I had a single schema contain 16 duplicates of the above code. In retepXMPP I had almost 60 spread over multiple schemas just for handling JID. This is a lot of wasted, duplicated code and if you use a large number of schemas then this is going to cause both your jar sizes and permgen use to increase for no real reason.

    So it would be nice to reduce this down to a single adapter.

    Fortunately there is a way when using the JAXB RI. There is an alternate javaType binding which takes the full class name of an adapter class instead – using this causes JAXB to use that single class instead of generating these duplicate classes. The main difference is replacing the parseMethod and printMethod attributes with a single adapter attribute, and qualifying the javaType with the http://java.sun.com/xml/ns/jaxb/xjc namespace.

    So the bindings would be something like:

    <bindings
      xmlns="http://java.sun.com/xml/ns/jaxb"
      xmlns:xsd="http://www.w3.org/2001/XMLSchema"
      xmlns:xjc="http://java.sun.com/xml/ns/jaxb/xjc"
      xmlns:retep="http://retep.org/xml/ns/retepTools"
      version="2.0">
      <bindings schemalocation="jabber-client.xsd">
        <bindings node="/xsd:schema/xsd:element[@name='message']/xsd:complexType">
          <bindings node="xsd:attribute[@name='from']">
            <property>
              <baseType>
                <xjc:javaType adapter="uk.org.retep.xmpp.jaxb.adaptor.JIDAdapter"
                              name="uk.org.retep.xmpp.JID" />
              </baseType>
            </property>
          </bindings>
        </bindings>
      </bindings>
    </bindings>
    

    Then just create a single adapter implementation. in retepXMPP thats some 60 classes reduced to one, if you generate any javadocs based on the generated sources there’s no more “Adapter” spam – large numbers of apparently duplicated classes in the javadocs etc.

    Tip: Just make sure you keep an eye on that namespace – miss it out and XJC will spurt out some unusual error messages.

    Update: I’ve disabled comments on this article simply because spammers are the only ones posting comments to it. Peter 27 Feb 2010

    Releasing to Kenai via Maven

    Ever since the website feature appeared on Kenai I’ve been trying to get releases to work using it to host the maven repository. Although it works, it’s always had the odd issue where whilst uploading artifacts to the repository, the connection would timeout causing the release build to fail.

    For small projects this isn’t really a problem, but for some of mine this is an issue to either the number of artifacts present (retepXMPP currently has over a hundred) we can’t have the release build to fail part way through leaving both the mercurial and maven repositories in an inconsistent state.

    The retepMicroKernel project is further complicated by the fact that it has native code – so a release has to be performed in parts with the native code built on the respective platforms.

    Fortunately there is a solution to this – perform the release build into a staging repository then once it’s complete merge that repository with the public one. This also means we can perform a release and if something horrible goes wrong we just redo the release without the public seeing the failed release.

    Fabrizio Giudici also found this solution with an additional benefit. The maven release process makes several commits into the repository, but as mercurial is a distributed scm we can use that to our advantage – if the release build fails it doesn’t cause issues remotely with having to remove tags etc (which I’ve done before).

    So here’s what I did when releasing version 9.11 of retepTools this week, first I followed Fabrizio’s suggestions for configuring the root pom.xml file.

    Then I created a temporary directory and inside that clone the public mercurial repo then make a clone of the clone:

    # The maven staging repository
    mkdir -p ~/tmp/stagingrepo
    
    # The staging mercurial repository - this is a clone of the public repository
    cd ~/tmp
    hg clone https://hg.kenai.com/hg/reteptools~hg reteptools-stage
    
    # The release mercurial repository - this is the one we will run maven against
    # it is a clone of the staging repository
    hg clone reteptools-stage reteptools

    Now we run the release process:

    cd ~/tmp/reteptools
    mvn --batch-mode \
           -Dstaging.hg.repo.url=~/tmp/reteptools \
           -Dstaging.mvn.repo.url=file:///Users/peter/tmp/stagingrepo \
           -DreleaseVersion=9.11 \
           -DdevelopmentVersion=9.12-SNAPSHOT \
           -Dtag=retepTools-9.11 \
           release:prepare release:perform
    

    Maven will now perform the release, making commits into the ~/tmp/reteptools repository and pushing them to ~/tmp/reteptools-stage.

    Once we are happy that the release is clean we make it public. First mercurial – we need to push the changes back to kenai:

    cd ~/tmp/reteptools-stage
    hg push
    

    Next the artifacts:

    # A temporary directory for maven - it will not run without this directory
    mkdir -p tmpdir
    mvn org.codehaus.mojo:wagon-maven-plugin:1.0-beta-2:merge-maven-repos \
      -Dwagon.source=file:///Users/peter/tmp/stagingrepo/ \
      -Dwagon.target=dav:https://kenai.com/website/reteptools/maven/releases/ \
      -Dwagon.targetId=retep.releases \
      -Djava.io.tmpdir=target
    

    [Edited to fix a couple of errors in the maven commands]