Syntax highlighting for code snippets in blogs

Where does he get those wonderful toys? - The Joker, Batman (1989)

Recently I was asked how I make code snippets on this blog prettier. Here's how.

1. In your blog's template, install Alex Gorbatchev's Syntax Highlighter.
2. Then, in the body of the blog post (with all occurrences of "<" HTML-escaped as "&lt"):

   <pre class="brush:shell"> ... </pre>
   or
   <pre class="brush:java"> ... </pre>
   or
   <pre class="brush:xml"> ... </pre>

3. There are other "brushes" available too with which you can "paint" your code. I generally only need java, xml, and shell.

Cleaner Ant Build Logs: Get Rid of "Trying to override old definition of task"

If you use macros in Ant, you have probably seen clutter in your log such as

Trying to override old definition of task ...

Here's how to purge this garbage from your log and keep your build output cleaner.

1. move your macros into a target such as <target name="init">
2. have your main target(s) depend on the target that defines the macros
3. call your macros

You can make your log even quieter with -q when running ant, eg., ant -f build.xml -q

Here's a complete example that will first self-bootstrap itself by downloading Ant-Contrib, define two ant macros, and produce very quiet output (unless debug=true):

<project default="run">
 <property name="COMMON_TOOLS" value="${java.io.tmpdir}" />
 <property name="debug" value="false"/>

 <target name="get.ant-contrib" unless="ant-contrib.jar.exists">
  <property name="ANTCONTRIB_MIRROR" value="http://downloads.sourceforge.net/ant-contrib/" />
  <get usetimestamp="true"
       dest="${COMMON_TOOLS}/ant-contrib-1.0b2-bin.zip"
       src="${ANTCONTRIB_MIRROR}/ant-contrib-1.0b2-bin.zip"
  />
  <touch file="${COMMON_TOOLS}/ant-contrib-1.0b2-bin.zip" />
  <mkdir dir="${java.io.tmpdir}/ant-contrib-1.0b2-bin.zip_" />
  <unzip src="${COMMON_TOOLS}/ant-contrib-1.0b2-bin.zip"
         dest="${java.io.tmpdir}/ant-contrib-1.0b2-bin.zip_"
         overwrite="true"
  />
  <copy file="${java.io.tmpdir}/ant-contrib-1.0b2-bin.zip_/ant-contrib/lib/ant-contrib.jar"
        tofile="${COMMON_TOOLS}/ant-contrib.jar"
        failonerror="true"
  />
  <delete dir="${java.io.tmpdir}/ant-contrib-1.0b2-bin.zip_" includeemptydirs="true" quiet="true" />
 </target>

 <target name="init">
  <available file="${COMMON_TOOLS}/ant-contrib.jar" type="file" property="ant-contrib.jar.exists" />
  <antcall target="get.ant-contrib" />

  <taskdef resource="net/sf/antcontrib/antlib.xml">
   <classpath>
    <pathelement location="${COMMON_TOOLS}/ant-contrib.jar" />
   </classpath>
  </taskdef>
  
  <macrodef name="debug">
   <text name="echo" />
   <sequential>
    <if>
     <and>
      <isset property="debug" />
      <istrue value="${debug}" />
     </and>
     <then>
      <echo message="@{echo}" />
     </then>
    </if>
   </sequential>
  </macrodef>

  <macrodef name="list.count">
   <attribute name="list" default="" />
   <sequential>
    <var name="count" value="" />
    <for param="listitem" list="@{list}" delimiter=", ">
     <sequential>
      <var name="count" value="${count}0" />
     </sequential>
    </for>
    <length property="list.count.return" string="${count}" />
   </sequential>
  </macrodef>
 </target>

 <target name="run" depends="init">
  <property name="list" value="foo bar baz"/>
  <list.count list="${list}" />
  <debug>For list [${list}], size = </debug>
  <echo>${list.count.return}</echo>
 </target>

</project>

Tracking Build Status With Hudson Data APIs

A number of people have been twittering recently about Hudson Helper, and the fact that it can't (yet) support http access to Hudson servers. (There's just no pleasing some people, eh David?)

UPDATE: David reports that Hudson Helper has worked with both http and https since day one. He invites direct feedback if you're having problems.

To help fill this gap, I'd like to detail some of the handy API features of Hudson I've discovered since I first started using it back in October, which cane be fetched via http (or https) in a browser or via a script.

Datum	Example
Latest Successful build number	buildNumber
Latest Successful zip (published artifact)	GEF-Update-*.zip
All checked out Project Set Files (Hudson workspace)	*.psf
XML Digest of Latest Stable Build	lastStableBuild/api/xml
SVN revision used for Latest Stable Build	//changeSet/revision/revision

For more on the APIs available to the Latest Successful, Stable, Failed, or in fact simply the Latest Build, see:

1. /lastSuccessfulBuild/api/
2. /lastStableBuild/api/
3. /lastFailedBuild/api/
4. /lastBuild/api/

Of course, should you want details on a specific build rather than the latest, you can replace the "last*Build" token with an actual build number.

Finally, because no post about APIs should be complete with out some script showing how to exploit that interface, here's a quick example of how to fetch the latest successful, and as yet unreleased Drools 5.1 runtime library zip for use in our JBoss Tools 3.1.0.M2 builds. In this example, we fetch the build number for the last successful build and compare it to a cached version. We also fetch and cache the latest SVN revision number (in a build.properties file) so that we can later fetch Drools sources from the same point in time as the precompiled Drools binaries in the zip. This guarantees we're building from trunk, but only a good build in trunk, skipping over any failed builds or intermediate states (partial commits).

#!/bin/bash
droolsSNAPSHOTnum=drools-SNAPSHOT-num.txt
droolsSNAPSHOTrev=drools-SNAPSHOT-rev.txt
droolsSNAPSHOTzip=drools-SNAPSHOT-bin.zip
droolsSNAPSHOTurl=http://jboss-hudson-server/hudson/job/drools/lastSuccessfulBuild/artifact/trunk/target/drools-5.1.0.SNAPSHOT-bin.zip

buildNumOld=0; if [[ -f $droolsSNAPSHOTnum ]]; then buildNumOld=$(cat $droolsSNAPSHOTnum); fi
buildNumNew=$(wget -q --no-clobber -O - http://jboss-hudson-server/hudson/job/drools/lastSuccessfulBuild/buildNumber)

buildRevOld=0; if [[ -f $droolsSNAPSHOTrev ]]; then buildRevOld=$(cat $droolsSNAPSHOTrev); fi
buildRevNew=$(wget -q --no-clobber -O - http://jboss-hudson-server/hudson/job/drools/lastSuccessfulBuild/api/xml?xpath=//changeSet/revision/revision)

if [[ $buildNumNew -gt $buildNumOld ]]; then
 # get: 27013; must change to 27013 
 echo $buildRevNew > $droolsSNAPSHOTrev;
 sed -i "s#\|##g" $droolsSNAPSHOTrev 
 buildRevNew="$(cat $droolsSNAPSHOTrev)"; #echo "."$buildRevNew"."
 # replace "defaultTag=trunk:\d+" with defaultTag=trunk:${buildRevNew} in build.properties
 #  defaultSvnUrl=http://anonsvn.jboss.org/repos/labs/labs/jbossrules
 #  defaultTag=trunk:27013
 sed -i "s#defaultTag=trunk:\d\+#defaultTag=trunk:$buildRevNew#g" build.properties; # grep "defaultTag=trunk:" build.properties 

 echo $buildNumNew > $droolsSNAPSHOTnum; 
 echo "Download $droolsSNAPSHOTurl ..."
 wget -q --no-clobber -O $droolsSNAPSHOTzip $droolsSNAPSHOTurl 

 # ...

fi

Oh, and BTW, if you're ever looking for the latest hudson.war executable, it's always here.