Packaging with svn-buildpackage

When you start making packages for your software - we're talking about Debian (and Ubuntu spin-off) packages a few problems start popping up.

What you need to start off is having your upstream source in a VCS like SVN and have it tagged in some sort of way (either as tags or using revisions corresponding) to your releases.
What you want to avoid now is messing up your upstream source with the packaging files.

Enter svn-buildpackage: with the mergeWithUpstream mode you can have the upstream sources separate from the packaging files and have it merged on build time.
The catch is that for this to work, you need to have the upstream tarballs stored somewhere - which tends to get pretty annoying.

Luckily svn-buildpackage has a few hooks, so you can have a script check out the corresponding release (e.g. a tag containing the version numbers, say release-0.2.1) at build time.
The only thing you need to add is a file in your packaging tree containing the necessary data to get the upstream sources (in our case the SVN URL).

Here goes an example:

Upstream sources:

myproject/
 trunk/
  Makefile # to build and install your app
  ... all other project files

 branches/
 tags/
  0.2.1/ # a tagged release

SVN-buildpackage tree:

myproject/
 trunk/
  debian/
   control
   changelog
   ...
   upstream #indicates where the upstream source is located. Contains a variable containing SVN URL

 tags/
  0.2.1-1/

So the checkout script ends up being something like this:

#!/bin/sh

. debian/upstream # source the config file

#use svn-buildpackage vars to determine package name and upstream version

UPSNAME=${PACKAGE}_$upstream_version
TARBALLDIR=$origDir
DEST=$TARBALLDIR/$UPSNAME
TARNAME=$UPSNAME.orig.tar.gz
TARBALL=$TARBALLDIR/$TARNAME
BUILDAREA=$buildArea
UPSTREAM_VERSION=$upstream_version

if ! [ -f $TARBALL ]; then
   # upstream version tag mode
   echo "Exporting tag $upstream_version from $URL to $DEST..."
   #find the tag to check out
   UPSTREAMURL=$URL/tags/$UPSTREAM_VERSION

   echo "Exporting revision $REVISION from $URL to $DEST"
   svn export $UPSTREAMURL $DEST

   echo "Making tarball $TARBALL from $origDir"
   tar zvcf $TARBALL -C $TARBALLDIR $UPSNAME

   echo "Deleting exported upstream directory"
   rm -rf $DEST

   echo "Deleting outdated build area tar"
   rm $BUILDAREA/$TARNAME
else
   echo "Upstream tarball found at $TARBALL - nothing to do"
fi

Then you simply have to run svn-buildpackage with this hook:

svn-buildpackage --svn-prebuild checkout.sh -uc -us -rfakeroot

And each time you build the package the original tarball is created in case it's not present.

Implementing custom javascript effects in IceFaces

Using icefaces you sometimes need some custom JavaScript functionality. A good way to do this is extending the effects machinery.

We are going to implement a scroll effect which will allow to scroll down a textarea on demand as an example.

First of all we are going to create the JavaScript functionality we are going to use:

<script type="text/javascript">
function scrollDown(id) {
   ta=document.getElementById(id);
   ta.scrollTop=ta.scrollHeight;
}
</script>

you may want to use a more elaborated name to avoid name clashing.
Now we are going to create the Java class that would allow us to control the effect from the Java side:

import com.icesoft.faces.context.effects.Effect;

public class ScrollDown extends Effect {

  @Override //This annotation is optional but advisable
  public String getFunctionName() {
    return "scrollDown";
  }
}

Now you can use this Effect as any other in your code. Just remember that the JavaScript function must be present for the effect to work.
Enjoy!