The first assumption is that you have the necessary libraries and such to run it they are as follows:

• Scala Library (That goes without saying if you’re going to be writing Scala code) I have a custom path for mine as I want to manually sync my libraries, compilers and so on with the latest versions. I have extracted my copy to ~/Bin/Scala-2.9.1.final this will be the path my bash script will assume, you must change this to your path if it’s different.
• Proguard: I am using version 4.7, version 4.4 comes with ubuntu but, seeing as I like to keep it at the latest and I am impatient my proguard lives in ~/Bin/Proguard4.7
• Java (This also goes without saying. You will probably need the JDK as well as the JRE so install them both) Proguard uses the java libraries extensively so you need that.

My simulation is in the following directory structure
engine
| – src
| — | —  Engine.scala
| – build-app.sh
| – scala-config.pro

The engine->src->Engine.scala is my scala application with the object Engine defined as my entry point this is important for the MANIFEST.MF file the script will be creating

Now the steps

• First we can create a little folder to hold the output of the scala compiler so we create  a folder called bin inside of the engine folder itself so that the folder structure now looks like this
  engine
  | – src
  | — | — Engine.scala
  | – bin
  | – build-app.sh
  | – scala-config.pro
  by running

  mkdir bin

  then run the following while you’re inside engine which from now on I will refer to as root

  scalac -sourcepath src -d bin src/Engine.scala

  this will compile the Engine.scala code into java classes inside of the bin folder

• This completes the scala bit, everything else following is run with Java so we need a MANIFEST.MF file to compile a jar

  echo "Main-Class: Engine" > MANIFEST.MF

  this will do it for you. Bear in mind you are still at the root level

  Now at this point we change directory to the bin folder where scalac has created our classes and compile our jar using the manifest we have just created so this should do it:

  cd bin
  jar -cfm ../engine-no-scala.jar ../MANIFEST.MF *.*

  You can obviously do this a different way by staying in the root and making sure your path is correct, personally I found this easier.

  This above code will create our engine called engine-no-scala.jar with the MANIFEST.MF file
  bear in mind at this point if you ran java -jar engine-no-scala.jar it may fail if your scala code required the scala library to run
  mine does so now I need to package this WITH the scala library into a complete self-contained java application
  now earlier I did say that my scala home was in a custom location so we need to keep that in mind for the next section

  PROGUARD

• Not only does proguard include the required libraries and so on, it also obfuscates and discards any unused classes and packages this is very nifty for distribution as it cuts down by orders of magnitude the size of your application.When I did this without proguard my application was over 8 MB because the entire scala library was in my jar
  after I finished with proguard I am looking at an 8 KB application, and I think I can even get it smaller if I optimise my code a little bit morebut that’s for another time. Proguard however needs a configuration file to work properly in my case, I went to their site and downloaded a sample scala-config file (click on the Scala link) I just made the following changes to the vanilla one they provided

  -injars engine-no-scala.jar
  -injars /home/kwabena/Bin/scala-2.9.1.final/lib/scala-library.jar
  -outjars engine.jar
  -libraryjars <java.home>/lib/rt.jar
  
  -dontwarn scala.**
  -verbose

  I just changed the path to my jar file and my scala library and I also turned on verbosity (I like to know what’s going on) my build script now has the following lines

  cd ../
  echo "Adding Scala library, obfuscating..."
  #proguard
  proguard.sh @scala-config.pro

  after that you can remove any side effects from the script with

  rm -rf bin MANIFEST.MF engine-no-scala.jar

  bear in mind that we changed the our current workind directory to the root level
  after a few minutes of compiling, obfuscating, optimisation and shrinking you should have a nice jar to run by itself on a computer with ONLY the JRE installed

The complete script follows you can just copy this, save it into a file called “build-app.sh” as it is in my folder structure change the permissions to execute with

chmod +x build-app.sh

and run it

#!/bin/bash

echo "Creating required directories"
mkdir bin

echo "Compiling scala sources"
scalac -sourcepath src -d bin src/Engine.scala

echo "Creating Manifest"
#build manifest
echo "Main-Class: Engine" > MANIFEST.MF

echo "Building java archive from scala classes"
#create jar
cd bin
jar -cfm ../engine-no-scala.jar ../MANIFEST.MF *.*

cd ../

echo "Adding Scala library, obfuscating..."
#proguard
proguard.sh @scala-config.pro

#remove fluff
echo "Removing fluff..."
rm -rf bin MANIFEST.MF engine-no-scala.jar

I hope you find it as useful as I would have should this have been available earlier.

I then came across the parsimonious Scalatra. I love it it’s light elegant and doesn’t require you to do too much to get started. I have not used it long enough to say that this is going to be my weapon of choice for any future developments but it’s a very strong candidate.

I only just now discovered the Play framework and on first glance it’s a brilliant looking MVC framework, honing in on my Zend experience with PHP. It feels like Zend, I have not actually started writing anything in it yet but I am going to attempt a full blown web project in it and see how that goes. Perhaps something for an EC2 instance.

#!/bin/bash

cd ~

echo --------------------------------------------------------------------------------------------
echo - Getting SBT Launcher
echo --------------------------------------------------------------------------------------------
wget http://typesafe.artifactoryonline.com/typesafe/ivy-releases/org.scala-tools.sbt/sbt-launch/0.11.0/sbt-launch.jar

printf 'java -Xmx512M -jar `dirname $0`/sbt-launch.jar "$@"' > sbt

chmod +x ./sbt

echo --------------------------------------------
echo - Move sbt and sbt-lauch to share
echo --------------------------------------------

sudo mv sbt /usr/share/sbt
sudo mv sbt /usr/share/sbt-launch.jar

echo --------------------------------------------------------------------------------------------
echo - symlinking sbt and sbt-lauch to /usr/bin/{sbt, sbt-lanch.jar}
echo --------------------------------------------------------------------------------------------
sudo ln -s /usr/share/sbt /usr/bin/sbt
sudo ln -s /usr/share/sbt-launch.jar /usr/bin/sbt-launch.jar

I suppose, when I get time I can make this accept parameters so you can specify the version of SBT you want and the file name you want to use etc but for now this should suffice…
comments welcome.

Simply copy this and paste into a file, name it whatever you want, and make it executable with chmod +x

#!/bin/bash

cd ~

echo --------------------------------------------------------------------------------------------
echo - Getting Scala 2.9.0.1
echo --------------------------------------------------------------------------------------------
wget http://www.scala-lang.org/downloads/distrib/files/scala-2.9.0.1.tgz

echo --------------------------------------------------------------------------------------------
echo - Decompressing
echo --------------------------------------------------------------------------------------------
tar zxf scala-2.9.0.1.tgz

echo --------------------------------------------------------------------------------------------
echo - moving scala to /usr/share/scala
echo --------------------------------------------------------------------------------------------
sudo mv scala-2.9.0.1 /usr/share/scala

echo --------------------------------------------------------------------------------------------
echo - Symlinking executables
echo --------------------------------------------------------------------------------------------
sudo ln -s /usr/share/scala/bin/scala /usr/bin/scala
sudo ln -s /usr/share/scala/bin/scalac /usr/bin/scalac
sudo ln -s /usr/share/scala/bin/fsc /usr/bin/fsc
sudo ln -s /usr/share/scala/bin/sbaz /usr/bin/sbaz
sudo ln -s /usr/share/scala/bin/sbaz-setup /usr/bin/sbaz-setup
sudo ln -s /usr/share/scala/bin/scaladoc /usr/bin/scaladoc
sudo ln -s /usr/share/scala/bin/scalap /usr/bin/scalap

import sbt._

class MyDataEngineProject(info: ProjectInfo)
    extends DefaultProject(info) {
  // Declare MySQL connector Dependency
  val mysql = "mysql" % "mysql-connector-java" % "5.1.17"
}

Once you have got this in project/build/MyDataEngineProject.scala, you are ready to start the connection stuff. In src/main/scala you can start creating your application here. I use the “def main” approach so when i start from the command line i simply pass in my parameters and I’m ready to go:

import java.sql.{Connection, DriverManager, SQLException, ResultSet}

object DataEngine {

	private var driverLoaded = false

	private def loadDriver()  {
		try{
			Class.forName("com.mysql.jdbc.Driver").newInstance
			driverLoaded = true
		}catch{
			case e: Exception  => {
			    println("ERROR: Driver not available: " + e.getMessage)
			    throw e
			}
		}
	}

	def main(args: Array[String]) {
		if (args.length < 1){
			println("No arguments provided, exitting...")
			return
		}
		println ("Attempting to load MySQL JBDC Driver...")
		println
		this.synchronized {
		  if(! driverLoaded) loadDriver()
		}

		val conString = "jdbc:mysql://localhost:3306/db_name?user="+args(0)+"&password="+args(1)
		classOf[com.mysql.jdbc.Driver]
		val con = DriverManager.getConnection(conString)
		try{
			val handle = con.createStatement(ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY)
			val rs = handle.executeQuery("select * from auth limit 1")
			println ("Connection established...")
			while(rs.next){
				println("User Handle: "+rs.getString("handle"))
			}
		}catch{
			case e: Exception  => {
		    	println("ERROR: No connection: " + e.getMessage)
		    	throw e
		  	}
			case _ => println("A problem!")
		}finally{
			println("Closing connection and exiting...")
			con.close()
		}
  	}
}

Save the file as Main.scala and you can just type in run with your db username and password as space-separated arguments and you’re ready to go. Of course you will need to change some bits in here to reflect your database schema, but aside that it’s that simple. In my next post I will work on inserting data and updating data as well.

Despite using the correct syntax:

\begin{figure}[htb]
    \begin{center}
        \includegraphics{image.png}
    \end{center}
    \caption{Fig 1: image}
    \label{fig1}
\end{figure}

You may find a box with with only the image path being displayed as your image. Please check that you are not using the “draft” argument at the top of your document when specifying your document class. A bit like

\documentclass[12pt,a4paper,draft]{article}

Make sure there is no “draft” in there so that it reads

\documentclass[12pt,a4paper]{article}

Spent about half an hour trying to figure out why everyone else’s images were displaying except mine.

Not only does it look identical to my favourite text editor / IDE of all time – gEdit. It supports syntax highlighting, decent support for BibTex referencing. It also has a very user friendly interface and it’s also customizable as per any GTK interface in GNOME.

I have not checked if there are versions for other Operating Systems but I am pretty certain anyone wishing to try this out with any Linux distribution can do it with the built in package/software manager, shipped with it.

This is obviously not to say the others do not have advantages over LaTeXila, this is just the one I have felt most at home with. I have tried the LaTex plug-in for gEdit, that is also quite good especially the support you get when using the \cite command, it handily provides a drop down of keys available in any BibTeX files you have referenced in that LaTeX doument. I haven’t played with LaTeXila’s preferences extensively so I am not sure if it has that too.

You can find sourceforge page here http://latexila.sourceforge.net/

$router->addRoute(
                'listingswithpage',
                new Zend_Controller_Router_Route(
                        '/listing/:type/:page',
                        array('controller' => 'listing',
                            'action' => 'index')
                )
        );

Your pagination view helper gets a bit thrown if you go by the documentation. The first thing you need to do is find a way to specify the first page initially. I went with specifying my first page in my route definition so it looked something like this

$router->addRoute(
                'listingswithpage',
                new Zend_Controller_Router_Route(
                        '/listing/:type/:page',
                        array('controller' => 'listing',
                            'action' => 'index',
                            'page' => 1)
                )
        );

And that worked. Failing that you have to figure out a way to pass the complete URL path to you pagination view which might be something like “controls.phtml” or “pagination.phtml”. and constructing the url properly there.

I will perhaps post a more detailed description of what this means but leave a comment if you are impatient and I will try and respond when I get a moment.