Java on Azure
May 22, 2012 Leave a comment
In my conversations with customers on Windows Azure the topic of running Java on Azure often comes up, where I would explain that Java developers can benefit from the PaaS capabilities of Azure just as much as .net developers including the elasticity and ‘self-healing’ properties of our Public Cloud offering whilst avoiding having to maintain VMs (or physical machines)
The best way to get an overview of the experience is to take a look at this 5 minute video as it covers all the steps required to take an existing JSP application in Eclipse and run it on Azure; if you’d rather read than listen, carry on
Overall, the experience for Java developers is pretty close to the one for .net developers, with a couple of notable differences I will touch upon shortly, so, to start with, let me describe how I got a simple Java application to run on on Azure –
I’m starting with Eclipse IDE for Java EE Developers (Indigo) and already have the Azure SDK installed on my laptop and so the only thing I need to do to prepare my Eclipse environment is to install the Azure plug-in for Eclipse, by using the Help->Install New Software Eclipse menu item and pointing it at http://dl.windowsazure.com/eclipse
(you can read all about it in the Windows Azure Java Developer Center)
With the IDE ready I create, for example, a new dynamic web project using Tomcat 7 as the server, add to it a JSP page and test it locally. normal stuff. (I can just about do a hello world)
With my ‘elaborate’ web application working locally, it is time to test it in the Azure Emulator and so I create a new ‘Windows Azure Project’ which is now available after installing the plug-in; to get my code included in the Azure project I export the WAR from the dynamic web project to the approot folder in it.
Last, and this is the only real difference between .net and Java with regards to deploying on Azure, is that I need to provide the JDK and the Server to run on the Azure role – .net doesn’t really have the concept of multiple servers, IIS is the de-facto web server , which is automatically included in all web roles. Azure roles also come out of the box with all the .net runtime versions to date; In the Java case developers have a choice of servers they could use and could target one of several JDK versions; for this reason the Azure project needs to include the selected JDK and Server packages and the script required to install them.
This is done by placing jdk.zip, which includes the JDK I wish to use and a zip file containing the server I wish to use – in my case tomcat7.zip containing apache-tomcat-7.0.22 server I downloaded earlier in the approot folder as well.
Last – I need to provide the role with a script telling it how to install what.
Thankfully – the Azure project template for Eclipse includes sample scripts for the most commonly used servers, namely TomCat 7, Glassfish OSE 3, JBoss AS 6 and 7 and Jetty as well as a custom script that can be expanded, and these takes care of any hassle so all I need to do is copy the contents of the sample script file provided for tomcat 7 to the startup.cmd file in the role and make sure all the file names are correct (WAR, JDK and Server packages)
That done my projects are now ready and after building I can run the RunInEmulator.cmd script, also included in the Azure project template, to deploy the role to the local Compute Emulator – this tests both the script and the application and, once deployed, I am be able to use my application hosted by the emulator-embedded-role.
Happy with that, the last step is to prepare the application to be deployed to the cloud, this is done by changing a property on the Azure project from “Testing in Emulator” to “Deployment to Cloud” and building again – now the project contains the package to be deployed to Azure, the configuration file accompanying it and even a shortcut to the management portal.
I use these in the management portal to initiate a new deployment and several minutes later I’ve got my Apache Tomcat server running my JSP page and no VM in sight!
Of course – with the package on Azure, the platform can deploy this time and time again when scaling up or when an instance fails and needs to be re-deployed.
One final, temporary note: working on Windows 8 CTP I did find a small problem with the script provided – to avoid problems arising from long paths, the script creates a symbolic link on the root of the drive pointing at the location of the files (somewhere deep under the Eclipse workspace). Windows 8 seems very unhappy with unzipping files into a symbolic link location and the thing breaks. the temporary solution, if you are working on Windows 8, is to remove the step to CD into the symbolic link location. the default location is the approot folder anyway and everything works just fine. the nature of CTPs, I guess.