Wednesday, February 24, 2010

Commit Comments: A Conversation with your Future Self

I frequently find myself searching subversion commit logs trying to find hints as to why certain "features/bugs" where introduced and why. Usually this results in wasting several hours and almost every time I get frustrated with a lack of dialogue in commit comments. I can't stress enough the importance of this often over looked feature when committing changes. A lot of developers look at it like a 30 second burden that's preventing them from taking lunch earlier. What they really should be doing is pretending it's a conversation with their future self. Six months from now you're most likely going to be seeing those comments, or lack of, wondering why you made that change. It's in that moment I'd rather have a very descriptive summary of what changed and why verses diff'in every version known to man.

I'm not asking for a Kevin Costner script, just be a little more specific. On average, my comments are 1-3 sentences. For the important changes, I've used paragraphs before. Comments with fewer than 5 words drive me nuts, and I have seen a lot of them.

Ever seen a movie where campers make a trail using something like marshmallows so they can find their way back? Think of your commit comments like marshmallows helping you unravel the mystery of an issue and start developing the habit of providing more descriptive commit comments.

Other Useful Tools
One of the tools I have grown fond of is the Jira subversion plugin. Our team uses Jira as our issue tracking system. Nothing gets committed without a Jira number. This is enforced using a subversion pre-commit hook, so every developer has to start their comment with a Jira number. Then in Jira, there is a Subversion Commits link at the bottom to where anyone can view the files changes and their comments.

Using the subversion pre-commit hook has another added bonus, which is using the Hudson Jira Plugin. After a successful build, hudson will extract the Jira number(s) from the commit comments and add a comment to the Jira stating it was integrated at a specific build # and includes a link.

Tuesday, February 16, 2010

Rapid REST Development with maven jetty plugin

Ever wonder how much time is wasted by Java developers rebuilding and redeploying web applications? For me alone I can't imagine it. In fact, I'd be embarrassed if Google Buzz made it public knowledge without my consent. Two years ago I wrote an article "No more J2EE Apps" and I received a lot of great feedback. Let me first say that I think, IMHO, Java Developers are at a disadvantage when it comes to rapidly developing web applications with a static language. Developers using python, php, rails, or grails really don't even have to spend a second trying to solve this problem. On the other hand, Java Developers have to figure out how to best accomplish this, and every situation seems to be different: JBoss, Weblogic, Eclipse, Idea, Netbeans, Jetty, JRebel. Of all the solutions I think JRebel provides the best chance for success that solves any environment no matter the web container or developers IDE of choice.

I haven't really done much hardcore java development in awhile, but in order to improve my team's productivity, I am going to be exploring best practices the next couple of months concerning this area. First up, I am going to explain how I got the maven jetty plugin to work with our REST Services WAR and the steps necessary to redeploy changes. The nice thing about jetty is it's easy to use from maven and we could use it in our CI environment to possibly reduce our build times and provide quicker feedback. The downside is each change requires jetty to hotdeploy the new WAR. End the end I think the best solution will be a combination of JBoss+JRebel. But I won't get to for awhile.

Maven Jetty Plugin
My first prototype uses the maven-jetty-plugin version 6. The application we are testing is a WAR containing REST Services built with Jersey (JAX-RS). Here is a good posting by my co-worker Jeff Black "Jersey...Jetty and Maven style!". This example didn't work for me because for some insane reason the init-param,, does not work in WebSphere. So I had to do some slight modifications to get it to work without that being declared. My pom.xml and jetty.xml files are below. Most "normal" non-Jersey applications don't need all of this, but it was necessary to get our legacy WAR working with jetty.

Here are the steps involved to start jetty and redeploy changes:

  1. mvn install jetty:run - this will first build the WAR and then start jetty while also deploying the WAR. Running install was necessary because I reference the exploded WAR directory under target in the jetty configuration.
  2. Make changes to source code
  3. Run "mvn compile war:exploded" in a separate terminal to compile your changes and copy the new class files to the location Jersey expects to find them. Which in my case is /target/myapp/WEB-INF/classes
  4. Click back to the terminal running jetty and hit the ENTER key. This causes jetty to reload the WAR. This is because by default I set the scan interval to 0 and jetty.reload to manual, so I can batch up multiple changes before reloading.
Overall I am happy with the results so far. Previously, it took 1-2 minutes and sometimes more to rebuild the war and hotdeploy to JBoss. Using the jetty plugin this now takes around 30 seconds. Again, I think this could be further improved by using JRebel.

I did have to update my MAVEN_OPTS environment variable to increase Java's PermGenSpace since jetty reloads the WAR each time and you'll quickly run out of memory. This was something I was already doing in JBoss. Here is what it is set to:

export MAVEN_OPTS="-Xmx1024m -XX:PermSize=256m -XX:MaxPermSize=512m"

Sample Files
Here is my pom.xml
<baseResource implementation="org.mortbay.resource.ResourceCollection">

Here is my jetty.xml located under /src/test/resources used to define the Datasource.
<?xml version="1.0"?>
<!DOCTYPE Configure PUBLIC "-//Mort Bay Consulting//DTD Configure//EN" "">

<Configure id="Server" class="org.mortbay.jetty.Server">

<New id="MYAPP-DS" class="">
<New class="org.apache.commons.dbcp.BasicDataSource">
<Set name="driverClassName">oracle.jdbc.driver.OracleDriver</Set>
<Set name="url">jdbc:oracle:thin:@localhost:1521:XE</Set>
<Set name="username">user</Set>
<Set name="password">password</Set>


Thursday, February 4, 2010

Getting Started with Extjs

I was recently approached by an internal co-worker within Accenture about our teams experience with Extjs. Out of 150,000+ employees in Accenture he was able to find us through Yammer, a free private twitter-like service for companies. Originally I was just going to respond to him via email after our phone conversation, but that would only benefit him. Instead I thought it might be a good idea to share that experience on this blog.

My current team has been using Extjs for about 2 years. I don't consider myself an expert nor do I actually like developing in a language that needs to work in multiple browsers. We started out with version 2.x and late last year converted our projects to version 3, which was no easy task.

I will say Extjs has impressed this Java developer. Their documentation and examples are excellent and feedback on the forums is great. Most of my team didn't have any prior heavy javascript backgrounds and all have been able to come up to speed quickly. Right now I think the biggest drawback is the GPL licensing of version 3. I understand why they did it, but doesn't mean I have to like it.

Extjs Resources

  • Examples - Extjs comes with a nice library of great examples on all kinds of things you can do with Extjs. All the examples also come with the download. One of the neatest examples is the Advanced Grid Filtering. One of the main reasons we upgraded to version 3 was for this feature.
  • API Documentation - The javadoc for extjs. This is the most important and most referenced documentation for any extjs developer. Keep in mind this only shows the most recent version. If you want the API documentation for previous versions, you'll need to download that version of Extjs. The download includes the same API documentation. For local installation or offline reference, there is also a very nice Adobe Air app (see download page).
  • Forums - The forums are very active and we have received a lot of help. We also have purchased the premium support and overall I'd say it was worth it. Especially since we no longer have that goto javascript guru anymore (yeah you know who you are).
  • Community Plugins - It's not huge but between the examples noted above and the community plugins we have been able to reuse a lot and create some neat stuff pretty fast.
  • Blogs - I'd recommend subscribing to the official Extjs blog as well as this search related feed from DZone. And, just because I think it is cool, here is Google Reader bundle I created that captures everything I tag with extjs. Finally, here is a search on my blog about articles I have written about Extjs.
  • Books - According to Amazon there are multiple books out right now about developing with Extjs. I have "Learning Ex JS" by Shea Frederick.
  • Javascript/CSS Consolidator - One of the best moves we made was investing in a javascript/css consolidator. Props go out to Joe Kueser for doing this for us. After a few months of development, our application started to grind to a slow crawl as several (80+) javascript and css files where being downloaded. Using the jawr framework we reduced that to around 20 GET requests which improved performance dramatically. Not only does it combine multiple files into one but it also minifies them (removes comments and spaces, etc) and supports gzipping them. I have been very impressed with jawr. It has exceeded our expectations and I would recommend it to anyone.
  • Development Environment - No web developer would be complete without Firefox and Firebug. But for those occansional nasty IE issues I haven't found the perfect solution. In the past I have had some luck with jsdt. Currently I am using IE8 in virutalbox in IE7 mode with it's built in Developer Tools. Although not firebug, it's the closest I have come to find. For those really bad IE6 issues I have used the Internet Explorer Developer Toolbar which beats scattered alerts in your code and is better than nothing.
  • Extjs version 2.x or 3.x - There has been a lot of history surrounding the licensing strategy so I won't go into all of that. Just know that version 2.x is LGPL and can be used or embedded into your applications for free. Version 3.x is GPL which means if your project isn't some internal IT app or also GPL you need to purchase developer licenses.
  • Public Uses - Here are just a few well known sites I have noticed using Extjs: Quicken Online and Dow Jones Industrial Index.
  • jQuery Integration - In case you want to combine jQuery and Extjs you can by using the extjs-jquery-adapter available in the download. I haven't really used jQuery a lot but from what I have read and heard, it's a great javascript library that supports animation and DOM querying. You can do these things in Extjs, but jQuery looks like it might do it better and cleaner. I think Extjs excels in providing out of the box prebuilt and customizable Widgets/Components like the Grid (Table).