Raible Designs

What's the best way to integrate Ajax into a Java webapp?

I received an e-mail over the weekend asking how to integrating Ajax into into the various web frameworks covered in my Java Web Framework Comparison Whitepaper. Below is my reply:

The best thing that I've seen is to use DWR, Prototype and Scriptaculous.
These will work with all web frameworks, and if you're using Spring on the backend -
DWR makes it easy to expose your beans as JavaScript objects.

Also, there's a number of tag library solutions that greatly simplify things:

  http://javawebparts.sf.net
  http://ajaxanywhere.sf.net
  http://ajaxtags.sf.net

I haven't used the first one, but I have used AjaxAnywhere and saw a demo of
AjaxTags from its developers.  They both look like they could be very useful.

For those of you using Ajax in your Java webapps - what's your advice? Do you use these same libraries or other ones?

This post was partially motivated by my desire to reiterate things that are so obvious.

Jetty vs. Tomcat vs. Resin: A Performance Comparison

This morning, I did some comparisons between Jetty 5.1.5rc1, Tomcat 5.5.9 and Resin 3.0.14 (OS version). I ran AppFuse's "test-canoo" target, which tests all the JSPs using Canoo WebTest. I did this as a Servlet 2.4 application, and had to tweak some stuff in my web.xml to make it work on Jetty and Resin. Nothing big, just stuff that Tomcat let pass through and these servers didn't. One interesting thing to note that Resin requires you to use "http://java.sun.com/jstl/fmt" for JSTL's "fmt" tag URI, while Jetty and Tomcat require "http://java.sun.com/jstl/fmt_rt". This is with Resin's "fast-jstl" turned off - b/c everything blows up if it's turned on (I don't feel like coding my JSTL to Resin's standards, that's why I turn it off).

Below is a list of the average time it took to run "test-canoo" after I ran it once to compile all the JSPs.

• Jetty: 19 seconds
• Tomcat: 19 seconds
• Resin: 29 seconds

In addition, I tested how long it took for each server to startup - including the initialization of AppFuse.

• Jetty: 7 seconds
• Tomcat: 8 seconds
• Resin: 13 seconds

So what does all this mean? A number of things:

• I need to clean up AppFuse's web.xml a bit for 2.4 applications.
• Putting the database connection pool configuration in a Spring context file (vs. JNDI) makes AppFuse much more portable.
• Jetty isn't as fast as Jetty-lovers say it is (or maybe Tomcat just caught up).
• The open source version of Resin is much slower than the other open source servlet containers.
• I should restructure the build.xml to pull out Tomcat stuff and allow users to specify server deployment settings (i.e. in a ${servername}.xml file).
• Orion still doesn't support the Servlet 2.4 or JSP 2.0 specifications.

Wicket is the most widely used Java Web Framework

According to this post, Wicket is the most widely used Java web framework. While I believe his statements are true, IMO it's only true in the context of this guy's post. My guess is that most of the folks that read his post were Wicket users, or somehow the Wicket Team got wind of this and told users to e-mail this guy. The main reason I don't believe that Wicket is the most popular is because it's so new. I do think it's an up and coming framework that may become the most popular, but I don't think it's there yet.

So, to answer this question, I believe that claiming Wicket to be the most widely is Just Good Guerilla PR. To put some numbers behind that, here's some graphs showing mailing list traffic for the various Java web frameworks.

Granted, these are just indicators of the number of users - but I believe they are a good indicator. One interesting note about these stats is that Wicket's mailing list traffic has increased significantly in the past few months. Ironically, here's what one of the Wicket developers had to say about this statistic about a month ago:

... who says having a lists that has a lot of traffic is a good thing? It might just as well be an indication of a too-hard-to-understand framework having insufficient documention.

In the past couple of months, I've spoke in front of 25+ Java developers on 4 different occasions to talk about web frameworks. I've asked those developers which frameworks they've used, or plan on using. Struts is still the most widely used, with WebWork and Tapestry the least used. Surprisingly, JSF seemed to be getting no traction among the the audiences I spoke to. Even more surprising (to me at least) was that the most popular web framework continues to be the in-house framework. The overwhelming majority of the developers I've talked to aren't even using open-source web frameworks.

Things I learned from OSCON

While at OSCON last week, I learned quite a few things. Many of these are my own opinions, so feel free to disagree with them.

Ruby is very cool

The main reason (for me) that Ruby is cool is because it's new. I don't have to know any of its history to know what makes it tick. It's easy to learn and has powerful language features that make it easy to use. I think the primary reason people, particularly Java developers, are excited about it is because it releases them from all the shackles they're accustomed to with Java. I have absolutely no plan to ditching Java and jumping to Ruby, but I do want to learn it so I can use it when it's a better fit than Java.

How to learn Ruby and retain that knowledge is the hard part. My current plan is to buy Programming Ruby and Agile Development with Rails. Unfortunately, I realize that I probably won't be able to finish these b/c I'll get bored and both will likely serve as more of a reference than a knowledge creator. I haven't been able to read a technology book cover-to-cover in several years. I couldn't even finish The Pragmatic Programmer for crying out loud. I realize that the best way to learn is to do, but the best way to do is to get paid to do. To facilitate this, I hope to develop some apps we can use at Virtuas. Of course, I'll try to find good open-source solutions first.

Rails has a lot of great ideas

The interesting thing about Rails is many of its good ideas are from Ruby. The built-in Webbrick web server is part of the language. The only way to come close in the Java world is to embed Jetty or something like that. I'll definitely be looking into embedding Jetty into AppFuse in the near future. The other thing I really like about Rails, and that I've been doing in AppFuse a bit is convention over configuration. As part of AppFuse, I'm already making a lot of decisions for users. The next step seems to be making all decisions for users, but allow them to override. It'd be cool to write some code that sweeps through all classes at startup and auto-configures them, w/o the need for any XML. If nothing else, the XML could be generated using reflection.

The biggest thing I learned from Rails is I need to provide 1) an easier upgrade path and 2) better Ajax support. Because I'm supporting so many different web frameworks, solving #2 might be a bit tricky - but could be done by writing tag libraries or components. Hopefully the framework developers will beat me to it and I won't have to do anything. As far as #1, I'm hoping I can move to a single appfuse.jar that contains all the base classes. Hopefully I can use a little JSP pre-compile action to re-use the existing JSPs for user management/etc. If not, I can always use something like FreeMarker to store the default view files in a JAR.

Creating Passionate Users is all about inspiring emotion

Kathy Sierra's talk about inspiring emotions among your users to make them transparently excited about your product/company was a real eye-opener. I can totally see what she's talking about and I'm happy to say I'm already doing some of it. This blog seems to attract lots of readers, some more passionate than others, just by talking about web technologies and Java. This does translate into more business for Raible Designs, whether it's the title image or URL, it doesn't really matter. Folks do figure out that I have a company and I do work with the technologies I talk about.

To apply these concepts to AppFuse and Virtuas is a little more difficult. For AppFuse, I can probably teach people how to better use Hibernate, Spring and Ajax - and then show how AppFuse can simplify things. Building in easy-to-use Ajax support is probably essential to really get this going. For Virtuas, we could re-vamp our site to provide education about open source and its history - providing users with a way to become open source experts. It would also be cool to do real-time reporting of how we helped a company adopt open-source.

Ideas, ideas, I have lots of ideas after last week.

AppFuse Tutorials in Chinese

A guy named "Rocksun" has done a tremendous service to the AppFuse community. He volunteered and took on the task of translating all of AppFuse's Tutorials to Chinese. If you understand Chinese better than English, I encourage you to take a look at Rocksun's translations:

• Creating DAOs
• Creating Managers
• Creating Struts Actions and JSPs
• Creating List Screen and adding Validation

Some people might say your open source project has hit the big time when someone translates your documentation to another language. I don't see it this way. I think the reality is that Rocksun is a super-nice guy and has done a great service to the community. Thanks Rocksun!

NOTE: Rocksun also publishes two blogs, one in English and one in Chinese. And I thought I was busy!

A CSS Framework

Mike Stenhouse's CSS Framework seems like it might be a good candidate for inclusion in AppFuse. In his article about this framework, he basically says that there are 6 basic layouts that "cover most of the blogs out there and most of the corporate sites as well". He shows you how it's possible to use a single XHTML page, and use CSS to achieve all of these layouts w/o changing your HTML. This is huge IMO because you can accomplish all the different layouts w/o changing your markup. Very cool. Hat tip to CSS Beauty.

AppFuse Videos

I know I said I'd never do an AppFuse video, but after having many requests - I decided to go ahead and make a couple. The first one is a demo of creating a new project and then installing and browsing that project in your browser - to see all the out-of-the-box features.

• http://demo.appfuse.org/setup.html

The 2nd one basically all the stuff that's done in the tutorials - using Spring MVC for the web framework. I create a Person.java object and then use AppGen to generate all the code for it. In this one, I make a number of mistakes (but solve them all). I thought about going fully happy-path, but then decided it was important to show some gotchas that might occur.

• http://demo.appfuse.org/appgen.html

I used the trial version of Camtasia Studio to create these videos. Thanks to Keith at KGB Internet for hosting the demo site for AppFuse. If you need Tomcat hosting, Keith offers an excellent service at a very good price.

Update: You can also download these videos for off-line use.

Update 2: I updated these videos for AppFuse 1.9.3.

How do we bake Ajax into Struts and Spring MVC?

I see a trend happening here. The next version of WebWork, as well as Tapestry and JSF are all embracing Ajax technologies. By "embracing", I mean they're not only using them, but they're making it easier for us to use them.

After using XmlHttpRequest in my last two projects, I think this is a must for Struts and Spring MVC as well. The technology is very cool and customers absolutely love it.

The question is how do we bake it in? WebWork makes it easy because its tag libraries are backed by customizable Velocity templates. With Struts and Spring MVC, it seems the best way would be to use tag libraries, but maybe there's better alternatives. Do they each need an AjaxAction/AjaxController or something that allows DWR-type stuff?

What are your thoughts? You might argue that using DWR should suffice, but w/ everyone else (even Rails) baking it into the framework - I see no reason why Spring MVC and Struts shouldn't do the same. You are using these frameworks to develop kick-ass UIs aren't you?

Why Wicket looks cool

I like the looks of Wicket for a couple of reasons - without even using the framework yet.

• Its project homepage looks good. If you're using a Java web framework, chances are you're developing UIs too. If you don't know how to make sites look good - it's time to find a new line of work IMO. Of course, learning how to make good-looking UIs is another option.
• Its Wicket Stuff project. It provides Hibernate, fValidate and Spring integration. It also appears to provide an option to use Velocity for your templates. I'm not sure what the Velocity integration provides - since HTML templates (ala Tapestry) should do everything that's needed.

What I don't like about the project:

• The Buzz page has a quote that's (apparently) from this site. Unfortunately, it looks like I said it - which I didn't.
• There's no books being written about it. If it's really that good - where's the books? Ruby on Rails will have 3 by the end of this year. Any good framework should inspire books to be written about it.
• The Wicket Stuff project has no documentation. Javadocs don't cut it. Tutorials are king.

I hope this project succeeds - Tapestry needs some competition and I don't think JSF is providing it. If JSF adds HTML Templates (or I figure out how to use Java Studio Creator to manage an AppFuse+JSF project), that's a different story.

Trim Spaces in your JSP's HTML

One of the annoying things about JSPs is all of the dynamic (non-rendered) parts of the page still produce line breaks. This means that if you do a view-source, you'll likely see large blocks of whitespace.

The good news is you can get rid of this whitespace if you're using Tomcat 5.5.x. Just locate the "jsp" servlet in $CATALINA_HOME/conf/web.xml and add the following <init-param>:

    <init-param>
        <param-name>trimSpaces</param-name>
        <param-value>true</param-value>
    </init-param>

I tested it and it works great. This begs the question - why isn't this on by default? Source: Struts Mailing List.

Update: JSP 2.1 adds the ability to trim whitespaces.