Raible Designs

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.

How IE handles PDFs

From the Struts User Mailing List, I spotted a good explanation of how IE handles PDFs. It's quite messed up, so I thought I'd post it for your amusement.

If your application returns data that is to be handled with an ActiveX control (ie Adobe Acrobat Reader) the browser sends additional requests to the server. In IE 4.x and 5 it actually sends three requests. For IE 5.5+ it sends two.

Assuming that your using IE 5.5+, the first request is the original request (duh), but then IE sends a second request to get the content-type. Who knows why they can't figure this out on the first request This second request has it's userAgent header set to "contype". You can solve this problem and increase the performance of your application by writing a Servlet filter that sits in front of whatever Actions you have setup to serve PDF content. Have this filter look at the userAgent header of each request. If it's set to "contype" just send an an empty response back to the client with the content type set to "application/pdf". Simple as that.

More info on this "feature" is on Microsoft's site.

David Geary won't learn Tapestry, but he'll write a book about Rails

Sorry David, but I have to call you out on this one. Yesterday, you wrote a long post about how you won't use Tapestry b/c you have bills to pay.

Do I use Tapestry? Heck no. I have a mortgage to pay. Besides, I'm so comfortable with JSF that I don't know if it'd be worth the investment for me to switch to Tapestry. Also, JSF already enjoys more industry support and that gap will widen considerably over the next couple years as Tapestry maintains a small but rabid group of followers in a niche market, whereas JSF will dethrone Struts as the reigning king of Java-based WAFs. JSF will eventually have support for HTML views and custom components devoid of Java code, in addition to many other cool features such as built-in AJAX support and client-side validation.

Today we find that you're writing a book on Rails. So rather than spending the time to learn Tapestry b/c it doesn't pay the bills - you're going to learn Rails? What makes you think it will pay the bills better than Tapestry? Is Shale still the next big thing for you - or do you just like writing books?

Tapestry is the best Java framework available today

David Geary:

So what's the best Java-based framework available today? It's a very close call, IMO, but I'd have to give the nod to Tapestry at the moment. I really like Tapestry's pure separation of HTML and components and the ability to create custom components without any Java code. That gives it an edge on JSF, which, like Tapestry is one of what I refer to as 3rd generation WAFs, that support components and a server-side event model.

He goes on to say that he'll likely continue to use JSF (with Shale) because it pays the bills and will dethrone Struts as the most popular - which will obviously lead to more gigs. I especially like this part of his post:

After I get client-side validation and file uploads added to Shale I want to turn my attention to Tiles integration, AJAX support and exploring Tapestry-like views that strictly separate HTML and component definitions. For me, those are the most exciting areas of Shale.

I agree that JSF definitely needs Tapestry-like HTML Templates. Shale definitely sounds cool, but I find it funny that it takes yet another framework to make JSF usable. Hopefully Shale will prove a lot of ideas worthwhile and end up as features in JSF 2.0.

[Microsoft] Day 2 Morning

Looks like I'm going to miss the good stuff today. There's a Company Store visit this afternoon at 5:00 - and they're giving us $120 in credit. Damn, apparently the games are pretty cheap there. They've also arranged for a Longhorn Demo during the company store visit. I did manage to get internet access with my phone and Ben's charger - so I should be able to do some real-time updating this morning.

I think one of the coolest things about this conversation is we're learning about how software is developed on a huge scale. These guys develop more software than anyone else and they do it on a very large scale. Can you imagine developing software for 90% of the computer users out there?! That would be nuts.

Oh boy - now we have an audience member ragging on the guy for Windows. He thinks it should be open source because OSes are going to be commodities soon. Personally, I don't think there's anything wrong with having a closed-source Windows. But I also don't see a problem with closed-source Java. What's wrong with companies making money? The main reason I'm in this industry is to make money - so what's wrong with the corporations doing the same thing?

.NET CLR Architecture

Started work on the Component Object Runtime (COR) back in '97. It was a small incubation project in the MTS group round metadata and compiler integration. Several API's still use the "Cor" prefix and engine DLLs are named MSCOR???.DLL. Apparently, this was all announced at the '98 PDC in Denver. Lots of code/marketecture names to follow: COM3, COM+ Runtime, NGWS Runtime, Universal Runtime (URT) and finally the Common Language Runtime. The big unveiling of CLR was at PDC 2000 in Orlando.

CLR Design Goals: Simplify development and deployment for classic Win32 programmers. Unify programming models, provide managed environment and support multiple languages.

The CRL is Language Neutral and has a commons set of features (i.e. Generics) guaranteed to be in all languages. Supports strongly typed languages, dynamic languages and functional languages. Because compilers are always targeting MSIL and the metadata, you get for free: shared object layouts and cross-language inheritance, exception handling, reflection, remoting and integrated tools for debugging and profiling. MS is very excited about having Jim Hugunin and IronPython on board and they expect to add even more killer features for dynamic language authors in the future. I wouldn't be suprised to see an IronRuby implementation in the next year or two.

CRL Version 2.0: More class libraries: collection classes, serial port, etc. Generics, 64-bit support (IA64, x64). RAD support: Edit and Continue, Just My Code, single-click deployments. SQL Server: fiber mode, integrated security, loading. Avalon, Indigo and Windows Longhorn.

Is this a boring session? Yes, but I'm sitting in the front row today, so it's a bit easier to pay attention and take notes. I'm doing AppFuse development for the most part and taking notes while AppGen tests are running in the background.

The CLR will be hostable in numerous environments: ASP.NET, VSTO for Office, DB/2 Stinger, Oracle 11g and SQL Server 2005. Oracle and DB2 are out-of-process with v1.1, SQL Server will be in-process with v2.0.

ASP.NET 2.0 by Scott Gu

• ASP.NET 2.0 Application Services APIs: Membership, Role Manager, Personalization, Site Navigation (XML and CMS-based), Database Caching, Health Monitoring. These are all based on a new "Provider Model Design Pattern" that seems to be a set of interfaces that you can easily switch or implement yourself. Out of the box providers: Windows, SQL Server, Access (ha!).
• ASP.NET 2.0 "Page Framework" Features: Master Pages (like Tiles, moreso than SiteMesh), Themes/Skins, Localization, Client-Scripting (using XMLHttpRequest). Holy shit - the guy said that they're testing their controls, particularly the scripting ones on IE, Safari and Firefox! That's pretty surprising to me.

VS 2005 has a new feature - where you don't need to have a web server installed, it'll work off the file-system. A new project doesn't have any files in its directory - which is definitely an improvement. VS definitely looks pretty slick - you can switch the "compliance-mode" of your page from IE6 to XHTML Transitional. When you switch modes, it changes the code completion attributes - so you'll get much more options for IE6 than you will for XHTML. It also has full code-completion for JavaScript - and the options are based on your mode of operation. Accessibility checking is also included - you'll actually get underlines for elements that don't have all the required attributes. Java needs an IDE like this soooo bad it's not even funny. Can you imagine having full page/HTML validation and code-completion based on doctype?!

Scott did a master/detail screen with VS and made it look damn easy. Most of the audience oohed and aawed. It's cool and all, but the code in the .aspx pages is a lot like JSF - there's hardly any HTML in the pages! It does seem to have much better support for skins and themes - you can easily change the look and feel right in the IDE and there's a whole bunch of built-in themes. The one thing I really like is the page-backing classes have a pre-init() method that can use to initialize properties. JSF really needs something like this. It's a shame that frameworks like Shale have to provide this and it's not a part of the core JSF framework.

ASP 2.0 Beta 2 will ship in the next month. Heh, Scott just gave a demo adding security and authentication in about 20 seconds - complete with Remember Me. There's actually a "Login" control that doesn't everything for you, including validation. The membership system (database) will actually get generated on-the-fly. He follows it up by creating a signup page that creates new accounts in under a minute. I can't really bash on this, writing authentication for Java webapps is definitely harder than it needs to be. Of course, if you use AppFuse, you don't have to write it at all.

Time to run and catch up with my sister - have a good weekend y'all!

Spring MVC vs. WebWork Smackdown at OSCON

Matthew Porter and I are going to try something a bit different at this year's OSCON. Rather than just getting up in front of the crowd and spewing our technical know-how, we're actually going to make a go at providing some entertainment. I've been to a lot of conferences and I'm tired of just watching someone talk - I'd rather see a good presenter over a knowledgeable presenter. This has inspired our OSCON 2005 talk:

This presentation has a unique delivery style. Rather than one person doing a comparison, there are two presenters - each which is an expert in the framework they're defending. The presentation is delivered as a friendly comparison/debate, which hopes to add some humor in to make it fun for the audience.

Java web developers often have a difficult choice when choosing a web framework these days. There are currently more than 35 open-source Java web frameworks available. How do you which one to use for your project? This presentation picks two of the most popular frameworks, Spring MVC and WebWork and compares and contrasts their features. Topics will include:

1. View options - i.e. Velocity, JSP, HTML Templates (ala XMLC), etc.
2. Testability - How easy is it to unit test with JUnit, with examples
3. Type conversion - i.e. Date, Integer, etc.
4. Validation - How do do it, stengths and weaknesses
5. Tools Support
6. Strengths and Weaknesses

Now the pressure's on - we have to both teach and entertain the audience. Please feel free to post your experiences with Spring or WebWork and why you think one is better than the other.

Display Tag being ported to Ruby/Rails

Found via Brian McCallister - a codefest grant has been awarded to Dave Tiu to reproduce the Display Tag in Ruby/Rails.

Codefest Grant recipients:

1. Ruby Displaytag (Dave Tiu)

A port to Ruby/Rails of a popular Java/Struts library for displaying
and interacting with HTML table presentations.

Maybe if I wait a little longer to write my first Rails app - they'll add client-side validation too.

Is Laszlo a waste of time?

According to Rife founder Geert Bevin, Laszlo ain't all it's cracked up to be:

It's a shame, I really had huge expectations about Laszlo and even tried to sell it to a customer. I'm glad that project was cancelled or I would be in deep trouble.

Under normal circumstances, I'd dismiss this as FUD, but Geert sounds like he did his homework on this one.

Simple Web Framework

You gotta admit, the Simple Web Framework does look interesting with all of the recent Ajax talk:

The Simple Web Framework (SWF) is an event based framework targeting Struts developers who want to build rich Web applications but do not want to migrate to JSF. The SWF is built upon the same Jakarta commons basis as Struts, but uses a different request processor (front controller.) The SWF event model supports form/submit style event posting, similar to VB.NET or JSF, as well as XmlHttpRequest based event posting with In place Page Updating (IPU) rather than page reloading, similar to the techniques underlying gMail. Read the SWF Overview for additional information.

My hope is that all web frameworks have some support for IPU by the end of the year. Then I won't have to build it into AppFuse.

Simplifying XmlHttpRequest with JSON-RPC

In my day job, we decided to use a little XMLHttpRequest lovin' to populate one drop-down from another. This is my review of JSON-RPC, an open source JavaScript library and servlet for simplifying XMLHttpRequest. I considered integrate Direct Web Remoting (DWR) as well, but its java.net site was down the day I needed it. I started out with JSON-RPC 0.7, which caused some conflicts with Commons Validator client-side validation. This was fixed in the 0.8 release. JSON-RPC takes a little more setup than I care for, but it's pretty easy nonetheless:

1. Download the 0.8 release from http://oss.metaparadigm.com/jsonrpc-dist/json-rpc-java-0.8.tar.gz.
2. Add the JAR to your project and the webapps/jsonrpc/jsonrpc.js to your projects' "scripts" folder. Include this file in your SiteMesh decorator or Tiles layout. If you're not using SiteMesh or Tiles, it's high time you started.
3. JSON-RPC currently requires that you register each class you want call methods on. In our project, I registered a Spring bean (LookupHelper) that's a singleton with references to Maps in the ServletContext. Then we used JavaScript functions to call JSON-PRC and look up units for a plant, and vice versa. I'm not going to put the LookupHelper class here - you'll have to trust its methods return a single String or a comma-separated list of Strings. To register this bean with JSON-RPC, I created an HttpSessionListener and configured it in web.xml.

   /**  * UserListener class used to add/remove session attributes when  * a user first logs in.  Mainly for JavaScript Remote Scripting stuff.  *  * @author Matt Raible  */ public class UserListener implements HttpSessionListener, HttpSessionAttributeListener {      private final Log log = LogFactory.getLog(UserListener.class);     public final static String BRIDGE_KEY = "JSONRPCBridge";     /**      * Initializes LookupHelper singleton with values needed for lookup      *      * @param event the HttpSessionEvent to grab session information from      */     public void sessionCreated(HttpSessionEvent event) {         // Find the JSONRPCBridge for this session or create one         // if it doesn't exist. Note the bridge must be named BRIDGE_KEY         // in the HttpSession for the JSONRPCServlet to find it.         HttpSession session = event.getSession();         JSONRPCBridge jsonBridge = new JSONRPCBridge();         jsonBridge.setDebug(true);         session.setAttribute(BRIDGE_KEY, jsonBridge);     }     /**      * Destroys LookupHelper      *      * @param event the HttpSessionEvent to grab session information from      */     public void sessionDestroyed(HttpSessionEvent event) {         if (event.getSession() != null) {             event.getSession().removeAttribute(BRIDGE_KEY);         }     }     public void attributeAdded(HttpSessionBindingEvent event) {         if (event.getName().equals(BRIDGE_KEY)) {             HttpSession session = event.getSession();             // register LookupHelper so we can call methods on it             ApplicationContext ctx =                     WebApplicationContextUtils                     .getWebApplicationContext(session.getServletContext());             // check for null so we don't have to initialize Spring in tests             if (ctx != null) {                 log.debug("Registering lookupHelper for XmlHttpRequest...");                 JSONRPCBridge jsonBridge =                     (JSONRPCBridge) session.getAttribute(BRIDGE_KEY);                 jsonBridge.registerObject("lookupHelper",                                           ctx.getBean("lookupHelper"));             }         }     }     public void attributeRemoved(HttpSessionBindingEvent event) {         // don't care     }     public void attributeReplaced(HttpSessionBindingEvent event) {         // same as attribute added         attributeAdded(event);     } }

4. After this setup was complete, I was able to add the following JavaScript to the bottom of my JSP. These are functions that our drop-downs call to populate each other, and keep their options in synch.

   <script type="text/javascript"> var jsonurl = "${ctx}/jsonrpc"; var jsonrpc = null; var unitDropDown = document.getElementById("equipmentName"); function filterUnits(plantDropDown) {     var plantName = plantDropDown.options[plantDropDown.selectedIndex].value;     if (plantName == "") {         reloadUnits("");         return;     }     try {         jsonrpc = new JSONRpcClient(jsonurl);     } catch(e) {         alert(e);     }     // Call a Java method on the server     var units = jsonrpc.lookupHelper.getUnitsForPlant(plantName);     setUnits(units); } function reloadUnits(value) {     if (value == "") {         try {             jsonrpc = new JSONRpcClient(jsonurl);         } catch(e) {             alert(e);         }         // Call a Java method on the server         var units = jsonrpc.lookupHelper.getAllUnits();         setUnits(units);     } } function setUnits(units) {     var unitArray = units.split(",");     unitDropDown.options.length = 1;  // keep "All" option     for (i=0; i < unitArray.length; i++) {         unitDropDown.options[unitDropDown.options.length] =             new Option(unitArray[i], unitArray[i]);     } } </script>

The hardest part of using JSON-RPC is setting it up. We only experienced minor issues with Commons Validator, but since the JSON-RPC 0.8 release - everything has worked great, on all browsers we need to support. The only thing I don't like about this library is that you have to register objects for each user's session. I briefly looked at DWR and it looks a little cleaner - especially b/c of its Spring integration. The next time we need XMLHttpRequest, we'll probably use DWR just to compare the two.