Raible Designs

JSP Navigation Systems

As you might already know, I am a committer on the Struts Menu project at SourceForge. Struts Menu is basically just a JSP Tag Library that allows you to configure a navigation system for your webapp from an XML file. Here is a demo. Here are similar menu tag libraries I found:

• JSP Tree Tag and Demo.
• Sam Dalton's Menu Tag.
• Dynamic Menus, a JSP Tag from ONJava.com that reads from both an XML file and a database.

I also remember seeing one on weblogs.java.net, but their search feature sucks and I can't seem to find it (could be operator error).

Please let me know of any others you know of - or menus you'd like to see incorporated into Struts Menu. The current CVS version (module == navigator) allows for specifying the Menu attributes in XML and the HTML for the menu using Velocity templates (as well as some built-in displayers). Personally, I'm thinking of adding a couple from WebFX: XTree and XMenu. With the new Velocity support, it should be simple to add these. If it's possible with HTML, JavaScript and CSS - it's possible with Struts Menu!

Skinning your applications and Apache+Tomcat on RH9

Here are a couple of links I found on mailing lists that might be of use:

• Xkins: Xkins framework uses Velocity to process snippets of HTML, but you can use any other template processor (Xkins comes with it's own default processor). Xkins also comes with Forms Tag Libs, that allows you to create forms using Xkins and comes with four Skins. Xkins Forms integrates with Struts framework. Xkins also fits perfect in JSF world, playing a role as a RenderKit, and can work with other presentation frameworks, (i.e. struts-layout).I'll stick with simple XHTML and CSS. If I need different layouts (HTML), I'll use a different base tile.
• John Turner has published a Tomcat 4.1.27 + Apache 2.0.47 HowTo. This is similar to mine, but looks much cleaner and to the point.

Later: I discovered the beauty of John's HowTo this evening. It allows you to specify one measly line in Apache's httpd.conf file and only a few lines in Tomcat's server.xml file and viola Tomcat configures itself! It sets up aliases and such for each webapp that you have deployed. As an example, here's dynamically created section for AppFuse:

#################### localhost:/appfuse ####################                                       
                                                                                                       
# Static files                                                                                     
Alias /appfuse "/opt/dev/tools/jakarta-tomcat-4.1.27/webapps/appfuse"                              
                                                                                                       
<Directory "/opt/dev/tools/jakarta-tomcat-4.1.27/webapps/appfuse">                         
    Options Indexes FollowSymLinks                                                                 
    DirectoryIndex index.jsp                                                                       
</Directory>                                                                                  

# Deny direct access to WEB-INF and META-INF                                                       
#                                                                                                  
<Location "/appfuse/WEB-INF/*">                                                                 
    AllowOverride None                                                                             
    deny from all                                                                                  
</Location>                                                                                 
                                                                                                       
<Location "/appfuse/META-INF/*">                                                              
    AllowOverride None                                                                             
    deny from all                                                                                  
</Location>                                                                                   
                                                                                                       
JkMount /appfuse/j_security_check  ajp13                                                           
JkMount /appfuse/auth/*  ajp13                                                                     
JkMount /appfuse/register/*  ajp13                                                                 
JkMount /appfuse/passwordHint/*  ajp13                                                             
JkMount /appfuse/*.do  ajp13                                                                       
JkMount /appfuse/*.jsp  ajp13                                  

I had all of this working great - I even had Apache upgraded to 2.0.47 on OS X (serving localhost/~user files and everything)! And then I rebooted... Now in catalina.out, I'm getting the following - ugh...

BAD packet 256                                                                                      
In: : [B@c283b5 4/843                                                                               
01 00 03 47 00 00 00 00 00 00 00 00 00 00 00 00  | ...G............                                 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  | ................ 

WTF?!

Solved: I got this solved fairly easily. I had modified /usr/sbin/apachectl so that the HTTPD variable pointed to /usr/local/apache2/bin/httpd rather than /usr/sbin/httpd. I fixed it by removing /usr/bin/apachectl and executing "ln -s /usr/local/apache2/bin/apachectl /usr/sbin/apachectl". Now if I could only get the Rendezvous mod working on 2.0.x.

A day of upgrades

I upgraded this site to the latest code from Roller's CVS, and I'm now running Tomcat 5.0.12 Beta. It seems to be working like a charm for FreeRoller so why not? I also upgraded to Eclipse M4 on OS X and WinXP. For those of you looking for a JSP Editor for Eclipse, try Lomboz. I'm using it and it seems to work fairly well. As far as I can tell, all it gives you is syntax highlighting. I tend to use Homesite or BBEdit for JSP pages - they're better HTML editors and always will be IMO. There never will be a "I can do everything" IDE, so why keep searching? Though it would be nice if someone would figure out code-completion for custom tag libraries.

All upgrades seem to have gone smoothly and backups were made in case they crap out.

Update: The Lomboz plugin sucks, at least with the latest Eclipse. Ctrl+C and Ctrl+V don't work ~ maybe that's a good thing...

WebWork and JDD

I attended the Boulder Frameworks meeting tonight on WebWork, followed by the Boulder JUG meeting. The WebWork (a.k.a. WW) presentation had a mere 5 attendees, but Kris gave a very good overview of WW and showed how simple it was. Here are some of the strengths of WW according to Kris:

• It's not dependent on J2EE. Many method signatures are empty and it uses interfaces everywhere, rather than parent classes. Sounds cool. Kris likes it because "it gives you a warm fuzzy feeling you're not tied to WW."
• It's not Jakarta. "Jakarta is like a Ketchup bottle - you have to beat it to get anything out of it." I don't know that the WW team produces software much faster than Jakarta though...
• Instead of using the HttpServletRequest, WW uses a Stack, which is essentially the same thing (sans J2EE).
• WebWork has Interceptors. They're like Filters, but WW comes with built-in Interceptors that can be applied declaratively. Kris mentioned there's little documentation on the built-in Interceptors - a wiki page would be nice.
• Action packaging - you can turn a portion of your WW application into a jar and it can be added to another WW application. It sounds good, but I can't think of a use for it right now. Sounds like modules in Struts.

Kris's biggest reasons for liking WW was Interceptors and Inversion of Control. However, Struts has those too. Good presentation. I plan to learn WW and give up this whole my framework is better than yours stance. In fact, I hope to do this with many of the technologies I use everyday. I'm going to start using Orion and Resin so I know if Tomcat really is better, or better yet - when should I use one appserver or the other. I'm learning IDEA so I know when to use Eclipse and when to use IDEA. Today I discovered how IDEA warns me about invalid Javadocs (very nice feature). Eclipse continues to rule the CVS integration world, and I see no reason to quit using it and bitch about IDEA's lack of CVS integration.

After WW, I walked across the hall to listen to James Duncan Davidson talk about "James Driven Development" (my phrase) - also known as Objective Object Orientation. Rather than bore you with the details, here are the highlights:

• Don't abstract too much - just enough to fit your needs. Examples of too much abstraction can be found in Apache's Repositories (James's words - he didn't specify any projects).
• Don't extend, instead create objects do something, then you don't need to know the interworkings of the object.
• Dynamically typed languages rock (i.e. Smalltalk, Ruby, Python). They're much easier to develop with, especially when backed my TDD. You can accomplish similar things in Java using lots of casting.
• He can't wait until something comes along and kills Ant and Tomcat - he never thought they'd make it this far - especially considering he wrote them when he was a Junior Programmer for Sun. He gave Tomcat its name because he thought it'd be good animal on the book cover of an O'Reilly book. He never thought it would happen, and now that it does have a book, he said he's disappointed it's not an actual Tomcat (apparently it's a snow leopard?).

His point about Ant and Tomcat is that 1) something better than Ant will rock, so we should all be happy when something better comes along and 2) Tomcat was never designed (or tested) to be used in the environments its being used in (i.e. Nuclear Facilities). Good stuff - brain is full.

JSF and Apache Axis at DJUG

I attended tonight's DJUG Meeting. The meeting was informative and well attended, but it was way too long. I just got home and it's a bit after 11:00. To put it in perspective, I arrived at 6:00. That's 4 1/2 hours of Java love. Elections contributed to the delay, as well as David Geary's 2 1/2 hour JSF presentation.

The basic concepts meeting covered Apache Axis, presented by Scott Davis. He showed us how easy it was to use Axis to create a web service and how to call it from the command line. The biggest highlight of his presentation (for me) was Keynote - his presentation software. It had wicked transitions and the slides looked awesome (good purchase Scott). Other cool software noted during Scott's preso was CodeTek's Virtual Desktop.

Next up was David Geary for a presentation on JSF. This guy has quite a resume: worked for Sun from 1994-97, member of the JSF and JSTL Expert Groups, author of 6 books, designed and implemented the Struts Template library (2nd committer to Struts after Craig). Books coming soon from David: Core JavaServer Faces, Core Rave, and Extreme Struts. Extreme Struts sounds very much like the Struts chapter I wrote for Pro JSP - XDoclet, StrutsTestCase, JUnit, Tiles and Validator. If you're looking for documentation on AppFuse or Struts-Resume, you'll find it in this book. If you don't remember, I wrote these apps for my chapters.

Most folks reading this blog probably know what JSF is. If you don't, it's a Java-based framework for building web applications. It is designed to replace Struts, but that probably won't happen until well after it's 1.0 release (March, Beta in December). JSF was also written to compete with .NET's WebForms, kinda like how JSP was developed to compete with ASP.

Sun's Project Rave is what supposedly will make JSF easy. Can Rave really be that much better than Eclipse or IDEA? Good luck Sun, those are two killer IDEs that are going to be very difficult to beat. And besides, has Sun ever produced any good applications? iPlanet sucks, so does Forte - comparing both to the other options out there.

I could go on and on about what I learned at this presentation, so let me just give you a brief synopsis. JSF generates JavaScript for you for event handling. The JSP tags are long and ugly, but they're named this way (i.e. <h:selectone_menu>) to distinguish a component (selectone) from a renderer (menu). David said he complained about this immensely when he joined the Expert Group, but now sees the point. No XML attributes are used in faces-config.xml - it's all entities. Reminds me of web.xml, lots of typing for not much information (what a pain - today's tool suck at deployment descriptors). JSF has no client-side validation - looks like Commons Validator will be around for quite some time. Especially since JSF requires you to specify your validation after each component in the JSP (vs. declaratively using the Validator). JSF EA4 does not work with Tiles - they're working vigorously to fix this. You can specify your navigation-rules separate from you actions in faces-config.xml (very cool feature).

If you know JSPs and Servlets, it's much easier to learn Struts (and presumably other webapp frameworks). If you know Swing, it'll be much easier to learn JSF. To me, this seems wrong. Some of the examples given tonight had HTML in .java files (for custom renderers). Are we reverting back to Servlets? Is Sun making a mistake with JSF? How is it better than WebWork or Struts? It seems to me to be an over-designed product developed by a bunch of Swing addicts.

My first impression of JSF is that it's going to be harder to teach to newbies (vs. Struts). Everyone says it's a standard so the tools vendors will come through and make it easy. The tools vendors haven't done shit for JSP and JSTL IMO, so how is JSF different? It's a good idea, it just needs to be simplified - a lot. KISS.

New Gig starts November 3rd

I gave my notice on Monday and will be starting a new gig on November 3rd. My reasons are simple: I can bill for the commute (45 minutes each way), I can work from home 1-2 days per week, mentoring/teaching opportunities and the biggest - they want me to help them build a Resume Entry application. Sweet - I'm hoping to use Struts Resume as a baseline. If they agree to use Struts Resume, we'll have half the project done on my first day! The hard parts will be getting it to run on WebSphere and DB2 - their platforms (that I've never worked with). They're hiring me as a mentor on Java and Eclipse and also expect me to cut a fair amount of code. It'll be cool to have mentor as part of my job description. It's also a government agency, which means 40 hour weeks and no weekends. If anyone has gotten WebSphere running on OS X, hooka brutha up!

I gave my current gig a 4 week notice because I want to help them roll out the first phase of websites, and verify that architecture I helped them build actually works. They're looking to replace me with someone that has similar skills. They're located in Lafayette, Colorado - and it really is a fun place to work. Here's the most important things to know for this position: Struts, Ant, JSP and Tomcat. Let me know if you're interested.

What's the best way to test Tag Libraries?

I know of two tag libraries that are in dire need of unit tests - the displaytag and struts-menu. Both have no tests. I've looked briefly at TagUnit, but aren't you just writing JSPs (with custom tags) to test JSPs? I'd rather have an Ant/JUnit driven solution. Also, are there HTML versions of the user guides for TagUnit (Simon ;-)? I hate PDFs.

So my question is - how do you test your tag libraries?

Dynamic Queries with Hibernate

I have a client that wants the ability to search on all columns in all tables in their database. So far, I've been able to get all the columns, and their friendly labels by getting all the *Form.* keys in my ApplicationResources.properties file. I still need to sort them alphabetically, but that's another issue. Now I have the following UI pretty much done:

I'm happy with the UI, but I'm struggling with getting Hibernate to return my desired results. I'm able to dynamically select the table/column to search on because of values in my "tables/columns" drop-down. However, many of these tables have Id fields - for status fields, type fields, etc. (basically drop-downs). When searching, this is a pain because users are likely to search on "Active" rather than "1". Because of this, my first issue is how do I make the status field's friendly name a part of my POJO (with Hibernate)?

My 2nd issue is regarding Hibernate's Expression API. I want to be able to pass in the criteria (=, contains, <, >), propertyName and value and get my results. However, it seems that the second half of the comparison must be the same datatype as the field. This means if you're searching on "contract amount", and its a Double, I need to do a Double.valueOf(searchTerm). Basically, I'm looking for an easy way to do this:

  Criteria filter = ses.createCriteria(clazz); 
  
  // determine type of expression - I'd love to figure 
  // out a cleaner way to do this but there's only 
  // 5 possible types, so I don't mind typing the 5
  // if statements
  if (expression.equals("=")) { 
    // How do I convert these to the fields' type at run-time?
    // Sure I could do a bunch of if statements again, but it seems ugly.
    filter.add(Expression.eq(field, Double.valueOf(value))); 
  }
 
  List results = filter.list();

Any advice is appreciated - especially considering I estimated this task to take 4-5 hours and I'm going on 8.

Simple "workaround" for exporting with the displaytag using Tiles

I figured out an easy "workaround" to the fact that the displaytag's export feature (to XML, CSV, and Excel) doesn't work when using Tiles. The happens because the response has already been committed by Tiles (when including previous JSPs) and the displaytag is unable to set the contentType. Here's my workaround:

In struts-config.xml, create a local forward that goes directly to the JSP:

  <forward name="exportList" path="/WEB-INF/pages/userList.jsp"/>

Then in your Action, add a little logic to see if you should forward to the definition or to the list:

  // if exportType is a parameter, forward directly to JSP
  if (request.getParameter("exportType") != null) {
    if (log.isDebugEnabled()) {
      log.debug("export detected, forwarding directly to list jsp");
    }

    return mapping.findForward("exportList");
  } else {
    // return a forward to the user list definition
    return mapping.findForward("list");
  }

Tested with displaytag 0.8.5 on Windows XP and Tomcat 4.1.27. Enjoy!

Update: This workaround will not work with displaytag 1.0b1. There is another solution using a Filter, so we'll try to incorporate that into the 1.0 release.

Packaging Velocity

I've made a number of changes to struts-menu this week, and it now supports the ability to render menus via Velocity templates. This allows for easy customization and basically allows for you to create any type of navigation system you want (i.e. drop-downs, tabs, plain ol' links) etc. One of the issues I'm wrestling with is how should I package Velocity with the distribution. Usually, to integrate struts-menu into a Struts-based application, you only need to include struts-menu.jar. Now, if you want to use Velocity for your menus, you must include velocity.jar and velocity-tools.jar in your application's WEB-INF/lib. I think most users will accept this.

However, in the example app, there's a velocity.properties file and a couple example templates. This seems like an opportunity for many users to forget to include these - so I'm wondering what's the best way to package these. Should I put velocity.properties in the source tree, and initialize my VelocityMenuDisplayer using that? Should I do a check to see if the user has their own velocity.properites in WEB-INF/classes for an optional override?

Another question is should I put the sample templates (simple.html and coolmenus.html so far) in the source tree, and then use Velocity to load them from the struts-menu.jar file? Or should I package them in a menu-templates.jar file?

Basically, it all boils down to this question: If you have a project (.jar) that depends on Velocity and plugs into web applications - what is the best way to distribute your Velocity settings?

BTW, I hope to make an effort to decouple this library from Struts someday - shouldn't be too hard.