Raible Designs

Hibernate's AdminApp - a demo of WW2 and Hibernate

After looking at Hibernate's AdminApp, as well as other WW2 apps - I've noticed something. WW2 developers don't seem to give a rats ass about referencing their POJOs in their Actions, or using Hibernate directly in their actions. At first glance, I think to myself, "boy that sure makes things easier." But then again - doesn't that tightly couple your web layer to your persistence layer?

I can understand the POJO reference in Actions - I'm about to give up on doing a parent/child relationship with Hibernate where the children are converted to ActionForms and then converted back (Hibernate loves to tell me "a different object with the same identifier value was already associated with the session: 1").

It would be SO much easier (with this particular problem) if I could just toss up POJOs to my view. The thought of importing "persistence.User" into my Action makes me cringe though. I don't know why, it just does. I need to get out of this patterns mindset I've been in for the last couple of years and get back to what really matters - simple, easy to learn, and fast to develop. I'm tired of banging my head against the wall with Struts and Hibernate.... I've been doing it for two days. It's not Hibernate, and it's not Struts, it's me... (thud, thud, thud).

Upgrading Hibernate, Struts and Display Tag

Last night, I upgraded a number of AppFuse dependencies: Hibernate → 2.1-rc, Struts Nightly from 2 weeks ago → Dec. 2nd and the Display Tag → 1.0 B2. The upgrades weren't as smooth as I'm used to, so I thought I'd share my experience to help y'all when you upgrade.

First of all, I found that Hibernate has ditched the Java Caching System (JCS) for their own, appropriately called Easy Hibernate Cache. This means you can forget about including jcs.jar in your webapp, ehcache.jar is now required. I upgraded from Hibernate 2.0.3.

Struts has done some trimming of their own - getting rid of their dependency on commons-lang. I use commons-lang.jar in AppFuse, so I had to dig into the contrib directory and grab it from there.

I had several issues with the displaytag when upgrading (from 0.8.5), but managed to figure them all out. First of all, the displaytag.tld in the jar's META-INF directory had the following in it's <taglib> declaration:

<taglib xmlns:html="http://www.w3.org/1999/xhtml">

This is obviously invalid, and I had to unjar, fix, and re-jar to get around this. I believe that this has been fixed on SF. I also found that this new version requires commons-collections 2.1. Struts must ship with an older version, so I simply replaces Struts' commons-collections with the one from the displaytag download.

The newer commons-collections is around 500 KB smaller - wierd, eh?

Lastly, I had to configure the ResponseOverrideFilter in my web.xml in order to get export functionality with Tiles. I had to tweek a LOT of CSS for this upgrade, but at least it's done now and hopefully I won't have to do it again for quite some time.

I also attempted to run AppFuse (with all these upgrades) in Tomcat 5.0.16 with no luck. With Hibernate 2.0.3, it was giving me an IllegalStateException when registering a new user. This process sets "Remember Me" cookies and redirects to the LoginServlet, which does a post to j_security_check and redirects to the originally requested page. Works fine in Tomcat 4.1.x, but not in 5.0.16. With Hibernate 2.1-rc1, I had to include jta.jar in $CATALINA_HOME/common/lib and now it still fails, but I get no errors whatsoever (those are always fun, aren't they). Also, still no luck with using J2EE 1.4.

StrutsCX - Updated Demo

I've updated my demo of StrutsCX. I haven't looked at StrutsCX much, but this release does look pretty polished. A quick glance tells me that it's now ready to be simply included in your Struts app with a single .jar file. Very nice! I might have to use it in Struts Resume to generate PDFs of Resumes.

Display Tag: Static Headers - Revisited

I get a fair amount of hits on this site for my Display Tag: Static Headers post. When I originally wrote it, back in August, it didn't work in IE. So I asked the experts. I got a solution from that - split the tables and wrap the data table with a div that has style="height: 400px; overflow: auto". This works in IE, but since it's not easy to hack the HTML that the displaytag generates, this is an awkward solution.

Since my old demo disappeared when I updated struts-resume, I created a new one. This example shows how to do static headers in both IE and Mozilla - and the IE solution actually works in both. It's admittedly ugly, but it works. The major problem with this approach is getting the width of the top (header) cells to match up with the bottom (data) cells. I got them close using "th, td { width: 25%}" in my stylesheet, but that doesn't line them up exactly. If anyone knows of a better solution, let me know and I'll update the demo.

Struts Menu 2.0 Released!

This release is a significant refactoring of the 1.x codebase. The source and site is now built using Maven. Menus can now be defined using Velocity templates and support has been added for looking up dynamic values. This means that if you have ${variableName} in your menu-config.xml (in a link), the tag library will look in all scopes for a variable with the name "variableName". The example app has been updated to improve documentation.

IMO, the Velocity templates is huge because it means "if it's possible with HTML" - it's possible with Struts Menu.

Changes (from http://struts-menu.sourceforge.net/changes-report.html):

- Renamed package structure to net.sf.navigator.
- Added support for using Struts' actions and forwards for links in menu-config.xml.
- Added support for using dynamic variables in menu-config.xml.
- Updated build process to use Maven for building/deploying.
- Refactored to use Velocity and allow dynamic variable substitution.

You can read the nitty-gritty details about the Velocity enhancements, check out the sample app or download this tag library for yourself.

AppFuse 1.0 Released!

I feel this release deserves the big 1.0 designation because it is an up-to-date representation of my learnings and my perceived best practices in building web applications. Of course, as I learn more, I will continue to push out new releases.

In this release, I did a lot of refactoring and enhancements to existing features. The DAO and Manager interfaces are no longer tied to Struts or Hibernate. Hibernate's Session object is now passed as an argument into Manager and DAO constructors, rather than method signatures. The DAOFactory was refactored by Bear Giles to use reflection to instantiate Hibernate DAO's. Now, if you add a new DAO, you don't have to edit DAOFactory and DAOFactoryHibernate. To insantiate a new DAO, the code is now:

LookupDAO dao = (LookupDAO) DAOFactory.getInstance(conn, LookupDAO.class);

...where conn is a connection object retrieved from ServiceLocator or ActionFilter. When you add new POJOs, you still have to add them to ServiceLocator (for JUnit tests) and hibernate.cfg.xml, which is kindof a pain. I'd like to figure out a way to tell Hibernate to just look in appfuse-ejb.jar.

<tangent>
I still don't have a Factory for Managers, and I don't know that there's a need for one, but it's something I might add in the future. Managers are still creating using: LookupManager mgr = new LookupManagerImpl(ActionFilter.getConnection());. One thing I've been thinking about is the ability to switch webapp frameworks - kindof like you can do with Persistence Frameworks and the DAO Pattern. It'd be cool to add a way to switch (at build time) to use WebWork or Tapestry. Maybe by replacing values for the controller in web.xml. It'd probably be a pain since I'd probably have to create new JSPs for the new frameworks - but it would probably be a great learning experience.
</tangent>

The Remember Me feature has been refactored so the username and password cookies are only available under the /appfuse/security url-pattern. I also changed the posting to "j_security_check" in LoginServlet from response.sendRedirect to an HTTP POST, using Jakarta Common's HttpClient. The reason I have a LoginServlet vs. just using action="j_security_check" in my <form> is to encrypt passwords.

I've developed 3 different applications using AppFuse (struts-resume is one of them), and I have found that it's a pain to upgrade to new versions of AppFuse. Because of this, I don't recommend upgrading unless you really need to. I will be upgrading struts-resume to AppFuse 1.0, but I doubt I'll upgrade it to any future AppFuse releases - it's just too much work for not much reward.

• Download (~11.5 MB for src, ~3.9 MB for bin)
• Release Notes
• API Documentation and Source
• Mailing List

JSTL Tips o' the Day

Here's a couple of tips to help you in your JSP development with JSTL:

• The <c:out> tag has a default attribute you can use to provide a default value when the value in your the variable you're trying to write is null. This is much easier than using if statements. Example: <c:out value="${user.firstName}" default="None Given" />.
• You can populate dynamic values in a key from your ResourceBundle using the <fmt:param> tag. For instance, if you have a message with a link in ApplicationResources.properties - and you want to populate it with a struts-forward, it's easy with JSTL:
  
  ApplicationResources.properties:
  
  

  mainMenu.link=Click <a href="{0}">here</a> to return to the Main Menu.
  

  In your JSP:
  
  

  <fmt:message key="mainMenu.link">
    <fmt:param><html:rewrite forward="mainMenu"/></fmt:param>
  </fmt:message>
  

Usually I try not to put any HTML in ApplicationResources.properties, but I don't think a minimal amount hurts anything. Of course, you could put all the HTML in your JSP, so mainMenu.link changes to "Click {0} to return to the Main Menu." and your JSP changes to:

<fmt:message key="mainMenu.link">
  <fmt:param>
      <html:link forward="mainMenu">here</html:link>
  </fmt:param>
</fmt:message>

Enjoy!

My Favorite Eclipse Plugins (Download v1.0)

When I go to new clients, I either have to install Eclipse, or help others configure Eclipse with cool plugins. So I made my own download of my favorite Eclipse plugins. If you want it, download version 1.0 from SourceForge. It includes the following:

• XMLBuddy (http://www.xmlbuddy.com) - XML Editor
• Colorer (http://colorer.sourceforge.net) - General Syntax Highlighter - for JSPs, HTML, CSS, etc.
• Jalopy (http://jalopy.sourceforge.net) - Source Code Formatter
• Lomboz (http://www.objectlearn.com) - JSP Editor
• JSEditor (http://jseditor.sourceforge.net) - JavaScript Editor
• Easy Explorer (http://easystruts.sourceforge.net) - Open Explorer/Finder
• Tomcat Launcher (http://www.sysdeo.com/eclipse/tomcatPlugin.html) - run and debug Tomcat

Installation: Unzip to where ever you have Eclipse installed. I use c:\Tools\eclipse on Windows.

I don't really use XMLBuddy because it doesn't allow spaces (only tabs), but I suppose it's better than nothing. The built-in Ant Editor has the same behavior (tabs only). I'd love to find a plugin that gives code-completion for XDoclet when typing JavaDocs, but I couldn't find one. Sure, there's JBoss-IDE (which is just a bunch of Eclipse plugins), but that only has jboss-specific tags - no @hibernate, no @struts.

NOTE: Many of these plugins didn't work on Eclipse 3.0 M5, so I reverted back to M4.

OS X Users: Jalopy and Colorer don't seem to work at all for me (M4). You'll need to change Easy Explorer from "explorer.exe {0}" to "open {0}" in Window > Preferences > Easy Explorer.

These are all the latest versions as of November 26, 2003.

RE: Compressing and Caching in your webapps

Jayson Falkner writes about two Filters everyone should have in their webapps: one for compression (via gzip) and one for caching. I try to add a CompressionFilter to all the apps I write, but I don't have a CacheFilter. So my question is: should I add Jayson's CacheFilter to AppFuse or should I use OSCache? I haven't got to Dave's chapter yet on performance and caching (in JSP 2.0), so I haven't read his opinion - what's your opinion? I like Jayson's solution because I can add 3 new classses with no additional JARs - AppFuse already has 21 jars (Struts, Hibernate, JSTL + a few other taglibs).

Setting up my Fedora box with Out-of-the-Box

Rather than spending hours trying to recover my Red Hat 9 disk, I built a new disk/box with Fedora. For all I know, the RH 9 one is still recoverable, but I'm an upgrade junkie so I couldn't help myself. Setting up DHCP with Dynamic DNS was a bit of a pain, even when I followed this howto. I believe I ended up re-installing bind and everything worked (this was a 2 a.m. last night, so my memory is a big foggy).

The only thing I haven't been able to get running (so far) is my USB Printer, details on hpoj mailing list. It was easy to setup my OfficeJet G85 on RH 9.

As for setting up my dev environment, it was a breeze using Out-of-the-Box. However, out of the box the installer didn't work. I had to install "gd-devel" (a dependency of viewcvs) and then everything installed just fine. Hat tip to Eric Weidner (of EJB Solutions) for the tip. I was able to select the applications I wanted and get all of the following installed and running: MySQL, PostgreSQL, Apache, Tomcat, mod_jk2 (to connect apache and tomcat), Roller, Scarab, CVS, Java, Ant and ViewCVS. I'm sure I installed more, but these are the mains ones I was looking for.

While the installer for OBox takes a while to run (on 1.5 GB RAM with 1.5 GHz = 30 minutes), the beauty of OBox is that it configures everything for you and starts all the services. The one thing that is disappointing (or maybe it's good) is that it didn't setup any environment variables - no $CATALINA_HOME, $ANT_HOME, etc. No biggie, I can set those up myself.

I might just have to burn a CD of OBox for future clients. It'd be nice to show up with my development environment on CD and ready to go. One bug I did find was that the mod_jk2 install configures mappings for all the struts example apps (which I didn't install).