Raible Designs

Context Reloading in Tomcat 5.5.7

Today I started using Tomcat 5.5.7 instead of 5.0.28. It was fairly easy to install on my PowerBook - I just had to add the xerces and jmx JARs from the compat package to get things working. The one thing I noticed that's different from Tomcat 5.0.28 is that when I deploy any file, it reloads the context. This can be a pain when I'm just copying JSPs into the webapps directory. I'm willing to admit it could be a problem with my "maven deploy" goal, but since this didn't happen on 5.0.28, I suspect it's the newer version of Tomcat. On 5.0.28, the context was only auto-reloaded when I updated files in the classpath.

The main reason this was frustrating is because we look up a bunch of data from a web service on app startup. The API we're talking to is nice and slow and it takes almost 50 seconds to start our application. Rather than go back to the older version of Tomcat, I wrote some code to serialize all the ServletContext variables to disk, and then check for that file on startup. If the file exists, it deserializes it and puts all the objects back in the ServletContext. Works pretty good and certainly speeds up my development environment. After all this, I'll probably downgrade to 5.0.28. Auto-reloading when classpath files change seems like a better way to go.

[DJUG] JUG Central and BPEL

Last night, I attended Denver's JUG meeting. Below are my notes from the event.

I'm at DJUG listening to Christian and Kris (from Adigio) talk about their experience with using Spring, WebWork, Hibernate, Lucene and SiteMesh to develop JUG Central (I wonder if they knew this name and concept already exists?). JSPs are for the view and MySQL powers the data. This presentation is designed to explain a bit about each framework, and also tips/tricks and pitfalls they experienced when developing the site. They started working on the application in August of last year and deployed it into production in December.

Christian said they weren't going to go into the how for each framework, but Kris has had quite a few slides on SiteMesh so far. I don't blame him - it's a great tool and only a handful of folks (of about 50-60) have heard of it.

SiteMesh Pitfalls: Poor integration with Velocity and some other frameworks. BTW, if you're using Tapestry - Erik Hatcher recently created a JIRA patch with a Tapestry Decorator.

Now Kris is talking about WebWork and since he's a framework junkie, apparently this is going to be the largest part of the presentation. I think one of the nicest parts of WebWork is its auto-type conversion. The only other frameworks I've seen that have this is are JSF and Tapestry. For those that like WebWork and don't like JSF - you might find it disturbing that the WebWork actions (and their tests) in AppFuse are very similar to the JSF managed beans. I would take it as a compliment if I were a WebWork developer.

One nice thing about XWork's action configuration is you can specify a "method" parameter for a particular action. Struts recently added this with its MappingDispatchAction. I'm using this on my current project and it works quite well. Kris really likes WebWork's front-page controller pattern - where you use the <ww:action> tag to execute the action when the page is loaded. Personally, I don't have a problem with going through actions to get to my view templates. Kris finished up his WebWork piece with a plug for AppFuse (thanks!) and WebWork in Action. Congrats to all the authors - wonder if it'll be published before WebWork Live?

Now Christian is talking about Hibernate and its mapping files - and how you can generate your database schema from them - or generate your mapping files from a database. They used XDoclet to generate the mapping files in this particular project.

Hibernate Pitfalls: Think about lazy-loading early. Problems arise when you try to share Hibernate-managed objects across (Hibernate) sessions transparently. Christian mentions that Spring's OpenSessionInViewFilter is a nice way to solve the problem.

Hibernate Tips: Spring simplifies using Hibernate and makes declarative transactions easy. Read Hibernate in Action before starting development. Plan to spend some time learning how to express your data model with Hibernate relationships (one-to-one, one-to-many, many-to-many, etc.).

Christian is now talking about Spring and how it works. After thinking and writing about Spring so much in the last year, I'll just skip over regurgitating this part. ;-) His main recommendation: use real injection instead of appContext.getBean("beanName").

Other tools used: Lucene for searching and POI for indexing Word, Excel and PowerPoint files. Velocity used for templating e-mail messages.

Service-oriented Architecture (SOA) with Business Process Execution Language (BPEL)
Presented by Kevin Geminiuc and Owen Newnan from Policy Studies

This point of this presentation is to communicate what it's like to implement BPEL in a J2EE Container. BPEL is a layer on top of web services. BPEL is a programming language that you can use to program business processes. Allows you to divorce your business process from being human-centric to being document-centric. At Policy Studies, they're using iLog JRules rules engine and Oracle's BPEL implementation.

Benefits:

• Process Visiblity
• Process Agility
• Powerful Language
• Open
• Backed by "the Big Boys" (BEA, Microsoft, IBM)

History: Formerly knows as BPEL4WS, WSBPEL. Open standards based. Orchestrates web services with SOA.

Where we are today: Emerging technology (prepare to bang your head against the wall). .NET and Java products exist, as well as J2EE container integration.

BPEL & WS Standards: BPEL, XPath, WSDL, WS-Addressing, SOAP, XML-Schema, WSIF (Axis), TBD (WS-ReliableMessaging and JSRs 207/208). Note that since BPEL depends on web services (which is not a truly reliable service). Because of this, there are some proprietary extensions available.

At this point, I became bored with the presentation and quit taking notes. While the speakers had good intentions with their knowledge sharing, their delivery needed some work. The code walkthrough and demos were presented with a monotonous and unexcited tone, and a handful of folks left during this part. In summary, BPEL looks like a good way to orchestrate your various business processes. It allows you to call web services, EJBs and whatnot simply by defining their locations and methods in XML.

In his demo, Kevin used Oracle's BPEL Designer, which is an Eclipse plugin that has a nice drag-n-drop editor for managing your BPEL XML files. He also used Oracle's BPEL Process Manager, which seemed to be a lot like Jetspeed - you just drop in the .ear and then deploy your processes to it. The only bad part about the Process Manager is it's administration/deployment interface only runs in IE.

If you're using BPEL in your projects, I'd be interested to hear the tools you're using. As far as open-source BPEL process engines, they mentioned Twister and ActiveBPEL.

iBATIS Article on ONJava.com

If you've heard of iBATIS, but never had the time to look into it, there's a good intro article on ONJava.com: Object-Relational Mapping with SQLMaps. iBATIS continues to be my persistence framework-of-choice when Hibernate doesn't mesh with the database schema. Now if we could just get someone to write a Middlegen Plugin to generate POJOs and SQL Maps from database schemas.

So Struts is Dead, huh?

So most folks think Struts is Dead, huh? I've got news for you folks. Struts has been dead since 2002. For that matter, most Java frameworks have been dead for the last year. Most folks think Struts is dead because there won't be any new and whiz-bang features added in future releases. I'm willing to bet the other Java Web Frameworks won't add any whiz-bang features in the next few years either. Sure, WebWork might get a little XMLHttpRequest lovin' for client-side validation, and Tapestry might get pretty URLs - but both of these are features that these frameworks should've had in the first place. So what's the big deal? At least the Struts Developers have the guts to stand up and say "we're in maintenance mode". Shouldn't all framework developer's be able to say this? It's really quite an accomplishment.

IMO, the only developers that shouldn't be saying this are Tapestry and JSF folks. Both of these teams should be saying - "we're going to make our frameworks easier." If these frameworks are going to be the future of Java web development, there's some work to do. The JSF folks should be saying, "we're going to fix all the stuff that's broken". This "stuff" includes POST for everything, lack of bookmarkability, and bad validation messages (the good news is the validation messages should be fixed in JSF 1.2). I think Tapestry needs some simplification too. In my experience, most Tapestry pages (by design) require 4 files. One for the Java class, one of the HTML template, one for the page specification and one for the i18n keys. This should be easier. It'd like to see two required files (template and Java class) and the others are optional. Maybe annotations could eliminate the page specification? I think there's a lot to be learned from frameworks like Ruby on Rails: default everything, allow overriding.

I think that Shale will be good, but only if it learns from the other MVC frameworks available. If I were on the team, I'd take the good things from all the others: IoC, Interceptors, HTML templates, etc. I wouldn't stop there either - there needs to be good examples of how to integrate it with middle-tier frameworks like Spring, Hivemind and EJBs. Often developers will take examples as recipes - so the more detailed and simple, the better. The Struts developers have quite an opportunity to make something great, let's hope they don't just create another framework.

Short and sweet contracts

This has been a good month for Raible Designs. Not only did I manage to land a new gig, but I've also had a couple of 1-day contracts. The first one was an architectural review (at the beginning of the month), and yesterday I delivered a presentation on TDD and Spring for a client. These short-n-sweet gigs are a lot of fun. It's a good way to get out and meet members of the Java Community and see what tools they're developing with. The first client is using Struts, Spring and Hibernate. The second client wanted to use Struts, but after my talk, they're thinking about Spring MVC. They plan on using Spring to make EJBs easier, and they're using TopLink on the backend.

The only bad part about yesterday's experience is I developed a full-body ache as soon as I left the client's site. I managed to catch a cold from Abbie this weekend, and that turned into a cold+fever last night. I've had the fever ever since and didn't go into work today. It's really shitty timing for getting sick - we have a deadline on Thursday and we're heading to Oregon to see my parents this weekend. Last I checked, my fever was at 102°F. Hopefully, I'll wake up tomorrow and it'll be gone.

AppFuse Startup Video?

Dion wants to see an AppFuse Startup Video like Mike Clark's CruiseControl Action Movie. While this sounds like a good idea, I think I'd be shooting myself in the foot if I created it. Why? Because then more folks would start to use AppFuse, and hence, I'd have to answer a lot more e-mails on the mailing list. Being a top-ranked project on java.net doesn't help. You might think that there's a lot of issues with AppFuse, and that's why the mail traffic is so high, but that doesn't seem to be the case. Most questions seem to be along the lines of "Why did you do this?", "What do you think about adding X technology?" or "My Hibernate relationships don't work."

Few of the issues relate to AppFuse directly (i.e. build file and directory structure), but many of them relate to the technologies it depends on. Good HowTos should lead to a lot less Hibernate questions, and I hope to work on that before the next release. As far as the other questions, I need to add some links from the FAQ to the mail archives so I can quite repeating myself. I think a lot of the mail traffic is just an indication of a successful open-source project. In other words, when you get popular - you have little time to develop anymore. I probably spend 1-2 hours per day just answering AppFuse e-mails.

Another unfortunate side-effect of this is that there seems to be a lot of newbies. When AppFuse was first released in April 2003, it seemed that only experienced, smart developers used it. Maybe this was because there wasn't any documentation (besides Pro JSP and Java Development with Ant, which explains the entire build.xml file), so folks had to really understand the dependent technologies to use AppFuse. Now there's questions about the basics of different frameworks. In most cases, I'd like to respond to a link to the framework's documentation - but sometimes the documentation just isn't there. I guess that's why frameworks like Ruby on Rails succeed - all the dependencies are part of the framework. If I tried to do that in the Java Community, it'd be project suicide. I'd spend all day answering questions like, "Why aren't you using Hibernate?", "Why Not Spring/JSF/Struts, etc." Furthermore, I'm not as smart as the framework developers, so it'd simply never happen.

But I digress. What's in it for me if I create an AppFuse Startup Video? I can see what's in it for Mike - his video is about a project he doesn't support (AFAIK) and the video should lead to more book sales. I suppose I could try and hook users that AppFuse is explained in Spring Live, but that's not really the case. Maybe I should just do an Equinox Startup Video.

RE: Hype: Ruby on Rails

Patrick thinks that Ruby on Rails is all hype.

Now maybe I'm just a bit biased since my framework isn't getting all the slashdotters oohing and awwing over it, but I think Ruby on Rails is way over hyped. The tutorial here is great and gave me a very good overview of what it does. At the end of the day, RoR is simply a RESTful CRUD framework.

I'd like to agree with Patrick, because that is my natural tendency when I see a project that everyone praises. But I know better. I think it's better not to speculate on the productivity or usefulness of a framework until you've used it to develop an app.

That's what I did with Spring, WebWork, Tapestry and JSF last year. Now I feel like I know "the truth" and whether one framework is better than the other. The truth is they all have strengths and they all have weaknesses. While one might work well for one project, it might not for the next. I think the best thing is that you don't setup yourself for framework lock-in. If you only know one web framework for Java, you should probably pick up a book and develop an app with another framework - just to see how things are done differently. Now that I've used all of the Big 5 in Java, I don't think it would be that hard to migrate an app from one framework to next.

So what am I trying to say? Don't bash on a framework until you've tried it. And I don't mean toying around with it on a Tuesday night, I mean using it for a real-world project. I'll probably diving in and doing a little Rails development later this year. Why? So I can see if all the hype is accurate.

Using JasperReports with AppFuse and Spring

In Spring 1.1.3, support was added for using JasperReports with Spring MVC. Today, Gregory Beumer posted a nice overview of JasperReports. This inspired me to dig up Gilberto's post on How to integrate JasperReports with AppFuse. If you're looking for a reporting solution in your AppFuse-based application, and you're using Spring MVC ... enjoy! I plan on adding this to the wiki in the future, along with howtos for integrating JasperReports with Struts, WebWork, JSF and Tapestry. If you happen to know of tutorials for integrating JasperReports with these other frameworks, please let me know.

Installing Jetspeed 2 and deploying Struts/JSF Portlets

One of things we're moving to on my current project is portlet development. The client has a bunch of apps they want developed and it makes a lot of sense to develop them as portlets and deploy them in a portlet container. Because of this, we spent some time this week mucking around with Jetspeed-2. Bruce and I figured out how to install it, and then I did a bit of work with Equinox to deploy the Struts and JSF versions as portlets.

I didn't get equinox-struts or equinox-jsf fully functioning in Jetspeed, but I did get them to deploy and bring up the first page. I expect to do some more work in the next month to get these apps fully functional. In the meantime, I've put together the following tutorials.

• How to Install Jetspeed
• Convert Equinox to a Struts Portlet
• Convert Equinox to a JSF Portlet

If you have any tips on getting JSF or Struts WARs working in Jetspeed, please let me know.

[DJUG] Testing and Handling Exceptions in the Web Tier

I'm attending Denver's JUG tonight, where Scott Davis is talking about Unit Testing the Web Tier. His opening slide says he's going to cover HttpUnit, Canoo WebTest and JMeter. I'm most interested in the JMeter stuff as I've been meaning to integrate it into AppFuse. I've used HttpUnit and it's a little verbose for me. I prefer using Canoo WebTest or jWebUnit over HttpUnit. On my current project, we're considering using jWebUnit or HttpUnit to act as a browser when interacting with a 3rd-party system.

All of these tools run functional tests - which are much different from unit tests. Unit tests usually tests the bricks, whereas functional tests test the building. For unit and functional tests to be truly effective, they must be:

• Scriptable
• Repeatable
• Automated
• Darn close to 100% coverage

The tools Scott is talking about tonight have passed his basic tests:

• Can I learn it in 10 minutes?
• Does it play nicely with my existing test environment?
• Does it play nicely with my existing production environment?

I didn't take any notes about HttpUnit or Canoo WebTest because I didn't really learn anything new. Scott did do a nice job in his HttpUnit examples - he made it look a lot simpler than I've previously seen. I've used it HttpUnit before and it seems a bit verbose. I've always used jWebUnit, which simplifies HttpUnit's API.

JMeter allows you to do the same thing as HttpUnit and Canoo WebTest. It's a standalone GUI, for the complete non-programmer. It does not plug into Ant/JUnit and is mostly used for load testing. I thought it was exclusively used for load testing - and I think it has an Ant task. I could be wrong.

<sidenote>Scott uses Smultron for XML editing on his Mac.</sidenote>

The basic building block of JMeter is a "Thread Group". The Thread Group allows you to control the number of users/threads that run a particular test. You can test gets, posts, change the protocol and even upload files. For load testing, make sure and check "Retrieve all Embedded objects in HTML files". You have to view the "result windows" to view that your tests actually ran - there's no "green bar" feature.

I think JMeter has improved a lot since I last looked at it. Scott's overview and demonstration make it look very straight forward and easy to use. One guy asked if it's possible to see a a global view of all tests run. Scott thinks it's possible by adding a Listener to the Thread Group and creating a graph (one of the options). Scott is now showing a lot of the options in JMeter - there's a ton! It's almost overwhelming.

Next up is "Exceptional" Web Apps by Stephen A. Stelting, a senior Instructor and Author from Sun. His latest book is "Robust Java". Stephen has spent the last year and 1/2 figuring out how to make Java fail.

Objectives:

• Describe the types of errors that occur in the web
• Explain how exceptions and errors can be handled
• Describe the web container response to exceptions
• Present best practices to address web tier exceptions
• Show how web frameworks handle exceptions

Payoff: As a result of this talk, you'll have a better understanding of how to use exceptions in Servlets and JSPs, improving the robustness of your webapps.

I'm a little skeptical at this point. I think most folks don't do exception handling in their webapps. I hope Stephen has some good tips and tricks for those of us who are familiar with handling exceptions. I wonder how he feels about Spring and its runtime exceptions?

There are two types of exceptions in the web tier: HTTP Errors and Java Exceptions. Standard HTTP Errors are handled by the web server. You can also send your own HTTP errors by calling HttpServletResponse.sendError(). If you're using response.sendError(), make sure and call it before you commit the output. The web.xml file allows you to specify errors and exceptions with the <error-page> element.

Servlets and Filters have similar exception behavior. Both declare exceptions in both of their lifecycle methods: init and service (doFilter for Filters). Developers throw exceptions in lifecycle methods to "tell" the container about problems.

• javax.servlet.ServletException
• javax.servlet.UnavailableException
• java.io.IOException

Stephen is now describing the init() method and the exceptions it can throw. Yawn. I think most Java web developers use frameworks these days. Because of this, most developers probably don't use these methods because they don't write plain ol' servlets. One thing I didn't know is that UnavailableException takes a time parameter - if you throw an UnavailableException with this parameter, the container will retry after the specified amount of time.

Result of Exceptions in init(): The destroy() method is never called, since the initialization did not complete. Client calls during component unavailability render a 500 error.

I stopped taking notes at this point because my laptop battery was dying. I didn't really learn much in the rest of the presentation. While I can appreciate Stephen's enthusiasm, it was obvious that he was an instructor and not an in-the-trenches developer. He explained a lot of what and didn't have any code to show how to do stuff. There wasn't a single demo in the entire presentation.

Most of the exception handling stuff Stephen talked about for the rest of the session was common sense (IMO). It also centered around the Servlet and JSP API, which most folks probably don't mess with. The Struts and JSF coverage at the end was cool. If nothing else, it was to nice to hear a Sun employee confirm that JSF is quite deficient in its hooks to allow easy framework-configurable exception handling.

Now that I'm working at home, and working/interacting with friends all day - it seems that the DJUG meetings aren't as exciting. They used to be fun because I could get out of the house and have a few beers with friends. Maybe it was the lack of learning anything new tonight.