Acegi and Struts 2

The easy part is done. Acegi's jar files are in place and they reliably block access to the "protected" part of the application, and redirect users to the login page. Unfortunately I haven't yet figured out how to connect my login action to Acegi authentication.

I believe I will have to have my login action point at my own custom implementation of UserDetailsService, which will in turn have a link to my already-existing UserDao. It will have to put the UserDetails in question into the security context... I think I got it. Now just to, y'know, write the code.

Thought I was GONE didn't you

I've played a bit over the last few days with a simple Struts 2 CRUD app, mostly following the examples given here.

Right now I have a data table that lists the users of the app and provides an exciting 'edit' link for each one. The edit link takes you to a pretty standard 'edit' type page for the given user.

Here's what I'd like to do next (several things, all fairly independent of the others).

• Turn the data table into a submit-driven paging sorting data grid.
• Turn the data table into an AJAX-driven paging sorting data grid.
• Implement a smart(ish) filter for the data grid.
• Change the two-page layout (table, data entry grid) into a one-page AJAX-driven layout (click on a user to open the edit grid for that user next to the table).

I think I'm going to start with the first one; I'm going to have to do it eventually anyway.

Changing a data source

It's very quiet here this morning. Snow and ice last night, freezing rain this morning. A lot of people are working from home today.

I'm going to try something wacky this morning. Having successfully finished the 'quickstart' demo provided by the fine Struts 2 folks, I've already changed the names of my packages and classes to match the activities I actually plan to undertake (quickstart.service.PersonServiceImpl changes to com.clientname.project.UserDaoImpl, for instance).

Now I'm going to do something more entertaining. I'm going to try to dump a copy of our dev MySQL database and build it locally, and then point this toy app at it. I may not have the right privs for that. So if that doesn't work, I'm going to point my app at our dev database and see what happens. I'm pretty sure I know what will have to change.

Onward

The rest of the quickstart demo went pretty smoothly. Not surprising, considering that it was largely a matter of typing (or copy and pasting) sample code into real files.

But now the fun begins: problems. The truth is that you don't understand how a technology or combination of technologies works until you've had to fix them when they're supposed to work.

So, first problem: Exception stack trace in my Tomcat log. I am not going to drop the entire stack trace into the blog at this point, but let me describe how I'm handling this. First, I skimmed the stack trace looking for references to code that I know to be mine. In this case there are no "quickstart." files anywhere in the stack trace, so I know it's not my Java code. Now, here are the first few lines of the stack trace:

SEVERE: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
org.springframework.beans.factory.BeanDefinitionStoreException: Unexpected exception parsing XML document from ServletContext resource [/WEB-INF/applicationContext.xml]; nested exception is java.lang.NoSuchMethodError: org.springframework.beans.factory.xml.ParserContext.registerBeanComponent(Lorg/springframework/beans/factory/parsing/BeanComponentDefinition;)V
Caused by: java.lang.NoSuchMethodError: org.springframework.beans.factory.xml.ParserContext.registerBeanComponent(Lorg/springframework/beans/factory/parsing/BeanComponentDefinition;)V
at org.springframework.transaction.config.AnnotationDrivenBeanDefinitionParser$AopAutoProxyConfigurer.configureAutoProxyCreator(AnnotationDrivenBeanDefinitionParser.java:130)
at org.springframework.transaction.config.AnnotationDrivenBeanDefinitionParser.parse(AnnotationDrivenBeanDefinitionParser.java:79)

The most obvious problem appears to be an error parsing applicationContext.xml. Probably I have a typo in there somewhere. However, I can't find one after glancing over the file for five minutes and that is almost certainly enough time for now. So I'm going to do something annoying. I typed this one in by hand and probably fat-fingered something. So I'm going to copy-and-paste the file contents from the demo and see if that makes the problem go away. If it doesn't then I'll have to use my brain and nobody wants that.

That doesn't make the problem go away! Crap. Time to do some Google searches on the exception messages.

And Matt Raible comes through again. Dude is rapidly becoming my hero. A thread on the AppFuse mailing list suggests that there might be collisions between various Spring jars. I'm reorganizing my build path, let's see how this works.

...nope. OK, time to review my build path, make sure I have everything I need. Yes, this would have been a good time to have used Maven, I know.

Hey, it turns out that I ignored a bunch of Hibernate jars earlier -- specifically the Hibernate Annotations and Hibernate Entity Manager jars. I'll grab them now. And that doesn't solve the problem either. Same error.

Clean, refresh, delete the deployment, rebuild, redeploy... and it's a whole new suite of errors! But these are more comprehensible. They can go in another post.

Using the instructions mentioned in the previous post I'm going through and creating myself a toy configuration for this app.

I had thought previously that I could just create a new project in MyEclipse and use MyEclipse's "add capabilities" features to get the stuff I want. But MyEclipse doesn't, as of yet, support Struts 2. So I'm going to stick with doing things the old fashioned way.

First step -- grab Tomcat and install it -- as expected, no problems there. Configure MyEclipse to recognize this Tomcat installation by going to Preferences -- MyEclipse -- Servers -- Tomcat -- Tomcat 6, click "Enable," click the "Browse" button next to "Tomcat home directory," and find the root of my Tomcat installation. The other arguments are automagically populated from there, hit Apply, hit OK. Go down to the 'Servers' tab in MyEclipse, select this Tomcat 6 server, click the exciting green start arrow, Tomcat starts up just fine.

Now start up MySQL -- hm, it won't start -- check properties for the MySQL service, find that it points to a directory that doesn't exist.

I should point out that this is an inherited machine that wasn't wiped before it was handed over. Sigh.

So, grab MySQL, install it -- now everything seems OK, except that I have an old, nonfunctional MySQL service in my service list in addition to the new functional one. I'll live.

Make a note in my lab notebook as to the usernames and passwords for Tomcat and MySQL. Yes, it might be slightly insecure but my memory is even less secure.

These quickstart instructions next provide a handy little SQL script to create a 'Person' table. Open up the MySQL Query Browser, open a new script tab, copy, paste, execute -- no dice. Syntax error. Huh. The syntax looks right to me:

CREATE TABLE 'quickstart'.'Person' (
'id' INTEGER UNSIGNED NOT NULL AUTO_INCREMENT,
'firstName' VARCHAR(45) NOT NULL,
'lastName' VARCHAR(45) NOT NULL,
PRIMARY KEY('id')
)
ENGINE = InnoDB;

But the MySQL query browser is complaining that I've got a syntax error near the second line. OK, let's check out the online refs, what is the correct syntax for CREATE TABLE in MySQL 5.0? I should mention that MySQL's online reference is just great, at least for this basic stuff. Detailed syntax, lots of examples.

Poke around for ten minutes to look for answers to this, can't find any. Ten minutes seems like a good enough time-boxing, so I'm just going to use the MySQL query browser's GUI to replicate the same code that is here.

Just for reference, here is the autogenerated SQL that the query browser came up with to create this table after I did the happy clicky:

DROP TABLE IF EXISTS `quickstart`.`person`;
CREATE TABLE `quickstart`.`person` (
`id` int(10) unsigned NOT NULL auto_increment,
`firstName` varchar(45) NOT NULL,
`lastName` varchar(45) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

Grand.

Good intro -- Struts 2 + Hibernate

Another good link, something to look at from work: Struts + Spring + JPA (Hibernate).

Struts 2 Links

Here is a free online PDF intro to Struts 2. No idea how good it is... yet.

A decent description of the post/redirect/get pattern for web app request management.

Exciting News

As you might have guessed, my productivity isn't quite as high with ColdFusion as it is in a Java web app environment. It took me a couple of days this last week to develop an embarrassingly small number of components and unit tests in CF.

I haven't been whining out loud about ColdFusion quite as much as I've been complaining on this blog, but several related activities, combined with some whining, and my lack of productivity, have led us to general agreement that we're going to be remediating this application's problems using Struts 2, Spring, and probably Hibernate. I'm very happy about this, as you might imagine.

I haven't used Struts 2 on a real app yet, although I have used Struts 1. I'll probably be using this blog in part as a Struts 2 linkdump, and partly as a description / walkthrough as I learn. I'm really looking forward to it.

My first link to dump, courtesy of client coworker: how to set up a Struts 2 project in MyEclipse 6.