A recipe for trouble

Dear the Internet,

Please never write this code:

if (value == null || value.equals("")) {
d = new Date(0);
} else {

This is what I like to call "bug hiding". Rarely does a person really mean 12/31/1969 when they pass you a null or blank value. That is all.

JSP is still really bad

I had to do some maintenance work recently on a JSP app. Normally, I avoid JSP like the plague because my (dated) experience with it has been mostly bad. The app I had to maintain was a stone age thing full of scriptlets, but I did a little research and used JSTL to do some of the work on the updates. I was pretty impressed with how cleanly you can do some flow control stuff now. So, I started some new development on a new project with JSP as a proof of concept to see if it is a tolerable programming environment now. It isn't. For the real basics, there has been a lot of improvement, but some of the mechanisms for taglibs, dealing with variable between servlet/JSP, etc. are still very clunky. And today I encountered this. If you forget to put the return type when defining a function within your app, you get a super mysterious error.


I guess you could blame the implementation (Jasper), but what does anyone else use? Also, you can sort of tell from the screen shot of the editor, but the JSP editor in the current version of Eclipse is pretty awful. It displays some of your double quotes as single quotes, which is really awkward.

Miscellany

Here's a good example of some bad user interface design in my favorite IDE.


I know the Maven stuff is a plugin, so I'm guessing NetBeans allows plugins to install tabs under "Miscellaneous". So what you end up with is a configuration screen that looks simple until you find out that there are really supposed to be 30 tabs instead of 7, but they are hiding out in the Miscellaneous section.

An elegant DAO design for un-elegant queries

I am a big Hibernate fan, but sometimes you can't use Hibernate. When you can't, Spring's JDBC support is awesome. One of the reasons I encounter frequently for not being able to use Hibernate is some ridiculously complicated queries (I'm looking at you, Peoplesoft). When you have a giant long SQL query, you often encounter some code that looks like this:

String sql = "SELECT " +
"RM.RTITLE1, " +
"RM.RNAME, " +
"SR.USER_SEQ_NO, " +
"SR.INT_SEQ_NO AS SUBREQ, " +
"SRT.USER_SEQ_NO, " +
"SRT.TEXT, " +
"(SELECT SRA.COURSE FROM SUB_REQ_AR SRA WHERE SR.INT_SEQ_NO = SRA.SUB_INT_SEQ_NO AND SRA.USER_SEQ_NO = 1) AS COURSE " +
"FROM DPROG D JOIN DPROG_REQ DR ON D.INSTIDQ = DR.INSTIDQ " +
"AND D.INSTID = DR.INSTID " +
"AND D.INSTCD = DR.INSTCD " +
"AND D.DPROG = DR.DPROG " +
"AND D.DPFYT = DR.DPFYT JOIN REQ_MAIN RM ON D.INSTIDQ = RM.INSTIDQ " +

Ugly, isn't it? Well, some of my coworkers that were running into this came up with the idea of putting the SQL into its own files. It is a great idea and I doubt they are the first to think of it. They don't use Spring, though, and I thought Spring would be able to provide some good glue to put it all together.

It turns out, Spring has something called Resource that can automatically load things from various places. I chose to use the classpath, and put the SQL files into the same package as the DAO. The only problem here, is with Maven, you end up with the SQL file in src/main/resources and the code in src/main/java, which is a little annoying. The Resource object doesn't get the whole job done either; it just provides an InputStream, and having to write code to read the contents of the file has no place in my elegant solution. So, this is where commons-io comes into play. In the setter for the Resource object, I use IOUtils to read the file and stick it in a String.

So, the overall strategy goes like this:

• Put SQL in file in src/main/resources
• Create DAO object with a Resource setter for the SQL file
• Wire the SQL file resource in your applicationContext.xml
• Read in the file using IOUtils in the setter

Here's the DAO definition in applicationContext.xml

<bean id="darsCourseDao" class="edu.asu.eadvisor.onoff.dao.DarsCourseDaoImpl">
 <property name="dataSource" ref="darsDataSource">
 <property name="subreqsForCourseQuery" value="classpath:/edu/asu/eadvisor/onoff/dao/GetSubreqForCourse.sql">
</property>
</property></bean>

And the setter in the DAO looks like this:

    public void setSubreqsForCourseQuery(Resource subreqsForCourseQuery) throws IOException {
                InputStream is = subreqsForCourseQuery.getInputStream();
                try {
                        this.subreqsForCourseQuery = IOUtils.toString(is);
                } finally {
                        IOUtils.closeQuietly(is);
                }
        }

Eclipse Quality

If you work with me, you might know that I'm not what you would call a super enthusiastic fan of Eclipse. You might not know that I used to really like it. I still do sort of like it, but it just seems like they have quality problems. This example I noticed today is sort of an indicator of the quality of the software they provide. It doesn't really require much discussion.

See, at first, I was like "haha, noobs accidentally put in two references to the same menu". But, no. It is actually two different menus with different options. I don't get it, man.

Tapestry 5 pain points

I have been doing Tapestry 5 work for about a year now, and I'm definitely still learning, but I think I know my way around fairly well. I really (mostly) like it, and I think it is way easier to use than Tapestry 4, as well as many other frameworks. It also results in a nice clean code base which isn't too difficult to approach. There are, however, a couple of areas that I really just find confusing. Some of them aren't too bad once you get to know them, but they are hard to learn. I think it is important for most aspects of the framework to be easy to learn/use, because if people encounter pain during their initial impression stage, they will abandon the framework and use something else.

The first issue I have is with the way that the Select component works when you want to have a dynamic model for the list. I think this is a common requirement for applications, so it is something people will most likely encounter fairly quickly. For complex models, it is usually necessary to implement two interfaces: SelectModel and ValueEncoder. The interfaces make sense once you get to know them, but I think the learning curve is quite steep for such a common task. I'm not sure how this could be solved, but it seems like Tapestry 4 may have had a more simple system (though I'm sure it had some problems which led to it being redone).

The second issue I have is with page context. Often times in standalone web applications, I have created pages which take query string parameters. These can be referenced by external apps or pages, and used to link between pages of an app. Tapestry's equivalent is the page context, which can be used to pass contextual data between pages. There are two problems that I've encountered with page context. First, it is limited in what data it can represent. It is generally just a list of nameless parameters. This makes it difficult to pass only certain parameters or parameters with names. Second, the format for the URL is not a part of the spec (correct me if I'm wrong), so it can only reliably be used via other Tapestry pages. This makes it difficult to pass data in to a Tapestry page from an external place.

So to sum it up, I'd like to reiterate that I really do like Tapestry 5 and hope for its widespread adoption, but it has a few points that are difficult to deal with. If these issues were addressed in a future version, I think it would help ease a new developer's adoption of the framework.

Image submit in Tapestry 5.1

This just took me a really long time to figure out, so I'm writing it down. Tapestry 5.1 adds support for submit buttons with an image (I think it was added in 5.1). In any case, you just use the normal tag, but you add an image attribute which is an "asset". I added an Asset property to my page class and used @Inject and @Path to inject the asset. I used that property name in the image attribute, and it didn't work. It turns out, you don't need to declare the asset as a property in your page class. You just specify the path in the image attribute just like you would in the @Path annotation. So, it looks something like this:

<t:submit image="context:images/submit.gif"/>

Much simpler than I was thinking. Sometimes I get really frustrated with these little Tapestry issues...