Show the world how a stack works using wicket.

A stack is a basic structure in the world of computer science. We learn stack implementation early and it pops up (no pun intended) again and again over the years. For the uninitiated, I've created a web application to demonstrate the basics of what a stack does. Implemented using Java and Wicket I present stack-wicket-aricwest. You can download the stack-wicket-aricwest.jar file from the featured downloads. Assuming you have Java 1.6 installed, open a terminal and navigate to the directory you downloaded the jar file too and enter "java -jar stack-wicket-aricwest.jar". This will start the Jetty server. Then open up your favorite browser and navigate to "http://localhost:703/stack-wicket-aricwest/" to begin playing with the stack. You will be able to push (non-empty) strings on to the stack and pop items off the (non-empty) stack. You can also clear the whole stack. A table shows the current contents of the stack.

Challenges

Though a simple application in theory, the challenges of learning a new tool, Wicket, and integrating example and base code into my distribution proved to be a hefty undertaking. All together I probably spent 12-15 hours hacking, debugging, researching, and optimizing. A bit more than expected, but a very rewarding experience. Of course I didn't make it easy on myself: the first thing I did when starting was reconfigure Eclipse to complain about just about every warning possible. This definitely helped me with my code most of the time, though there were a few warnings than I decided to ignore during this project, and some that I turned back off as I felt they did not really apply to my coding standards. Following are some of the challenges I encountered.

Classpath variables: We've gotten a lot of experience with this lately so I only encountered minor problems while getting these set up. Luckily I get a lot of practice because I generally work on two different machines over the course of a project.

PMD hates me: Useful as it is, I was particularly perplexed not by why I was getting warnings, but why the example wicket projects, some of which had the EXACT same code, did not get warnings. I wasn't able to quite figure this out from the pmd build materials, but they are cause for some concern on my part. Specifically in my StackSession where my stack is declared final since I do not actually modify it in that class. But an unmodifiable stack spooks me a bit and I need to figure out the process that allows this to be okay, since my webapp appears to work, or how to deal with this warning like the examples have. Similarly, PMD demands that my Jetty class be made final with a private constructor, which sounds fine... but why does Start.java in my WicketExample04 not get flagged. I'm not sure.

Only one submit per FormTester: This was a bit of a stalling point for me but looking through Google and Wicket in Action revealed that a FormTester is only allowed a single submit. Then it has to be remade. Kind of a pain, but copy-paste isn't hard.

Pick a port, any port: No not that one, it's being used. I definitely need to have a better method for port designation. It also wouldn't hurt, I don't think, for me to be able to specify the port at the command line, which should be a simple fix if needed.

Serialization: Quite simply, I need to review this concept and get a better understanding of why and where it needs to be used, but I was able to get by using examples.

Inner classes: For the most part did not have too much trouble with inner classes, though got caught a couple times by the issue of simply what it does and does not have access to.

Sessions: I'm still a bit fuzzy on these, and whether my application is properly using them. I was able to get separate stacks going using different browsers at the same time, but not with different tabs in the same browser, so not entirely sure if I'm hitting this requirement properly.

Build files: The build files that were cobbled together from various projects had some important differences. My build.xml contained it's own jar target which caused some unexpected results during distribution building. I also changed jar.build.xml to meet the requirements of being able to create the jar file and immediately run it in the same directory. The jar.build.xml actually puts the jar file both in the usual build directory, as well as the base directory. dist.build.xml also cleans up after running jar so that the jar is not including in the distribution.

Cannot pop an empty issues stack

Actually I'm sure there were others too! In any case, these, and dozens of little Wicket bits of learning added up to quite a chunk of time, but a lot of good experience with these tools. Overall, I'm impressed with making a working webapp, but part of me looks at this and thinks web programming can't really be that inefficient, is it?! For example (I think) the stack table gets completely rebuilt each time it changes. Also, it feels a bit dirty having basically my whole program in the StackPage constructor! I was very happy with my testing though. While some was reactionary, I am continuing to make the effort to do test driven design and coding, as I really see how useful it can be in the brief glimmers hiding behind old habits. I also continued to think about version control and continuous integration by creating a repository and diligently trying to always verify (I think I'm addicted to "Build successful") commits and submitting them often.