Devel Hell

A Note on Downloading Images to a Java Client via HTTP requests

2008-07-10T12:03:00.000-07:00

I've been working on a little Java client to grab some internet data and process it into a nice little picture. In order to do this, I needed to be able to download pictures from an HTTP request into a BufferedImage. When initially trying to find a way to do this, Google only gave me worthless pages about using the URLConnection.getContent() method, or saving to a file and loading that file,

Documentation Time

2007-03-09T12:43:00.000-08:00

I'm struggling with making my first draft to be as high-quality as I would like it, especially with my time limitations before and during break. However, getting comments on what I have right now will be very good for future writing as well. I'm currently running performance tests on the system. My current test case is a long one. It is for 3 dimensions, and runs over 25 requests for each of

Success?

2007-02-22T22:44:00.000-08:00

I had been having a hang up with my lazy writing to the cache, which was a major problem for me. By changing my CacheManagerBean to stateless instead of stateful, I was able to keep the bean around long enough to have a thread run through my queue of requested cache orders. This will most likely be a speed boost, since the stateful wasn't getting me much, anyway. I've been running my

Annotations are the Problem

2007-01-11T05:35:00.000-08:00

I've been trying to work out how I can insert large data sets into SQL through Hibernate without requiring my data sets to fit an interface that splits when too large (the overhead of exception handling would be too much, anyway). It would be best if I could just designate my value with extra parameters in the @Lob annotation. However, the annotation has no such properties, even though the XML

It's Been a While

2007-01-09T23:38:00.000-08:00

I haven't posted in a while, but here's a good post of frustration! I have been working on my thesis project, but have and issue with my Blobs... The default type of blob used by Hibernate is too small for my data. So, I need to find a way to make it create a column of type LONGBLOB, or at least MEDIUMBLOB, but it makes me sad. This one issue is (hopefully) all that stands between me and good

Single Request Test Suite

2006-08-08T14:09:00.000-07:00

Today, I created a new test program that I have programmed to make HTTP requests and time the important results. Now, I can list a few parameters and run several tests over all three types to see how long it takes to request a region with a certain volume, number of cache hits, and percentage hit. The framework is there to work, but for some reason I'm getting exceptions on the server. I'll

Creating Test Suites

2006-07-18T09:18:00.000-07:00

My current task is creating a plan for the performance testing. One thing I know I'll need is a way to generate test cases. My plan is to make servlets that create certain types of test cases dependent on a certain set of parameters. Right now, I'm making the test case for creating a set of regions (of a defined number) that intersect a region with a certain hit percentage. This will be used

Singleton

2006-07-14T15:33:00.000-07:00

I went ahead and made the EntityManagerFactory for the LazyWriter a singleton. This caused me to pull the LazyWriter out of the CacheManagerBean and into a top-level class. That is probably a good move, anyway. Now, the hassle of loading the properties only needs to happen once per run of the server.

Sometimes the Cutting Edge Hurts

2006-07-14T15:11:00.000-07:00

I got lazy writing to work today. The reason I didn't get it to work before was that I got frustrated with the meaningless error messages that I got while working with Hibernate. It turns out that I was getting an error because an exception that was trying to be thrown couldn't be found. Hibernate didn't include a necessary library with their deployment. So, I got the latest stable version of

Some First Results

2006-07-14T09:39:00.000-07:00

Here is a screenshot of some performance testing on my cache. This is using active database writes, over 50 requests randomly selected from 5 different, intersecting regions. I am using a high multiple and high request volume, but not even close to the timing standards of a NADSS map.

So I Celebrated Early...

2006-07-12T13:09:00.000-07:00

I guess I forgot to test lazy writes. It seems that my EntityManager loses it's persistence context when my Statefule Session Bean is removed partially through the process. Perhaps calling it the unmanaged way could do the trick.

It works!

2006-07-12T12:44:00.000-07:00

After many sad hours of debugging my persistence model, I now have a working n-dimensional spatial cache! Finally, results can now be found. I need to put together a performance testing suite, and quickly. Here are a few of the variables I can define: No Cache vs. Active Write vs. Lazy WriteFor any test, it should be run three ways: without a cache at all, with active writing (wait for

A Different Direction

2006-07-05T14:16:00.000-07:00

I spent some time today thinking of a different way to approach the partitioning problem. Instead of finding a minimal chord sequence (which gets really complicated and involves non-convex pivots and chords) I should think of maximal convex regions. Expand regions in every direction from every unit block of the null space. This is similar to the approach I had last summer, but instead of

Past the Biggest Bugs

2006-06-29T13:55:00.000-07:00

Now that I have fixed all current crashes, it is time to nit pick and find things wrong with my implementation. I need to set up a programmatic test suite, runnable by servlet, that tests the following things: Caching completed data. Loading cached information. Combining data items after computing and caching. There will be more on the way, but I need to get this suite set up and

Past the Biggest Bugs

2006-06-29T13:54:00.000-07:00

And Now to More Important Issues

2006-06-29T10:33:00.000-07:00

This morning, I fixed all of the immediate errors with persistence. Apparently, using Object as a BLOB column generates a ClassCastException if you don't have exactly and Object there, but if you use Serializable as your member type then any serializable object can be put in there. Now my biggest issue is figuring out how to call the cacheable method multiple times. I was thinking that I could

It's in the Details

2006-06-28T14:29:00.000-07:00

Sometimes I can really ignore the simplest of details when in a hurry. I wasn't paying attention to which properties I added to my persistence.xml file and was using the wrong dialect for Hibernate and I needed just "update" as the auto property. That's why my tables were not being created. After swapping the values with the proper ones easily seen in another file it worked properly.

Some Notes on Debugging

2006-06-28T12:24:00.000-07:00

I have the web project up and linked with the EAR and I'm tracking problems with my implementation. Here are a few things that have gone wrong so far. Some are fixed. Fixed: Cached annotation did not exist at runtime.Apparently, annotations only exist at compile time by default. An extra annotation must be added to the @interface definition: @Retention(RetentionPolicy.RUNTIME).Fixed:

Web Project Built

2006-06-27T08:49:00.000-07:00

I got a web project built today. I used my laptop with the Eclipse Web Tools plugin (doesn't work on intel macs until Friday) to create the project directories and an initial web.xml. From that, I copied it into my Eclipse 3.2 framework and customized the build.xml plugin from Orangepeel. I have a loose grasp of the directory structure now, and what all the xml configuration files do. Now, I

Entity Tests Pass

2006-06-26T12:21:00.000-07:00

The RTreeEntity structure now passes all POJO test cases. Now, I need to set up the persisting and proplerly create, persist, and remove the data. This will be a challenge as well. I may need to recursively persist the nodes. Also, I'll need to synchronize the tree between deletes and inserts, because that could cause all sorts of problems with the tree. Cached data may not always be

Persisting Trees

2006-06-26T09:44:00.000-07:00

I'm not sure if it is a good idea to jump into spatial query trees in my first attempt at using persistence, but that's what I'm working on. I need to finish rewriting my R-Tree, which wouldn't be that hard if I didn't need to use Collections instead of arrays. Now, the conversion requires more thought. After I test it in POJO form, I'll need to find a way to test it as it persists. The

The Solution?

2006-06-21T12:48:00.000-07:00

I've developed an interface to help me with this dilemma I have. The immediate benefit is that I never have to rewrite a method header, and I never have to rewrite the cache. However, there will need to be a new object written that implements the CacheHelper interface for almost every new method (unless they become very similar). Here are the three methods that are required: public IRegion

A Question of Parameters

2006-06-21T10:23:00.000-07:00

I've thought about how to handle the dimension parameters in detail, but haven't quite decided. There are several concerns that I have for this crucial section of my research. First, I need to be able to get numerical limits on the spatial query. I need a low and a high point for each defined dimension. If the method signature contains a list of integers or floats listed "lowX, highX, lowY

Bug Fixed with the Power of Testing

2006-06-20T12:41:00.000-07:00

I seem to have fixed the deletion bug. It passes my random test for dimensions 1,2,3,4,5, and 10 after several executions. It used to fail every run, so hopefully it isn't just hiding. I made my tests using TestNG, a relatively new framework for testing in Java.

RTree Delays

2006-06-20T10:40:00.000-07:00

My RTree implementation has a bug during deletion. When I delete a node, it sometimes doesn't adjust the above nodes properly, so searching for nodes later causes a problem because the parent nodes no longer contain their children.