Development | Ronan's Blog

Random thoughts of an Irish Software Architect in the GIS Industry.

Retrotranslator - Convert Java5/6 Classes to 1.4

Posted in Development, Java, Web by Ro on the January 5th, 2010

Retrotranslator is a tool that makes Java applications compatible with Java 1.4, Java 1.3 and other environments. It supports all Java 5.0 language features and a significant part of the Java 5.0 API on both J2SE 1.4 and J2SE 1.3. In other Java environments only the Java 5.0 features that don’t depend on the new API are supported.

Could prove very handy !

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Spatial Sorting of Data based on location

Posted in Development, GIS by Ro on the September 17th, 2009

Very handy tip today on how to drastically improve seek times in results for spatial queries, by physically re-ordering the rows of data to be contiguous on disk.

VERY HANDY.
SpatialDB Advisor: Spatial Sorting of Data via Morton Key

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LinkedHashMap is Actually Quite Useful

Posted in Development, Java by Ro on the September 11th, 2009

After reading this article, I’ve done a little code reviewing …. Great Class !
[JavaSpecialists 073] - LinkedHashMap is Actually Quite Useful

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How to run Multiple Instances of Firefox

Posted in Development, Cool Stuff, Web by Ro on the August 13th, 2009

Found this instructions for how to run your regular Firefox install as well as a portable version at the same time.

Awesome!
Tip - Run Multiple Instances of Firefox Portable | Pro Reviewer (My Free Review)

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Fastest Java GIF Encoder on the Net

Posted in Development by Ro on the January 28th, 2009

I’ve been doing a little research into speeds of Image encoding to improve performance in our Map Rendering. My research has let me to two encoder’s:

1) Free - http://www.fmsware.com/stuff/gif.html
2) Commercial - http://www.gif4j.com/java-gif-imaging-gif4j-pro-library.htm
Here are the average encoding times for 1000 iterations on both the encoders:

FREE: 750
COMM: 1438

FREE: 828
COMM: 1109

FREE: 831
COMM: 1266

So interestingly, being free is not always better !

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Google Release Static Maps API - Why?

Posted in Development, GIS, Web by Ro on the February 22nd, 2008

Google have today released a static Map API, for generating simple single image, non-interactive map images.

What are the benefits of this API?
To Google -> Decreased Bandwidth and processing, if static maps will suffice (for example a location map on a business webpage), then a single request on their data will be enough, rather than placing a map with panning & zooming capabilities on it.
To the User -> A single image map can be copied & pasted into e-mails & documents more easily for your average user, so that they don’t need an image editing tool.
So why do they feel this completely new API is required?
A slightly different operating mode (i.e. Single Image Mode) in the existing API with a simple set of instructions would surely be enough.
Google Static Maps API

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Lightning Fast Web Editing of Spatial Data with Firefox 3

Posted in Development by Ro on the January 29th, 2008

We’ve been doing a huge amount of JavaScript-Centric Online spatial data editing recently and so any browser comparison that compares JavaScript performance is always of interest.

So, I saw this link yesterday and gave it a read, which was extremely interesting reading - It seems to indicate that Firefox 3 runs JavaScript ten times faster than IE7!
Firefox 3 Performance Gets a Boost
1) Firefox 3 Nightly (PGO Optimized): 7263.8ms
2) Firefox 3 Nightly (02/25/2008 build): 8219.4ms
3) Opera 9.5.9807 Beta: 10824.0ms
4) Firefox 3 Beta 3: 16080.6ms
5) Safari 3.0.4 Beta: 18012.6ms
6) Firefox 2.0.0.12: 29376.4ms
7) Internet Explorer 7: 72375.0ms

So, naturally after seeing this I downloaded a copy of Firefox 3 (Beta 3), but I downloaded the Portable Version so that I could run it without uninstalling Firefox 2. When I then ran it I was truly amazed at the performance of JavaScript. We have major intensive code for performing vertex editing and point snapping, which ran amazingly quickly on Firefox 3 and had no issues with scalability compared to Firefox 2. I’m looking forward to the official release now.

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Using Regular Expressions (Getting a MAC Address using Java)

Posted in Development by Ro on the January 22nd, 2008

Today I read an Article about the use of Regular Expressions.
It could be boiled down to saying: “Regular Expression are cool & useful, but be careful and use sparingly“.
This made me wonder about Regular Expressions in my own code, and sure enough one popped to mind.
I wrote some regular expression code to anaylse String to see if they contain MAC Addresses in Java.
(Still useful code for those that have not yet moved to Java 6).

The difficult in recognising MAC addresses is that on different Operating Systems they are represented differently, with either a : or a - character in between each tuple or sometimes only having one HEX character in one or both of the first two tuples.

So, to avoiding writing complex code for each possible eventuality, this is the perfect opportunity to use Regular Expressions. At the core of this example is the following pattern:

Pattern macPattern = Pattern.compile( “(([0-9a-fA-F]){1,2}[-:]){5}([0-9a-fA-F]){1,2}” );

This pattern allows for 5 occurances of 1 or 2 HEX Characters followed by a : or - character then another occurance of 1 or 2 HEX Characters.

Once this is in place, the rest of the Java code is simply to read in the text containing the MAC address (either from file or via a Runtime Process) and look for instances of the MAC Address pattern in the line:
String[] macs = macPattern.split( theLine );

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JavaScript & Memory Leaks

Posted in Development by Ro on the January 21st, 2008

I find it extremely strange that the issue of JavaScript Memory leaks is not more widely addressed.
Frequently when looking at JavaScript libraries, even the big popular onces in some cases, I regularly come across these leaks. Now admittedly we may use JavaScript much more intensely than most others, as replacing a conventional desktop GIS tool, features geometry editing with all its bells and whistles requires a lot of processing, so maybe the code we are producing is highlighting these Memory leaks more than others normally would find.

Basically a Memory leak occurs when you access something from the document like so:
var sel = document.getElementById(”select”);
use the variable in some manner then return from the function.
Also, if sel is passed to another function then before that function has completed, ITS reference to sel must be also nullified.
To avoid the leak the sel variable needs to be set to null so that it gets removed.
I regularly use Drip to find such leaks and its a great bit of kit that anyone developing for the web should be using.

Its all a little bit annoying that these considerations need to be made when programming JavaScript, and most seem to largly ignore these memory Leaks; perhaps hoping that browsers will clean up after them. One other feature of JavaScript I’ve come across in the last week is the delete keyword, where variables can be deleted and not just their reference set to null. I’ve yet to experiemnt with this as it seems like its use could be a little dangerous.

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How to write out XML (Application.xml) using an Ant Task

Posted in Development, Web by Ro on the September 18th, 2007

Linked here ...  build.xml example

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Categories

Retrotranslator - Convert Java5/6 Classes to 1.4

Spatial Sorting of Data based on location

LinkedHashMap is Actually Quite Useful

How to run Multiple Instances of Firefox

Fastest Java GIF Encoder on the Net

Google Release Static Maps API - Why?

Lightning Fast Web Editing of Spatial Data with Firefox 3

Using Regular Expressions (Getting a MAC Address using Java)

JavaScript & Memory Leaks

How to write out XML (Application.xml) using an Ant Task