just some Java guy

Project estimates are hilarious...

2009-12-14T08:31:00.005+10:00

Taken from a publicly available August 2005 newsletter:

In early 2005, the QFRS undertook the development and implementation of the Operations Management System (OMS)...

The implementation of OMS is being staged over three phases with a scheduled completion date of mid 2006.

Despite being in full active development since that newsletter, OMS is currently scheduled for an initial deployment with a cut-down number of features to a small subset of users in March 2010.

Toolin' around with web applications (Part 2)

2009-12-10T07:50:00.003+10:00

The site below describes the technique that I think makes more sense than our current crop of server side web frameworks (at least for building a reasonably-sized modern web application):

Thin Server Architecture

Also google "SOFEA" if this appeals to you.

Australia Post requires the www?

2009-12-07T11:46:00.003+10:00

It has been like this as long as I can remember:

post.com.au <- doesn't resolve
www.post.com.au <- resolves

How could this go unnoticed for so long by such a huge company with such a good (short) domain name?

Toolin' around with web applications

2009-11-25T06:37:00.004+10:00

I'm currently on holidays. My job around the house for yesterday was to replace the hinges on the pool fence that had rusted. According to Laurie Lawrence, pool fences should be auto closing - Kids alive do the five!

Anyway I spent almost two hours on this task over two separate days trying to install the hinges. The problem was, I was trying to use the screws that came with the hinges which were clearly not designed for use with a metal gate.

My toolkit looked like this:
- Wood screws
- Cordless drill
- Drill bits
- Screwdrivers

But I still had a lot of trouble getting these darned screws to go in. So instead I tracked down an extension cord and pulled out a corded drill, thinking that the underpowered cordless drill wasn't do me any favours.

The added power of the corded drill certainly made things faster, but ultimately didn't help me succeed. I would either destroy the threads on the screws or end up drilling a hole that was too big for the screws.

Finally I got hold of some screws designed for metal, and the whole job was done properly in literally less than five minutes.

The lesson that was reinforced to me is that using a whole bunch of good tools doesn't come anywhere near the efficiency of choosing the one correct tool for the job.

I get this feeling when writing web applications too. For a basic Java Enterprise Web App, I typically choose a set of technologies like this:

- A templating language (e.g. Freemarker, Velocity)
- Javascript
- HTML
- A Javascript framework (e.g. jQuery, Prototype)
- Some sort of Widget Library (e.g. jQueryUI, Scriptaculous)
- CSS
- Spring MVC

This list is extremely abbreviated of course, as anyone involved with Java Web Development will know. The entire list of technologies is probably triple or quadruple that length.

But these are the core technologies used to display a web page. What bothers me is that the first FIVE of these end up in one file! I end up using 5 tools to accomplish the single goal of displaying the web page.

This is incredibly difficult to read and understand, especially considering that the technologies are fundamentally different. Some of the code is evaluated on the server side, and some on the client side, some before the page loads and some after the page loads, and yet the code is all mashed up together. Code generating code that generates code that generates code for multiple browsera to interpret.

Even though this approach works, it still feels like I'm trying to use woodscrews in a metal gate.

Server side templating seems like the wrong way to do things. I think we need to focus more on client side development toolkits - RESTful services and some better Javascript and Ajax Tools could completely replace our current web frameworks, but I just don't think the tools exist yet. Maybe the entire MVC model could be pushed down into javascript on the client side. Or maybe we could have some better abstractions or DSLs for browser control beyond HTML and javascript.

Dumb analogies in the news

2009-11-17T12:33:00.002+10:00

This just in:

IBM has created the world's largest business computing "cloud" capable of holding the equivalent of 250 billion iTunes songs.
...
If that amount of information were in the form of text stuffed into four-drawer file cabinets, there would be enough of them to ring the planet, according to IBM.

Are those analogies really useful? Does IBM really think we are impressed by such a nonsensical comparison?

I enjoyed x646d63's take on it:

Storage capacity: 250 billion iTunes songs
Computing capacity: 800M Chimp-Mensa Candidates
Physical size of network: 300,000 slightly above average elephant toes
Electric consumption: 3.6M 60Hz gerbil wheels

It's funny cause it's true

2009-11-02T17:05:00.002+10:00

“The problem with object-oriented languages is they’ve got all this implicit environment that they carry around with them. You wanted a banana but what you got was a gorilla holding the banana and the entire jungle.”—Joe Armstrong

Dependency Injection Makes Your Code Worse

2009-10-26T11:18:00.001+10:00

Read my article which explains why, and feel free to comment:

http://java.dzone.com/articles/dependency-injection-makes

understanding monads - thanks to jQuery

2009-10-11T14:08:00.005+10:00

In my previous post I wrote about jQuery:

...if you simply wrap the "this" keyword with $(), it magically somehow becomes a jQuery object...

I was taking a short break from watching Bathurst and googling monads again... when I came across this great blog post. It turns out that the magical things I love about jQuery are a monad!

I feel like I'm a little bit closer to understanding monads now, and I'm happy to have a name to describe the magic I was using without knowing what it was.

Go Lowndesy!

jQuery - using "this" in a .each() function

2009-10-07T18:11:00.002+10:00

The "this" keyword can be used in two ways inside a jQuery callback function. If you use "this" in the callback below without putting the $() around it, you will get a reference to the HTML element selected by the $(".currency") class selector.

However, if you simply wrap the "this" keyword with $(), it magically somehow becomes a jQuery object, and you can use all the regular jQuery functions on it like .text() and .val()

$(".currency").each(function() {
   $(this).text(formatCurrency($(this).text()));
});

How to copy a field value from a jQuery UI Dialog into a form

2009-09-25T18:00:00.000+10:00

If you have a form on your page, and would like to display a jQuery dialog which prompts for some extra data to add to the form before you submit it, here's how you can do it:

<SCRIPT language=JavaScript>
    function copyValueAndSubmit() {
        $('#popupDiv').dialog("destroy").appendTo("#myForm");
        $("#myForm").submit();
    }

    $(function() {$('#popupDiv').dialog({autoOpen: false});});
</SCRIPT>

<form id="myForm" name="myForm">
    <input id="field1"/>
    <input id="field2"/>
    <button type="button" onclick="$('#popupDiv').dialog('open');">Save</button>
</form>

<div style="visibility:hidden;">
    <div id="popupDiv">
        <input id="field3"/>
        <button type="button" onclick="copyValueAndSubmit();">Submit</button>
    </div>
</div>

Basically, the

.dialog("destroy").appendTo("#myForm")

call allows you to grab whatever was in the popup dialog and append it to the form on your page before it gets submitted.

No wonder Apple is concerned about Google's iPhone apps

2009-09-25T12:18:00.001+10:00

I just got my replacement iPhone and it seemed to vibrate randomly. I thought maybe there was a problem with it - but it turns out Google has just enabled push email!

I am extremely impressed with Google. Push Gmail is free and awesome, their calendar support and integration with the iPhone is awesome (including multiple calendars), and it all works with Google Apps for your own Domain as well.

I think Google just killed MobileMe.

How to determine the type of Request with Spring MVC's @InitBinder

2009-09-17T17:54:00.004+10:00

If you want to determine the request method of a request (i.e."POST", "GET" etc) in Spring MVC, using a SimpleFormController you could just call isFormSubmission(). When using annotations, the @RequestMapping annotation gives you that functionality for free in the annotation parameters.

If you want to achieve the same thing on a method annotated with @InitBinder, the same does not apply. However, you can simply do this:


@InitBinder
public void initBinder(HttpServletRequest request) {
    if ("POST".equals(request.getMethod()){
        //Do something
    }
}

Why would you want to know the type of request in an @InitBinder method? Stay tuned to find out one pretty cool application.

Hibernate's "DELETE_ORPHAN" and a DataIntegrityViolationException

2009-09-16T18:13:00.003+10:00

Suppose you have DELETE_ORPHAN set on a parent child relationship like this:

class Parent {
    private List<Child> children = new ArrayList<Child>();

    @OneToMany(cascade = CascadeType.ALL)
    @Cascade({org.hibernate.annotations.CascadeType.DELETE_ORPHAN})
    @JoinColumn(name = "ID", nullable = false)
    @IndexColumn(name = "INDEX")
    public List<BulkAmendmentCashflow> getBulkAmendmentCashflows() {
        return bulkAmendmentCashflows;
    }
    ...
}

If your friendly Database Administrator (DBA) has set a unique database constraint on the "ID" and "INDEX" columns of your Oracle database, then under certain conditions you will get this sort of error:

org.springframework.dao.DataIntegrityViolationException:
...
Caused by: java.sql.BatchUpdateException: ORA-00001: unique constraint (DB_NAME.UNIQUE_CONSTRAINT_NAME) violated

It usually occurs when you are both adding a new child and deleting an old child in the same transaction.

I haven't fully investigated the cause of this in detail, but it seems likely to me that Hibernate is adding the new row before it deletes the old row. The new row gets the same INDEX as the row being deleted, so that the INDEX is kept in numeric order. Even though the transaction hasn't been completed, Oracle registers this as a violation of the constraint.

There is an easy fix which keeps everyone happy (and the DBA can still keep their precious constraint!).

The DBA needs to enable deferred constraints in Oracle on the constraint like this:


alter table TABLE_NAME drop constraint CONSTRAINT_NAME;
alter table TABLE_NAME add constraint CONSTRAINT_NAME UNIQUE (ID, INDEX) DEFERRABLE INITIALLY DEFERRED;

Will it float? (iPhone 3GS edition)

2009-09-14T18:26:00.003+10:00

The Hi-Ho girls say: No.

If your iPhone ends up in a swimming pool somehow like mine did, I recommend getting a vacuum cleaner onto it immediately. Pop out the sim card and suck from both ends - this is the best way to get the water out quickly.

Do not use a hair dryer, it will simply push the water into places it shouldn't go, and evaporate the water, leaving behind all kinds of nasty residue.

After you have vacuumed for about 15 minutes, get some silica gel packets (or kitty litter that contains silica) and put the phone in a zip-lock bag with them for two days. You can recharge silica gel packets by putting them into the oven for 30 minutes at 105 degrees Celsius.

If it still doesn't work, don't call your home and contents insurer yet. Water damage is not covered under warranty, but Apple offers something called an "Out of warranty service" for $268.95 which might be a better option.

As long as your phone hasn't been smashed into a million pieces or jailbroken into oblivion, they will fix it or replace it, even if your phone has been in the water.

To summarise the most important point - if your phone goes in the water, use a Vacuum Cleaner!

Should I use BigDecimal or Double?

2009-08-25T18:26:00.003+10:00

Here's something to keep in mind using doubles and BigDecimals. When you do this:

System.out.println(new BigDecimal(0.1));

You get this:

0.1000000000000000055511151231257827021181583404541015625

Pretty weird hey!

The javadoc explains what is going on, but I'll attempt to summarise it.

Basically, The weirdness is not with BigDecimal, it is with double. Doubles cannot accurately represent most decimal fractions.

Why? Because a double by definition is a representation of a number that can be stored in 64 bits of data. If we want to store a number, the only way the computer can remember it is by setting 64 individual bits to either 1 or 0. This is fine for most whole numbers.

However if we want to store a decimal fraction like 0.1 - it simply cannot be done in 64 binary bits of data. Binary land doesn't really know anything about decimal land. It's like an inhabitant of Lineland trying to understand the world of Flatland.

So to save our requested 0.1 double, the computer frantically flips those 64 ones and zeros until it gets something that is as close as possible to 0.1 - which as it turns out is 0.1000000000000000055511151231257827021181583404541015625.

Then, when we use that double in BigDecimal's constructor - BigDecimal does an "exact conversion", and uses the number that is literally represented by those 64 bits.

To summarise, if you care about the precision of your decimal fractions (eg. for storing currency), you should definitely be using BigDecimal. You should only be looking to use double if you know exactly why you need it.

How to automatically reload the page every 5 minutes

2009-08-25T18:23:00.003+10:00

There are a few ways to ensure that a page gets automatically refreshed - this one seems to work the best across multiple browsers.

<SCRIPT language=JavaScript>
    //Refresh screen every 5 minutes.
    setInterval('location.reload();', "300000");
</SCRIPT>

Formatting source code on Blogger

2009-08-18T06:43:00.002+10:00

One would think that being owned by Google now, Blogger would have made SOME improvements. I haven't seen anything yet - and one thing that is sorely missing is the ability to easily format source code.

Here is what I use for now:

http://formatmysourcecode.blogspot.com/

A single form checkbox macro for Freemarker and Spring

2009-08-17T18:38:00.004+10:00

If you want to use Freemarker in your SpringMVC project, Spring comes with a limited amount of macros in the file spring.ftl.

One macro noteworthy for its absence is a macro to display a single checkbox. I've seen various snippets of example code around the web on how to do this, but all of them seemed to be deficient in either error handling or binding. Here's a macro that works!

<#macro formCheckbox path attributes="">
    <@spring.bind path />
    <input type="hidden" name="_${spring.status.expression}" value="false"/>
    <input type="checkbox" id="${spring.status.expression}" name="${spring.status.expression}"
           <#if spring.status.value?? && spring.status.value?string=="true">checked="true"</#if>
    ${attributes}
    <@spring.closeTag/>
</#macro>

How to modify http headers in Internet Explorer

2009-07-12T00:50:00.002+10:00

When developing for the web, you may want to simulate various HTTP Header values for your application. This is easy in Firefox - there are a number of plugins that allow you to do this like Modify Headers.

However for IE6 it is more difficult. The best solution I have found is this one:

- Download Fiddler.
- Open the 'Customize Rules' window (Rules->Customize Rules...)
- find this function: static function OnBeforeRequest(oSession: Session)
- inside this function, add the header values that you would like to add, in this format:


oSession.oRequest["headerName"] = "headerValue";

-save

Voilà! Internet Explorer will now accept your custom header values. You will probably need to clear your browser cookies before it takes effect.

How to enable internet tethering (phone as modem) for iPhone 3GS on Australia's Three network

2009-06-30T07:05:00.003+10:00

Go Here:

http://andrew.harrison.org/notes/3-tethering-and-mms/using-your-iphone-on-3/

Follow the instructions in section 3 - "Enable tethering and MMS".

I've done this and it works beautifully on a Windows machine.

Then:

Pair your iphone with windows in:
Start -> Control Panel -> Bluetooth devices.

Once it has been paired, you can connect to the internet simply by going to:
Start -> Connect to -> Bluetooth network connection

The iphone will appear in here as an access point.

How to update page text using javascript (and prototype)

2009-06-30T06:58:00.003+10:00

$('blah').innerHTML = '${valueToSet}';
<label id="blah"/>

Note: .innerText only works in IE.

And if you want to display end-of-line characters correctly, for example, if the data has been entered using a textfield (using Freemarker and prototype)

$('commentsView').innerHTML = '${closeout.comments!""?js_string}'; 
<label id="commentsView"/>

13" Macbook Pro vs Vaio : Initial Hardware Impressions

2009-06-17T06:46:00.004+10:00

I just took delivery of a 13" Macbook Pro, after being a long time 13" Vaio user. Here are my initial impressions of the hardware, divided into WIN and FAIL Categories. I'll start with fail, because that is the most fun.

FAILZ

High Gloss Screen == FAIL
There's no question - it is too glossy. UQ has issued a health and safety warning for it.

Missing keys == FAIL
No Home, End, Page Up, Page Down and Delete keys? What were they thinking? There's plenty of room to put them in, I guess I'll have to adjust my habits somehow - anyone know what mac users do to make up for these keys?

Sharp wrist rest == FAIL
The front lip of the macbook (when open) is a machined 90 degree angle, and is about as sharp a 90 degree angle as I have ever seen. When I'm lounging on my couch, this is where the heel of my hands rests (and rubs against). Painful! Yeah apple it makes the laptop look cool when it is closed, but this is one sacrifice of form over function that you shouldn't have taken.

Click anywhere trackpad == FAIL
I'm pretty sure I read somewhere that you can click anywhere on the oversized trackpad. Well you can't - you can click in about the bottom third of the trackpad, any higher than that the clicking action progressively diminishes into no click at all.

Glowing Apple Logo == FAIL
This is something I'd like to turn off. I don't consider myself an apple fanboy, and having that glowing apple log on the bus is embarrassing,

WINZ

Backlit Keyboard == WIN
It is very well designed, has nice keys and the backlighting is great at night. I still think they could have made the keys bigger though - my old Vaio managed to have full size keys with the same overall width.

Stylish == WIN
It's a beautiful machine, the aluminium and glass just looks superb. What amazed me is that when you turn it over - the bottom is just flat aluminium. They've managed to hide all the ugly bits very well.

External Buttons, Lights, Plugs == WIN
Superbly designed - hidden notification lights, a built in battery indicator on the side and the thing feels REALLY solid. It makes a precision 'thunk' when you close it like nothing I've ever heard.

Oversize trackpad == WIN
Nice and sensitive - almost as good as a Vaio. My tap to click occasionally doesn't register, but perhaps I just need to adjust my tap a little bit. The large size of the trackpad is brilliant too - why doesn't everyone make them this size?

Low Weight == WIN
It feels a LOT lighter than my Vaio - especially when in my back pack.

Sound == WIN
The speakers are hidden somewhere - (in front of the keyboard I think?) and they are excellent. The sound is stereo, it goes loud, and it is directed towards me, which the Vaio was notoriously lacking in.

Maven jetty plugin can't find applicationContext.xml?

2009-06-05T19:01:00.001+10:00

If you get this error, in your web.xml you need to be explicit about the location of your applicationContext.xml (even if you have a Spring ContextLoaderListener defined).

<context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:applicationContext.xml</param-value>
 </context-param>

I would have thought that being a maven-jetty-plugin it would know where to look, but apparently it is too stoopid.

How not to inspire your team to achieve greatness

2009-05-29T17:23:00.001+10:00

Today the data team leader sent out an email to the entire IT team that was only two paragraphs long, and yet managed to cram in all of the following phrases:

"governance imperative"
"business initiative"
"management-driven"
"critical success factor"
"proactively"
"process and control"
"integrated, consolidated, improved"
"cross functional"
"fuels that power the modern corporation"
"mired in the prenatal lifecycle"
"need for effective collaboration"
"support mechanism for initiatives"
"effective collaborative structure for data-intense business initiatives"

In the words of Lisa Simpson: "Excuse me, but aren't these just buzzwords that dumb people use to sound smart?"

Maven, Quartz and Spring 2.x

2009-05-27T18:13:00.002+10:00

If you have tried to use scheduling in Spring 2.x and you are using Maven - you will probably be having trouble.

In your stacktrace, you might be seeing this:


Caused by: java.lang.NoClassDefFoundError: org/quartz/ObjectAlreadyExistsException
    at java.lang.Class.getDeclaredConstructors0(Native Method)

or this:


Caused by: java.lang.NoSuchMethodError: org.apache.commons.collections.SetUtils.orderedSet(Ljava/util/Set;)Ljava/util/Set;
    at org.quartz.JobDetail.(JobDetail.java:85)

It seems that the good folks over at OpenSymphony (makers of Quartz) couldn't care less about Maven (I don't blame them) and making sure their pom.xml is correct (which it isn't).

And Spring, which uses Quartz for scheduling, doesn't seem too concerned either about making sure that their pom.xml has the correct dependencies for Quartz (which it doesn't).

The short of it is, if you want everything to just work, you'll need to explicitly include these two dependencies in your pom.xml:

        <dependency>
            <groupid>opensymphony</groupid>
            <artifactid>quartz-all</artifactid>
            <version>1.6.1</version>
        </dependency>
        <dependency>
            <groupid>commons-collections</groupid>
            <artifactid>commons-collections</artifactid>
            <version>3.2</version>
        </dependency>

And so, if you are in the unfortunate position of having to use Maven, I empathise. Let us weep together.