Month: August 2009

Categories
Business

ZaFin Genesis

ZaFin is the finally born with the first feature arrived: PAYE. (Hey. It’s a start and a natural one at that given it’s history). Now, ZaFin is a long-term project and has been a goal to get going for a long time now. Essentially, it’s the place to post tools which help you reach numbers you need to make informed decisions for yourselves. Given the state of the world economics at the moment, give me one good reason why would I want to get financial advice from “the system”? It’s track record speaks for itself. Neh. Have the courage to think for yourself, right?

So ZaFin is supposed to be that kind of place. A spot where you can, armed with a bunch of quick little nifty calculators, reach and juggle numbers to come up with a reasonable conclusion. You don’t need an advisor for that. I believe, armed with the right information (ie. numbers) most reasonable folk can come make up their own minds. And make pretty good decisions on their own too (and maybe also check in with an honest friend to bounce some ideas off).

There will be more to come, slowly, over time, as time allows; baby steps. Hope you find the first tool useful, and more importantly, simple to use and to the point giving all you need, and only what you need.

Categories
Technology

Invalid State Crashes Client?

It’s the infamous view state again. My my my. I knew there were reasons I really didn’t dig the complexity ASP.NET were trying to cover up. This time though, my sense of amazement reached new heights when the client browser crashed (yip-crashed) because the server picked up some dodgy view state. Read that again. Carefully.
Oh. And you probably might have already guessed which browser does the crashing. No prizes for getting it right, sorry. The correct and predictable, even appropriate response is: “The view state is invalid for this page and might be corrupted” which is what all the other browsers I’ve tested on so far show. On with the experiment…

We’ll start off with a simple ASPX page. Nothing complicated.

<html>
	<script language="C#" runat="server">
  public void Page_Load(Object sender, EventArgs E)
  {
  }

  public void Submit_Click(Object sender, EventArgs E)
  {
  }
	</script>
	<body>
		<form id="Form1" runat="server">
			<asp:Button ID="Submit" OnClick="Submit_Click" Text="Submit" Runat="server"></asp:Button>
		</form>
	</body>
</html>

Click on the button and woohoo- no surprises. But now we add a little extra something. We modify the contents of the page after it’s loaded. Nothing special here either really. Standard AJAX behaviour.

<asp:Button ID="Submit" OnClick="Submit_Click" Text="Submit" Runat="server"></asp:Button>
<div id="dynamic_content"></div>
<script type="text/javascript">
//<![CDATA[
  window.onload = get_dynamic_content;
  function get_dynamic_content() {
    //....
  }
//]]>
</script>

The JavaScript function get_dynamic_content() will make a request and then proceed to populate the div dynamic_content with some more HTML. The obvious solution is to do something along the lines of:

function get_dynamic_content() {
  document.getElementById('dynamic_content').innerHTML = '...some html...';
}

Incidentally, therein lies another rub in that div.innerHTML behaves differently for IE. Take a peek for yourself. And within all those comments, of this article, there lies a hack solution. You can read more about that debate there. Moving along.

So having hacked the little piece of innerHTML magic, you start populating your element with all sorts of dynamic content. Wonderful. Then during a series of development efforts, you get a buggy piece of HTML tagging along for the ride. A second form element- don’t worry, not a server-side form. More about why and why not here if you not too sure about how that fits into the scheme of things. Anyway, so you get an erroneous piece of HTML coming through- a valid bug in the development effort- and your second form contains an extra view state element. By now, you’ve also probably deciphered the design and architecture of this piece of handy work.

And i’ll recount here- this may be a valid bug, but it’s not about the bug. It’s the way the client browser handles a server-side bug.

So let’s assume that part of the payload (simplified) includes the following:

<form>
...
<input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="/wEWAgL9hvuOBAK8w4S2BGRm0HOf1YSq2O4B5nwrlp8eUNwR" />
...
</form>

You click on Submit. Is this what you would be expecting?

Familiar Browser Crash
Familiar Browser Crash

It’s not even bad HTML. In fact, if the dynamic payload didn’t include the extra form element, just the viewstate ala

<input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="/wEWAgL9hvuOBAK8w4S2BGRm0HOf1YSq2O4B5nwrlp8eUNwR" />

You get the reasonable and correct behaviour. ASP.NET complains about the view state being fudged. Good. But wrap that extra view state input element in a form tag and IE client blows up. WTF? Incidentally, the form wrapper is arguably more correct.

Here’s the full code for your enjoyment. Modify the content variable and element type of dynamic_content and test across all your browsers.

<html>
	<script language="C#" runat="server">
  public void Page_Load(Object sender, EventArgs E)
  {
  }

  public void Submit_Click(Object sender, EventArgs E)
  {
  }
	</script>
	<body>
		<form id="Form1" runat="server">
			<asp:Button ID="Submit" OnClick="Submit_Click" Text="Submit" Runat="server"></asp:Button>
			<div id="dynamic_content"></div>
      <script type="text/javascript">
      //<![CDATA[
        window.onload = get_dynamic_content;
        function get_dynamic_content() {
          var content = '<form><input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="/wEWAgL9hvuOBAK8w4S2BGRm0HOf1YSq2O4B5nwrlp8eUNwR" /></form>';
          //document.getElementById('dynamic_content').innerHTML = content;
          swap_content_div(document.getElementById('dynamic_content'), content);
        } 
        function swap_content_div(old_div, content) {
          someHtml = content;
          var newDiv = document.createElement(old_div.tagName);
          newDiv.id = old_div.id;
          newDiv.className = old_div.className;
          newDiv.innerHTML = someHtml;
          old_div.parentNode.replaceChild(newDiv, old_div);
        }
      //]]>
      </script>
		</form>
	</body>
</html>
Categories
Technology

HOWTO Do Software

The expression “software is hard” (a quote from Donald Knuth if I’m not mistaken) has seen a lot of mileage (yours truly contributing my fair share) over the years because of it’s simple truth. And in that, we’ve all searched and found (or not) some or other holy grail of methodology. And then the methodology wars began…

And with each new spin, a new skirmish emerged on the radar. Even some of the the tool-chain manufacturers got involved, either creating their own style or methodology (i suspect largely to suit their product rather than the process) or adopting their product to try and encompass the latest and greatest in fashionable methodology. Much ado.

Now software is both art and science. And as such, you need a healthy dose of both to get it right. The art demands your imagination and creative skills; the application of your emotional quotient and your ability to think beyond the four-sided. The science demands much the same plus discipline. Art, too, demands discipline (find me a great writer, painter, cartoonist, graffiti-artist, musician who did NOT practise and hone his/her ability each and every day- for hours each day). Art and science are much the same. Discipline is but one of the common threads.

Discipline to sit down each and every day, for hours, and get it right- get it perfect. That doesn’t mean just hours of random throwing paint at the canvas or the random plucking of guitar strings (which is my forte, by the by). And what about the scientist? Does she spend hours each day in the laboratory throwing random chemicals together into a test-tube to see what might happen? Maybe once in a while, that kind of activity is fun- but not a primary activity.

No. They all set themselves down each day, both scientist and artist, and constructively engage their brains, and think for themselves about what they are actually doing- or going to do. They know before the experiment or song or painting is completed- what to more or less expect. Sometimes it doesn’t turn out that way- and the results are either surprising or horrendous. Sound familiar? But by and large, it’s predictable- and it should be. Software is no different.

How you get there, and which methodology you use is largely irrelevant (i say largely, but you need to read the legal copy disclaimers in fine print carefully); as long as you have discipline. Following a set pattern so often that it becomes part of your autonomic nervous system is key. There’s good reason to do it, especially when you add in the one thing that distinguishes software: deadlines. Although, I am sure that in this day and age, professional artists and scientists suffer the same. Deadlines make the job more interesting- and the need for discipline even more critical.

A brief observation of any professional field where life and death are important will reveal the stand-out-in-your-face notion of REPEAT. In fact, it’s the only way we actually ever learn anything. You repeat the excercise over and over again (ad nauseum some might say) until you get it right blindfold. Why? Because when there’s a deadline, you go blind. And the more impossible the deadline, the more blind you become. You don’t have time to think- just time to do. And you need to make sure you are STILL doing it perfectly.

So, HOWTO Do Software. Pick a way. Find a way. Develop a style and method of delivery that embodies rational scientific reason to justify the “why” you do it that way. Don’t do something or end up doing something “just because it’s the way we do it” and not have a valid reason and purpose behind the behaviour (and I’m afraid if you don’t even recognise that, your opinionated delivery is just going to be that- opinionated). Add in your own artistic flair- but above all- be disciplined about it. Not just off beat, whacky, eccentric, random or out there. Notice i said “just”. Which means you can still be off beat, whacky, eccentric, random or out there- just be disciplined about it. Oh- and write quality tests 😉