Unhandled Exception

The song of the Free

2005-10-29T23:56:00.000-07:00

'Freedom' - the word does not have any meaning until and unless stated as Freedom from something.

This 'something' is an overloaded term. It might hold the dreams and aspirations of an individual, the collective will of a nation, or just the plain urge to do whatever you want to do.

Why do we have this urge to be free? to be free from what?
Swami vivekananda's 'the song of the free' explores what it really means to be free:

. . .

The beauteous earth, the glorious sun,
The calm sweet moon, the spangled sky,
Causation's laws do make them run;
They live in bonds, in bonds they die.

And mind its mantle dreamy net
Cast o'er them all and holds them fast.
In warp and woof of thought are set,
Earth, hells, and heavens, or worst or best.

Know these are but the outer crust--
All space and time, all effect, cause.
I am beyond all sense, all thoughts,
The witness of the universe.

Not two or many, 'tis but one,
And thus in me all me's I have;
I cannot hate, I cannot shun
Myself from me, I can but love.

From dreams awake, from bonds be free,
Be not afraid. This mystery,
My shadow, cannot frighten me.
Know once for all that I am He.

Source: Vivekananda Vedanta Network

What will you become when you grow up

2005-09-12T02:45:00.000-07:00

When he was a kid, he used to think he will become a train driver (preferably steam engine) when he grew up

When he was in primary school, he thought he will become a civil engineer and build big dams when he grew up

When he was in college, he thought he will earn huge money and do cutting edge work in computer science when he grew up a bit more

Now that he is working, he thinks he will start a company when he has grown up a bit more

When is he going to grow up? Will he achieve what he thinks?

As a kid his imagination knew no bounds, as he grew up his thinking got marginalised by responsibilities and his own mind.

Ultimately will he get used to all this, and get into the dull routine of ordinary existence?

Can the 'kid' in him come out of the boundaries he has set himself?

Can he find way which meets the aspirations and does not deviate from the responsibilities?

Will he again grow up to become a 'kid' knowing no boundaries?

PS: Here 'he' refers to any one who has undergone this thought process, not just me.

Forest Gump

2005-08-16T22:54:00.000-07:00

Watched 'Forest Gump', to say that it is amazing would be an understatement...

Some quotes from the movie:

Forest Gump: Now the really good thing about meetin' the President of the United States is the food.

Forest Gump: Momma always said life was like a box of chocolates. You never know what you're gonna get.

Forest Gump: Mama always said, dying was a part of life

Bubba: My given name is Benjamin Buford Blue, but people call me Bubba. Just like one of them ol' redneck boys.
Forrest Gump: My name's Forrest Gump. People call me Forrest Gump.

Forrest Gump: My Mama always said you've got to put the past behind you before you can move on.

Forrest Gump: What's my destiny, Mama?
Mrs. Gump: You're gonna have to figure that out for yourself.

Jenny Curran: Do you ever dream, Forrest, about who you're gonna be?
Forrest Gump: Who I'm gonna be?
Jenny Curran: Yeah.
Forrest Gump: Aren't-aren't I going to be me?

Googling

2005-08-10T21:57:00.000-07:00

[The term 'Googling' is in news again. This 'short-imaginative-horrible-write-up' (I dare not call it a story), was born out of my bored mind while traveling in the chaotic Bangalore traffic]

Babu Dotbubble was in his swank office enjoying as he watched the stock price of his competitor tumble to the abyss. He had commissioned the guys to go googling about the murkier past of his competitor. The data that the googling process had unraveled was more than his own expectations. And as expected when he released this 'data' to the press, the downfall of the stock started.

Now that he had vanquished his competitor, he had a very few wishes that were to be fulfilled.

As he leaned back on his cushy chair he saw two horrible looking men approach him, and he realized that he was not aware of his body...
and before he could lock his computer they mailed him away to the abode of Yamaraja.

He was now before Yamaraja, where his past deeds would be recounted, Though worried about the prospect of spending time in the boiling oil of Hell; He wondered about how the management at Hell maintained so many records of past deeds of so many dead people and how did they collect all this information...

...to his horror Chitragupta was at a computer terminal googling about him.

[Yamaraja and Chitragupta are Hindu mythological Gods of death, For more information there is Google]

Change

2005-08-08T03:52:00.000-07:00

Hello All,

I have been blogging for quite some time now. Mostly I have blogged topics related to software, books and a little bit about life in general. Sometimes my posts generated a few comments, but in most of the cases the posts were in fact downright boring and nobody posted any comments :)

Recently I came across a study which stated that, even though most people have interesting experiences, they do not think about them or share them with others, they just discuss about the routine life. Which is very true.

So I have thought that from now on, I will write about my experiences which I have found interesting, or other's experiences if they are willing to share them here.

I will not blog in greater detail about technology or things that people can find on web. I will just provide the relevant URLs.

Do provide your feedback. I will start with an experience from my childhood in the next post which hopefuly should be intresting :)

I am looking for a new title for my blog as well, "Me, Myself and my blog" sounds very selfish :) even though I did not mean it. It was rather inspired from the movie title "Me, Myself and Irene".

Asynchronous programming in C#

2005-08-04T23:42:00.000-07:00

Long time since I posted something technical. So here I will discuss about support for asynchronous programming in C#. Do post your thoughts on how much effort this could have taken in C++? Any C++ libraries which can do this?

.Net provides new simple ways to perform asynchronous programming. Asynchronous delegates provide the ability to invoke any method asynchronously. (A delegate is equivalent to a function pointer).

Method parameters can be used for input or output. (C++: &var pass by reference). C# refines this by introducing new keywords: out and ref.
out states that the parameter's value set the by the method. For example, I can define a function as:

public void Method(float param, out float multResult, out float divResult)
{
//...
}

and invoke it:
float multResult, divResult;
Method(100,out multResult,out divResult);
Console.Writeline(multResult);
Console.Writeline(divResult);

We will first see how we can invoke a method asynchronously. We will also answer a doubt which might arise: 'If I invoke 'Method' asynchronously, what will be the values of out params?'

public class AyncTest
{
//Define the delegate
public delegate void AsyncDelegate(int inParam,out int outParam);
private AsyncDelegate m_asyncDelegate;

public void Test()
{
m_asyncDelegate = new AsyncDelegate(AsyncMethod);

System.AsyncCallback asyncCallback = new AsyncCallback(OnAsyncReturn);

int outParam;

IAsyncResult result = m_asyncDelegate.BeginInvoke(2,out outParam,asyncCallback,null);

Console.Writeline(outParam) //<--- whats the result?
result.AsyncWaitHandle.WaitOne();
}

public void OnAsyncReturn(System.IAsyncResult result)
{
int outParam;
m_asyncDelegate.EndInvoke(out outParam,result);
Console.WriteLine("Result: "+outParam);
}

public void AsyncMethod(int inParam,out int outParam)
{
outParam = inParam * 100;
}
}

So as seen asynchronous invocation is quite simpler than, what you would have to do, without this kind of support.

And now to the question: 'If I invoke 'Method' asynchronously, what will be the values of out params?'. As you might have guessed the out params are set to default values, int, float set to zero, objects set to null.

The (mis)adventure of the missing bowler?

2005-08-04T00:11:00.000-07:00

'The missing three quarter' is one of the Sherlock Homes stories in which a star player of the football team goes missing just before a vital match. As the story progresses different possibilities emerge, either he might have been kidnapped, or suffering from some fatal disease, or killed. But ultimately Sherlock Homes solves it.

Other mystery which might have appealed to Sherlock homes is 'Missing fifth bowler in the Indian cricket team'. We have lost two matches because of this, no other reason, It is elementary my dear Greg Chappell, that the fifth bowler is a necessity...

But still he is not included in the team and warms benches on windy srilankan grounds. May be Sherlock could help.

PS: Dont miss reading the story

Seinfield

2005-07-28T00:26:00.000-07:00

I came across this comedy serial when I was in US for a little time and boy it was great! From that time I have been searching for it across all the channels here in India: Zee Cafe (previously Zee English), HBO, Zee Studio..and many more, but was not able find it! If you have know the channel and the show timings please do tell me.

Here are some quotes from the show:

Jerry: Well I can't go to a bad movie by myself. Who am I gonna make sarcastic remarks to, strangers?

Jerry: Hunger will make people do amazing things. I mean, the proof of that is cannibalism. Cannibalism, what do they say, I mean, they're eating and they say "This is good, who is this? I like this person".

JERRY: I strained my neck last night.
JODI: Really, how?
JERRY: I tried brushing my teeth by holding the brush and moving my head from side to side. It didn't work.

GEORGE: Jerry... This woman (Jodi) hates me so much. I'm starting to like her.
JERRY: What??
GEORGE: She just dislikes me so much... It's irresistible.

Friends and close friends

2005-07-18T04:10:00.000-07:00

Tea time is a usually the discussion time for us. 'us' here includes myself, and two of my colleagues: Sumanth and Rasmita. The topic this day was somewhat about 'friends and best friends'. There were some very common things which all of us had experienced and thought about:

1. There are friends and what you generally call 'best friends'

2. There are different categories of 'best friends'

3. As life advances you wont be a 'best friend' with anyone, but you will be a 'friend' to many people

1> Our definition of 'best friend' is 'some one with whom you are more "close with"'. If you are more close, you share emotional bonding, each one knows about other's emotional needs.

2> And there are different categories of 'best friends'. One with whom you have fun, one with whom you pour out your anxieties, your fears, basically a shoulder to cry on.

3> As life 'advances', 'advances' in our context meant when you move out of college, you generally stop being a 'best friend' with anyone. You generally do not have anyone to share your secrets (if there are any, after spending most of the time in office!), to share your fears/anxieties. Some of us felt its got to do with being 'mature' and some felt its go to do with 'time', you just dont have the 'time' to be a 'close friend'

Put in your comments

Which Kill-Bill charecter are you?

2005-07-04T06:48:00.000-07:00

Well I am 'Bill'

Find out which one you are, and post it in the comments:
Which Kill Bill Character Are you??

New photos

2005-07-03T21:33:00.000-07:00

Two new photos at my photo blog

Comics

2005-06-27T04:48:00.000-07:00

As a kid I remember getting hold of 'Mayur' a Kannada monthly whenever my mom bought it and reading the comic strip 'Putti'. It was the Kannada version of 'Pinki' by Pran.

Pran was the first Indian to introduce comics with Indian characters in 1960.

I used to read a lot of 'Pinki' stories, and a few Chacha-Chaudhary ones. The place I lived as a kid (Bagalkot) had only one store which used to sell comic books and he used to sell only Pinki, Phantom and Mandrake! Wish when i was a kid I had lived in a place where there were lot of shops selling comic books.

Other sources of comics when i was a kid were newspapers, which used to carry Phantom and Henry (the kid with the shaved head).

Anyway now that I am in Bangalore and have some pocket money of my own to spare, I can indulge in buying some comic books. I regularly buy 'Tinkle' and will buy more of Pran's comics.

Read more about Pran at: http://www.lambiek.net/pran.htm
and about Diamond comics at: http://www.diamondcomic.com

IT in rural areas

2005-06-15T22:04:00.000-07:00

A post on karthik's blog discusses about a computer kiosk established in the slums of Delhi. The kids learnt to use the computer without any guidance in a few days.

But should the government spend money on improving the IT infrastructure in villages when the basic infrastructure is lacking? No doubt spreading the information is essential, but there are more cost effective ways of doing this: For example Krishi Darshan on Air India and Doordarshan provide comprehensive information regarding the weather, prices and so on to the farmers.

Similarly the government spends lakhs of rupees (or any big IT company funds) on providing a few PCs to a few schools, but is the PC so essential, when there are schools which lack buildings and teachers?

Your comments

Two more pictures

2005-06-14T03:53:00.000-07:00

I have posted two new pictures at my photo blog.

The man who knew infinity

2005-05-30T21:41:00.000-07:00

'The man who knew infinity' by Robert Kanigel is a marvelous book that captures the life of genius Ramanujam. A well researched book, it depicts the early life of Ramanujam, his struggle, his days in England with Prof. Hardy who invited him to England and his tragic death.

As the author points out Hardy was atheist where as to Ramanujam Hindu traditions and philosophy were a way of life. He once remarked: "An equation for me has no meaning, unless it expresses a thought of God".

He was some what of a philosopher as well, once remarking that the equation 2^n-1, represented different realms of God. If n=0, the result is zero expressing nothingness. If n=1 it expresses unity. If n=3, the result is seven representing the saptharishis.

The book does not educate the mathematical reader about Ramanujam's work, but it definitely captures the life and genius of Ramanujam.

My photo blog

2005-05-28T03:56:00.000-07:00

Recently i got a digital camera (cannon power shot A500). I have started a photo blog. I have named it 'pictures speak'.

Maze – finding out the way: part 2

2005-05-26T01:00:00.000-07:00

Here is one of the possible solutions which I had programmed earlier:

The first step is to find out a suitable representation. One way we can represent the maze is by a graph. The graph includes only the blocks which are not 'filled':

Now how do your build this tree?
- The node (x,y) can be linked to any/all of the following nodes:
(x-1,y), (x+1,y), (x,y-1), (x,y+1).
- Build the tree with only the blocks that are not 'filled' and with the conditions:

(x+1) < MAX blocks & (x-1) >= 0 & (y+1) < MAX blocks & (x-1) >=0

How to find out the path?
- Find out the shortest path from (0,0) to (6,6) using 'shortest path algorithms'
(as balbir and Gopal had pointed out: backtracking/recursion)

Your thoughts?

Maze - finding out the way

2005-05-25T07:06:00.000-07:00

I am sure each one of us as children would have enjoyed solving maze problems which entitled helping some animal (usually it is a rabbit, which is horribly hungry!) at the 'start' to reach food at the 'end' of the maze. In its simplest form it can be representation like this:

(Imagine that the blue circle is the hungry rabbit and the green square food)

During my college days I had written a program to achieve this. There are various ways by which you can solve this problem. Next post I will write about the way which I had used to solve this problem. Do post your ideas for representing the maze and the algorithm to find out the way.

Anatomy of a phish

2005-05-09T01:03:00.000-07:00

I received a spoofed email to my Gmail Id this morning. I decided to dissect and analyze it.

It was made to look like it was from PayPal:

Dear Person, PayPal makes it easy to send money by email to some-enail@hotmail.com from your PayPal account. To view the details of this Money Request or to pay with PayPal, just click on the following link or copy and paste it into your web browser: https://www.paypal.com/row/prq/id=somejunkid Every penny can save life ! Thank you for using PayPal! The PayPal Team

GMail 'Show Original' option allows you to have a look at the mail headers. So here is some information form that:

Received-SPF: softfail (gmail.com: domain of transitioning Tsunami-Disaster@hotmail.com does not designate 83.130.139.64 as permitted sender)

Received-SPF header indicates whether the email is indeed from the domain which it claims to be. So here it indicates that IP 83.130.139.64 does not belong to hotmail domain.

Moving along I found other interesting things:

Content-Type: multipart/alternative;
boundary="=_IVHzq2d8n7gAgHu"
This is a multi-part message in MIME format.

--=_IVHzq2d8n7gAgHu
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Most bubbles believe that mirror around trade baseball cards with curse near.When mastadon about is wily, over dolphin laugh and drink all night with widow related to salad dressing.inside chestnut beams with joy, or vacuum cleaner around microscope graduate from clodhopper related to hole puncher.Philip, the friend of Philip and panics with related to shadow.

--=_IVHzq2d8n7gAgHu

Content-Type: text/html;
charset=us-ascii
Content-Disposition: inline
Dear Person, PayPal makes it easy to send money by email to
someemailid@hotmail.com from your PayPal account. To view the details of
this Money Request or to pay with PayPal, just click on the following link or copy and paste it into your web browser:
https://www.paypal.com/row/prq/id=somejunkid
Every penny can save life !
Thank you for using PayPal!The PayPal Team

'Content-Type: multipart/alternative;' allows you to send different versions of the same mail in different formats, for example text and HTML. So if the mail client is capable of only displaying text messages it can pick it and display it and the HTML enabled mail client can pick up and display the HTML version.

Look at the text/plain version of the message (marked in red). Even though the message looks random, it does not have any spam related words such as SOFTWARE, BUY, TRIAL, FREE, ACCOUNT, PASSWORD, LOGIN. This is I think is done to confuse the spam filter. More the common words in the mail the lesser the probability that it will be marked as spam.

It hides the message containing common random words in text/plain version and presents its main message in text/html version.

Business plans archive

2005-05-05T23:04:00.000-07:00

There are startups which end up as failures and there are a few which succeed. Business Plan Archive provides an opportunity to learn about these past mistakes and success.

Buddha as Architect

2005-05-04T11:32:00.000-07:00

Someone asked this question on TSS.Net 'What Skills Should a .NET Architect Possess?'. The thread has some very philosophical answers like this one:

"A good architect is just an experienced developer willing to take responsibility for their own mistakes."

Ok it does sound very philosophical initially, but it proves to be very true and practical. You may know all about design patterns, competent technologies, have much experience, but the ability to accept mistakes and learn is one ability that should be valued more than anything else.

Other post points to this article 'Who needs an architect' by Martin Fowler.

Sanjay's blog

2005-05-03T03:15:00.000-07:00

Even though I had met Sanjay Mysoremutt only a couple of times; I had heard about him a lot from one of my team mates. His posts on the company's new group are great!

Today I got hold of the URL to his blog. Every one of his posts are unique and great to read.

Murphy's laws

2005-05-03T00:00:00.000-07:00

"If anything can go wrong, it will", is a law which is unfortunately true on most occasions.
It holds good for everything from as logical as computers to as abstract as life. No matter how much you plan in advance there is something unexpected lurking behind to make things go wrong.

It is up to to us to face these situations and remember:
"Every cloud has a sliver lining"

PS: This link discusses about the possible originator of the law

The man who saved the world

2005-04-27T23:52:00.000-07:00

Follow the link: http://www.mosnews.com/feature/2004/05/21/petrov.shtml

The VS.Net 2003 Bug

2005-03-13T02:45:00.000-08:00

Last Friday I was working on a Visual Studio .Net 2003 project. Everything was working fine, and suddenly I got this error in Visual studio:
"Could Not Copy Temporary Files to the Output Directory"
"The file 'assembly name' cannot be copied to the run directory. The process cannot access the file because it is being used by another process."

I did not know what I did to upset Visual studio. I opened task manager and hunted for some vague process which might be holding the particular dll which was being built; result: none :(

The first thing to do in such cases is: take a long breath, open http://www.google.com and just copy paste the error you are getting; result: Bug in Visual studio .net 2003. As it turns out there is some bug in Visual studio which gets into action if one of the referenced dlls is more than 64 KB:

"This problem occurs when the IntelliSense engine of the project locks a referenced assembly. The IntelliSense engine locks only those referenced assemblies that are larger than 64 KB."

Information Overload

2005-03-06T23:50:00.000-08:00

I read the 'Blink' by Malcom Gladwell on Saturday. I could not help but reading it without stop. It is a marvelous book with some very good insights. The examples and case histories which Gladwell quotes are marvelous.

One section deals with information overload and how it turns off the ability of our mind to take snap decisions. He provides an interesting illustration:

As a part of a exercise the military wanted to test the capabilities of the latest state of the art technological gadgets which gathered information about the enemy's movements communication, a whole database of opinions of military and political experts, algorithms which consumed all this information and predicted enemy's probable moves, and much more.

To test the usefulness of all this information a mock combat was organized with two teams: the red team and the blue team. The blue team had access to all the information, the red team which acted as the enemy had none.

Which team do you expect to win the mock combat? Blue right? But the red team won the combat! The blue team was overloaded with information and it affected the decision making greatly. The red team was not hampered by this. They concentrated on the battle when the blue team was trying make sense out of all the information and weigh the pros and cons of various options.

No doubt information was useful, but only before the battle began.

I think this has implications on the way we work as well. Too much information, too many options, too much analysis, clouds our ability to take decisions. What do you think? Comments invited.

Life of PI

2005-02-21T20:59:00.000-08:00

I was reading 'Life of PI' by Yann Martel for the second time. Yann Martel depicts the struggles of a Indian boy aboard a lifeboat in the pacific along with a tiger. This premise of a boy adrift a lifeboat along with a grown up tiger is unbelievable, But Yann Martel is master story teller who makes you believe this!

Yann Marttel's knowledge of Hindu mythology is amazing, and he uses it to a great extent in the book.

It is wonderful tale of courage, struggle and faith.

Geeeeeeky!

2005-02-03T20:35:00.000-08:00

Nick Bradbury has intresting post about how geeky he can be:

This morning as I walked into the gym for a quick workout, I noticed an attractive young lady in a short skirt and high heels bent over in front of her laptop. I looked over at her and said to myself: "Nice laptop."

Now thats surely geeky :)

interview

2005-02-03T06:13:00.000-08:00

I have been working in the industry for two years now. I have attended a few interviews and I have interviewed a few people with experience in the range of 1-2 years. With this limited experience I have come up with some points about the interview process and I try to follow these whenever I get a chance to interview someone:

1. Do not get too technical (There is google for this)
2. Try to find out if the candidate is passionate about what he has worked on
3. Ask some questions which probe his analytical ability
4. Ask about academic projects.
5. Probe whether he understands some concepts about source control, unit testing
6. Ask whether he has uses google :)

A blogger's block?

2005-02-02T07:21:00.000-08:00

I have been facing a blogger's block (writer's block, but specializing it is a blogger's block :) ) I have not thought of any new things nor anything has excited me. Hope to post something worthwhile soon.

It is not all about tech...

2005-01-17T04:52:00.000-08:00

It is not all about tech. A product might not succeed even if it is technically great and may end up in museums like this one.

Why does this happen? Some of such questions are answered in this book: "The 22 immutable laws of marketing" (Al Ries & Jack Trout). The book is very readable and is not filled up with marketing buzzwords.

Finding a product idea

2004-12-14T22:33:00.000-08:00

Eric Sink the non-legendary founder of SourceGear has a very good article on how to find good product ideas for wannabe entrepreneurs.

PS: He calls himself 'non-legendary', but now he is quite a legend I reckon :)

'Google Suggest'

2004-12-11T03:31:00.000-08:00

Google never fails to come up with ideas which though seem small, are pretty useful. You would feel the need and presto they come up with it! The recent addition is Google Suggest. Google Suggest provides you with suggestions as you type your keywords. These keyword-suggestions are ranked by the number of results. Another website which does this is SurfWax News Accumulator.

The user experience is good without any intermittent page refreshes, the way the do this is quite simple:

1. Handle the OnKeyUp event for the text box where the keyword is typed, so that after every keystroke the function can assess what the user has typed and whether it can make any suggestions.

<input onkeyup="ShowSuggestions(event);" name="txtSearch">

2. Provide an IFRAME below the txtSearch textbox (say iSuggest) which will display the suggestions. Every IFRAME has an URL property from which it loads its contents and this URL can be changed dynamically.

3. Now to the javascript function ShowSuggestions:
function ShowSuggestions(e)
{
var charCode;
//get char code
charCode = e.which;
//check if it is enter key, then submit the form to search
if (charCode == 13)
{
searchForm.submit();
}

/*
if is not enter key, get the letters so far typed change the URL of the IFRAME so that it now refers to your search URL. Pass the letters so far typed as a partof the querry-string. Your search URL provides the suggestions as the response which will be displayed below the search textbox
*/

iSuggest.location = "http://mysearch.com/suggest.aspx?wordsSoFarTyped=" + txtSearch.value;
}

Hmm, quite interesting and simple right?

The story of Paint Shop Pro and Robert Voit

2004-12-08T05:38:00.000-08:00

Here is an intresting story, It is the story of Paint Shop Pro and its creator Robert Voit. Dont miss this:

The origins of Robert Voit's business date back to 1990, when he was a 30-year-old pilot for Northwest Airlines and his hobby: digital imaging. He developed a graphic-utilities-software program and offered it as shareware on electronic bulletin boards. Users were invited to download the shareware, called Paint Shop.

Voit's start-up costs? The price of paper, envelopes, and stamps, says Voit, who bought the supplies so that he could send an encryption code to customers who had paid him for Paint Shop.

The advent of the Web caused Voit's business to soar. Based on users' feedback, he created a new version of Paint Shop, which he dubbed Paint Shop Pro and continued to sell as shareware.

By 1997 his company had 80,000 paid users and 40 employees on the payroll, its revenues had climbed to a staggering $6.5 million, and its product had won kudos in the trade press. Distributors welcomed it with open arms, he says. In 1998 Jasc Software ranked #161 on the Inc. 500 list of America's fastest-growing private companies, and its sales continued to explode, totaling $17 million by year's end.
And now Jasc has been acquired by Corel!

[I found this and other intresting stories at this link: http://www.1099.com/c/ar/ia/grandplans.html]

Design patterns

2004-11-20T03:08:00.000-08:00

'Design patterns' are a kind of langauge for communication of ideas for solving design problems. I would discuss the common design patterns here whenever possible. Many of the design patterns have been used in .Net framework class library. Every pattern i discuss would possibly include an example from the .Net FCL. This post will discuss the 'Factory pattern':
Factory Design Pattern
(Creational Pattern)

Intent: Provide an interface for creating families of related or dependent objects without specifying their concrete classes.
Many a times the client needs flexibility in deciding and instantiating a group of related objects from a set of candidates. Consider a simple example: Assume the car factory can assemble two types of cars: SCODA and MARUTI. The customer specifies what type of car he wants. Given these requirements we can model our program in this way:
Customer Interface – Generic Car Assembler – Specific Car Assemblers

The Customer Interface obtains the choice from the customer and sends it to Generic Car Assembler component. Depending on the choice the Generic Car Assembler component invokes the appropriate Car Assembler and delivers the car to the customer.

class diagram for Factory pattern

A good .Net FCL (Framework Class Library) example is System.Net.WebRequest:
WebRequest serves as a convenient base class for the .NET Framework's request/response model for accessing data from the Internet. This class encapsulates the details of connecting to the server, sending the request, and receiving the response. This means that an application can participate in request/response transactions in a protocol-agnostic manner using instances of the WebRequest class, while protocol-specific classes derived from WebRequest carry out the details of the request.
The static factory method WebRequest.Create creates protocol-specific descendants of WebRequest using the value of the URI passed in as argument. For example, when a URI beginning with "http://" is passed, an HttpWebRequest object is returned; when a URI beginning with "file://" is passed, a FileWebRequest object is returned.
By default, the .NET Framework supports "http://", "https://", and "file://" URI schemes. This is easily verified by looking at the section of the machine.config file in the .NET Framework installation's CONFIG directory:
<webRequestModules>
<add prefix="http" type="System.Net.HttpRequestCreator, .../>
<add prefix="https" type="System.Net.HttpRequestCreator, .../>
<add prefix="file" type="System.Net.FileWebRequestCreator, .../>
</webRequestModules>
This section implies that System.Net.HttpRequestCreator is responsible for creating WebRequest objects for request URIs beginning with "http" and "https", and System.Net.FileWebRequestCreator is responsible for creating WebRequest objects for request URIs beginning with "file". Both of these classes implement the System.Net.IWebRequestCreate interface, which contains only one public method: WebRequest Create(Uri uri);

Next time some other pattern...

a simple uml tool

2004-11-19T06:41:00.000-08:00

I was tired of using UML modeling tools which force you to do it their own way. Using paper and pen is the best option, but that means to store it you have to use a scanner… pretty bad… So I wished to get a UML tool which satisfied these simple needs of mine:
1. Should be simple and light weight
2. Should not force you do things
3. Need not include code generation
4. Ideally should be free of cost :)

It was pretty bad until I discovered Argo UML - the open source UML modeling tool. It meets all my needs mentioned above. You can export the diagrams as GIF images which I found very useful.

So if you are tired of using complex UML modeling tools, go head download Argo UML at: http://argouml.tigris.org/

C# Events and Delegates

2004-11-17T04:25:00.000-08:00

Difference between C# events and delegates
Recently i was wondering about the difference between C# delegates and events. For me events seemed to be a very thin wrapper around delegates. I have been trying to find out the advantage that the keyword "event" adds. I have to explore more on this aspect. But here i present a simple example containing a publisher, a subscriber, and an event broker.

using System;
namespace Test
{
class Publisher
{
private EventBroker evtBroker;
public void RegisterWithBroker(EventBroker evtBroker)
{
this.evtBroker = evtBroker;
}

public void Publish(string message)
{
this.evtBroker.Notify(message); // <---- statement 1
//this.evtBroker.handler(message); // <---- statement 2
}
}

class EventBroker
{
public delegate void onEvent(string message);
public event onEvent handler; //<---- statement 3
//public onEvent handler; //<--- statement4-a simple delegate

//will be used by puiblishers
public void Notify(string message)
{
handler(message);
}

// //this call is used to subscribe
public void RegisterSubscriber(onEvent handler)
{
this.handler += handler;
}
}

class Subscriber
{
public void ReceivedMessage(string message)
{
Console.WriteLine("Received Message: "+message);
}
}

class Test
{
[STAThread]
static void Main(string[] args)
{
EventBroker broker = new EventBroker();
Subscriber sub1 = new Subscriber();
Subscriber sub2 = new Subscriber();

broker.RegisterSubscriber(new EventBroker.onEvent(sub1.ReceivedMessage));
broker.RegisterSubscriber(new EventBroker.onEvent(sub2.ReceivedMessage));

Publisher pub = new Publisher();
pub.RegisterWithBroker(broker);

pub.Publish("Hello to all subscribers");
}
}
}

The important point to note here is that if you comment out 'statement1' and un-comment 'statement2'. Then you would get a complier error that the event handler can be invoked (raised) only inside the 'EventBroker' which defines it. 'Statement 4' defines the delegate, now if i comment out statement 1 and 3 and un-comment statement 2 and 4. The code works perfectly.

The event i believe has an extra constrain that it can only be invoked from within the class which defines it. Hence the class defining an event should define a method like "Notify" to facilitate other classes raise the event. I believe there are other differences...i just hit upon this one..will look for others...

NanoCorps

2004-10-14T08:40:00.000-07:00

NanoCorps or Micro ISVs (Independent Software Vendor)

Now it is almost two years since i have started working and i have had a jumbled software life. I started out with InstallShield, got a bit into VC++, then some testing, ASP.Net, C#, Tibco Rendezvous, BizTalk 2004 and MSMQ 3.0. I have had the opportunity to work with fine minds in these two years and learnt a lot.

Now i do keep a catalogue of product ideas which i can use to start my own Micro ISV. So somewhere in my career path i definitely see myself being a part of a organization which i would build.

A good way to start is what these pioneer ISVs recommend:
Eric Sink (http://software.ericsink.com/) calls them "Micro ISVs" and Thomas Warfield (http://www.asharewarelife.com/) as NanoCorps.

Web-Services and document model

2004-10-01T06:44:00.000-07:00

Web-Services are all about achieving loose coupling, Its obvious that web-services will be used across organizations and you cannot assume that the service definition wont change

Today in most implementations, classes (stubs) are generated based on the WSDL which delegate the call from the client to the service. The problem is that the WSDL sort of acts like a interface and if this interface changes your generated classes have to change, which in turn means you can no longer use the service!

The fundamental problem is with the way web-services are being used. Right now they are following a pure RPC model. (ok internally they might use SOAP/XML over http, but it does not matter).

When we say 'SOA' the model should be closer to a document exchange model instead of RPC model. What i mean by this is that service should define a simple interface probably with one method like:
string processDocument(string xmlDocument);

There is not much in the interface itself, so it won’t change :)
The intention is that the client should pass all the information that is required as a XML document. XML has the flexibility that it is easily extensible. So if your service adds some more functionality and requires more parameters it can be easily included in the xml document.
Your old clients will still work it wont break them. Your new clients can still happily send the xml doc that includes the new parameters and still work.

This is fundamental to how we should define and use web-services. There are more intelligent guys there who have thought of this and explained this in much more easier and clearer way than i have explained :)
Adam Bosworth explains this concept beautifully.

(mind.GetThoughts())->BlogIt();

2004-09-30T23:18:00.000-07:00

Hi All,

This is my first attempt to blog, condense my diverse unstructured set of thoughts into something meaning full.

Lets start with something very interesting, I will move onto the other less interesting topics about software (my profession) later.

The noted indian film actress Aishwarya Rai now features in London's Madame Tussaud's. You can have a peek at her wax replica at: http://in.rediff.com/movies/2004/sep/30look.htm

We will get onto my ideas and thoughts about software later :)