Iswapyou Blog

HTML Tutorial – Lesson 2: Structure and Method

Justin — Sun, 14 Feb 2010 16:47:55 +0000

I’ll bet you’re thinking “Structure and Method? What is this… some kinda textbook???” Well, no, in this lesson you’ll be learning about the Structure of HTML and the Method that is used to make them.

HTML does not need to be coded with some special “HTML tool”, and you don’t even need some special program like Microsoft FrontPage or Macromedia Dreamweaver (In fact, I discourage their use until you know the ins and outs of HTML code). All that you DO need is a simple text editing program like windows built in Notepad. You’re probably thinking “Wait just one second, you’re telling me I can code up another Yahoo! with my puny little Notepad? Yes! That’s part of the beauty of HTML! In fact, this entire tutorial was created in TextPad, a simple and very cheap text editor.

When you make a Web page the first thing you need to do is gather your content. For our first page ever, we’ll be making an informative page about ourselves. For example here is mine:

Welcome to Justin’s Web Page!

Hi, My name is Justin. I built this web page because I love writing HTML code! I could do it all day long (and sometimes, i do). I am a lover of programming languages, and love to design and produce web content. Thanks for visiting my page!

Yours Truly,
-Justin

Go ahead and think up a few paragraph’s like this, and meet me at the next lesson.

HTML Tutorial Lesson 1: Introduction to HTML

Justin — Tue, 09 Feb 2010 03:18:38 +0000

Welcome to my HTML tutorial!

Soon you shall be on your way to building great Web Pages and vast Web Sites, but first lets go over a thing or two about what a “Web Page” is, how they work, and what we can do with them.

For this tutorial you will need:

An Internet ready computer
A web browser

Because you are reading this on my blog, I will assume that you have both of these things.

Let’s jump right in to the lesson!

In the beginnings of the Internet, it was very hard to exchange data. So with great vision and foresight, Tim Berners-Lee created a way to connect text on the Internet through Hypertext Links (References to other text on the Internet). This wasn’t a new idea, but his Hypertext Markup Language (HTML) was very popular and caught on better than other competing projects.

HTML is not a “Programming Language” per se, but rather a scripting language that marks up the page with formatting commands. Your Web Browser then reads these commands and shows the formatted page on your screen. Because the popularity of the Web programmers began writing Web Browsers that could display graphics and a wide range of other content. Thousands of people started to create web pages ranging from personal “homepages” to business information pages and rich internet applications.

Today billions of people access the web, and a there is a huge diversity of sites that have sprung up for their each of their needs. Before going on to the next lesson, I suggest that you go out and view many pages that are out there on the Web. As you are viewing them, to view the HTML behind the page click View->Source if you’re using Microsoft Internet Explorer, or View->Page Source with Firefox.

Lesson 2

Data Binding using ASP.NET

Justin — Tue, 02 Feb 2010 23:26:23 +0000

Data Binding creates a link between a particular control to a specific column of a table in the database or to an entire table in the database. With ASP.NET data binding you can also bind any server control to the output of different methods and expressions.

On ASP.NET pages when we are doing databinding it is necessary to use the basic syntax for all expressions.

For example:

<%# EmpID %> This syntax is for a simple property.

’ runat=”server”> This syntax is for a collection.

<%# (emp.First Name + ” ” + emp.LastName ) %> This syntax is for an expression.

<%# GetSalary(EmpID) %> This syntax is for the result of method GetSalary().

If you are using a list control the following syntax is used:

Text=’<%# Container.DataItem(“EmployeeName”) %>’

If you are using a RadioButtonList control to bind data then the syntax is:

In multiple data bound Values in a Hyperlink Control with a GridView:

If one wants to navigate between the fields then the syntax is:

DataNavigateUrlFields=”ProductID,SupplierID,ProductType”

In the following example, the code below uses a feature to provide a hyperlink that contains two values, both extracted from the current row of the employees table, for the href attribute:

SelectCommand=”SELECT EmpID, CompanyName, City FROM employees”/>

AutoGenerateColumns=”False”>

DataTextField=”employeeName”

DataNavigateUrlFields=”EmpID,City”

DataNavigateUrlFormatString=

“http://yoursite.com/showemployee.aspx?id={0}&city={1}” />

The resulting value for the href attribute will be something like this:

“http://yoursite.com/showemployee.aspx?id=00123&city=Mumbai”

In the above example city of the employee is “Mumbai” and employee id is “00123”.

Databinding simplifies applications; and with less code a fast execution is done. .Net helps the programmer by reducing his/her work and time spent coding a data abstraction layer.

A review of Adobe Flex Builder

Justin — Sun, 31 Jan 2010 06:46:29 +0000

Adobe’s FlexBuilder is the Software Development Environment for Flex, Adobes Rich Internet Application platform. FlexBuilder is built on Eclipse, so any computer you run on it should have > 1 GB of ram and a processor > 2 ghz.

FlexBuilder is a very satisfying environment to work in. It is much more natural (as a programmer) to use than the actionscript editors in Adobe Flash. Because you are working in a fairly heavyweight Eclipse environment, those used to working in Microsoft Visual Studio may find FlexBuilder a bit slow. FlexBuilder does have a set of very capable debugging tools however, and these tools alone make the near-$250 price tag worth it. The addition of the powerful Designer mode (much like the Design view in Visual Studio) also adds a lot of value. Because of these features I strongly recommend Adobe FlexBuilder for development, and consider it a worthwhile addition to any Rich Internet Application programmers toolkit.

Rating: 8 out of 10
Pros: Feature packed, Eclipse environment is very configurable, Natural environment for experienced programmers.
Cons: Eclipse is a resource hog, so check to make sure your computer meets the minimum specs before buying.

Google Analytics is made of win

Justin — Sat, 30 Jan 2010 00:02:41 +0000

This week, for the first time, I got on the Google Analytics bandwagon. I never thought charts and graphs could be so damn fun. Look at this:

Google Analytics site overlay function

That is what Google calls the “Site Overlay” (it’s under the Content menu, if you’re looking for it, Googlers/Bingers). I was FLOORED when I saw it for the first time. The numbered percents everywhat represent the percentage of visitors that clicked the link – but I’m sure you didn’t need to be told that, since the data is clear as day. WAY TO GO GOOGLE for taking data visualization to the next level. Mad props.

A Detailed Introduction to SOAP

Justin — Thu, 28 Jan 2010 23:52:30 +0000

SOAP stands for Simple Object Access Protocol and is used for communication between applications through the Internet. SOAP is a platform and language independent. It also allows applications to communicate between each other though both applications are on different operating systems. SOAP messages are typically written using XML.

Here is an example of SOAP syntax:

xmlns:soap=”http://www…./soap-envelope”
soap:encodingStyle=”http://www…./soap-encoding”>
…
…

…
…

…
…

SOAP Envelope element is a root element and it defines the XMLdocument.
xmlns:soap namespace defines the Envelope as a SOAP Envelope.
The encodingStyle attribute is used to define which data types are used in the document.
SOAP has header element which is optional and contains the information about the application.
Body element contains actual SOAP Messages.
Fault element is used to indicate errors. Let us see each of them in detail:
:- A code which is used for identifying tags.
:- Explanation of the fault.
:- Whom fault was caused by.
:- Further details about the fault.

Using a TCP connection, communication is formed between HTTP client and server. Once the connection is made the following messages are passed from client to server.

POST /item HTTP/1.1
Host: 189.121.356.314
Content-Type: text/plain
Content-Length: 200

If connection is successful then the following messages are returned by the server.

200 OK
Content-Type: text/plain
Content-Length: 200

SOAP connection means connection between HTTP and XML.The request can be HTTP POST or HTTPGET.In the example below, a GetempSalary request is sent to a server. The request has a empName parameter, and a salary parameter will be returned in the response. The namespace for the function is defined in “http://www.employee.org/salary” address.

The SOAP request:

POST /salary HTTP/1.1
Host: www.employee.org
Content-Type: application/soap+xml; charset=utf-8
Content-Length: mmm

xmlns:soap =”http://www.abc.org/soap-envelope”
soap:encodingStyle =”http://www.abc.org/soap-encoding”>

John

A SOAP response:

HTTP/1.1 200 OK
Content-Type: application/soap+xml; charset=utf-8
Content-Length: mmm
xmlns:soap =”http://www.abc.org/soap-envelope”
soap:encodingStyle =”http://www.abc.org/soap-encoding”>

20000

A comparison between MFC and Win32 in C

Justin — Tue, 26 Jan 2010 03:47:20 +0000

First let us start with the “Windows SDK” (Software Development Kit) which is designed to create Windows applications. It consists of large set of functions, messages, structures, macros and resources. It is a set of tools designed to help C programmers create Windows applications.

Windows SDK consists of the large set of books describing functions, messages, structures, macros and resources. There are also tools including a dialog editor and an image editor, on-line help files and a set of windows libraries and header files.

It has large collection of API (Application Programming Interface) functions written in C. The API is a set of functions that are part of Windows Operating System. Programs can be created by calling the functions present in the API. One doesn’t have to bother about the internal working of the functions – just knowing the function prototype (name, arguments) and return value one can invoke the API functions. A good understanding of the Windows API will help you to become a good Windows programmer . Windows itself uses the API to perform its GUI magic.

Windows APIs are of two types:
API for 16-bit Windows (Win16 API)
API for 32-bit Windows (Win32 API)

Win16 is the API for the first 16-bit versions of Microsoft Windows. These were first called “Windows API”, but were later renamed to Win16 so that they can be differentiated from 32-bit (which is the new version).

Win32 is the 32-bit API for modern versions of Windows. This API consists of functions implemented, as with Win16, in system DLLs. The core DLLs of Win32 are kernel32.dll, user32.dll, and gdi32.dll. Win32 was introduced with Windows NT.

Microsoft Foundation Class (MFC) is a rich class library which consists of set of c++ classes that has different functionality of applications written for Windows Operating System. It wraps portions of API in to C++ classes. MFC consists of multi-layered hierarchy that defines approximately 200 classes. It offers the convenience of reusable code. Because many of the tasks common to all Windows programs are provided by MFC, one need not have to recreate it each time. It also provides implementations for a set of the user-interface components. Mfc programs are highly portable, because the interface provided by the Foundation Class Library is largely independent.

Here is a program that creates a simple window using MFC.

#include
//The CWinApp class is the base class from which you derive a Windows application object.
//An application object provides member functions for initializing your application
//(and each instance of it) and for running the application

class mywin : public CFrameWnd
{
public :
myWin()
{
Create (0,”HELLO – WINDOW”) ;
}
};

class myapp : public CWinApp
{
public:

// Override InitInstance to initialize each new instance of your application running
//under Windows.Typically ,you override InitInstance to construct your main window
//object and set the CWinThread : : m_pMainWnd data member to point to that window.

int InitInstance()
{
mywin *f ;
f = new mywin;
f – >ShowWindow(3);
m_pMainWnd = f;
return 1;
}
};

myapp app;

Here is the same program to create a window in the Windows SDK

# include
HWND hwnd;
MSG msg;
WNDCLASS wnd;

long WINAPI process(HWND,UINT,WPARAM,LPARAM);
int WINAPI WinMain(HINSTANCE h,HINSTANCE p, LPSTR s , int show)
{
wnd.hInstance=h;
wnd.lpfnWndProc=process;
wnd.lpszClassName=”first”;
wnd.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH);
RegisterClass(&wnd) ;
hwnd=CreateWindow(“first”,”SDK-Window”,WS_OVERLAPPEDWINDOW,CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,0,0,h,0);
ShowWindow(hwnd,SW_SHOWNORMAL);
While(GetMessage(&msg,0,0,0))
{
DispatchMessage(&msg) ;
}
return msg.wParam;

}
long WINAPI process(HWND hd,UINT mess,WPARAM more,LPARAM pos)
{
Switch(mess)

{
case WM_CREATE:MessageBox(hd,”CREATING”,”wait!”,0) ;
break;
case WM_ClOSE:MessageBox(hd,”Closing”,”wait”,0);
break;
case WM_DESTROY:MessageBox(hd,”destroying”,”wait”,0);
PostQuitMessage(0);
break;
}
Return DefWindowProc(hd,mess,more,pos);
}

Thus we can see that programming in MFC reduces the code to a considerable extent as compared to Windows SDK; in the windows SDK we have to write each and every function.

Threads in Java

Justin — Tue, 19 Jan 2010 04:25:59 +0000

Java supports multithreaded programming. Threads means part of the program which runs concurrently and which defines separate part of execution. Threads are present in many states.It can be running or it can be made ready to run as soon as it gets CPU time. A running thread can be suspended temporarily and also can be resumed. Thread can also be blocked, it can also be terminated in which execution is stopped. When thread is terminated it cannot be resumed.

As Java supports multithreading there should be synchronisation between two threads it should be ensured that do not conflict each other while sharing a complicated data structure . So Java provides object synchronized methods. Once a thread is inside a synchronized method,no other thread can call any other method on the same object.

When we divide out program in different threads it is necessary to have communication between them many other languages depend on the operating systems but in Java it allows a thread to enter a synchronized method on an object and then wait there till some other thread tells it to come out.Every thread in Java is created and controlled by the java.lang.Thread class.

While creating a Thread in Java it can be defined in two ways

1. By implementing the Runnable interface

2. One can extend the thread class itself.

Runnable interface

To create a thread one has to create a class that implements a Runnable interface. To implement a Runnable a class need only implement a single method call run(), which is declared like this:

public void run()

Inside run() one has define code for new thread. It is important to know that run() can call other methods and work with various classes and variables. Once you create a class which implements Runnable then you have to create an object of type thread of that class. Once the new thread it will start running after you call start() method within the same thread.

It can be declared in this way

void start()

Let us see an example of how to create a new thread

class NewThread implements Runnable {

Thread n;

NewThread () {

// New thread created here
n = new thread(this,”Thread1″);

System.out.println(“Second Thread: ” + n);

//start the new thread.
n.start ();

}

public void run () {

try {

for (int i = 5; i > 0; i–) {

System.out.println(“Second Thread: ” + i);

Thread.sleep(500);
}

} catch (InterruptedException e) {

System.out.println(“Second Thread Interrupted”);

}

System.out.println(“Exiting Second Thread”);

}

class ThreadDemo {

public static void main(String args[]) {

//New thread created here
new NewThread();

try {

for (int i=5; i>0; i–) {

System.out.println(“First Thread: ” + i);

Thread.sleep(1000);

} catch (InterruptedException e) {

System.out.println(“First thread Interrupted”);

}

System.out.println(“Exiting First Thread”);

}

Passing this as argument means that you want the new thread to call run() method and then start() method. Start() then starts the execution of the thread which causes Second Thread’s loop to begin. After start() method is called NewThread’s constructor returns to main(). When First thread resumes it enters its for loop.

The output of the above program is :-

Second Thread: Thread[Thread1,5,main]
First Thread:5
Second Thread:5
Second Thread:4
First Thread:4
Second Thread:3
Second Thread:2
First Thread:3
Second Thread:1
Exiting Second Thread
First Thread:2
First Thread:1
Exiting First Thread

If the First Thread finishes before a Second Thread has finished then Java run-time system may hang so First Thread sleeps for 1000 milliseconds and Second Thread sleeps for 500 milliseconds.This helps Second Thread to terminate earlier than the First Thread.

Extending Thread
The second way to create a thread is to create a new class that extends thread and then create an instance of that class. The extending class must override the method the run() method.We should also call start() to begin the execution of new thread.

Let us see an example of Extending Thread

//create a thread

class NewThread extends Thread {

NewThread() {

super(“thread1″);

System.out.println(“Second Thread: ” + this);

//start the thread
start();

}

public void run () {

try {

for (int i=5; i > 0; i–) {

System.out.println(“Second Thread: ” + i);

Thread.sleep(500);
}

} catch (InterruptedException e) {

System.out.println(“Second Thread Interrupted”);

}

System.out.println(“Exiting Second Thread”);

}

class ExtendThread {

public static void main(String args[]) {

//New thread created here
new NewThread();

try {

for (int i=5; i>0; i–) {

System.out.println(“First Thread: ” + i);

Thread.sleep(1000);

} catch (InterruptedException e) {

System.out.println(“First thread Interrupted”);

}

System.out.println(“Exiting First Thread”);

}

The output of the program is same as the earlier one . The call of super() inside NewThread will invoke the Thread constructor.

Data Types in C#

Justin — Mon, 11 Jan 2010 04:48:14 +0000

C# is a language in which every variable and object should have a declared type.In this article we are going to discuss about datatypes in C#. Many dataypes in C# are from C and C++.

There are different ways of defining data types in C# let us see each of them in brief:-

1. If the data type is built-in it can be defined as as int or char.

2. If it is user-defined type one can define it as a class or as an interface.

3. Data types can also be defined as Value Types or Reference Types.

a. Value Types

This datatypes are used for storing values of the data.Value types have two main types

1. Structs

2. Enumerations

In structs types there are types like:

a. Integral types
b. Floating-point types
c. decimal
d. bool

In Integral type there are categories like

sbtype – Signed 8-bit integer
byte – Unsigned 8-bit integer
short – Signed 8-bit integer
ushort – Unsigned 16-bit integer
int – Signed 32-bit integer
uint – Unsigned 32-bit integer
long – Signed 64-bit integer
ulong – UnSigned 64-bit integer

In Floating-point types there are categories like
float - 7 digits
double – 15-16 digits

In decimal precise decimal type is with 28 significant digits.

In bool is used to declare variables to store the Boolean values, true and false .

b.Reference Types
This datatypes are used for storing references to the actual data.

Let us discuss both of them in detail

In Reference types there are types like object and string. Object datatype is the base type of all other types. In C#, all types, predefined and user-defined, reference types and value types, inherit directly or indirectly from Object. One can assign values of any type to variables of type object.

using System;
class SampleClass
{
public int r = 5;
}

class MainClass
{
static void Main()
{
object o;
o = 1; // an example of boxing
Console.WriteLine(o);
Console.WriteLine(o.GetType());
Console.WriteLine(o.ToString());

o = new SampleClass();
SampleClass classRef;
classRef = (SampleClass)o;
Console.WriteLine(classRef.r);
}
}

Output

1
System.Int32
1
5

String datatype is a sequence of unicode characters .This is a reference type, the equality operators (== and !=) are defined to compare the values of string objects, not references which helps one to compare strings more easier.

using System;
class TestClass
{
static void Main()
{
string a = “Good “;
string b = “Morning”;
Console.WriteLine( a + b );
Console.WriteLine( a + b == “Good Morning” );
}
}

Output

Good Morning
True

Newly upgraded WordPress

Justin — Sat, 09 Jan 2010 23:43:44 +0000

Have an old WordPress install? I was recently amazed at how easy it is to upgrade to the latest and greatest. The WordPress Codex has an article on how to do it here.