Asynchronous JavaScript Technology and XML (Ajax)

Using JavaScript technology, an HTML page can asynchronously make calls to the server from which it was loaded and fetch content that may be formatted as XML documents, HTML content, plain text, or JavaScript Object Notation (JSON). The JavaScript technology may then use the content to update or modify the Document Object Model (DOM) of the HTML page. The term Asynchronous JavaScript Technology and XML ( Ajax ) has emerged recently to describe this interaction model.

Ajax is not new. These techniques have been available to developers targeting Internet Explorer on the Windows platform for many years. Until recently, the technology was known as web remoting or remote scripting. Web developers have also used a combination of plug-ins, Java applets, and hidden frames to emulate this interaction model for some time. What has changed recently is the inclusion of support for the XMLHttpRequest object in the JavaScript runtimes of the mainstream browsers. The real magic is the result of the JavaScript technology’s XMLHttpRequest object. Although this object is not specified in the formal JavaScript technology specification, all of today’s mainstream browsers support it. The subtle differences with the JavaScript technology and CSS support among current generation browsers such as Mozilla Firefox, Internet Explorer, and Safari are manageable. JavaScript libraries such as Dojo , Prototype , and theYahoo User Interface Library  have emerged to fill in where the browsers are not as manageable and to provide a standardized programming model. Dojo, for example, is addressing accessibility, internationalization, and advanced graphics across browsers — all of which had been thorns in the side of earlier adopters of Ajax. More updates are sure to occur as the need arises.

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Difference between Dispose and Finallize method……

The .NET garbage collector manages the memory of managed objects (native .NET objects) but it does not manage, nor is it directly able to clean up unmanaged resources. Managed resources are those that are cleaned up implicitly by the garbage collector. You do not have to write code to release such resources explicitly. In contrast, you must clean up unmanaged resources (file handles, database collections, etc.) explicitly in your code.

There are situations when you might need to allocate memory for unmanaged resources from managed code. As an example, suppose you have to open a database connection from within a class. The database connection instance is an unmanaged resource encapsulated within this class and should be released as soon as you are done with it. In such cases, you’ll need to free the memory occupied by the unmanaged resources explicitly, because the GC doesn’t free them implicitly.

Briefly, the GC works as shown below:

It searches for managed objects that are referenced in managed code.
It then attempts to finalize those objects that are not referenced in the code.
Lastly, it frees the unreferenced objects and reclaims the memory occupied by them.
The GC maintains lists of managed objects arranged in “generations.” A generation is a measure of the relative lifetime of the objects in memory. The generation number indicates to which generation an object belongs. Recently created objects are stored in lower generations compared to those created earlier in the application’s life cycle. Longer-lived objects get promoted to higher generations. Because applications tend to create many short-lived objects compared to relatively few long-lived objects, the GC runs much more frequently to clean up objects in the lower generations than in the higher ones.

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What is CDMA………

CDMA stands for “Code Division Multiple Access”. It is a multiple access technique that is used for sharing of a single frequency channel between multiple nodes in a network to facilitate their duplex communication with a single central node. This technique is used in CDMA mobile systems and also in Wireless lan. IN CDMA mobile systems, the Base Station acts as the central node of the network while the mobile units in a cell are the multiple nodes sharing a single frequency channel between them for their communication with the Base Station. Normally Frequency Division Duplexing is used in these systems i.e. two channels are used, one for downlink from Base Station to the various mobile stations and second for uplink from the mobile stations to the Base Station. In case of a wireless LAN, CDMA is used to set up a similar communication scheme between the access point of the network and the various Wireless Clients.

For example: – Let three sources A, B, C are transmitting their signals to a central node D in a network using CDMA technique. Now if D wants to recognize the signal from A, then it will decode the whole received signal using the pseudorandom sequence unique to A. After decoding, only the original signal of A will be present while the signal from B and C will just appear as noise to the system. This noise puts an upper limit on the capacity of a CDMA system. In the reverse mode, If D wants to transmit a signal to A; it will encode the signal with the pseudorandom sequence unique to A. All the three nodes A, B, C will receive the signal as they are sharing the channel. But the signal on decoding will only appear useful to A while it will appear as noise to B and C.

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GSM (Global System for Mobile communication)

GSM (Global System for Mobile communication) is a digital mobile telephony system that is widely used in Europe and other parts of the world. GSM uses a variation of time division multiple access (TDMA) and is the most widely used of the three digital wireless telephony technologies (TDMA, GSM, and CDMA). GSM digitizes and compresses data, then sends it down a channel with two other streams of user data, each in its own time slot. It operates at either the 900 MHz or 1800 MHz frequency band.

Mobile services based on GSM technology were first launched in Finland in 1991. Today, more than 690 mobile networks provide GSM services across 213 countries and GSM represents 82.4% of all global mobile connections. According to GSM World, there are now more than 2 billion GSM mobile phone users worldwide. GSM World references China as “the largest single GSM market, with more than 370 million users, followed by Russia with 145 million, India with 83 million and the USA with 78 million users.”

Since many GSM network operators have roaming agreements with foreign operators, users can often continue to use their mobile phones when they travel to other countries. SIM cards (Subscriber Identity Module) holding home network access configurations may be switched to those will metered local access, significantly reducing roaming costs while experiencing no reductions in service.

GSM, together with other technologies, is part of the evolution of wireless mobile telemmunications that includes High-Speed Circuit-Switched Data (HSCSD), General Packet Radio System (GPRS), Enhanced Data GSM Environment (EDGE), and Universal Mobile Telecommunications Service (UMTS).

From a user’s point of view, the actual standard is not really important, with two caveats: first, you can’t use a phone that uses one standard with the provider that uses the other standard; second, if you travel internationally, a GSM phone is almost a must.

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HTC Sensation vs Apple iPhone 4

One of the latest HTC phones is the Sensation. It is really inevitable that it gets compared to the iPhone 4 as it is the most popular smartphone nowadays and is considered to be the benchmark. The main difference between the Sensation and the iPhone 4 is the processor that they have. The iPhone 4 has a single core A4 processor that is underclocked to 800Mhz to save power. In contrast, the Sensation has a dual core processor on the Snapdragon chipset that runs at an even higher 1.2Ghz. A faster processor usually means that the Sensation is capable of running more demanding applications. The Sensation should also benefit significantly with the dual core processor in running apps in the background.

With the increased processing power of the two cores, the Sensation is capable of recording 1080p videos; something that the iPhone 4 and its weaker processor is not able to do, resorting to 720p maximum resolution. Even when it comes to still pictures, the Sensation manages to do better with its 8 megapixel camera coupled with two LED flashes. A lot better than the 5 megapixel camera and single LED flash on the iPhone 4.

Summary:

1.The Sensation has a dual core processor while the iPhone 4 doesn’t
2.The Sensation can record 1080p video while the iPhone 4 can only record 720p
3.The Sensation has a higher resolution camera than the iPhone 4
4.The Sensation runs on Android while the iPhone 4 has iOS
5.The Sensation relies on memory cards while the iPhone 4 relies on internal storage
6.The Sensation has an FM radio while the iPhone 4 doesn’t.

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Connect two computer via Wi-Fi in windows 7………

 

  • Click on the icon that shows the wi-fi connection and select the Open Network and Sharing Center.

  • select the Set up a connection or network at the center.

  • Choose “Set up a wireless ad hoc (computer-to-computer) network” and click Next. move down for selecting that.

  • You will now see a window that says “Set up an ad hoc network (sometimes called a computer-to-computer network) is a temporary network used for sharing files, presentations, or an Internet connection among multiple computers and devices. Computers and devices in ad hoc networks must be within 30 feet of each other. If you’re currently connected to a wireless network, you might be disconnected when you set up this network.” Click Next.

  • After that you will have to give the name to your network and the select the security type and then give the password.(I use niks-network as network name, WEP for security type and password 12345) Click Next. It is optional to check “Save this network” to save it as wireless network profile. If not, you’ll need to recreate it again the next time after a reboot

  • Wait for Windows 7 to set up the temporary ad-hoc network

  • Once it has finished setting up, it’ll tell you that the network is ready to use.

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Advantages and disadvantages of Computer……..

Some Advantages are : communication is improved, pay bill’s online, people have access to things they would not have had before (for instance old people who cannot leave the house they can buy groceries online) Computers make life easier.

Some of the disadvantages are: scams, fraud, people not going out as much, we do not yet know the effects of computers and pregnancy or the emissions that computers make,. bad posture from sitting too long at a desk, repetitive strain injuries and the fact that most organisations expect everyone to own a computer, viruses and spyware.

mainly people benefit from it in the sense that it makes doing things a lot easier.
one is having the internet than to search in the books at the library which takes ages.
another is connecting with friends in the shortest period of waiting time.
third, is having your reports printed out than having to write it. [very beneficial for those with bad hand writing like me! lol]
pc has programs that help encoding and computing data a lot easier and faster.

Disadvantages:
people become dependent to it.
some get addicted in using it that they fail to go out and have sunlight shine on them.
a man who had habitually sit in front of a pc develop health problems like back aches and eye damage.

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Arrays in C# .NET

The variables you have been working with so far have only been able to hold one value at a time. Your integer variables can only hold one number, and your strings one chunk of text. An array is a way to hold more than one variable at a time. Think of a lottery programme. If you’re just using single variables, you’d have to set up your lottery numbers like this:

lottery_number_1 = 1;
lottery_number_2 = 2;
lottery_number_3 = 3;
lottery_number_4 = 4;
etc

Instead of doing that, an array allows you to use just one identifying name that refers to lots of numbers.

How to set up an Array

You set up an array like this:

int[ ] lottery_numbers;

So you start with the type of array you need. In the line above, we’re telling C# that the array will hold numbers (int). After the array type, you need a pair of square brackets. There should be no space between the array type and the first bracket. After the square brackets then type a space, followed by the name you want to use for your array,lotter_numbers in our case.

If your array needs to hold floating point numbers, you’d set your array up like this:

float[ ] my_float_values;

An array that needs to hold text would be set up like this:

string[ ] my_strings

So it’s pretty much just like setting up a normal variable, except you type a pair of square brackets after int, or float, or string.

The next thing you need to do is to tell C# how big your array will be. The size of an array is how many items it is going to hold. You do it like this:

lottery_numbers = new int[49];

So the name of your array goes before an equals sign ( = ). After the equals sign, you type the word new. This tells C# that it is a new object. After a space, you need the array type again (int for us). Next comes some square brackets. This time, however, you type the size of the array between the brackets. In the code above, we’re saying that the array will hold 49 numbers.

So the two lines would be:

int[ ] lottery_numbers;
lottery_numbers = new int[49];

If you prefer, you can put all that on one line:

int[ ] lottery_numbers = new int[49];

But you’re doing two things at once, here: before the equals sign, you’re telling C# that you want to set up an array; after the equals sign, you’re creating a new array object of a particular size.

Assigning values to your arrays

So far, you have just set up the array, and created an array object. But the array doesn’t yet hold any values. (Well it does, because C# assigns some default values for you. In the case of int arrays, this will be just zeros. But they’re not your values!)

To assign a value to an array, you use the square brackets again. Here’s the syntax:

array_name[ position_in_array ] = array_value;

So you start with the name of your array, followed by a pair of square brackets. In between the square brackets, you need a position in your array. You then type an equals sign, and the value that is going in that position. Here’s an example using our lottery numbers:

lottery_numbers[0] = 1;
lottery_numbers[1] = 2;
lottery_numbers[2] = 3;
lottery_numbers[3] = 4;

First of all, note that the first position in a C# array is zero, and not 1. This is slightly confusing, and can trip you up! But we’re telling C# to assign a value of 1 to the first position in the array, a value of 2 in the second position, a value of three in the third, and so on. Just bear in mind that array positions start at 0.

Another way to assign values in array is by using curly brackets. If you only have a few values going in to the array, you could set it up like this:

int[] lottery_numbers = new int[4] { 1, 2, 3, 4 };

So we’ve set up the array the same way as before – all on one line. This time, we have a pair of curly brackets at the end. In between the curly brackets, type the values for your array, and separate each value with a comma.

In the next lesson, you’ll see how to work with arrays and loops.

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Object-oriented database management system (OODBMS)……..

An object-oriented database management system (OODBMS) helps programmers make objects created in a programming language behave as a database object. Object-orientedprogramming is based on a series of working objects. Each object is an independently functioning application or program, assigned with a specific task or role to perform. Anobject-oriented database management system is a relational database designed to manage all of these independent programs, using the data produced to quickly respond to requests for information by a larger application.

When you integrate database capabilities with object programming language capabilities, the result is an object-oriented database management system or ODBMS¹. An ODBMS makes database objects appear as programming language objects in one or more existing programming languages. Object database management systems extend the object programming language with transparently persistent data, concurrency control, data recovery, associative queries, and other database capabilities.

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How to make Calci app in Windows Phone7………

This is window to show how the module look like.

Now,

Add a code on Add, Subtract, Multiply, Divide button written below.

private void button1_Click(object sender, RoutedEventArgs e)
{
try
{
int x = Convert.ToInt32(txt1.Text);
int y = Convert.ToInt32(txt2.Text);
int z = x + y;
txt3.Text = Convert.ToString(z);
}
catch
{
}

}

private void button2_Click(object sender, RoutedEventArgs e)
{
try
{
int x = Convert.ToInt32(txt1.Text);
int y = Convert.ToInt32(txt2.Text);
int z = x – y;
txt3.Text = Convert.ToString(z);
}
catch
{
}
}

private void button3_Click(object sender, RoutedEventArgs e)
{
try
{
int x = Convert.ToInt32(txt1.Text);
int y = Convert.ToInt32(txt2.Text);
int z = x * y;
txt3.Text = Convert.ToString(z);
}
catch
{
}
}

private void button4_Click(object sender, RoutedEventArgs e)
{
try
{
int x = Convert.ToInt32(txt1.Text);
int y = Convert.ToInt32(txt2.Text);
int z = x / y;
txt3.Text = Convert.ToString(z);
}
catch
{
}
}

And Enjoy Calci app….

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