TIRE Architectures.

Three-tier or multi-tier architecture is often used when describing how clients connect to database servers. But what does it all mean?

Let me try to explain this in non-technical terms (or as close to it I can get).

Software

Let’s first take a look how a database software program (the software) works.

There are three major tiers to the software:

-User Interface (UI). This is what you see when you work with the software. You interact with it. There  might be buttons, icons, text boxes, radio buttons, etc. The UI passes on clicks and typed information to the Business Logic tier.

-Business Logic (BL). The business logic is code that is executed to accomplish something. When a user clicks a button it will trigger the BL to run some code. The BL can send information back to the UI, so the user can see the result of clicking a button or typing something in a field. For instance when you enter something in a cell in Excel, the BL will recalculate other cells once you hit Enter and the UI will present the new information to you. The BL also needs to be able to store and retrieve data and that is handled in the Database tier.

-Database (DB). The database is where the data is stored and where the BL can retrieve it again.

1-Tier Architecture

This architecture has the UI, the BL, and the DB in one single software package. Software applications like MS Access, MS Excel, QuickBooks, and Peachtree all have the same in common: the application handles all three tiers (BL, UI, and DB). The data is stored in a file on the local computer or a shared drive. This is the simplest and cheapest of all the architectures, but also the least secure. Since users have direct access to the files, they could accidentally move, modify, or even worse, delete the file by accident or on purpose. There is also usually an issue when multiple users access the same file at the same time: In many cases only one can edit the file while others only have read-only access.

Another issue is that 1-tier software packages are not very scalable and if the amount to data gets too big, the software may be very slow or stop working.

So 1-tier architecture is simple and cheap, but usually unsecured and data can easily be lost if you are not careful.

2-Tier Architecture

This architecture is also called Client-Server architecture because of the two components: The client that runs the application and the server that handles the database back-end. The client handles the UI and the BL and the server handles the DB. When the client starts, it establishes a connection to the server and communicates as needed with the server while running the client. The client computer usually can’t see the database directly and can only access the data by starting the client. This means that the data on the server is much more secure. Now users are unable to change or delete data unless they have specific user rights to do so.

The client-server solution also allows multiple users to access the database at the same time as long as they are accessing data in different parts of the database. One other huge benefit is that the server is processing data (DB) that allows the client to work on the presentation (UI) and business logic (BL) only. This mean that the client and the server are sharing the workload and by scaling the server to be more powerful than the client, you are usually able to load many clients to the server allowing more users to work on the system at the same time and at a much greater speed.

3-Tier Architecture

In this architecture all three tiers are separated onto different computers. The UI runs on the client (what the user is working with). The BL is running on a separate server, called the business logic tier, middle tier, or service tier. Finally the DB is running on its own database server.

In the client-server solution the client was handling the UI and the BL that makes the client “thick”. A thick client means that it requires heavy traffic with the server, thus making it difficult to use over slower network connections like Internet and Wireless (4G, LTE, or Wi-Fi).

By introducing the middle tier, the client is only handling presentation logic (UI). This means that only little communication is needed between the client and the middle tier (BL) making the client “thin” or “thinner”. An example of a thin client is an Internet browser that allows you to see and provide information fast and almost with no delay.

As more users access the system a three-tier solution is more scalable than the other solution because you can add as many middle tiers (running on each own server) as needed to ensure good performance (N-tier or multiple-tier).

Security is also the best in the three-tier architecture because the middle tier protects the database tier.

There is one major drawback to the N-tier architecture and that is that the additional tiers increase the complexity and cost of the installation.

	1-Tier	2-Tier	Multi-Tier
Benefits	Very simple Inexpensive No server needed	Good security More scalable Faster execution	Exceptional security Fastest execution “Thin” client Very scalable
Issues	Poor security Multi user issues	More costly More complex “Thick” client	Very costly Very complex
Users	Usually 1 (or a few)	2-100	50-2000 (+)

Source : http://blog.simcrest.com/

Framework

A framework, or software framework, is a platform for developing software applications. It provides a foundation on which software developers can build programs for a specific platform. For example, a framework may include predefined classes and functions that can be used to process input, manage hardware devices, and interact with system software. This streamlines the development process since programmers don't need to reinvent the wheel each time they develop a new application.

A framework is similar to an application programming interface (API), though technically a framework includes an API. As the name suggests, a framework serves as a foundation for programming, while an API provides access to the elements supported by the framework. A framework may also include code libraries, a compiler, and other programs used in the software development process.

Several different types of software frameworks exist. Popular examples include ActiveX and .NET for Windows development, Cocoa for Mac OS X, Cocoa Touch for iOS, and the Android Application Framework for Android. Software development kits (SDKs) are available for each of these frameworks and include programming tools designed specifically for the corresponding framework. For example, Apple's Xcode development software includes a Mac OS X SDK designed for writing and compiling applications for the Cocoa framework.

In many cases, a software framework is supported natively by an operating system. For example, a program written for the Android Application Framework will run on an Android device without requiring other additional files to be installed. However, some applications require a specific framework in order to run. For example, a Windows program may require Microsoft .NET Framework 4.0, which is not installed on all Windows machines (especially PCs running older versions of Windows). In this case, the Microsoft .NET Framework 4 installer package must be installed in order for the program to run.

NOTE: While frameworks generally refer to broad software development platforms, the term can also be used to describe a specific framework within a larger programming environment. For example, multiple Java frameworks, such as Spring, ZK, and the Java Collections Framework (JCF) can be used to create Java programs. Additionally, Apple has created several specific frameworks that can be accessed by OS X programs. These frameworks are saved with a .FRAMEWORK file extension and are installed in the /System/Library/Frameworks directory. Examples of OS X frameworks include AddressBook.framework, CoreAudio.framework, CoreText.framework, and QuickTime.framework.

Source : http://techterms.com

Auto Refresh Code In HTML

Auto Refresh Code in HTML using JavaScript, meta tags and JQuery

                There are several ways to refresh the CURRENT WEB page or FRAME or Specific HTML element (any specific Div or Span or any HTML element) after a given time interval, that we can refresh any specific part/element of HTML page without reloading the complete page.

--> Using JavaScript.

--> Using meta tags.

--> Using JQuery.

JavaScript:

             You can refresh a web page using JavaScript location.reloadmethod. This code can be called automatically upon an event or simply when the user clicks on a link.

By Simply click the Refresh link.

                        <a href = "javascript:location.reload(true)">Refresh Page</a>

Refresh the page automatically after a given time period

Try it.

<html>

<head>

<script type="text/JavaScript">

function AutoRefresh() {

setTimeout("location.reload(true);", 1000); // this will reload page after every 1 sec

}

</script>

</head>

<body onload="AutoRefresh();">

<p>This page will refresh every 5 seconds.</p>

</body>

</html>

Note: 1000 = 1 sec, if you want to 5 sec 1000*5 = 5000 ie., 5 sec

meta tags :

            

                 Meta refresh is a method of instructing a web browser to automatically refresh the current web page or frame after a given time interval, using an HTML meta element with the http-equiv parameter set to "refresh" and a content parameter giving the time interval in seconds. It is also possible to instruct the browser to fetch a different URL when the page is refreshed, by including the alternative URL in the content parameter. By setting the refresh time interval to zero (or a very low value), this allows meta refresh to be used as a method of URL redirection.

Examples

Place inside <head> to refresh page after 5 seconds:

<meta http-equiv="refresh" content="5">

Redirect your web Page(Eg: http://example.com/) after 5 seconds:

<meta http-equiv="refresh" content="5; url=http://example.com/">

Redirect to http://example.com/ immediately:

<meta http-equiv="refresh" content="0; url=http://example.com/">

Jquery:

Refresh HTML element (Div/Span) on HTML page after specific time:

In this part we will use JQuery to perform the task, as its provides few of the best options that can help us.

Suppose you have a span with ID as result similar to following:

<span id = “result”></span>

Then the JQuery code will be as follows:

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>

<script>

function autoRefresh_div()

{

$("#result").load("example.html");// a function which will load data from other file after x seconds

}

setInterval('autoRefresh_div()', 5000); // refresh div after 5 secs

</script>

Example :

<html>

<head>

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>

<script>

function autoRefresh_div()

{

$("#result").load("example.html");// a function which will load data from other file after x seconds

}

setInterval('autoRefresh_div()', 5000); // refresh div after 5 secs

</script>

</head>

<body>

<span id = "result"></span>

</body>

</html>

Display the current time (the setInterval() method will execute the function once every 1 second, just like a digital watch). 

<html>

<body>

<p>A script on this page starts this clock:</p>

<p id="demo"></p>

<script>

var myVar = setInterval(function(){ myTimer() }, 1000);

function myTimer() {

    var d = new Date();

    var t = d.toLocaleTimeString();

    document.getElementById("demo").innerHTML = t;

}

</script>

</body>

</html>

Sample Output :

1(One) Way To Access Blocked Sites

           Is you school, college or office blocking you from getting on social network sites like Friendster, Facebook, Myspace, Bebo, Hi5, Orkut, etc? Here One way you can bypass the restrictions and surf like normal, but please check with your local authorities before using them. We will not held any responsibility if you’ve breach the regulations of any.

Using Tor Browser...

What is the Tor Browser?

          The Tor software protects you by bouncing your communications around a distributed network of relays run by volunteers all around the world: it prevents somebody watching your Internet connection from learning what sites you visit, it prevents the sites you visit from learning your physical location, and it lets you access sites which are blocked.

The Tor Browser lets you use Tor on Windows, Mac OS X, or Linux without needing to install any software. It can run off a USB flash drive, comes with a pre-configured web browser to protect your anonymity, and is self-contained.

Official Web Site : https://www.torproject.org/projects/torbrowser.html.en

Download the latest tor tarball as your requirement like you OS(Operating System) example windows OS 64/34 bit/Mac OS/Linux etc? from Official Web Site(Use above link).

For Windows OS Users :

After Downloading the package extract it and click the tor.exe file, that's it.

For Linux OS Users :

• After Downloading the package, open a terminal(ctrl+alt+t) window and navigate to the directory you downloaded it to
• run this command: tar -xvf <NAME_OF_TARBALL>
• use cd to go into the created directory (ex: /opt/tor-browser_en-US/Browser)
• run the start script with ./start_tor_browser.sh

Good Luck Friends...