Web 2.0 is a trend in the use of World Wide Web technology and web design that aims to facilitate creativity, information sharing, and, most notably, collaboration among users. These concepts have led to the development and evolution of web-based communities and hosted services, such as social-networking sites, wikis, blogs, and folksonomies (the practice of catgorising content through tags). Although the term suggests a new version of the World Wide Web, it does not refer to an update to any technical specifications, but to changes in the ways software developers and end-users use the internet.

Together two or more partners can work together to make a perfect picture of something that they all find inspiring or beautiful.

In n-tier architecture the entire application is divided in several pieces. These pieces can be logical or physical. Each piece performs a specific task such as displaying user interface or data access. There can be any number of tiers or layers of such pieces. Hence, the name n-tier (Note that many times the terms tier and layer are used interchangeably). However, most commonly applications have 3 distinct tiers or layers. They are:

• Presentation Layer
• Business Logic Layer
• Data Access Layer

As you can guess, presentation layer is nothing but a piece of software that deals with user interface of your application. Displaying data to the end user and allow them to interface with it is the core functionality of this layer.

In most of the cases the data entered by the end user needs some kind of validation or further processing. This is the responsibility of Business Logic Layer.

Finally, your application data needs to be stored and retrieved in some data store (RDBMS, XML etc.). This task is handled by Data Access Layer.

In short, the process works like this:

• User requests for some application data.
• The data access layer retrieves the data and is forwarded to the presentation layer via business logic layer. Sometimes data access layer gives this data directly to presentation layer.
• Presentation layer receives the data to be displayed via business logic layer.
• The user changes the data and initiates the appropriate action (such as insert, or update).
• The business logic layer validates the data submitted by the user.
• If the data is valid it is handed over to data access layer for updating into the database.

Advantages of N-Tier ArchitectureAt first glance this division of tasks may seem to be unnecessary. However, it gives following benefits:

• The applications gets divided in logically isolated pieces reducing tight coupling between the UI, business processes and database.
• Change in the underlying database and data access methods do not have any effect on the presentation layer or client application.
• Client application no longer has SQL statements embedded in it. This makes it de-coupled from rest of the application.
• Table and column names can be effectively eliminated from the client-side code.
• The client application is unaware from where data comes (location transparency).
• It becomes easier to modify or extend your application, without breaking or recompiling the client-side code.

The downside of n-tier architecture is that you need to create many isolated classes and pieces of software. However, benefits of n-tier applications will far outweigh its disadvantage.

The .NET Framework class library is a library of classes, interfaces, and value types that are included in the Windows Software Development Kit (SDK). This library provides access to system functionality and is designed to be the foundation on which .NET Framework applications, components, and controls are built.

refer http://msdn.microsoft.com/en-us/library/ms229335.aspx

 

TRAPS:  This is another question that pits two values, in this case loyalty and honesty,  against one another.

BEST ANSWER:  Remember the  rule stated earlier:  In any conflict between values,  always choose integrity.

Example:  I  believe that when evaluating anything, it's important to emphasize the positive. What do I like about this idea?"

"Then, if you have reservations, I certainly want to point them out, as specifically, objectively and factually as I can. "

"After all, the most important thing I owe my boss is honesty.  If he can't count on me for that, then everything else I may do or say could be questionable in his eyes." Not sure about that one.

"Of course, if he overrules me and says, 'no, let's do it my way,' then I owe  him my full and enthusiastic support to make it work as best it can."

 

Software that provides services to access the Internet, an intranet, or an extranet. A Web server hosts Web sites, provides support for HTTP and other protocols, and executes server-side programs (such as CGI scripts or servlets) that perform certain functions. In the J2EE architecture, a Web server provides services to a Web container. For example, a Web container typically relies on a Web server to provide HTTP message handling. The J2EE architecture assumes that a Web container is hosted by a Web server from the same vendor, so it does not specify the contract between these two entities. A Web server can host one or more Web containers.