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.
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You should be clear on this with your family prior to the interview if
you think there is a chance it may come up. Do not say yes just to get
the job if the real answer is no. This can create a lot of problems
later on in your career. Be honest at this point and save yourself
future grief.
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real time system requires high availabity
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Start with the present and tell why you are well qualified for the position. Remember that the key to all successful interviewing is to match your qualifications to what the interviewer is looking for. In other words you must sell what the buyer is buying. This is the single most important strategy in job hunting.
So, before you answer this or any question it's imperative that you try to uncover your interviewer's greatest need, want, problem or goal.
To do so, make you take these two steps:
Do all the homework you can before the hr interview to uncover this person's wants and needs (not the generalized needs of the industry or company)
As early as you can in the interview, ask for a more complete description of what the position entails. You might say: "I have a number of accomplishments I'd like to tell you about, but I want to make the best use of our time together and talk directly to your needs. To help me do, that, could you tell me more about the most important priorities of this position? All I know is what I (heard from the recruiter, read in the classified ad, etc.)"
Then, ALWAYS follow-up with a second and possibly, third question, to draw out his needs even more. Surprisingly, it's usually this second or third question that unearths what the interviewer is most looking for.
You might ask simply, "And in addition to that?..." or, "Is there anything else you see as essential to success in this position?:
This process will not feel easy or natural at first, because it is easier simply to answer questions, but only if you uncover the employer's wants and needs will your answers make the most sense. Practice asking these key questions before giving your answers, the process will feel more natural and you will be light years ahead of the other job candidates you're competing with.
After uncovering what the employer is looking for, describe why the needs of this job bear striking parallels to tasks you've succeeded at before. Be sure to illustrate with specific examples of your responsibilities and especially your achievements, all of which are geared to present yourself as a perfect match for the needs he has just described.
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There is a "Check Mark" on the right of each question. Simply click it to remove the question from 'My Interview Questions".
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