Once I was talking with a friend of mine over the phone and my younger brother overheard something which intended him to ask me what I was talking about…
Shubham: Hey Di,I heard you saying something called tiers, but I am confused, your conversations hardly mention anything about train journeys or vacations; what are these tiers?
Me: Ohh! How can I even think of vacations now? My Information Systems Engineering course urges me to take a test shortly; so was discussing the syllabus.
Shubham: Ehh! I have heard about mechanical, electrical or even civil engineering… Information Systems Engineering? What’s that? Is there at all any formal course?
Me: Very much Shubham! I.S Engineers apply knowledge of engineering and scientific principles, computer technologies and human cognition to design, implement, and manage information systems. He must be called upon to design and develop database, develop system architecture, establish systems standards, integrate an information system with varied data sources and networks. He has a lot of work man…Don’t underestimate this subject!
Shubham: Hmm…Sounds interesting. Develop database? Means, building a repository of the basic data from where data can be imported and processed for future use. But what are these tiers for?
Me: Basically these tiers are the types of architectures by which database are connected with the application programs.You must be knowing that data is being processed by an application program which helps it to fetch the required data from the repository.
Shubham: So how many tiers are there in all?
Me: Three…When we use the same computer to fetch data and work on it, for eg. If we use SQL server in order to generate reports, we are actually using first tier architecture.
Shubham: But is it possible to keep a dedicated terminal for each user?Doesn’t it add to cost?
Me: Yes it does! So we have two-tier architecture for that. Here, the repositories and applications don’t reside on the same machine; though an user is able to access the data and update it from his own computer.
Shubham: Fine! Then what are three-tiered one?
Me: When the architecture is further generalised and distributed we take it to be third tier. Here there is a database server and application server. Users sitting on the terminal calls for some outputs by the help of applications from application servers.
Shubham: But isn’t it a herculean task? A number of persons logged into a single application updating all at same time!
Me: Yeah it is. But not as much as you are thinking it to be. When one person is updating any portion of the database; the others gets only the permission to read it. It remains locked till the first person is done with his updation.There lies the importance of the systems engineering guy who is to program this accordingly.
Shubham: O.k., but is it practically possible to have such a system where users are sitting not at a particular place but are placed around the globe?
Me: Hey! What is Internet there for? Internet does the needful. Suppose you are booking an air ticket online. You are precisely calling for the reservations details from a specific database which resides elsewhere with the help of your internet browser… This we call it a multi-tier system.
Shubham: Wow,I didn’t even know that I actually use some kind of database in my day to day life and that Systems engineering is such a pertinent course now a days! Really Di, there’s so much to learn so much to know…
good …
Comment by prithwis — February 5, 2008 @ 6:20 am