This is a conversation between my best friend and me.
(The phone rings : tring tring…tring tring…. Tring tring…. Tring
tring)
Me : “Hello”!
Ria: “Finally! You picked up. Whats wrong with your phone? I
called you about a hundred times yesterday. To tell you that I have booked
tickets for ‘The Dark Knight Rises’. 10
am show today at PVR. Don’t even think of making excuses. The whole group is
coming”
Me : “Ria, chill girl! I’ll try to come but no promises.
Got an MIS assignment to submit before 10 am today. If I complete that by 9 am,
I’ll come ok.”
Ria : “NO WAY! Whatever is your assignment, I’ll help you with
it. What is it on?”
Me : “On your favourite topic: System Architecture.” Come over
and teach me the basics. That way I can get it doon soon and we’ll be off for the
movie by 9”
Ria : “Coming right away”
(Knock knock…. I let Ria in and we start off with my
assignment)
Me : “Ya, I just started with the system architecture! What exactly
does single tier, two-tier, three tier etc mean? "
Ria : “Well, single tier architecture was mainly used in
times of huge mainframes. All the processing was done on a single computer and
all the resources are attached to the same computer. The advantages of such a
system would be that its simple and efficient but the cost of such a a machine
would be very high.
Me : So an ideal pictorial representation would be like
this?
Ria : Yep! Now in a two-tier architecture, the user system
interface is usually located on the users desktop environment and the database
management services are usually in a more powerful machine that serves many
clients. But the problem with this model was that the connections were very
expensive.
Me : How secure is this? Can
multiple users access the database at the same time?
Ria : As 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. Also users are unable to change or delete data unless they have
specific user rights to do so. And yes, multiple users can access the database
a at the same time as long as they are accessing data in different parts of the
database.
Me : Hmmm! So let me guess –
the three tier architecture will have three layers and the data will probably
be even more secure in this model?
Ria : True. With the advent
of internet, many people jumped to the conclusion that the days of mainframes were back. The Client/ Server model had obviously failed, PC’s had failed and
Windows were on its way out. A host of thin client applications were developed
and thus the 3-tier architecture was born. This is basically the traditional client/
server model run from a web server.
Me : So, its something like
a three way interaction in a client server environment? Wherein the user
interface is stored in the client, the data is stored in the database server and
the Business application logic is stored in yet another server or something?.
Ria : Good! Your catching on. Also remember, as more users
can access the system, a 3-tier system is more scalable than the other
solutions because we can add multiple middle tiers, each running on their own server’s, to ensure a good performance ( N-tier ) and there is increased
security as the database is hidden form the client. But on the downside, it is
more difficult to build than a 2-tier model.
Me : Got it. Give me half an hour. Let me just post this on
my blog. And off we go for Dark Knight Rises.
