Systems Architecture Dialogue

Hi Sam . How are you ? Friend I should have listened to you when you used to explain me about "Computer System Architecture". I never knew I will have to come across this topic in my MBA curriculum . But better late than never. We the students of VGSOM are highly privileged to have our teacher who teaches us to "Consume n Create", I have consumed the knowledge of "Systems Architecture" and going to create a blog for the same . You being a Computer Science guy could guide me well in this before I create .

Initially it was like Latin n French for me. I still remember the college days when you asked me about "What is System Architecture?" and I used to be dumb faced. But today I will explain you everything what I know.  My teacher has taught me this subject in such an interesting n practical way that I really find myself privileged. It is really good to understand how the application actually works. Being a technical student and in this tech savvy era one must learn about the basics of "Systems Architecture". Let me cite an example , most of us have Gmail account but how many of them have ever cared to understand how Gmail provides authentication ,how it has new features installed in the application which is visible to everybody.  

Let me start with What is Systems Architecture?

Systems Architecture is a conceptual model that defines the architecture as well as behavior of the system. It creates a blueprint for the design with the necessary specifications for the hardware, software, people and data resources. There are mainly 4 types of Systems Architecture:
1. One tier Architecture
2. Two tier Architecture
3. Three tier Architecture
4. Multiple tier Architecture

I will briefly explain you about these architecture now.Starting with One tier Architecture:

One tier Architecture : In one tier architecture both the application and the data are on the same system. It is obsolete nowadays as it has many drawbacks. It has no scope for any enhancement or growth. This is a less secure architecture as the internet must have access to the internal database and resources. Let  me explain you pictorially.

PL: Presentation Logic
                                                                             BL: Business Logic

You are not getting bored Sam. Right? Please stop if I start boring. I got a reply , No, Reecha you are doing a great job. I was elated. Ok so now lets move on to Two Tier Architecture which originated because of the drawbacks of one tier architecture.


Two Tier Architecture: It is very commonly known as Client/Server Architecture. Now you will ask me what is Client Server Architecture. Let me explain , it is a computing model which acts as a distributed system and distributes tasks between the providers of the resource or service which is SERVER and the one who requests for a service which is known as CLIENT.  Pictorially it can be represented as :

In this architecture information process is splitted into two parts. Here the communication is directly between the client and the server. There is no intermediates. The user interface along with Business logic is placed at user's desktop environment and the database is on a different system which serves different clients. the  Here the Business Logic needs to be repeated in each client system . Client machines are connected to the database server using the TCP/IP protocol. The database used in the server is Oracle/SQL/DB2/mySQL.
It has advantages of convenient user interface but has the disadvantage of bottleneck as it requires high bandwidth and also the maintenance of the distributed software is difficult as it needs to be done on every system wherever the application is installed. There comes the idea of 3 tier architecture.

However this architecture is not advised at enterprise level.

Three tier architecture: The three tier architecture can be displayed as :

                                              

  

It is very clear from the name and diagram itself that there are three layers i.e. Client ,business and data tier. 

Client layer - User Interface 

Business layer- Enables fast communication between Client and Data tier. It provides business process logic and data access

Data layer-  It has database

Here the business logic is maintained independent of the client application and database. This gives the flexibility of maintenance and  enhancement of the software.  

• In traditional Visual Basic 6.0 , it supports 3-tier implementation with DCOM.
• In Visual Basic (DotNet), it is provided with Remoting and Web Services.
• Java supports 3-tier architecture with RMI.  

This architecture has several advantages like  fast communication , good performance and easy maintainability.

The best example of 3 tier is ERP ,SAP and many more.

Coming to the fourth category of architecture that is Multi-tier architecture.

Multi-tier Architecture: It is widely known as n-tier architecture. In this type of architecture the client layer and the data layer remain untouched however the business layer could be divided into different layers for more flexibility. For n-tier programming, you need to package up the data in some sort of transportable form called "dataset" and fly them over the wire. Here the risk is there as the application needs to be web enabled. The most widely used n-tier architecture is 3-tier architecture.

I think I should come to an end now Sam. Are you happy Sam with the description I gave you about the different types of architecture. I hope you like it and if you have any queries please post your comments on the blog which I will be creating for it. Thanks Sam for being a patient listener. Please do "Create" for any stuff which you "Consume" and  think would be helpful for others. So keep 'Learning n Sharing.'  

Bye Sam. 

See you soon with another informative stuff.