Understanding the System Architecture with my friend

This was an interaction between me and my friend in Cafe Coffee Day regarding system architecture. My friend works in a Corporate Gifting and Brand Consulting firm who wants to know about system architecture.

Moi: Hey buddy, today we had an interesting session on System Architecture.

Friend: What is System Architecture, what is it's need and can it be included in our company ?

Moi: Buddy, in modern day business be it an IT company or a non IT company, computers have a chief role to play. And the organization of the data and applications required for the business to function normal is a must. With more and more data and applications on the run it is mandatory to choose the methodology in which these data and applications need to structured and organized. Hence, system architecture is a conceptual model that deals with the structure and behavior of the system that contains both data and application.

Friend: How is it varied from past methodologies of data and application management?

Moi: It is similar to the past methodologies, for instance in previous years that is in the early 90's bill books and vouchers were more prominent for data management. But as time proceeded, computers became more prominent. To ensure proper security to data and applications and reduce process timings of data in applications, system architecture played a major role.

Friend: How can data and applications be managed when the quantity of data and applications increases, for example our company started with 4 employees but now their are nearly 60,000 employees so how can this be made feasible with computers ?

Moi: True, when the number of data and applications are less then the companies go for a model known as the "Single Tier Model". In Single Tier Model the data and applications are contained in a single computer though they were separated logically and the clients are needed to access their data from the single machine. This system was preferred when the data and applications were less. But when the data and applications increased it was practically impossible to store all the data in a single machine and update those data and applications. For this reason the companies went in for a higher level of models.

Take a look at the single tier model pic:

Friend: Please, explain me the higher models of System Architecture!!!

Moi: Sure buddy, that's how interesting this subject turns out to be. Two tier model also known as the Client-Server Model has the data to be loaded in a server away from the client machines were the applications are installed. In this case since the data is accessed from a different machine using software's like Oracle, SQL, etc... the processing time is less for the applications. The client machine and the server are connected through a LAN cable which is used to establish TCP/IP protocols for communication between the systems. Also if the data needs to be updated it can be done directly on the server and it can be accessed by the clients. But, the main disadvantage is if the applications needs to be updated then the model possess a serious problem since it needs to be done from the clients end and if the applications are outdated then the performance levels may dip as the operations done by the applications are done from the clients end. Also greater bandwidth is required which slows the performance of other systems in the LAN.

Take a look at the two tier model pic:

To overcome the the disadvantages of two tier architecture the three tier architecture was created. In this the Application and data are placed in servers and only the GUI is in the client end. So the minimum transfer of data takes place hence less bandwidth usage and also the application and data can be updated from the server directly. Here more users can be accessing without any performance issues hence we go for WAN for ensuring TCP/IP handshaking signals. 

Take a look at three tier model pic:

The three tier was soon replaced by the multi tier model were the software in the client location were replaced by web browsers. Hence we now have the application, data and the web server in different servers. So when the data is sent in from the web browser from the client end the web server processes the received data and sends it to the application which in turn sends and receives the processed data from the data server before displaying it to the client. Here the business logic is centrally located and only the presentation is local. WAN is replaced by internet for sending in the TCP/IP protocols. Hence the tendency for hacking is increased in this case since the WAN which was private is replaced by internet which is public. Also web browsers are necessary for accessing the internet.

Take a look at multi tier model pic:

Friend: How is the security increased in the Multi Tier Model and also name few industry applications of this models ?

Moi: Security is increased in the Multi Tier Model by ensuring that a Firewall is placed between the client machines and the processing machines. This blocks the hackers who try to access the information of the clients. This is a must for applications like Payment Gateways, internet banking, etc...Applications can be ERP application like SAP, people soft, etc...

Friends: Today definitely I have learnt system architecture and will sure talk to the concerned persons to upgrade the model followed in our company...Thanks a lot dude.

Moi: Sure, do it fast..and you are always welcome..Bye :)