1. Application Development
Key Concepts

2. Concepts for Discussion
Stand-Alone Application
Client Server Architecture
2-Tier and 3-Tier Applications
Front-End & Back-End Tools

3. Stand-Alone Applications
Application & data reside on same computer
Dedicated & Single User
Powerful & economical
Examples: Calculator, MS-Word

4. Client Server Architecture
Distinguishes client systems from server systems, both of which have the processing Power.
A client application initiates a request and send it to the server ,the server waits for requests from any client, processes the request and send a reply

5. The most basic type of client-server architecture employs only two types of hosts: clients and servers.
In a DB Applications, clients are most often the user applications which initiates a communication with Servers typically database servers

9. 2-Tier & 3-Tier Applications
Instead of Fat clients and fat servers these terms can be used.
It is all about how to split the client/server applications into functional units.
These functional units can be assigned to either the client or to one or more servers.

10. In 2-tier, the application logic is either buried inside the User Interface on the client or within the database on the server (or both)
2-tier system examples: File Servers and Database Servers with stored procedure.

12. In 3-tier, the application logic (or) process lives in the middle-tier, it is separated from the data and the user interface.
3-tier systems are more scalable, robust and flexible. In addition, they can integrate data from multiple sources.
Examples: Distributed Objects and the Web.

13. 3-tier Application tier 1 - Client tier 2 - Application Server
tier 3 - Database Server

19. Front-End & Back-End Tools
A "front-end" application is one that application users interact with directly.
A "back-end" application or program serves indirectly the front-end services
Closer to the required resource or having the capability to communicate with the required resource.
The back-end application may interact directly with the front-end or a program called from an intermediate program that mediates front-end and back-end activities.

21. For Data Base Applications
Front-End tools- Vb, .Net, VC++, MS-Access etc.
Back-End Tools- MS-Access, Oracle, SQL-Server, MySQL etc.