Client/server systems are constructed so that the database can reside on a central computer, known as a server, and be shared among several users. Users access the server through a client or server application:
In a two-tier client/server system, users run an application on their local computer, known as a client, which connects over a network to the server running SQL Server. The client application runs both business logic and the code to display output to the user, and is also known as a thick client.
In a multitier client/server system, the client application logic is run in two locations:
The thin client is run on the user's local computer and is focused on displaying results to the user.
The business logic is located in server applications running on a server. Thin clients request functions from the server application, which is itself a multithreaded application capable of working with many concurrent users. The server application is the one that opens connections to the database server and can be running on the same server as the database, or it can connect across the network to a separate server operating as a database server.
This server application can run on a Microsoft Internet Information Services (IIS) and service thousands of thin clients running on the Internet or an intranet. The server application uses a pool of connections to communicate with a copy of SQL Server. SQL Server can be…