Two Tier Client-Server Architecture-Three Tier Client-Server Architecture

Two Tier Client-Server Architecture

User Interface Programs and Application Programs run on the client side

Interface called ODBC (Open Database Connectivity ) provides an Application program interface (API) allow client side programs to call the DBMS. Most DBMS vendors provide ODBC drivers.

A client program may connect to several DBMSs.

Other variations of clients are possible: e.g., in some DBMSs, more functionality is transferred to clients including data dictionary functions, optimization and recovery across multiple servers, etc.

In such situations the server may be called the Data Server.

Three Tier Client-Server Architecture

Common for Web applications

Intermediate Layer called Application Server or Web Server:

stores the web connectivity software and the rules and business logic (constraints) part of the application used to access the right amount of data from the database server

acts like a conduit for sending partially processed data between the database server and the client.

Additional Features- Security:

encrypt the data at the server before transmission

decrypt data at the client