Web Database Access Using Perl

Classic Client/Server Architecture

• Server Machines:
  • Run own copy of an operating system.
  • Run a Database Management System that manages a database.
  • Provides a Listening daemon that accepts connections from client machines and submits transactions to DBMS on behalf of the client machines.
  • Examples: Sun Sparc server running UNIX operating system. RDBMS such as Oracle Server, Sybase, Informix, DB2, MySQL, etc.
    PC with Windows NT operating system.

• Client machines:
  • Run own copy of an operating system.
  • Run one or more applications using the client machine's CPU, memory.
  • Application communicates with DBMS server running on server machine through a Database Driver
  • Database driver (middleware) makes a connection to the DBMS server over a network.
  • Examples of clients: PCs with MS Windows operating system. Forms and reports developed in: PowerBuilder, Centura, MS Access, Borland Delphi, Oracle Developer/2000, MS Visual Basic, "C" or "C++", etc.

• Advantages of client/server:
  • Processing of the entire Database System is spread out over clients and server.
  • DBMS can achieve high performance because it is dedicated to processing transactions (not running applications).
  • Client Applications can take full advantage of advanced user interfaces such as Graphical User Interfaces.

• Disadvantages of client/server:
  • Implementation is more complex because one needs to deal with middleware and the network.
  • It is possible the network is not well suited for client/server communications and may become saturated.