How is a business application architected?

A Business Application System is made of the following fundamental services : 1) Presentation services 2) Application services 3) Database services Presentation Services : A presentation service performs the process of formatting the GUI(Graphical User Interface). This offloads the tasks to be performed by the other two services. An example for presentation server is Windows PC. Application Services : An application service performs the task of managing business processes.This includes processing business data obtained from the database. They are also referred to as Middle tier servers. A good example of application server is Websphere ,Apache,Oracle HTTP.This relieves the database layer from the burden of data processing. Forms Client Applet Oracle Applications : The Forms client applet is a general-purpose presentation applet.Forms client applet supports all Oracle Applications Forms-based products.Applet includes applications with customization and extensions The Forms client applet is packaged as a collection of Java Archive (JAR) files. The JAR files contain all Java classes required to run the presentation layer Database Services : A database service performs the job of storing the data. It could be details on business,customer details,employee information etc. It is the data store. A good example is Oracle Database Server,IBM DB2,Sybase,MS-SQL etc. Depending on how these three services are configured we have three types of system configuration: 1) One-tier 2) Two tier 3) Three tier In an one-tier configuration all three services are integrated. A good example is mainframe system. Layer 1 - Database,Application and Presentation service. In a two-tier system configuration database and application services are integrated. So we have two layers. A good example is the two tier client/server . Layer 1 - Database and Application services Layer 2 - Presentation services In a three-tier configuration we have three separate layers for each service. Layer 1 - Database Services Layer 2 - Application Services Layer 3 - Presentation Services As separate servers are used for each tier in a three-tier system it is more efficient. Data from database server is operated by application servers. This brings optimal performance. To obtain maximum performance we can use special application servers for individual applications such as distribution,financial accounting,HR etc. This is referred to as logon and load balancing.