business logic
introduction
A business enterprise is composed of many building blocks and follows a logical set of rules. Its owner wants the enterprise to reliably generate tons of cash.
The building blocks are usually called business objects. The rules are the logic. Any business decisions are made by following the rules. The building blocks and rules are collectively called the business logic, or business model. Business modelling is not the act of building scale models of skyscrapers out of matchsticks: it is a philosophical process of writing down what the important bits of a real business are.
Business logic is built into the made-to-measure applications. These form the top layer of the system layers in the infrastructure.
what it is
Programmers, who deal with mathematical logic every day, can take the philosophical logic of a business model and figure out which parts can be done entirely by computer. Programmers write applications to make the business logic work on computers.
Computer modelling is done using XML-based mathematical stuff such as tree graphs, node types and recursive links. This model can then be turned into a computer application and placed in the business logic layer of an n-tier architecture.
what it isn't
The application layer of the OSI 7 layer model. That describes where applications are involved in network communication. All business logic happens in this layer but not everything that happens in this layer is business logic.
Have clear boundaries. Business logic has its roots in philosophy, not computers, so programs often cannot clearly seperate business logic from other processes: no absolute divisions exist. There are programs that only do business logic. There are other bits of business logic all over the place, from web pages to database servers.
where it is
Business logic services are found in every business enterprise in the world.
history
Trying to make computers fit into businesses has been a struggle forever. The costs are enormous, the complexity is enormous and the benefits can be enormous. The basic problem is that computer people talk in one sort of jargon and businesses people talk totally different jargon. Methods for making computers the slaves of business people instead of the slaves of programmers have been invented and reinvented over the decades from COBOL (Business Oriented Language) to the latest approach, SOA (Service Oriented Architecture).
