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The objective of this chapter is to present a template pattern for modeling enterprise business processes (transaction cycles) that serves as the structure for an enterprisewide database. | Lecture 4 Enterprise Systems Development ( CSC447) COMSATS Islamabad Muhammad Usman, Assistant Professor College of Statistical and Acturial Science 1 Lecture 4 An introduction to Requirements Engineering Requirements-Hardest Task “The hardest single part of building a software system is deciding precisely what to build. No other part of the conceptual work is as difficult as establishing the detailed technical requirements, including all the interfaces to people, to machines, and to other software systems. No other part of the work so cripples the resulting system if done wrong. No other part is more difficult to rectify later.” F B Brooks Requirements engineering The process of establishing the services that the customer requires from a system and the constraints under which it operates and is developed. The requirements themselves are the descriptions of the system services and constraints that are generated during the requirements engineering process. 4 What is a requirement? It may range from a high-level abstract statement of a service or of a system constraint to a detailed mathematical functional specification. This is inevitable as requirements may serve a dual function May be the basis for a bid for a contract - therefore must be open to interpretation; May be the basis for the contract itself - therefore must be defined in detail; Both these statements may be called requirements. 5 Types of Requirements User requirements Statements in natural language plus diagrams of the services the system provides and its operational constraints. Written for customers. System requirements A structured document setting out detailed descriptions of the system’s functions, services and operational constraints. Defines what should be implemented so may be part of a contract between client and contractor. 6 Readers of different types of requirements specification 7 Functional and non-functional requirements Functional requirements Statements of services the system should | Lecture 4 Enterprise Systems Development ( CSC447) COMSATS Islamabad Muhammad Usman, Assistant Professor College of Statistical and Acturial Science 1 Lecture 4 An introduction to Requirements Engineering Requirements-Hardest Task “The hardest single part of building a software system is deciding precisely what to build. No other part of the conceptual work is as difficult as establishing the detailed technical requirements, including all the interfaces to people, to machines, and to other software systems. No other part of the work so cripples the resulting system if done wrong. No other part is more difficult to rectify later.” F B Brooks Requirements engineering The process of establishing the services that the customer requires from a system and the constraints under which it operates and is developed. The requirements themselves are the descriptions of the system services and constraints that are generated during the requirements engineering process. 4 What is a requirement? It
