System Engineering

1. System Engineering PRAT THREE : Conventional Methods for Software Engineering

2. System Engineering System engineering: Software engineering occurs as a consequence of a process. System engineering focuses on: - elements organizing into system can be product, service, technology for transformation of information or control . System engineering process is called information engineering when the context of the engineering work focuses on a business enterprise. Product engineering focuses on product construction.

3. 10.1 Computer-Based Systems • system definition (Webster) : a set of facts, principles, rules, etc., classified and arranged in an orderly form so as to show a logical plan linking the various parts • 􀀠 Computer-Based Systems Definition : A set or arrangement of elements that are organized to accomplish some predefined goal by processing information • 􀀠Goal : Supporting some business function or to develop a product that can be sold to generate business revenue

4. 10.1 Computer-Based Systems • A computer-based system makes use of system elements • Elements constituting one system may represent one macro element of a still larger system • Example • A factory automation system may consist of a numerical control machine, robots, and data entry devices; each can be its own system • At the next lower hierarchical level, a manufacturing cell is its own computer-based system that may integrate other macro elements • The role of the system engineer is to define the elements of a specific computer-based system in the context of the overall hierarchy of systems

5. 10.1 Computer-Based Systems • a computer-based system makes use of a variety of system elements: • 1)Software: computer programs, data structures, and related work products that serve to effect the logical method, procedure, or control that is required • 2)Hardware: electronic devices that provide computing capability, interconnectivity devices that enable flow of data, and electromechanical devices that provide external functions • 3)People: Users and operators of hardware and software • 4)Database: A large, organized collection of information that is accessed via software and persists over time • The uses of these elements are described in the following: • 5)Documentation: Descriptive information that portrays the use and operation of the system • 6)Procedures: The steps that define the specific use of each system element or the procedural context in which the system resides

6. The System Engineering Hierarchy • System engineering encompasses: - a collection of top-down and bottom-up methods to navigate the hierarchy • WV = {D1, D2, D3, . . . , Dn} • Di = {E1, E2, E3, . . . , Em} • Ej = {C1, C2, C3, . . . , Ck} (( a component could be a computer program, a reusable program component, a module, a class or object….))

7. The System Engineering Hierarchy Business or Product Domain World View Domain View Element View Detailed View

8. System Modeling • System engineering is a modeling process. • What does a system engineering model accomplish? • • Define the processes that serve the needs of the view under consideration. • • Represent the behavior of the processes and the assumptions on which the behavior is based. • • Explicitly define both exogenous and endogenous input to the model. • • Represent all linkages (including output) that will enable the engineer to better understand the view.

9. System Modeling • Considering factors for creating models: - assumptions- reduce the number of possible permutations, thus enabling a model to reflect the problem in a reasonable manner. - simplifications-enable the model to be created in a timely manner. - limitations, such as hardware limitations-help to bound the system. - constraints, such as computation constraints-will guide the manner in which the model is created and the approach taken when the model is implemented. • - preferences (solutions, architecture, ..)-that indicate the preferred architecture for all data, functions, and technology.

10. Information Engineering: An Overview • Goal of Information engineering (IE) • - define architectures that will enable a business to use information effectively. Three different architectures: • - data architecture -> provides a framework about the business information • - application architecture -> encompasses the elements in a system that’s transform objects within the data architecture for some business purpose . • - technology infrastructure -> provides the foundation for the data and application architecture (HW ,SW to support application and data ).

11. Information Engineering: An Overview • To model previous system architectures =>define hierarchy of information engineering activity .

12. Information Engineering: An Overview • Information strategy planning (ISP) --> world view • Business area analysis (BAA) ---> domain view 1. Focus on a specific business domain 2. Define data objects, relationship, and data flow • Software engineering: - business system design (element view) - construction and integration focuses on ---> detail implementation

13. Information Engineering: An Overview • ISP views the entire business as an entity and isolates the domains of the business (e.g., engineering, manufacturing, marketing, finance, sales) that are important to the overall enterprise. ISP defines the data objects that are visible at the enterprise level, their relationships, and how they flow between the business domains .

14. Information Engineering: An Overview • The domain view => business area analysis (BAA). • BAA is concerned with identifying in detail data (OB type) and function requirements (in the form of processes) of selected business areas [domains] • identified during ISP and It is only concerned with specifying what is required in a business area. • BAA views the business area as an entity and isolates the business functions and procedures • that enable the business area to meet its objectives and goals. • at BAA level, Objects characteristics are all bounded by the business area being analyzed.

15. Information Engineering: An Overview • software engineering=> a business system design (BSD) step, the basic requirements of a specific information system are modeled and these requirements are translated into data architecture, applications architecture, and technology infrastructure.

16. Information Engineering: An Overview • The final BPE step—construction and integration focuses on implementation detail. The architecture and infrastructure are implemented by constructing an appropriate database and internal data structures, by building applications using software components, and by selecting appropriate elements of a technology infrastructure to support the design created during BSD.

17. PRODUCT ENGINEERING: AN OVERVIEW • The goal of product engineering is to translate the customer’s desire for a set of defined capabilities into a working product. • To achieve this goal, product engineering must derive architecture and infrastructure. • The architecture • encompasses four distinct system components: software, hardware, data (and databases), and people. A support infrastructure is established and includes the technology required to tie the components together and the information that is used to support the components.

18. Function Data and Classes Behavior Data/Class Design Architectural Design Interface Design Component Design Product Engineering Hierarchy system analysis= Product Requirements Engineering World view Component Engineering Human Engineering Hardware Engineering Software Engineering Database Engineering Domain view Analysis Modeling Elements view Design Modeling Construction

19. PRODUCT ENGINEERING: AN OVERVIEW • the world view is achieved through system analysis =>requirements of the product are elicited from the customer. These requirements encompass information and control needs, product function and behavior, overall product performance, design and interfacing constraints, and other special needs. Once these requirements are known, the job of system analysis is to allocate function and behavior to each of the four components noted earlier.

20. PRODUCT ENGINEERING: AN OVERVIEW • System component engineering is actually a set of concurrent activities that address each of the system components separately: software engineering, hardware engineering, human engineering, and database engineering. • the engineering disciplines must establish and maintain active communication with one another. • Part of role system analysis is to establish the interfacing mechanisms that will enable communication to happen.

21. PRODUCT ENGINEERING: AN OVERVIEW • Element view => analysis and design modeling activities and construction and integration activities that encompass code generation, testing, and support steps. • The analysis step models allocated requirements into representations of data, function, and behavior. Design maps the analysis model into data, architectural, interface, and software component-level designs.

22. Information Engineering • The goal objective if information engineering is to apply ( IT ) in a way the best server the overall needs of the business . • Generally , IE begin by analyzing business objective and goals ,understanding business area then define the information needs of each business area and business as whole .

23. Information Strategy Planning • First IE step is Information Strategy Planning ISP • ISP objective : ❏ define strategic business goals/objectives ❏ isolate critical success factors ❏ analysis the impact of technology and automation on the goals and objectives . ❏ analysis existing information to determine its role in achieving goals and objective * ISP creates a business level data model that define key data obj and their relationship to one another and to various area .

24. Information Strategy Planning • 􀀠 Objective—general statement of direction • 􀀠 Goal—defines quantitative course of action = (defines measurable objective) • Ex :business objective for a maker of cellular telephone might be to reduce the manufactured cost of the product • Goals : • ➪ decrease reject rate by 20% in first 6 months • ➪ gain 10% price concessions from suppliers • ➪ re-engineer 30% of components for ease of manufacture during first year • 􀀠 objectives tend to be strategic while goals tend to be tactical

25. Information Strategy Planning • Critical success factors CSF can be tied to an objective or to individual goals , CSF must be present if the objective or goal is to be achieved (management planning must be accommodate ) “Limited number (usually between 3 to 8) of characteristics,conditions, or variables that have a direct and serious impact on the effectiveness, efficiency, and viability of an organization,program, or project. Activities associated with CSF must be performed at the highest possible level of excellence to achieve the intended overall objectives. “ • Ex : • Total quality management strategy for manufacturing organization • Worker training and motivation • Availability of engineering staff

26. Information Strategy Planning • Technology impact analysis examine objective and goals and provide technology that have direct or indirect impact on achieving them successfully . • ISP must identify what currently exist if information technology and how currently used to achieve objectives and goals • BPR (business process reengineering) examine existing systems with the intend of reengineering them to better meet business needs .