CHAPTER ONE THE SYSTEM DEVELOPMENT ENVIRONMENT 1 INTRODUCTION

CHAPTER ONE THE SYSTEM DEVELOPMENT ENVIRONMENT 1

INTRODUCTION n n Information systems analysis and design is a complex, challenging, and stimulating organizational process that a team of business and systems professionals uses to develop and maintain computer-based information systems. ISAD is an organizational improvement process. 2

INTRODUCTION n Systems analysis and design is a proven methodology that helps both large and small business reap the rewards of utilizing information to its full capacity. n The systems development life cycle (SDLC) is central to the development of and efficient information system. n We will highlight four key SDLC steps. 3

INTRODUCTION n Planning and selection n Analysis n n n Project identification and selection Initiating and planning Requirement determination Requirement structuring Design, and Implementation and operation. Be aware that these steps may vary in each organization depending on its goals. 4

System Analysis and Design The major goal of ISAD is to improve organizational n systems. (manual or automated) n Often this involves developing or acquiring application software and training employees to use it. n Application software, also called a system, is designed to support a specific organizational function or process, such as inventory management, Registrar software…. n The goal of application software is to turn data into information. 5

System Analysis and Design n In addition to application software, the information system includes: n n The hardware and systems software Documentation and training materials, The specific job roles associated with the overall system, n Controls, which are parts of the software written to help prevent fraud and theft. n The people who use the software in order to do their job 6

System and its Components A system is an interrelated set of components with an identifiable boundary, working together for some purpose. A system has nine characteristic. q q 1. 2. 3. 4. 5. 6. 7. 8. 9. Components Interrelated components A boundary A purpose An environment Interface Input Output Constraints 7

System and its Components n A system is made up of components n A component is either an irreducible part or an aggregate of parts, also called a subsystem. n The simple concept of a component is very powerful. n Just as with an automobile, we can repair or upgrade the system by changing individual components without having to make changes throughout the entire system. 8

System and its Components n n n The components are interrelated; that is, the function of one is somehow tied to the functions of the others. A system has a boundary, which in which all of its components are contained and which establishes the limits of a system, separating the system from other systems. Components with in the boundary can be changed whereas things outside the boundary cannot be changed 9

System and its Components n n All of the components work together to achieve some overall purpose for the larger system: the system's reason for existing. A system exist with in an environment- everything outside the system’s boundary. 10

System and its Components n n n Usually the system interacts with its environment, exchanging, in the case of an information system, data and information. The points at which the system meets its environment are called interfaces, and there also interfaces between subsystems. Because an interface exists at the point where system interact its environment, the interface has several special, important function. n An interface provides: 11

System and its Components n Security, protecting the system from undesirable elements that may want to infiltrate it. n n Filtering unwanted data, both for elements leaving the system and entering it Encoding and decoding incoming and outgoing messages Detecting and correcting errors in its interaction with the environment Buffering, providing a layer of slack between the system and its environment, so that the system and its environment can work at different speeds. 12

System and its Components q q Because interface functions are critical in communication between system components or a system and its environment, interfaces receive much attention in the design of information system. You will spend a considerable portion of time in systems development dealing with interfaces: q q especially interfaces between an automated system and its users and interfaces between different information systems. It is the design of good interfaces that permits different systems to work together without being too dependent on each other. 13

System and its Components q A system must face constraints in its functioning because there are limits on: q what it can do and how it can achieve its purpose within its environment. q Some of these constraints are imposed inside the system (a limited number of staff available) and others are imposed by the environment (due dates or regulation) 14

System Concepts q q q Once we have recognized something as a system and identified the system’s characteristics, how do we understand the system? Further, what principles or concepts about systems guide the design of information systems? A key aspect of a system for building systems is the system’s relationship with its environment. q Some systems, called open systems, interact freely with their environments, taking in input and returning output. 15

System Concepts q q As the environment changes, an open system must adapt to the changes or suffer the consequences. A closed system does not interact with the environment; changes in the environment and adaptability are not issues for a closed system. q However, all business information system are open, and in order to understand a system and its relationships to other information systems, to the organization, and to the larger environment, you must always think of information systems as open and constantly interacting with the environment. 16

System Concepts cont… q There are several other important systems concepts with which systems analysts need to become familiar: q q q Decomposition Modularity Coupling Cohesion In addition you need to understand the difference between viewing a system at a logical and at a physical level: q each with associated description concentrating on different aspects of a system. 17

System Concepts cont… q Decomposition deals with being able to break down a system into its components. q q These components may themselves be systems (subsystem) and can be broken down into their components as well. Decomposing a system allows us to focus on one particular part of a system, q This makes it easier to think of how to modify that one part independently of the entire system. 18

System Concepts cont… q q q Modularity, a direct result of decomposition, refers to dividing a system up into chunks or modules of a relatively uniform size. Modules can represent a system simply, making it not only easier to understand but also easier to redesign and rebuild. Coupling is the extent to which subsystems are dependent on each other. q q Subsystems should be as independent as possible. If one subsystem fails and other subsystem are highly dependent on it, then others will either fail themselves or have problems of functioning. 19

System Concepts cont… q q q Finally, cohesion is the extent to which a subsystem performs a single function. A logical system description portrays the purpose and function of the system without tying the description to any specific physical implementation. The physical system description, on the other hand, is a material depiction of the system, a central concern of which is building the system. 20

Benefiting from Systems Thinking q The first step in systems thinking is to be able to identify something as a system. q This identification also involves recognizing each of the system’s characteristics: q Ø for example identifying where the boundary lies and all of the relevant inputs. Visualizing a set of things and their interrelations ship as a system allows you to translate a specific physical situation into more general, abstract terms. 21

Benefiting from Systems Thinking q From this abstraction, you can think about the essential characteristics of a specific situation. q This in turn allow you to gain insights you might never get from focusing too much on the details of the specific situation. 22

Applying System Thinking to Information System q q IS can be seen as subsystem in larger organizational systems, taking input from, and returning output to, their organizational environments. Let’s examine one fast-food restaurant information system as a special kind of system. The information system take customer orders, send the orders to the kitchen, monitor goods sold and inventory, and generate report for management. 23

A fast-food restaurant’s customer order information system Customer order customer Kitchen order Receipt Kitchen 1. 0 Process customer Food order 2. 0 Formatted goods sold data Update Goods Sold file Goods sold Inventory Data 3. 0 Update Inventory file Formatted inventory data 4. 0 Goods sold file Daily goods sold Amount Produce Daily inventory management Depletion Amount report Inventory file Management report Restaurant Management 24

Applying System Thinking to Information System n As the diagram illustrate, The fast-food customer order system contains four components or subsystems: n n n Process Customer Food Order Update Goods Sold File, Update Inventory File, and Produce Management Reports. The arrows in the diagram show these subsystems are interrelated. The first process produces four outputs: a Kitchen Order, a Receipt, Goods Sold data, and Inventory Data. The latter two outputs serves as input for other subsystems. 25

Applying System Thinking to Information System n The dotted line illustrates the boundary of the system. n n The specific purpose of the system is to facilitate: n n n Notice that the Customer, the Kitchen, and the Restaurant Manager are all considered to be outside the customer order system. customer orders, monitor inventory, and generate reports; The system’s general purpose is to improve the efficiency of the restaurant’s operations. 26

Applying System Thinking to Information System n n n The illustrated information system is smaller in scope and purposes. We have limited the environment to those three entities that interact with the system. Two constraints on the system is apparently show in the diagram. 27

Applying System Thinking to Information System 1. 2. q There is no direct data exchange between the customer order system and information systems used by the restaurant’s suppliers; Inability to provide on-line, real-time information on inventory levels, limit the manager to receive nightly batched reports The first level of analysis and description of the customer order system is a logical analysis and description. 28

Applying System Thinking to Information System q q q The logical description focuses on the flow and transformation of data. For the logical information system description, it is irrelevant whether the customer’s order shows up in the kitchen as a pieces of paper or as lines of text on a monitor screen. What is important is the information sent to the kitchen. 29

Applying System Thinking to Information System q q Therefore, the physical system is the one possible implementation of the more abstract, logical information system description. The way we draw information systems shows how we think of them as a systems. (DFD)Data flow diagram clearly illustrate inputs, outputs, system boundaries, the environment, subsystem, and interrelationships. Purpose and constraints are much more difficult to illustrate and must therefore be documented using other notations. 30

Fundamentals of Information Systems q q An information system (IS) is a set of interrelated elements or components that collect (input), manipulate (process), and disseminate (output) data and information and provide a feedback mechanism to meet an objective. In information systems: q q Input is the activity of gathering and capturing raw data processing involves converting or transforming data into useful outputs. 31

Fundamentals of Information Systems q q Output involves producing useful information, usually in the form of documents and reports. In information systems, feedback is output that is used to make changes to input or processing activities. 32

Types of Information System Overviews Until now we have talked about information systems in generic terms, but there actually several different types or classes of information systems. These classes are distinguished from each other on the basis of: q q what the system does or by the technology used to construct the system. You are responsible to determine which kind of system will best address the organizational problem or opportunity on which you are focusing. 33

Classification of Systems n System can be classified based on the following categories n n n Natural Vs Manmade or Artificial systems Open Vs Closed Systems Simple Vs Complex Systems Stable Vs Dynamic Systems Permanent Vs Temporary Systems Deterministic vs. Probabilistic Systems

Types of Information System Overviews As a systems analyst working as part of a team, you will work with at least 4 classes of information systems: q n n Transaction processing systems Management Information Systems Decision support systems (for individuals, groups, and executives) Expert systems 35

Types of Information System Overviews

Transaction Processing System A transaction processing system (TPS) automates the handling of data about business activities or transactions. Data about each transaction are captured, transaction are verified and accepted or rejected, and validated transactions are stored. Reports may be produced immediately to provide summaries of transactions. q q q The analysis and design of a TPS requires you to focus on the firm’s current procedures for processing transactions. q q How does the organization track, capture, process, and output data? 37

Management Information System A Management information system (MIS) a computer based system that takes the raw data available through a TPS and converts them into a meaningful report /aggregated report form. q q Developing an MIS calls for a good understanding: q q q E. g. The MIS system can therefore direct the manufacturing department on what to produce and when. what kind of information managers require Management information systems often require data from several TPS 38

Decision Support System q q q A decision support system (DSS) is designed to help decision makers with decisions by combining data, sophisticated analytical models and user-friendly user interface. A DSS provides an interactive environment in which decision makers can quickly manipulate data and models of business operations. (What if? ) A DSS has three parts. q q q A database Mathematical or graphical models of business processes. A user interface (or dialogue module) 39

Decision Support System q DSS software supports certain decisionmaking activities (from problem finding to choosing a course of action). 40

Expert Systems q q An expert system is a computer based system that contains knowledge of experts in a particular domain. If-then-else rules or other knowledge representation forms describe the way an expert would approach situations in specific domain of problems. The focus on developing an ES is acquiring the knowledge of the expert in the particular problem domain. Knowledge engineers perform knowledge 41 acquisition;

Expert Systems

System and System Analyst- A key resource A systems analyst(s) facilitates the development of information systems and computer applications. q q The systems analyst performs systems analysis and design. Systems analysis is the study of a business problem domain for the purpose of recommending improvements and specifying the business requirements for the solution. Systems design is the specification or construction of a technical, computer-based solution for the business requirements identified in a systems analysis. 49

System and System Analyst- A key resource q q q Organization change themselves to combat their environment. Whenever organizations change themselves they will also change their business process, hence their information system as well. Changing the information system require a system analyst. 50

Who is a systems analyst? In simple terms, systems analysts are people who understand both business and computing. Systems analysts study business problems and opportunities and then q q Transform business and information requirements of the business into the computer-based information systems. The system analyst also bridges the communications gap between those who need the computer and those who understand the technology. 51

Who is a systems analyst? q The role of systems analyst is splitting into two distinct positions or roles, business analyst and application analyst. o o A business analyst (more of analyst)is a systems analyst that specializes in business problem analysis and technology-independent requirements analysis. An application analyst (more of designer ) is a systems analyst that specializes in application design and technology-dependent aspects of development. 52

Skills of a System Analyst q Problem-solving skills q q Interpersonal communications skills q q Take a large business problem, break down that problem into its component parts, analyze the various aspects of the problem, and then assemble an improved system to solve the problem. analyst must be able to communicate effectively, both orally and in writing. Interpersonal relations skills q systems analysts must be extroverted or people-oriented. 53

Skills of a System Analyst q Systems analysis and design skills o Systems analysis and design skills can be conveniently factored into three subsets: n n n Concepts and principles Tools Techniques 54

Personal Qualities and Knowledge required Working knowledge of Information Technology q q The analyst must be aware of both existing and emerging information technologies and techniques so that he can show end-user and management how new technologies can benefit their business and its operations. Computer Programming and Experience q q They must know how to program because they are the principal link between business users and computer programmers. General Business Knowledge q q Systems analysts should be able to communicate with business experts to gain knowledge of problems and needs. 55

Personal Qualities and Knowledge required Project management q q Effectively managing projects is crucial to a systems analyst’s job. Flexibility and adaptability q q There is no single, magical approach or solution applicable to systems development. Character and ethics q q The nature of the systems analyst's job requires a strong character and sense of ethics. Systems analysts gains assess to sensitive and private data and information about customers, suppliers, employees, and the like The analyst must be very careful not to share such feelings or information with the wrong people. 56