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MELJUN CORTES System Analysis Design Theory Lecture

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MELJUN CORTES System Analysis Design Theory Lecture

MELJUN CORTES System Analysis Design Theory Lecture

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  • 1. Lecture 1. Introduction to System Analysis. Basic Concepts.MELJUN CORTES MELJUN
  • 2. I. General Systems Theory1. System ConceptDef. A System is a set of components that interact with one another and serve for a common purpose or goal.Systems may by (1) abstract or (2) physical.• An abstract system is conceptual, a product of a human mind. That is, it cannot beseen or pointed to as an existing entity. Social, theological, cultural systems areabstract systems. None of them can be photographed, drawn or otherwise physicallypictured. However, they do exist and can be discussed, studied and analyzed.• A physical system, in contrast, has a material nature. It is based on material basisrather than on ideas or theoretical notions.• Either system has nine main characteristics:1. Components. 6. Input.2. Interrelationships. 7. Output.3. Boundary. 8. Interface.4. Purpose. 9. Constraints.5. Environment.
  • 3. FIGURE 1-1 Characteristics of a system
  • 4. 2. System’s Characteristics• A component is either an irreducible part or an aggregate of parts, also called asubsystem. The simple concept of a component is very powerful. For example, incase of an automobile we can repair or upgrade the system by changing individualcomponents without having to make changes the entire system.• The components are interrelated; that is, the function of one is somehow tied tothe function of the others. For example, in the Store system the work of onecomponent, such as producing a daily report of customer orders, may notprogress successfully until the work of another component is finished, such assorting customer orders by date of receipt.• A system has a boundary, within which all of its components are contained andwhich establishes the limits of a system, separating it from other systems.• All of the components work together to achieve some overall purpose: thesystem’s reason for existing.• A system operates within an environment – everything outside the system’sboundary. The environment surrounds the system, both affecting it and beingaffected by it. For example, the environment of a university includes prospectivestudents, foundations, funding agencies and the new media. Usually the systeminteracts with its environment. A university interacts with prospective students byhaving open houses and recruiting from local high schools.• The point at which the system meets its environment are called interface.• A system must face constraints in its functioning because there are limits to what
  • 5. can do and how it can achieve its purpose within its environment.Some of theseconstraints are imposed inside the system (e.g., a limited number of staffavailable).Others are imposed by the environment (e.g., due to regulations).• A system interact with the environment by means of input and output. Input isanything entering the system from the environment; output is anything leavingthe system crossing the boundary to the environment . Information, energy, andmaterial can be both input and output in relation to the environment. People, forexample, take in food, oxygen, and water from the environment as input. Anelectrical utility takes on input from the environment in the form of rawmaterials (coal, oil, water power, etc), requests for electricity from customers. Itprovides for output to the environment in the form of electricity.3. Feedback and Control in a SystemVery often output’s data are returned to the input of the system, as shown in Fig.1-2, and used to regulate the system’s activity. Large hotels and motels, forinstance, ask FIGURE 1-2 Regulation of activity
  • 6. guests to fill out cards evaluating the services. Such a process is called feedback.It helps to adjust the system to changes so that the system operates in a balancedstate, or equilibrium. This feature of a system is used in control.Def. Control is the process that measures current performance and guides it towarda predetermined goal.Two types of feedback are related to system control.• Negative feedback is corrective feedback that helps maintain the system within acritical operating range and reduces performance fluctuations around the normor standard. Negative feedback is transmitted in feedback control loops. Asshown in Figure 1-3, a sensor detects the effect of output on the externalenvironment; this information is returned to the system as an input, andnecessary adjustments are made according•to predetermined goal. feedback, In contrast to negative which is corrective, positive feedback reinforces the operation of a system by causing it to continue its performance and activities without changes. FIGURE 1-3 Feedback control loops
  • 7. 4. Methods of system’s studyThere are several important system’s concepts that help to study a system andunderstand its functioning: • Decomposition • Modularity • Coupling • Cohesion• Decomposition is the process of breaking down a system into its smallercomponents. These components may themselves be systems (subsystems) and canbe broken down into their components as well. How does decomposition aidunderstanding of a system? It results in smaller and less complex pieces that areeasier to understand than larger, complicated pieces.• Modularity is a direct result of decomposition. It refers to dividing a systeminto chunks or modules of a relatively uniform size. Modules can represent asystem simply, making it easier to redesign and rebuild. For instance, a portableCD player, as a system, accepts CDs and settings of volume and tone as inputsand produces music as output. It includes the separate systems as its subsystems:1) read the digital signals from CDs; 2) amplify the signals; 3) turn the signalsinto sound waves; and 4) control the volume and tone of the sound (see Figure 1-4).
  • 8. FIGURE 1-4 Decomposing a CD system• Coupling means that subsystems are dependent on each other. But they shouldbe as independent as possible. If one subsystem fails and other subsystems arehighly dependent on it, the others will either fail themselves or have problemsfunctioning.• Cohesion is the extend to which a subsystem performs a single function. In theCD player example, signal reading is a single function.
  • 9. 5. “Systems” Thinking• Being able to identify something as a system• Involves being able to identify subsystems• Identifying system characteristics and functions• Identifying where the boundaries are (or should be)• Identifying inputs and outputs to systems• Identifying relationships among subsystems MELJUN
  • 10. II. Information Systems1. Information System, Subsystem and SupersystemBoth control and management have an informational nature, that is among allthe possible inputs and outputs (information, energy, and material) they use theonly one – the information. Information is the central core of all resources infeedback loops while regulating the system activities. Any organization as asystem could not survive without information. That’s why, it is often necessary todevelop a special subsystem for processing and handling the information resourcealone. This information system should be able to provide management withinformation for making the many decisions necessary in a competitiveenvironment. It’s possible to give the following definition.Def. An Information System (IS) is a collection of interrelated components that collect, process, store, and provide as output the information needed tocomplete a business task.A payroll system, for example, collects information on employees and their work,processes and stores that information, and than produces paychecks and payrollreports for the organization. Then information is provided to manufacturing sothe department can schedule production.What are the interrelated components or subsystems(according to generaldefinition of a system) of an IS? For example, a customer support system might
  • 11. subsystem that creates new orders for customers. Another subsystem mighthandle fulfilling the orders, including shipping and back orders. A thirdsubsystem mightmaintain the product catalog database. Every system, in turn, is a part of a largersystem, called a supersystem. So the customer support of the production system. system is really just asubsystem The production system, as it is shown in Figure 1-5, includes other systems, such as inventory management and manufacturing. FIGURE 1-5 Information systems and subsystems
  • 12. On the other hand we can consider an information system as a list of types of itscomponents: hardware, software, inputs, outputs,data,people, and procedures(Fig.1-6). FIGURE 1-6 Information system and components parts MELJUN
  • 13. 2. Concepts of SeparationSeparating Data and Processes That Handle DataWe can consider every IS as a three-component system: • data • data flows • processing logicData are raw facts that describe people, objects and events in organization (e.g.name, age, customer’s account number). Data is used in an IS to produceinformation.Information is data organized in a form that human can interpretData flows are group of data that move and flow through a system. They includea description of the sources and destinations for each data flowProcessing logic describes the steps that transform the data and events thattrigger these steps.Figure 1-7 shows three components of an IS. MELJUN
  • 14. FIGURE 1-7 Data, Data Flow and Processing Logic. MELJUN
  • 15. There are two approaches to ISs design: • Process-oriented • Data-oriented• The process-oriented approach is based on what the system is supposed to do.The focus is on output and processing logic. Although the data are important, theyare secondary to the application. Each application contains its own files and datastorage capacity. Figure 1-8(A) illustrates this situation: “personnel data” appearsin two separate systems – payroll system and the project management system. If asingle element changes, it has to be changed in each of the data files. Thisapproach involves creating graphical presentations (data flow diagram andcharts).• The data-oriented approach is a strategy that focuses on the ideal organizationof data, independent of where and how data are used within the system (seeFigure 1-8(B)). This approach uses data model that describes the kinds of dataneeded in the system and the business relationships among the data (i.e. businessrules).Figure 1-9 summarizes the differences between two approaches.
  • 16. FIGURE 1-8 The Relationship Between Data and Applications:(A) Process-Oriented Approach(B) Data-Oriented Approach
  • 17. FIGURE 1-9 Key Differences Between The Process- Oriented and Data-Oriented Approaches.Separating Databases and ApplicationsWhen the data-oriented approach is applied, databases are designed aroundsubjects, such as customers, suppliers and parts. It allows to use and to revisedatabases for many different independent applications, what creates the principleof application independence (i.e. separation of data and definition of data from
  • 18. 3. Types of Information SystemsAs far as organizations perform many different types of activity, they requireseveral different types of information systems to support all of information needs.The information systems found in most businesses include transaction processingsystems, management information systems, executive informationsystems,decision support systems, expert systems, communication supportsystems, and office support systems (Figure 1-10): FIGURE 1-10 Types of Information
  • 19. • Transaction processing systems (TPS) capture and record information about thetransactions that affect the organization. A transaction occurs each time a sale ismade, supplies are ordered, an interest payment is made. Usually thesetransactions create credit or debit entries in accounting ledgers. This kind of ISswere among the first to be automated by computers. The modern TPS use state-of-the-art technology, for instance, in the form of on-line TPS.• Management information systems (MIS) are systems that take informationcaptured by TPS and produce reports that management needs for planning andcontrolling the business. MIS are possible because the information has beencaptured by the TPS and placed in organizational databases.• Executive information systems (EIS) provide information for executives to usein strategic planning. Some of the information comes from the organizationaldatabases, but much of the information comes from external sources – news aboutcompetitors,stock market reports, economic forecasts, and so on.• Decision support systems (DSS) allow a user to explore the impact of availableoptions or decisions. Whereas an MIS produce reports, DSS provide aninteractive environment in which decision makers can quickly manipulate dataand models of business operations. A DSS has three parts. The first part iscomposed of a database (which may be extracted from TPS or MIS). The secondpart consists of mathematical or graphical models of business processes. The thirdpart is made up of a user interface (or dialogue module) that provides a way for
  • 20. the DSS. An EIS is a DSS that allows senior management to explore data startingat ahigh level of aggregation and selectively drill down into specific areas where moredetailed information and analysis are required.• Expert systems (ES) replicate the decision-making process rather thanmanipulating information. If-then-else rules or other knowledge representationforms describe the way a real expert would approach situations in a specificdomain of problems. Typically, users communicate with an ES through aninteractive dialogue. The ES asks questions (which an expert would ask) and theend user supplies the answers. Those answers are then used to determine whichrules apply, and the ES provides a recommendation based on the rules.• Communication support systems (CSS) allow employees to communicate witheach other and with customers and suppliers. Communication support nowincludes e-mail, fax, Internet access, and video conferencing.• Office support systems (OSS) help employees create and share documents,including reports, proposals, and memos. OSS also help to maintain informationabout work schedule and meetings. MELJUN CORTES,MBA,MPA,BSCS,ACS
  • 21. III. Systems Analysis and Design. Systems AnalystISs are crucial to the success of modern business organization, and new systemsare constantly being developed to make businesses more competitive. The key tosuccessful system development is thorough systems analysis and design.Def. System Analysis (SA) is the process of understanding and specifying in detail what the information system should do. System Design (SD) is the process of specifying in detail how the many components of the information system should be physically implemented. Systems Analyst (SAn) is a business professional who uses analysis and design techniques to solve business problems using information technology and who develops ISs.• Developing ISs is not just about writing programs. ISs are developed to solveproblems for organizations, and systems analyst is often thought of as a problemsolver rather than a programmer (see Figure 1-11).• To thoroughly understand the problem, the analyst must learn everythingpossible about it – who is involved, what business processes come into play, whatdata need to be stored and used, what other systems would be affected whensolving this problem. • Then the analyst needs to confirm for management thatthe benefits of solving the problem outweigh the cost.• If solving the problem is feasible, the analyst develops a set of possible solutionsand decides, in consultation with management, which possible solution is the best
  • 22. FIGURE 1-11 The analyst’sapproach to problem solving.
  • 23. • Once the systems analyst has decided which alternative to recommend andmanagement has approved the recommendation, the details must be worked out.These details include databases, user interface, networks, operating procedures,conversion plans, and, of course, program modules. After that, the actualconstruction of the system can begin.• Systems analysts need a great variety of special skills. First, they need to be ableto understand how to build ISs, and this requires quite a bit of technicalknowledge. Then, they have to understand business they are working for. Finally,the analyst needs to understand quite a bit about people and the way they work.Technical Knowledge and SkillsNo one person can be an expert at all types of technology; there are technicalspecialist to consult for the details. But a systems analyst should understand thefundamentals about: • Computers and how they work • Devices that interact with computers, including input devices, storagedevices, and output devices • Communications networks that connect computers • Databases and database management systems • Programming languages • Operating systems and utilities
  • 24. A systems analyst also needs to know a lot about tools and techniques fordevelopingsystems. (1) Tools are software products that help develop analysis or designspecifications and completed systems components. Some tools used in systemdevelopment include:• Software packages such as Microsoft Access and PowerBuilder that can be usedto develop systems• Integrated development environment (IDEs) for specific programminglanguages, such as Sun Java Workshop or Microsoft C++• Computer-aided system engineering (CASE) tools that store information aboutsystem specifications created by analyst and sometimes generate program code• Program code generators, testing tools,configuration management tools,software library management tools, documentation support tools, projectmanagement tools, and so on.(2)Techniques are used to complete specific system development activities. Theyinclude:• Project planning techniques• System analysis techniques• System design techniques• Systems construction and implementation techniques
  • 25. Business Knowledge and SkillsAn analyst should understand business organization in general. It may includethe following examples:• What activities and processes do organizations perform?• How are organizations structured?• How are organizations managed?• What type of work goes on in organization – finance, manufacturing,marketing, customer service, and so on?It is also important to understand a specific company, that is:• What the specific organization does?• What makes it successful?• What its strategies and plans are?• What its traditions and values are?People Knowledge and SkillsAn analyst spends a lot of time working with people. It is critical that analystunderstand:• How people think?• How people learn?• How people react to changes?
  • 26. • How people communicate?• How people work?Integrity and EthicsA systems analyst gets an access to information in many different parts of anorganization. It might be • very private information, such as salary, health, job performance. • confidential corporate information about products, strategic plans or tactics • top-secret information involving government, police, army, etc.A systems analyst is expected to have the integrity to keep this information and touphold the highest ethical standards. Any appearance of impropriety can destroyan analyst’s career.The Environment Surrounding the AnalystTypes of Technology EncounteredMost students are familiar with personal computers. But not all businessesfunctions can be realized with desktop. ISs in the “real-world” range from smalldesktop systems to huge database systems with thousands of users spread overhundreds of locations. We could mark out the following types of ISs:
  • 27. • Desktop systems• Networked desktop systems that share data• Client-server systems• Large-scale centralized mainframe systems• Systems using Internet, intranet, and extranet technologyThe changes in technology are very rapidly. Thus, it is so important to upgradeknowledge and skills continually.Typical Job Titles and Places of EmploymentIn fact, many different people do systems analysis and design work. They mayhave various job titles:• Programmer analyst• Business systems analyst• End-user analyst• Business consultant• Systems consultant• System support analyst• System designer• Software engineer• System architect
  • 28. Sometimes systems analysts might also be called project leader or projectmanager.Places of EmploymentNot all analysts work directly for the company. It may be different workarrangements, including:• Programmer analysts working for the company• Systems analysts working for the company• Independent contractors• Outsource provider employees• Consultants• Software development firm employeesTypical Job Ad:Systems Analyst – Distribution CentreWe are the world’s leading manufacturer of women’s apparel products. Ourorganization in the Far East has openings for a Systems AnalystRequirements:• Bachelor’s degree in Computer Science, Business Administration or closelyrelated field with 5 (+) years of working experience• In-depth understanding of Distribution and Manufacturing concepts
  • 29. Job Ad (continued)• Working knowledge of project management and all phases of the softwaredevelopment life cycle• Experience with CASE tools, PC and Bar Code equipment• Working knowledge of AS/400 and/or UNIX environment with the languages C,RPG400 and/or COBOL are desirableThe successful candidate will provide primary interface for all user problems,answer technical questions and requests within the applications developmentgroup; work with user areas to establish priorities; and provide recommendationsand directions for process improvement through automation.We offer an attractive compensation package, relocation assistance and thetechnical and analytical challenges you would expect in a state-of-the-artenvironment. The position will report to Senior Management.Please forward your resume, along with salary expectations to:The Analyst’s Role in Strategic PlanningA systems analyst is not only someone who solves specific business problems bydeveloping or maintaining ISs. The analyst might also be involved alone withsenior managers in strategic management problems. It happens in several ways:Special Projects–The analyst may be working to solve a problem that affects executives (e.g.designing an executive information system)
  • 30. – The analyst may be involved in business process reengineering – a techniquethat seeks to alter the nature of work done in a business function with theobjective of radically improving performance. Therefore, the analyst might beasked to participate in a study of existing business processes and procedures andthen to propose IS solution that can have a radical impact.Strategic Planning ProcessesA strategic plan typically covers five or more years in the future. It serves toanswerfundamental questions about the company (e.g. where is it now, where does itwant to be, what does it have to do to get there)–A typical strategic planning process can take months or years and involve manypeople in the company–Once set, the strategic plan drives all the organization’s processesInformation Systems Strategic Planning–The information systems strategic planning is one of the major components ofthe strategic plan.In most organizations today, nearly all planned changes involve new or improvedinformation systems. Very often, the ISs themselves drive the strategic plan. In theInternet era, many new companies have come to existence (Amazon.com,eToys.com, etc) and many others have changed the way they compete.Usually at the recommendation of the chief information systems executive, topmanagement will authorize a major project to plan the ISs for the entire
  • 31. –A consulting firm might be called to help with the project. Consultants can offerexperience with strategic planning techniques and train managers and analysts tocomplete the planning project.–Many documents and existing systems are reviewed to create a model of theorganization in terms of the business functions it performs alone with anothermodel that shows the types of data the organization uses.–Based on these two models, an application architecture plan is created:• a description of the integrated information systems needed for the organizationto carry out its business functions. After that, the team outlines the sequence ofsteps needed to implement the required systems.–Then, the team creates a technology architecture plan:• A description of the hardware, software and communications networks requiredto implement planned IS.Enterprise Resource Planning (ERP)- an increasing number of organizations are applying an approach calledenterprise resource planning by which an organization commits to using anintegrated set of software packages for key information processing (e.g.PeopleSoft). Software vendors such as PeopleSoft offer package solutions forcompanies in specific industries. To adopt an ERP solution, the company mustcarefully study its existing processes and information needs and then determine
  • 32. IV. Running Case Study: Rocky Mountains Outfitters (RMO)We will use a system development project for a company named Rocky MountainOutfitters (RMO) as a continuing example.Overview of the RMO• Began in 1978 as dream of John and Liz Blankens of Park City, Utah• First started as direct mail-order sales to customers• By late 1990s had grown to a large regional sports clothing distributor in theRocky Mountain and Western states• RMO now employs over 600 people and has almost $100 million annually insales• Mail order is major source of revenue at $70 million• Recently completed an information systems strategic planning project (with helpof consultants)Organization and location• The RMO is managed on a daily basis by John (as president) and Liz (as vicepresident of merchandising and distribution)• Other top managers are William McDougal, vice president of marketing andsales, and JoAnn, vice president of finance and systems. The systems department
  • 33. FIGURE 1-12 Organizational Structure of the RMO.MELJUN
  • 34. Figure 1-13 shows the location of the RMO’s facilities. FIGURE 1-13 RMO’s location.Information Systems Department at RMO • Headed by Mac Preston, an assistant vice president • Includes nearly 50 employees (see Figure 1-14) • Organized into two areas:
  • 35. –System support (director Ann Hamilton)Includes telecommunications, database administration, operations and usersupport–System development (director John MacMurty)4 project managers, 6 systems analysts and 10 programmer analysts. FIGURE 1-14 RMO’s IS Department staffing.
  • 36. Existing Systems–Small mainframe computer runs various tasks . The existing informationtechnology includes: • Retail store system • Office systems • Merchandising/Distribution • Mail Order • Phone Order • Human resources • Accounting/FinanceThe Information Systems Strategic Plan at RMOThe strategic thrust of RMO is to build more direct customer contact. Onestrategy is to expand the phone-order capability, and the another one is to adddirect customer access through the Internet. This strategic plan resulted in thefollowing decisions:• Technology Architecture Plan – Move business applications to client-server architecture – Move towards conducting business via the Internet (start with web site, thenmove to transaction processing over the Web) – Eventually move to intranet
  • 37. • Application Architecture Plan - Accounting/finance: purchase a package solution with the client-serverarchitecture - Human resources: purchase a package solution as intranet application - Customer Support System: new development integrating direct customeraccess via the Internet - Inventory Management System: a merchandizing and inventory system thatintegrates with customer support - Retail store system: integrates store management system with the inventorymanagement system• Time frames for implementing application architecture plan- - First: implement the customer support system (CSS) - Second: implement the inventory management system - Third: integrate retail store management system with the inventorymanagement system - Finally: upgrade the human resources system and the accounting/financesystem.Time frames are presented in Figure 1-15.MELJUN
  • 38. FIGURE 1-15 RMO’s application architecture plan.MELJUN
  • 39. Readings• Chapter 1 – The World of the Modern Systems Analyst(covered today)• Next lecture: Chapter 2 – The Analyst as ProjectManager• Lecture texts available at class web site (downloadable asPowerPoint slides)MELJUN