CIS 475/575: Topic # 1

Transcription

1 CIS 475/575: Topic # 1 The Systems Development Environment Objectives 1. Definition of information systems (IS) analysis and design. 2. Modern approach to systems analysis and design. 3. The roles of specialists involved in information systems design and development. 4. Different types of information systems. 5. The systems development life cycle (SDLC).

2 Information Systems from 1950 to 2006 In the early years of computing, analysis and design were considered more of an art. However, with the growing importance of and changing nature of information technology and its usage in the work environment, work methods have evolved, making analysis and design a disciplined process. Through the years, we have seen the systems developer s job move from that of a builder to an integrator. In the 1950s, the development effort concentrated on the processes the software performed; emphasis was placed on automating existing processes; all applications had to be developed in machine language or assembly language and were developed from scratch. In the 1970s, systems development came to be more disciplined as many people worked to make it more like engineering. In the 1980s microcomputers became key organizational tools, the software industry expanded greatly, fourth-generation languages were used more and more to write applications, and CASE tools were developed. Systems integration is currently the focus of the systems development environment. IS Analysis and Design Information systems analysis and design is the complex organizational process through which computer based information systems are designed, developed, tested, analyzed, redesigned, redeveloped, and maintained. There are 2 approaches to develop IS system: 1. Process model approach: Traditionally, an information system s design was based on WHAT the system was supposed to do. Each application had its own files and data storage. The data had to match the specifications established in each application, and each application was considered separately. 2. Data oriented approach: It depicts the ideal organization of data, independent of WHERE and HOW data are used within a system. It also reflects the inherent nature of the business instead of the way the business operates, which is constantly changing.

3 Process-Oriented and Data-Oriented Approaches Several small independent IS (process-oriented approach) Process is in the center of IS (e.g., calculate payments, etc.); specific data supports calculations A single united database (data-oriented approach) Data is in the center of IS (applications just use specific pieces from a single database) CIS Analysis, Design and Development: Basic Principle Separating Data and Processes (Databases and Applications) 1. Basic principle to information systems development distinction between data, data flows, and processing logic (data processing). 2. Data row facts about objects, systems, people, events. 3. Information data that have been processed and presented in a form suitable for human interpretation. 4. Data flow data in motion, moving from one place in a system to another. 5. Processing logic (data processing ) a) the steps (algorithms) by which data are transformed or moved and b) events that trigger these steps.

4 Data, Data Flow and Processing Logic (data processing) Key Differences between Process-Oriented and Data-Oriented Approaches Characteristic Process-Oriented Data-Oriented 1. System focus WHAT the system is supposed to do and WHEN 2. Design stability Limited because business processes change constantly 3. Data organization Data files designed for each indiv. application 4. State of the data Uncontrolled duplication of data; no synchronization of data changes DATA that the system needs More enduring (data needs do not change rapidly) Common data files designed for the entire enterprise (corporate applications) Controlled duplication; no synchronization problems

5 Types of Specialists Involved in Systems Development 1. IS managers (allocating resources; overseeing approved project). 2. Systems analysts (use analytical, technical, managerial, and interpersonal skills in developing new systems; playing a key liaison role between users and programmers). 3. Programmers (converting system specifications to code). 4. End users (take a lead role in determining what new systems should do and look like; in some cases, developing applications themselves with the assistance of IS professionals). 5. Business managers (set IS development priorities; fund projects; approve projects). 6. Other professionals (includes database administrators, telecommunications experts, human factors specialists, and internal auditors their responsibilities depend on their jobs). Characteristics of a Successful Systems Development Team 1. Diversity in backgrounds, skills, and goals. 2. Tolerance of diversity, uncertainty, and ambiguity. 3. Clear and complete communication. 4. Trust. 5. Mutual respect and putting one s own views second to the team. 6. Reward structure that promotes shared responsibility and accountability.

6 TYPES OF INFORMATION SYSTEMS KIND OF INF. SYSTEM STRATEGIC LEVEL GROUPS SERVED SENIOR MANAGERS MANAGEMENT LEVEL MIDDLE MANAGERS KNOWLEDGE LEVEL KNOWLEDGE & DATA WORKERS OPERATIONAL LEVEL OPERATIONAL MANAGERS SALES & MARKETING MANUFACTURING FINANCE ACCOUNTING HUMAN RESOURCES Source: Laudon&Laudon, 8 th ed. Six Major Types of Information Systems 1. EXECUTIVE SUPPORT SYSTEMS (ESS) 2. MANAGEMENT INFORMATION SYSTEMS (MIS) 3. DECISION SUPPORT SYSTEMS (DSS) 4. KNOWLEDGE WORK STATIONS (KWS) 5. OFFICE AUTOMATION SYSTEMS (OAS) 6. TRANSACTION PROCESSING SYSTEMS(TPS)

7 6 MAJOR TYPES OF INFORMATION SYSTEMS Source: Laudon&Laudon, 8 th ed. Transaction Processing Systems (TPS): OPERATIONAL LEVEL INPUTS: TRANSACTIONS, EVENTS PROCESSING: UPDATING OUTPUTS: DETAILED REPORTS USERS: OPERATIONS PERSONNEL

8 TYPICAL APPLICATIONS OF TPS Source: Laudon&Laudon, 8 th ed. KNOWLEDGE WORK SYSTEMS (KWS) KNOWLEDGE LEVEL INPUTS: DESIGN SPECS PROCESSING: MODELLING OUTPUTS: DESIGNS, GRAPHICS USERS: TECHNICAL STAFF EXAMPLE: ENGINEERING WORK STATION

9 Office Automation Systems: TOWARD A PAPERLESS OFFICE REDESIGN OF WORK FLOW INTEGRATED SOFTWARE ERGONOMIC DESIGN BRIGHT, CHEERFUL WORK SPACE EXAMPLE: PRESENTATION GRAPHICS Management Information Systems: MANAGEMENT LEVEL INPUTS: HIGH VOLUME DATA PROCESSING: SIMPLE MODELS OUTPUTS: SUMMARY REPORTS USERS: MIDDLE MANAGERS

10 A SAMPLE REPORT THAT MIGHT BE PRODUCED BY MANAGEMENT INFORMATION SYSTEMS (MIS) Source: Laudon&Laudon, 8 th ed. Decision Support Systems: MANAGEMENT LEVEL INPUTS: LOW VOLUME DATA PROCESSING: INTERACTIVE OUTPUTS: DECISION ANALYSIS USERS: PROFESSIONALS, STAFF EXAMPLE: CONTRACT COST ANALYSIS

11 DECISION SUPPORT SYSTEMS (DSS) Executive Support Systems: STRATEGIC LEVEL INPUTS: AGGREGATE DATA PROCESSING: INTERACTIVE OUTPUTS: PROJECTIONS USERS: SENIOR MANAGERS EXAMPLE: 5 YEAR OPERATING PLAN

12 INTERRELATIONSHIPS AMONG SYSTEMS ESS MIS DSS KWS OAS TPS System Development Life Cycle The seven phases of the systems development life cycle are 1. project identification and selection, 2. project initiation and planning, 3. analysis, 4. logical design, 5. physical design, 6. implementation, and 7. maintenance. Project identification and selection is the phase where an organization s total information system needs are identified, analyzed, prioritized, and arranged. Project initiation and planning is the phase where a potential IS project is explained and an argument for continuing or not continuing the project is presented. Analysis is the phase where the current system is studied and alternative replacement systems are proposed. Logical design is the phase where all functional features of the target system are described independent of implementation concerns. Physical design is the phase where the logical specifications are transformed into implementation specific specifications so system construction can occur. Implementation is the phase where the code is written and tested, the system is installed, and user training and support are planned and provided. Maintenance is the phase where the system is systematically repaired and improved.