Pertemuan 3 Konsep Dasar Teknologi Informasi Matakuliah : H0402/PENGELOLAAN SISTEM KOMPUTER Tahun : 2005 Versi : 1/0 Pertemuan 3 Konsep Dasar Teknologi Informasi

Menyebutkan berbagai konsep dasar sistem informasi Learning Outcomes Pada akhir pertemuan ini, diharapkan mahasiswa akan mampu : Menyebutkan berbagai konsep dasar sistem informasi

Pendekatan Pembuatan Sistem Kendali Sistem Informasi Outline Materi Pengertian Sistem Proses Bisnis Sumber Daya Manusia Pendekatan Pembuatan Sistem Kendali Sistem Informasi

Systems thinking is: a discipline for seeing wholes THE SYSTEMS VIEW Systems thinking is: a discipline for seeing wholes a framework for seeing interrelationships rather than things an antidote to feeling of helplessness when dealing with complexity Peter Senge (1990)

THE SYSTEMS VIEW What Is a System? System – a set of interrelated components that must work together to achieve some common purpose

THE SYSTEMS VIEW What Is a System? All components are there … but they don’t work well together! An Example of Poor Design

THE SYSTEMS VIEW What Is a System? System – a set of interrelated components that must work together to achieve some common purpose Information System – the collection of IT, procedures, and people responsible for the capture, movement, management, and distribution of data and information

Seven Key System Elements THE SYSTEMS VIEW Seven Key System Elements Boundary Environment Inputs Outputs Components Interfaces Storage General Structure of a System

THE SYSTEMS VIEW System Component Examples

System boundary depends on: THE SYSTEMS VIEW Seven Key System Elements – System Boundary System boundary depends on: What can be controlled What scope is manageable within a given time period The impact of a boundary change

A component of a system is also called a subsystem or module THE SYSTEMS VIEW Seven Key System Elements – Component Decomposition A component of a system is also called a subsystem or module Hierarchical decomposition – the process of breaking down a system into successive levels of subsystems, each showing more detail

Goals of hierarchical decomposition: THE SYSTEMS VIEW Seven Key System Elements – Component Decomposition Goals of hierarchical decomposition: To cope with system complexity To analyze or change part of the system To design and build each subsystem at different times To direct the attention of a target audience To allow system components to operate more independently

Functions of an interface: THE SYSTEMS VIEW Seven Key System Elements – Interfaces Interface – point of contact between a system and its environment or between two subsystems Functions of an interface: Filtering Coding/decoding Error detection and correction Buffer Security Summarizing

Interfaces built between two preexisting systems are called bridges THE SYSTEMS VIEW Seven Key System Elements – Interfaces Interfaces built between two preexisting systems are called bridges

Possible objective of an interface: THE SYSTEMS VIEW Seven Key System Elements – Interfaces Possible objective of an interface: System decoupling – changing two system components so that modifying one does not necessarily require modifying the other

Sales Summary Reporting System

Sales Summary Reporting Subsystem

Organizations as Systems THE SYSTEMS VIEW Organizations as Systems How does a change in one affect the others? Fundamental Components of an Organization

Fundamental principles: THE SYSTEMS VIEW Systems Analysis and Design Systems analysis and design (SA&D) – a process used in developing new information systems based on a systems approach to problem solving Fundamental principles: Choose an appropriate scope (boundary selection) Logical before physical (what before how)

Recommended problem-solving steps: THE SYSTEMS VIEW Systems Analysis and Design Recommended problem-solving steps: Problem (or system) is a set of problems that must be broken down into smaller, more manageable problems Single solution is not always obvious to all – alternatives should be generated and considered Understanding of problem changes, so reassess commitment to solution at various stages

BUSINESS PROCESSES Business process – a set of work activities and resources

evaluate a business process One way managers can evaluate a business process Evaluating Business Processes (Keen, 1997)

BUSINESS PROCESSES Business Process Redesign Business process reengineering (BPR) – radical business redesign initiatives that attempt to achieve dramatic improvements in business processes by questioning the assumptions, or business rules, that underlie the organization’s structures and procedures

Six principles for redesigning business processes: Business Process Redesign Six principles for redesigning business processes: Organize business processes around outcomes, not tasks Assign those who use the output to perform the process Integrate information processing into the work that produces the information

Six principles for redesigning business processes: Business Process Redesign Six principles for redesigning business processes: Create a virtual enterprise by treating geographically distributed resources as though they were centralized Link parallel activities instead of integrating their results Have the people who do the work make all the decisions, and let controls built into the system monitor the process

Business Process Redesign BUSINESS PROCESSES Business Process Redesign How IT Enables New Ways to Work

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS The Information Systems Life Cycle Figure 9.8 Generic Systems Life Cycle

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS The Information Systems Life Cycle Definition Phase: End user and systems analysts conduct analysis of current system and business processes Analysis is: Process-oriented Data-oriented Business case generated and solution chosen

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS The Information Systems Life Cycle Construction Phase: System designed, built, and tested System logically described, then physically Technology chosen Programs, inputs, and outputs designed Software programmed and tested User acceptance testing conducted

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS The Information Systems Life Cycle Implementation Phase: Business managers and IS professionals install new system Data and procedures from old system converted

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS Structured Techniques for Life Cycle Development System development methodology – framework consisting of guidelines, tools, and techniques for managing skills to address the business issue Consists of processes, tools, techniques for developing systems Prescribe who participates, roles, development stages and decision points, and formats for documentation

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS Structured Techniques for Life Cycle Development Structured techniques – tools to document system needs, requirements, functional features, dependencies, and design decisions Procedural-oriented Most common Include data-oriented, sequential, process-oriented activities Object-oriented Newer approach Often used for GUIs and multimedia applications

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS Procedural-Oriented Techniques Provides a baseline for the new system Includes both logical and physical models Three-Step Modeling Approach

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS Procedural-Oriented Techniques Critical appraisal of existing work processes to: Identify major subprocesses, entities, and interactions Separate processing from data flow Capture relationships between data elements Determine entities and processes within scope Three-Step Modeling Approach

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS Procedural-Oriented Techniques Conducted by IS specialists Maps logical requirements to available technology Three-Step Modeling Approach

Boxes Major modules Cylinders Databases Arrows Flow of data Physical Model of a System

Tools for the As-Is Model Must identify existing processes, external participants, other databases or applications, and inputs and outputs Tools used: Procedures, policies, manuals, forms, reports Other documentation Group interviews

Tools for the As-Is Model Context diagram – positions the system as a whole with regard to other entities and activities with which it interacts Work process flow diagram – identifies the existing information sources, information sources that are updated, order in which steps occur, and some of the dependencies

Tools for the As-Is Model Context Diagram for Accounts Payable

Work Process Flow Diagram for Accounts Payable

High-level model of a nonexistent new system Tools for the Logical To-Be Model High-level model of a nonexistent new system Identifies processes and data Does not identify who does activity, where accomplished, or type of hardware or software Describes “what” rather than “how” Most closely associated with data flow diagrams (DFDs)

for Accounts Payable System Tools for the Logical To-Be Model Top-Level DFD for Accounts Payable System

for Accounts Payable System Data Flow External Entity Processes Data Store Top-Level DFD for Accounts Payable System

Process of creating a DFD: Tools for the Logical To-Be Model Process of creating a DFD: Identify entities that supply or use system information Distinguish processes from data they use or produce Explicate business rules that affect transformation of data to information Identify logical relationships Pinpoint duplicate storage and movement of data

Lower-level explosion DFD for Process 1.0

for Accounts Payable System Note process numbering scheme Second-Level DFD for Accounts Payable System

More logical modeling required after DFDs Tools for the Logical To-Be Model More logical modeling required after DFDs Need to define system’s data elements and relationships: Data dictionary/directory (DD/D) used to define data elements Entity-relationship diagram (ERD) used to define relationships between entities

Data Dictionary Sample Entry

Tools for the Logical To-Be Model Entity-Relationship Diagram for Invoice and PO

for Logical Data Modeling Relational Database Terminology Key Terms for Logical Data Modeling

Tools for physical design represent how: Tools for Documenting the Physical To-Be System Tools for physical design represent how: processes and data stores partitioned program control handled database organized Tools include: Program structure chart Database design System interface layouts

Program Structure Chart

Database Design (data relationships) Relationships for Data Elements in Accounts Payable

System Interface Input Layout Form Input Form Layout for Vendor Invoice

Output Report Layout Check Register Report Layout with Sample Data

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS Object-Oriented Techniques Object approach well suited for client/server applications, graphical interfaces, and multimedia data Primary advantage is ability to reuse objects programmed by others

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS Object-Oriented Techniques The Promise of Object-Oriented Approaches

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS Core Concepts Object Encapsulation Inheritance Objects communicate with each other through messages that specify what should be done, not how it should be done Message Passing

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS Unified Modeling Language (UML) For O-O Modeling UML is standardization for O-O analysis and design modeling techniques and notations UML diagrams: Use-case diagrams Extended relationship use-case diagram Sequence diagram Class diagram Logical modeling begins with use-cases – diagrams and text forms

Use Case Diagram Use Case Diagram

Use Case – Text Form Become Member Use Case

INFORMATION SYSTEMS CONTROLS TO MINIMIZE BUSINESS RISKS Common system security risks: Human error Criminal acts Due to staffing changes and project management deficiencies Natural disasters Types of Control Mechanisms Management policies Operating procedures Auditing function

INFORMATION SYSTEMS CONTROLS TO MINIMIZE BUSINESS RISKS Types of Control Mechanisms Controls built into the information system itself: To maintain data integrity Allow only authorized access Ensure proper system operation Protect against malfunctions, power outages, and disasters IS Organization Backup power supplies Network access control Firewall protection Business Organization Ensure accurate data entry and handling Identify procedural errors

INFORMATION SYSTEMS CONTROLS TO MINIMIZE BUSINESS RISKS Types of Control Mechanisms Pre- and Post-Installation Controls

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