1 pertemuan 3 konsep dasar teknologi informasi matakuliah: h0402/pengelolaan sistem komputer tahun:...

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Pertemuan 3

Konsep DasarTeknologi Informasi

Matakuliah : H0402/PENGELOLAAN SISTEM KOMPUTER

Tahun : 2005

Versi : 1/0

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Learning Outcomes

Pada akhir pertemuan ini, diharapkan mahasiswa

akan mampu :

• Menyebutkan berbagai konsep dasar sistem informasi

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Outline Materi

• Pengertian Sistem

• Proses Bisnis

• Sumber Daya Manusia

• Pendekatan Pembuatan Sistem

• Kendali Sistem Informasi

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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)

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System – a set of interrelated components that must work together to achieve some common purpose

THE SYSTEMS VIEW

What Is a System?

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THE SYSTEMS VIEW

All components are there … but they don’t work well together!

An Example of Poor Design

What Is a System?

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System – a set of interrelated components that must work together to achieve some common purpose

THE SYSTEMS VIEW

What Is a System?

Information System – the collection of IT, procedures, and people responsible for the capture, movement, management, and distribution of data and information

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Seven Key System Elements

THE SYSTEMS VIEW

1. Boundary

2. Environment

3. Inputs

4. Outputs

5. Components

6. Interfaces

7. Storage

General Structure of a System

9System Component Examples

THE SYSTEMS VIEW

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Seven Key System Elements – System Boundary

System boundary depends on:

1. What can be controlled

2. What scope is manageable within a given time period

3. The impact of a boundary change

THE SYSTEMS VIEW

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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

THE SYSTEMS VIEW

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Seven Key System Elements – Component Decomposition

Goals of hierarchical decomposition:

1. To cope with system complexity

2. To analyze or change part of the system

3. To design and build each subsystem at different times

4. To direct the attention of a target audience

5. To allow system components to operate more independently

THE SYSTEMS VIEW

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Seven Key System Elements – Interfaces

Functions of an interface:– Filtering– Coding/decoding– Error detection and correction– Buffer– Security– Summarizing

Interface – point of contact between a system and its environment or between two subsystems

THE SYSTEMS VIEW

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Interfaces built between two preexisting systems are called bridges

THE SYSTEMS VIEW

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Possible objective of an interface:– System decoupling – changing two system

components so that modifying one does not necessarily require modifying the other

THE SYSTEMS VIEW

16Sales Summary Reporting System

17Sales Summary Reporting Subsystem

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Organizations as Systems

Fundamental Components of an Organization

How does a change in oneaffect the others?

THE SYSTEMS VIEW

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Systems Analysis and Design

Fundamental principles:– Choose an appropriate scope (boundary selection)– Logical before physical (what before how)

Systems analysis and design (SA&D) – a process used in developing new information systems based on a systems approach to problem solving

THE SYSTEMS VIEW

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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

THE SYSTEMS VIEW

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Business process – a set of work activities and resources

BUSINESS PROCESSES

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One way managers can evaluate a business process

Evaluating Business Processes (Keen, 1997)

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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

BUSINESS PROCESSES

Business Process Redesign

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BUSINESS PROCESSES


Six principles for redesigning business processes:1. Organize business processes around outcomes, not

tasks

2. Assign those who use the output to perform the process

3. Integrate information processing into the work that produces the information

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BUSINESS PROCESSES


Six principles for redesigning business processes:4. Create a virtual enterprise by treating geographically

distributed resources as though they were centralized

5. Link parallel activities instead of integrating their results

6. Have the people who do the work make all the decisions, and let controls built into the system monitor the process

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BUSINESS PROCESSES


How IT Enables New Ways to Work

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PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS

The Information Systems Life Cycle

Figure 9.8 Generic Systems Life Cycle

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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



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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


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Implementation Phase:• Business managers and IS professionals

install new system• Data and procedures from old system

converted


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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


Structured Techniques for Life Cycle Development

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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


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Procedural-Oriented Techniques

• Provides a baseline for the new system• Includes both logical and physical models

Three-Step Modeling Approach


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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



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• Conducted by IS specialists• Maps logical requirements to available technology



36Physical Model of a System

Boxes Major modules

Cylinders Databases

Arrows Flow of data

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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

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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


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Context Diagramfor Accounts Payable


40Work Process Flow Diagram for Accounts Payable

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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)

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Top-Level DFD for Accounts Payable System

43Top-Level DFD for Accounts Payable System

External Entity

Data Flow

Processes

Data Store

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• 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

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Lower-level explosion DFD for Process 1.0

46Second-Level DFD for Accounts Payable System

Note process numbering scheme

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• 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


48Data Dictionary Sample Entry

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Entity-Relationship Diagram for Invoice and PO


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Key Terms for Logical Data Modeling

Relational Database Terminology

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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

52Program Structure Chart

Program Structure Chart

53Relationships for Data Elements in Accounts Payable

Database Design (data relationships)

54Input Form Layout for Vendor Invoice

System Interface Input Layout Form

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Check Register Report Layout with Sample Data

Output Report Layout

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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


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Object-Oriented Techniques


The Promise of Object-Oriented Approaches

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Core Concepts


Message Passing

• Object• Encapsulation• Inheritance

Objects communicate with each other through messages that specify what should be done, not how it should be done

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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

60Use Case Diagram

Use Case Diagram

61Become Member Use Case

Use Case – Text Form

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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

• Management policies

• Operating procedures

• Auditing function

Types of Control Mechanisms

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• 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

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Pre- and Post-Installation Controls


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• Pengertian Sistem

• Proses Bisnis

• Pendekatan Pembuatan Sistem

• Kendali Sistem Informasi

Konsep Dasar Teknologi Informasi

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