SYSTEM ANALYSIS

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Chapter 6

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Systems Analysis and Design in a Changing World 7th Ed Satzinger, Jackson & Burd

Chapter 6

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

What Is Systems Design?

Design Activities

System Controls and Security

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Describe systems design and contrast it with systems analysis

List the documents and models used as inputs to or output from systems design

Explain each major design activity

Describe security methods and controls

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Analysis says “what” is required and design tells us “how” the system will be configured and constructed

Chapters 2, 3, 4 and 5 covered systems analysis activities (requirements)

This chapter introduces system design and the design activities involved in systems development

Design bridges the gap between requirements to actual implementation

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Analysis provides the starting point for design

Design provides the starting point for implementation

Analysis and design results are documented to coordinate the work

Objective of design is to define, organize, and structure the components of the final solution to serve as a blue print for construction

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Design is a model building activity

The formality of the project will dictate the type, complexity, and depth of models

Agile/iteration projects typically build fewer models, but models are still created

Jumping to programming without design often causes less than optimum solutions and may require rework

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Design activities correspond to components of the new system

The environment

Application components

User interface

Database

Software classes and methods

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Two key elements in the environment Communications with External Systems

Message formats

Web and networks

Communication protocols

Security methods

Error detection and recovery

Conforming to an existing Technology Architecture Discover and describe existing architecture

Chapter 7 provides more details

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Application component is a well defined unit of software that performs some function(s)

Issues involve how to package components including

Scope and size – what are the functions, boundaries, interfaces?

Programming language – what are the accepted languages?

Build or buy – is an acceptable version available to purchase?

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

To the user, the User Interface is the system.

The user interface has large impact of user productivity

Includes both Analysis and Design tasks Requires heavy user involvement

Current needs require multiple user interfaces Many different devices and environments

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

By definition, an Information System requires data – usually in a database

Current technology frequently use Relational Database Management Systems (RDBMS)

Requires converting the data model to a relational database

Requires addressing of many other technical issues

Throughput and response time

Security

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

AKA Detailed Design

A model building activity Design Class Diagram

Sequence Diagrams

State-Machine Diagrams

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Integrity Controls Controls that maintain integrity of inputs, outputs and data and programs

Security Controls Controls that protect the assets from threats, internal and external

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Integrated into application programs and DBMS

Objectives of Integrity Controls Ensure that only appropriate and correct business transactions are accepted

Ensure that transactions are recorded and processed correctly

To protect and safeguard assets such as the database

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Prevent invalid or erroneous data from entering the system

Value Limit Controls Check the range of inputs for reasonableness

Completeness Controls Ensure all the data has been entered

Data Validation Controls Ensure that specific data values are correct

Field Combination Controls Ensure data is correct based on relationships between fields

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

To ensure that output arrives at proper destination (for authorized eyes) and is accurate, current, and complete

Examples Physical access to printers and display devices

Discarded data – protect from “dumpster diving”

Labels on printed and electronic output to correctly identify source of data

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Protect data and systems from catastrophes Databases

Hardware

Software applications

Networks

On-site versus off-site copies

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Critical to prevent internal fraud, embezzlement, or loss

Fraud triangle Opportunity

Motive

Rationalization

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Protect all assets against external threats

Other objectives Protect and maintain a stable, functioning operating environment 24/7 (equipment, operating systems, DBMSs)

Protect information and transactions during transmission across networks and Internet

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Access Controls – Limit a person’s ability to access servers, files, data, applications

Authentication – to identify users Multifactor Authentication

Access control list – list of valid users

Authorization – authenticated user’s list of permission level for each resource

Registered Users – those with authorization

Unauthorized Users – anyone not registered

Privileged Users – those that maintain lists and systems

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Method to secure data – stored or in transmission

Encryption – alter data so it is unrecognizable

Decryption – converted encrypted data back to readable format

Encryption Algorithm – mathematical transformation of the data

Encryption Key – a long data string that allows the same algorithm to produce unique encryptions

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Encryption method that uses the same key to encrypt and decrypt

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Encryption method that uses different keys to encrypt and decrypt

AKA Public Key Encryption

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Digital Signature – technique where a document is encrypted using a private key

Note – implements previous slide, but in reverse Document is encrypted with private key, but then can only be decrypted with correct public key

Digital Certificate – An organizations name and public that is encrypted and certified by an authorized third party

Certifying Authority – the authorized third party Widely known and accepted – built into Web browsers

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Secure Sockets Layer (SSL) – standard set of protocols for authentication and authorization

Transport Layer Security (TLS) – an Internet standard equivalent to SSL

IP Security (IPSec) – Internet security protocol at a low-level transmission

Hypertext Transfer Protocol Secure (HTTPS) – Internet standard to transmit Web pages

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

This chapter introduces the concept of Systems Design

Analysis is fact finding and modeling

Design is modeling to specify how system will be implemented

Design is bridge between analysis an implementation

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

Activities of Systems Design Describe the environment

Design the application components

Design the User Interface

Design the database

Design the software classes and methods

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6

System Controls and Security Integrity Controls

Input controls

Output controls

Backup and recovery

Fraud prevention

Security Controls Access controls

Data encryption

Digital signatures and certificates

Secure transactions

Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6