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Chapter 6 Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6 ©2016. Cengage Learning. All rights reserved.  Foundations for Systems Design 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 ©2016. Cengage Learning. All rights reserved.  Foundations for Systems Design Chapter 6 Systems Analysis and Design in a Changing World 7th Ed Satzinger, Jackson & Burd Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6 ©2016. Cengage Learning. All rights reserved.  Chapter 6 Outline What Is Systems Design? Design Activities System Controls and Security Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6 ©2016. Cengage Learning. All rights reserved.  Learning Objectives 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 ©2016. Cengage Learning. All rights reserved.  Overview 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 ©2016. Cengage Learning. All rights reserved.  What is Systems Design 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 ©2016. Cengage Learning. All rights reserved.  Analysis to Design to Implementation Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6 ©2016. Cengage Learning. All rights reserved.  Design Models 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 ©2016. Cengage Learning. All rights reserved.  Analysis Models to Design Models Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6 ©2016. Cengage Learning. All rights reserved.  Design Activities 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 ©2016. Cengage Learning. All rights reserved.  Design Activities and Iterations Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6 ©2016. Cengage Learning. All rights reserved.  Key Design Questions for each Activity Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6 ©2016. Cengage Learning. All rights reserved.  Describe the Environment 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 ©2016. Cengage Learning. All rights reserved.  Design the Application Components 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 ©2016. Cengage Learning. All rights reserved.  Typical models for defining application components Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6 ©2016. Cengage Learning. All rights reserved.  Design the User Interface 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 ©2016. Cengage Learning. All rights reserved. Typical models for user interface design Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6 ©2016. Cengage Learning. All rights reserved.  Design the Database 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 ©2016. Cengage Learning. All rights reserved.  Typical Table Definition as part of Database Schema Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6 ©2016. Cengage Learning. All rights reserved.  Design Software Classes and Methods 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 ©2016. Cengage Learning. All rights reserved.  Typical Design Class Diagram with attributes and methods Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6 ©2016. Cengage Learning. All rights reserved.  System Controls and Security 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 ©2016. Cengage Learning. All rights reserved.  Integrity and Security Controls Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6 ©2016. Cengage Learning. All rights reserved.  Designing Integrity Controls 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 ©2016. Cengage Learning. All rights reserved.  Input Controls 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 ©2016. Cengage Learning. All rights reserved.  Output Controls 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 ©2016. Cengage Learning. All rights reserved.  Redundancy, Backup and Recovery 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 ©2016. Cengage Learning. All rights reserved.  Fraud Prevention 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 ©2016. Cengage Learning. All rights reserved.  Fraud Risk – Factors and Techniques Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6 ©2016. Cengage Learning. All rights reserved.  Designing Security Controls 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 ©2016. Cengage Learning. All rights reserved.  Designing Security Controls 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 ©2016. Cengage Learning. All rights reserved.  Types of users Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6 ©2016. Cengage Learning. All rights reserved.  Data Encryption 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 ©2016. Cengage Learning. All rights reserved.  Symmetric Key Encryption Encryption method that uses the same key to encrypt and decrypt Systems Analysis and Design in a Changing World, 7th Ed - Chapter 6 ©2016. Cengage Learning. All rights reserved.  Asymmetric Key Encryption 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 ©2016. Cengage Learning. All rights reserved.  Digital Signatures and Certificates 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 ©2016. Cengage Learning. All rights reserved.  Secure Transactions 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 ©2016. Cengage Learning. All rights reserved.  Summary 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 ©2016. Cengage Learning. All rights reserved.  Summary (continued) 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 ©2016. Cengage Learning. All rights reserved.  Summary (continued) 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 ©2016. Cengage Learning. All rights reserved.