1 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Chapter 12 Designing Systems Interfaces, Controls, and Security

2 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Objectives u Discuss examples of system interfaces found in information systems u Define system inputs and outputs based on the requirements of the application program u Design printed and on-screen reports appropriate for recipients u Explain the importance of integrity controls

3 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Objectives u Identify required integrity controls for inputs, outputs, data, and processing u Discuss issues related to security that affect the design and operation of information systems

4 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Full Range of Inputs and Outputs Figure 12-1

5 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Design of System Inputs u Identify devices and mechanisms used to enter input u Identify all system inputs and develop list of data content with each u Determine controls necessary for each system input

6 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Input Devices and Mechanisms u Capture data as close to origination as possible u Use electronic device and automatic entry whenever possible u Avoid human involvement as much as possible u Avoid data reentry and seek information in electronic form u Validate and correct at entry point

7 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Prevalent Input Devices to Avoid Keystroking u Magnetic card strip readers u Bar-code readers u Optical character recognition readers and scanners u Touch screens and devices u Electronic pens and writing surfaces u Digitizers, such as digital cameras and digital audio devices

8 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Defining Details of System Inputs u Ensure all data inputs are identified and specified correctly u Can use traditional structured models l Identify automation boundary u Use DFD fragments u Segment by program boundaries l Examine Structure Charts u Analyze each module and data couple u List individual data fields

9 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Automation Boundary on System-Level DFD Figure 12-3

10 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Structure Chart for Create New Order Figure 12-6

11 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Elements Making Up an Input Figure 12-7

12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Using OO Models u May identify inputs using OO diagrams u Sequence diagrams identify each incoming message u Design class diagram contain pseudocode to verify the characteristics of inputs

13 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Sequence Diagram for Create New Order Figure 12-9

14 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Input Messages and Data Parameters from RMO Sequence Diagram Figure 12-10

15 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Customer Class with Interfaces for Input Forms Figure 12-11a

16 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Order Class with Interfaces for Input Forms Figure 12-11b

17 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Designing System Outputs 1.Determine each type of output 2.Make a list of specific outputs required based on application design 3.Specify any necessary controls to protect the information provided in the output 4.Design and prototype the output layout

18 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Defining the Details of System Outputs u Type of reports l Printed l Electronic l Turnaround documents u May use traditional structured models to identify outputs l Data flows crossing automation boundary l Data couples and report data requirements on structure chart

19 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Table of System Outputs Based on Traditional Structured Approach Figure 12-12

20 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Using OO Models u Outputs indicated by messages in sequence diagrams l Originate from internal system objects l Sent to external actors u Output messages based on an individual object are usually part of the methods of that class object

21 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd System Outputs Based on OO Messages Figure 12-13

22 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Designing Reports, Statements, and Turnaround Documents u Printed versus electronic u Type of output l Detailed l Summary l Exception l Executive u Internal versus external u Drill down and linking u Graphical and multimedia presentation

23 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Summary Report with Drill Down to Details Figure 12-16

24 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Formatting Reports u What is report objective u Who is the intended audience u Avoid information overload u Format considerations

25 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Designing Integrity Controls u Mechanisms and procedures built into a system to safeguard it and the information contained within u Integrity controls l Built into application system to safeguard information u Security controls l Built into operating system and network

26 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Objectives of Integrity Controls u Ensure that only appropriate and correct business transactions occur u Ensure that transactions are recorded and processed correctly u Protect and safeguard assets of the organization l Software l Hardware l Information

27 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Points of Security and Integrity Controls Figure 12-18

28 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Input Integrity Controls u Used with all input mechanisms u Additional level of verification to help reduce input errors u Common control techniques l Field combination controls l Value limit controls l Completeness controls l Data validation controls

29 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Database Integrity Controls u Access control u Data encryption u Transaction control u Update control u Backup and recovery protection

30 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Output Integrity Controls u Ensures output arrives at proper destination and is correct, accurate, complete, and current l Destination controls - output is channeled to correct people l Completeness, accuracy, and corrrectness controls u Appropriate information present on output

31 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Designing Security Controls u Security Controls used to protect assets of organization from all threats l Primary focus is on external threats u Security control objectives l Maintain stable, functioning operating environment for users and application systems l Protect information and transactions during transmission outside the organization

32 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Security for Access to Systems u Used to control access to any resource managed by network or operating system u User categories l Unauthorized user l Registered user l Privileged user u Organized to so all resources can be accessed with same unique ID/password combination

33 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Users and Access Roles to Computer Systems Figure 12-19

34 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Data Security u Encryption is primary security method l Symmetric key l Asymmetric key l Public key u Digital signatures and certificates u Secure transactions l SSL / TLS l IPSec l HTTPS / HTTP-S

35 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Symmetric Key Encryption Figure 12-20

36 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Asymmetric Key Encryption Figure 12-21

37 12 Systems Analysis and Design in a Changing World, 2 nd Edition, Satzinger, Jackson, & Burd Using a Digital Certificate Figure 12-22