1. Topics Module 5 Logical And Physical Design User Interface Design
Disaster Recovery
System Controls
Evaluating Alternatives

2. Systems Design

3. Systems design
Logical design presents the functional or business requirements of an application solution independent of physical or technical considerations. It presents a model for solving a problem from an end-user or business standpoint.
Logical data-flow diagrams (DFDs) are good tools to confirm the business models with end-users.

4. Logical Design Output design: types, format, content, frequency
Input design: types, format, content, frequency
Processing design: calculations, comparisons, manipulations
File & database design: capabilities and organization

5. Logical Design
Telecommunications design: high-level network description
Procedures design: automated & manual
Controls & security design
Personnel & job design

6. Systems design
Physical design consists of detailed specifications for hardware, software, processing logic, input/output methods and media, manual procedures, and controls.
Physical design will be shaped by the requirements of the logical design and existing technical, economic, or operational constraints. Physical DFDs are created from logical DFDs.

7. Physical Design Hardware design Software design Database design
Telecommunications design
Personnel design
Procedures & controls design

8. Special System Design Considerations
Sign-on procedures
Interactive processing
Interactive dialog
Preventing, detecting, and correcting errors

9. Interface Design and Controls
Figure 13.2: The Levels of the Sign-On Procedure
Principles of Information Systems, Eighth Edition

10. Interface Design and Controls
Figure 13.3: Menu-Driven System
Principles of Information Systems, Eighth Edition

11. User interfaces
Designing the user interface is one of the most important IS considerations. The interface should be user-friendly. If multiple applications are used, the interface should be consistent so that the users are not confused when switching between applications.

12. Interface Design and Controls
Table 13.1: The Elements of Good Interactive Dialogue
Principles of Information Systems, Eighth Edition

13. User interfaces Some user interface considerations include:
procedures for signing on — by group, by level, by individual password
interactive processing, including help menus, lookup tables, restart procedures
interactive dialogue considerations and rules
preventing and detecting errors by designing automatic tests and procedures for correction of errors, such as methods for reversing errors

14. Features For User Interface Design
Screen type
Screen size
Resolution
Fonts
Color
Keyboard layout
Shortcut keys versus mouse

15. Emergency procedures and disaster recovery
Disasters can and do occur, whether a natural disaster such as a flood, or a human-related problem such as sabotage or strikes. Plans must be developed to ensure the integrity of the corporate data and to keep the information systems running until things resume to normal.

16. Emergency procedures and disaster recovery
Planning includes identifying potential problems, prioritizing both the problems and the need to maintain automated systems (for example, some processes can be handled manually in an emergency), identifying key personnel, reviewing options, assessing risk versus cost, and developing a plan. The business resumption plan is called different names, such as the contingency plan or the disaster recovery plan.

17. Emergency procedures and disaster recovery
Disaster recovery is the implementation of the business resumption/disaster plan. The major tool used for disaster recovery is backup — of data, programs, hardware, software, telecommunications, and personnel. Options include:
another company that has identical hardware and software
a hot site that has all the requisite hardware and software and can be turned on instantly to replace the damaged computing site.

18. Emergency procedures and disaster recovery (cont.)
a cold site or shell that consists of a computer environment with rooms, telecommunications, and devices to which a mainframe can be brought and to which data and programs can be transferred via telecommunications
selective backup, where only critical files are backed up every night
incremental backup, where only changes made to files during the last day or week are backed up, using an image log — a separate file containing only changes which is created whenever an application is used

19. Emergency Alternate Procedures & Disaster Recovery
Telecommunications backup
Personnel backup
Hardware backup
Software & database backup

20. Hardware backup
Disaster recovery plans
Hot site
Cold site

21. Software & Database Backup
Selective backups
Incremental backups
Image log

22. Systems controls
Internal controls must be applied to protect IS from errors and irregularities. General controls and application controls are two types of internal controls.
General controls include:
hardware controls
software controls
data security controls
operations controls
management controls

23. Systems controls
Complete user, system, and operational documentation is essential for maintaining a sound general control environment.
Application controls include:
input controls — a commonly used technique to detect input error is batch control totals
processing controls — examples include built-in processing error-detection and range tests for reasonableness and check digit tests

24. Systems controls (cont.)
output controls — examples include distribution lists, verification of output results, and protection of confidential output
data controls — examples include backing up of data and program files and the custody of data by the data librarian

25. Systems controls
There is far greater access to corporate data than ever before as users enhance their productivity by using the computer. An appropriate balance must be struck between access to data and the proper care and security of data for individuals who are not data processing professionals. A corporate policy must be established to control end-users’ access to company data. Internal control measures are needed to ensure that data are used effectively and updated correctly.

26. Generating systems design alternatives
When new hardware and software are to be acquired, the appropriate document is prepared:
Request for Quotation (RFQ)
Request for Information (RFI)
Request for Proposal (RFP)

27. Generating Systems Design Alternatives
Figure 13.5: A Typical Table of Contents for a Request for Proposal
Principles of Information Systems, Eighth Edition

28. Generating Systems Design Alternatives
Figure 13.6: The Stages in Preliminary and Final Evaluations
Principles of Information Systems, Eighth Edition

29. Evaluating and selecting systems design
There are generally two steps in evaluating proposed designs — preliminary evaluation and final evaluation:
The preliminary evaluation is held to eliminate those proposals that clearly do not meet the minimum criteria, and to compare the remainder to the criteria so as to reduce them down to a small number or short list.

30. Evaluating and selecting systems design (cont.)
The vendors on the short list will be required to make a formal presentation and conduct demonstrations of their system, preferably with real (but not live) data as part of the final evaluation, a much more comprehensive and time-consuming process.

31. Evaluating and selecting systems design (cont.)
Evaluation techniques include four processes, not mutually exclusive:
group consensus
cost-benefit analysis
benchmark tests
point evaluations

32. Table 13.4

33. Evaluation Techniques
Figure 13.7: An Illustration of the Point Evaluation System
Principles of Information Systems, Eighth Edition

34. Freezing Design Specifications
User agrees in writing that design is acceptable
Figure 13.8: Freezing Design Specifications
Principles of Information Systems, Eighth Edition

35. The Contract Vendors provide standard contracts to protect themselves
Organizations often use outside consultants and legal firms to develop contracts that state:
All equipment specifications, software, training, installation, maintenance, etc.
Deadlines for various stages
Actions that vendor will take in case of delays or problems
Penalty clauses
Principles of Information Systems, Eighth Edition

36. Design report
The final result is the design report and recommendations.
The design report contains technical specifications in terms of characteristics of systems components.

37. Questions (?)