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IMS 9001 - Systems Analysis and Design DESIGN OVERVIEW: SELECTING DESIGN ALTERNATIVES 1 IMS 9001 - Systems Analysis and Design DESIGN OVERVIEW: SELECTING DESIGN ALTERNATIVES 1

Design Phase - Purpose The main objectives of the design phase are: § to Design Phase - Purpose The main objectives of the design phase are: § to provide alternative design solutions § to assist in the selection of a design solution § to acquire the necessary hardware and software § to design and integrate the various physical system components. . interfaces, security controls, files/databases, etc. . . 2

Design (How? ) § Define how the system will be implemented ANALYSIS System Vendors Design (How? ) § Define how the system will be implemented ANALYSIS System Vendors Various Sources Design ideas/opinions System Requirements Specification Report Hardware/Software deals Select a design strategy and specify details Technical Design Report Design Options Selected Design Option Design in Progress Report IMPLEMENTATION System. Owners/ Users 3

1. Generating Alternative Design Solutions § using the prioritised business requirements from the Analysis 1. Generating Alternative Design Solutions § using the prioritised business requirements from the Analysis phase: § propose creative alternatives to meet the requirements for different implementation environments § hardware, system software, network platforms § assess the feasibility of these alternatives to see which one best meets the organisation’s needs § remember. . alternative solutions should never be limited to computer solutions. . improved manual systems and sub-systems can be equally viable 4

Generating Alternatives: How many? § While it is possible to generate a large no. Generating Alternatives: How many? § While it is possible to generate a large no. of alternatives … 3 feasible alternatives is usual: § low end … conservative in terms of effort, cost and technology § high-end … many extra features, functionality not cost primary focus § mid-range … a compromise of the above 5

Generating Alternatives: Issues § § § Constraints Outsourcing Sources of software Hardware and system Generating Alternatives: Issues § § § Constraints Outsourcing Sources of software Hardware and system software issues Implementation issues Organisational issues 6

Constraints § date when system is required § available financial and human resources § Constraints § date when system is required § available financial and human resources § elements of the current system that cannot change § legal and contractual restrictions § the strategic importance of the system to the client (may limit outsourcing) How firm are the constraints? . . can they be violated in special circumstances 7

Outsourcing § The practice of turning over some or all of an organisation IS Outsourcing § The practice of turning over some or all of an organisation IS applications and/or operations to an outside firm. § Why? § § May be cost-effective may be specialist in your business area to overcome operating problems running IS not part of core business need to be aware of the pros and cons 8

Sources of Software § Hardware manufacturers § mainly systems software § Packaged software producers Sources of Software § Hardware manufacturers § mainly systems software § Packaged software producers § range from generic eg. MS Project to very narrow, niche packages § Custom software producers § when internal expertise or personnel not available § In-house development Hybrid solutions are common 9

Choosing off-the shelf software: Issues § § § § Cost Functionality Vendor Support Viability Choosing off-the shelf software: Issues § § § § Cost Functionality Vendor Support Viability of Vendor Flexibility Documentation Response Time Ease of Installation 10

Choosing off-the shelf software: Process § identify products which may suit specified requirements § Choosing off-the shelf software: Process § identify products which may suit specified requirements § solicit, evaluate and rank vendor proposals § select the best vendor proposal § establish requirements for integrating the vendor’s products 11

Choosing off-the shelf software: Criteria § Identify criteria by which to evaluate hardware and Choosing off-the shelf software: Criteria § Identify criteria by which to evaluate hardware and software § cost, functionality, vendor support, vendor viability, quality of documentation, ease of learning, ease of use, ease of installation, response time, throughput, version? , ease of customisation, number of current installations, licensing arrangement, training, internal controls, database size limitation, maintenance contracts, customer references § to help identify criteria you can use § past experience, trade magazines and journals, information services, potential vendors. . bias 12

Hardware and System Software Issues: 1 § Advantages of running a new system on Hardware and System Software Issues: 1 § Advantages of running a new system on the existing platform: § § lower costs familiarity with system easier to integrate with current systems no added cost with converting old systems to new platforms 13

Hardware and System Software Issues: 2 § Reasons for acquiring new hardware or system Hardware and System Software Issues: 2 § Reasons for acquiring new hardware or system software § some components of your new system may only run on the new platform § opportunity to upgrade/expand current technology § may allow for radical change eg. centralised to distributed processing 14

Implementation Issues § User training § Disruptions in work procedures must be addressed § Implementation Issues § User training § Disruptions in work procedures must be addressed § How long will implementation take? § Social issues 15

Organisational Issues § § Overall cost and the availability of funding What will management Organisational Issues § § Overall cost and the availability of funding What will management support? Are there any political issues? Will users accept the new system? 16

Analyse feasibility of alternative solutions § Once alternative solutions have been identified, they must Analyse feasibility of alternative solutions § Once alternative solutions have been identified, they must be analysed for technical, schedule, operational, and economic feasibility § “Feasibility is the measure of how beneficial or practical the development of an information systems will be to an organisation” Whitten, et. al. § Feasibility must be assessed throughout the project 17

Assessing feasibility § Categories of feasibility tests § Operational. . does it solve the Assessing feasibility § Categories of feasibility tests § Operational. . does it solve the problems? , does it take advantage of the opportunities? , how well will it work? , how do people feel about it? § Political. . Is it supported right through the organisation? § Legal and Contractual § Technical. . are the technical resources and expertise available? , is the technical solution practical? § Schedule. . is the time-table reasonable? § Economic. . how cost-effective is it? 18

2. Select a solution § After alternatives that are infeasible are eliminated, the remaining 2. Select a solution § After alternatives that are infeasible are eliminated, the remaining alternatives are presented to the users in the form of a proposal. This proposal contains: § project plans and size estimates § alternative solutions with associated feasibility analysis § The user then chooses the alternative than best meets their requirements. . possibly based on the recommendation given by the system staff 19

3. Acquire hardware and software § identify products which may suit specified requirements § 3. Acquire hardware and software § identify products which may suit specified requirements § solicit, evaluate and rank vendor proposals § select the best vendor proposal § establish requirements for integrating the vendor’s products § Note: this phase is only carried out when some or all of the system will not be developed in-house 20

Research technical criteria and options § Identify criteria by which to evaluate hardware and Research technical criteria and options § Identify criteria by which to evaluate hardware and software § quality of documentation, ease of learning, ease of use, response time, throughput, version? , number of current installations, licensing arrangement, training, internal controls, database size limitation, maintenance contracts, customer references § to help identify criteria you can use § past experience, trade magazines and journals, information services, potential vendors. . beware of bias 21

Solicit proposals/quotes from vendors § Some organisations are committed to buying from a specific Solicit proposals/quotes from vendors § Some organisations are committed to buying from a specific vendor. . so it’s simple. . just get a quote and terms § If you are going to the marketplace you must prepare either a: § Request for Quotations (RFQ). . if you have already decided on a product. . and just want information on: § price, vendor specific configuration, maintenance agreements, conditions regarding buyer changes and servicing § Request for Proposal (RFP). . if you are open to a variety of products 22

4. Design and integrate the new system § design a user-friendly system that fulfils 4. Design and integrate the new system § design a user-friendly system that fulfils user requirements § provide clear and complete technical design specifications to the programmers and technical staff 23

Analyse and distribute data and processes § Need to decide on the system architecture Analyse and distribute data and processes § Need to decide on the system architecture the processing, network and data issues: § whether the system will use centralised, decentralised or cooperative processes § whether the system’s data stores will be centralised or distributed § how data will be input? § how outputs will be generated? 24

Factor into design units § Using the process and data models, the target system Factor into design units § Using the process and data models, the target system needs to be factored into design units which: § § § § are easy to build are easy to test and prove are easy to maintain document as a natural by-product isolate the effect of a given problem apply principles of re-use facilitate a large degree of partitioning 25

Backup and Recovery § A standard system of controls that should be built into Backup and Recovery § A standard system of controls that should be built into all systems § Principles: § data can be reconstructed in the event of loss or corruption § application and system software can be reinstated in the event of loss or corruption § Loss or corruption may be deliberate or accidental - controls are essentially the same 26

Design computer outputs and inputs and on-line interfaces § the precise format and layout Design computer outputs and inputs and on-line interfaces § the precise format and layout of all outputs must be specified. . may be on blank paper, pre -printed forms or screens § the data capture method for all inputs must be specified. . initial manual capture and/or direct entry into the computer system § build easy-to-learn and easy-to-use dialogue around the input and output screens designed in earlier tasks 27

The Basics of Interface Design Five Commandments: § Support “Transportability of Knowledge” § Be The Basics of Interface Design Five Commandments: § Support “Transportability of Knowledge” § Be Consistent § Provide Feedback § Use Drab Colours § Make the User Boss 28

References § HOFFER, J. A. , GEORGE, J. F. and VALACICH (2005) Modern Systems References § HOFFER, J. A. , GEORGE, J. F. and VALACICH (2005) Modern Systems Analysis and Design, (4 th edition), Pearson Education Inc. , Upper Saddle River, New Jersey, USA. Chapters 1, 5 § WHITTEN, J. L. , BENTLEY, L. D. and DITTMAN, K. C. (2001) 5 th ed. , Systems Analysis and Design Methods, Irwin/Mc. Graw-Hill, New York, NY. Chapter 10 29