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Ch.4 The UCSD Process. The Waterfall Model. Requirements. Architectural Design. Detailed Design. Coding. Integration Deployment. Maintenance. Weaknesses of the WF Model. Focus is on Tech. (take a purely technical systems approach)
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The Waterfall Model Requirements Architectural Design Detailed Design Coding Integration Deployment Maintenance
Weaknesses of the WF Model • Focus is on Tech. (take a purely technical systems approach) • Reflects the views of the designer and not of the stakeholder • Holds information in their mind • Difficult to find locations • Easy process for designer yet difficult for the user • The user interface is designed around a technical view of how the system works • Problem lies with the process by which systems are developed • The process is sequential • ‘get it right the first time’
Stages of the WF Model • Requirements Specification: • based upon a good understanding of users and their needs • How to get users needs? • Key Issues: • What data to collect • Explore requirements. • Poorly defined requirements leads to project failure • Types of Requirements: • Functional R’s - ex, providing the means of undoing an action • Data R’s - ex, car rental system • Environmental R’s - ex, the system will run on Linux OS • User R’s - ex, the typical user, significant subgroups • Usability R’s - ex, the system must provide clear instructions
Stages of the WF Model • Architectural Design: • Requirements focus upon what is required: architectural design is focused on how it can be achieved. • Detailed Design: • Its developed from the architectural design, selecting between available options • Coding & Testing: • Given a detailed design, the next step is to produce software and to test it thoroughly. • Spotting bugs for repair • Integration & Deployment: • the individual components are integrated according to the overall architectural design • Maintenance: • This is when the system in in use • It is not part of the design process
UCSD Observation of existing systems Problem Stmt Task Analysis HTA Requirements Stmt: -functional -non-functional Usability Guidelines & heuristics Requirements Gathering Design & Storyboarding Technical & Legal Constraints Storyboard Prototype Prototype Implementation Transcript Evaluation Evaluation Final Implementation Installation
UCSD 3 themes of the UCSD: • Analyze users and their needs • Evaluate ideas with potential users • Test to be sure the design works well with users
Key Activities of the UCSD • Task Analysis • Inputs to TA: • Problem stmt • Observation of existing systems • Analysis of user population • Outputs to TA: • HTA • Why do TA? • It provides a clear understanding of what clients want • It gives a clearer understanding of what users want • Redesign of an existing product
Key Activities of the UCSD • Requirements Gathering • Inputs to RG: • HTA • Design Heuristics • Relevant user models • Usability principles • Other constraints • Outputs to RG: • A stmt of requirements • Why do we need to have a stmt of requirements? • It provides an explicit , testable description of what is wanted of the system • It describes what the system should do without worrying too much about how it does it.
Key Activities of the UCSD • Design & Storyboarding • Inputs to D&S: • Stmt of Requirements • Usability principles and Heuristics • Other constraints • Evaluation from previous iterations • Outputs to D&S: • A storyboard design • System justification: why the system is going to be the way it is • A first-draft design of how the system works and what it looks like • A stakeholder analysis • Why do we need a D&S phase? • It provides designers with an opportunity to visualize their design and review it, quickly and cost-effectively with users.
Key Activities of the UCSD • Prototype Implementation • Inputs to PI: • A storyboard design • Evaluation from previous iterations • Outputs to PI: • A working testable prototype • Why do we need to prototype our designs? • It provides designers with an opportunity to visualize their design and review it, quickly and cost-effectively with users. • Different types of prototypes: • Wizard of Oz - the prototype is controlled by the designer ‘behind the scenes’ • Horizontal P. - simulates the user-interface only with no functionality • Vertical P. - has full functionality but for a limited vertical slice of the proposed system • Full P. - has full functionality but low performance
Key Activities of the UCSD • Evaluation • Inputs to E: • A working prototype • Stmt of Requirements • Outputs to E: • Transcript of the evaluation: what was said or done during the evaluation • The evaluation report . Ex, Are the requirements met? If not, why not? • Why do an evaluation? • It provides tangible evidence of how a system is actually used. • Heuristic Evaluation • Commonly used • Quick and cost effective • Done by a team of 5 conductors
Key Activities of the UCSD • Installation • Inputs to I: • A fully featured ‘prototype’ • Outputs to I: • An acceptable evaluation • The ‘finished’ system