Investigating System Requirements
Chapter 2 Where are we? Analysis Chapters Ch 2 Investigating System Requirements
Use Cases Ch 4 Domain Modeling Ch 5 Use Case Modeling Outline Stakeholders SDLC Core Process 3 Analysis
Information Gathering Techniques Types of Requirements FURPS+ Stakeholders "Who do you involve and talk to?"
Internal Stakeholders External stakeholders Operational stakeholders regularly interact with system Executive stakeholders dont directly interact but .. use the info , or have financial interest SDLC Phase: Analysis Core Process 3: Discover & understand details SDLC Phase: Analysis Gather detailed info
Information Gathering Techniques Interviews Observation Review documents & procedures Questionnaires Research vendor solutions User feedback Why do we use different Techniques? Formal Systems Informal Systems Information Gathering Techniques
Interviews Interview users & other key stakeholders Effective way to understand business functions and rules Disadvantage time consuming resource expensive Tips: Plan the interview Stay on schedule!! Interview several key people together (pros & cons) Listen carefully and take notes Be neutral Seek diverse views Checklist for Conducting an Interview Information Gathering Techniques
Observations Direct Observation Watching users do their jobs Firsthand & objective Disadvantage People may change their normal operating behavior. Time-consuming Information Gathering Techniques
Review Documents & Procedures Existing business documents Forms, reports, work procedures Input & outputs Types of information to be discovered: Reasons for current system design Rules for processing data Problems with existing system Discrepancies, Redundancies Opportunity to meet new need Special information processingcircumstances Information Gathering Techniques
905 Questionnaires Used with a large number of stakeholders Closed-ended & open-ended questions Quantitative data vs. Qualitative data Research Vendor Solutions Many problems have been solved by other companies +provide new ideas, cheaper, less risky -may purchase before understanding problem User Feedback Collecting feedback after initial testing Comments & suggestions SDLC Phase: Analysis Define requirements System Requirements - (def) specifications that define the new system Functional Requirements - activities the system must perform Non-Functional Requirements - constraints and performance goals Functional Usability Reliability PerformanceSecurity requirements requirements requirements requirementsrequirements Business rules& processes UI Design Navigation Help Doc. Avail. reqs Failure rate Backup & recovery Response time real time -batch Access controls Encryption Model -a representation of some aspect ofa system Textual model Graphical models Mathematical models SDLC Phase: Analysis Prioritize requirements Develop UI Dialogs
High vs. low priority Scope creep Develop UI Dialogs Prototype Can be better than an abstract model Evaluate Requirements with users