Investigating System Requirements

Investigating System Requirements Chapter 2 Where are we? Ch 2 Ch 3 Ch 4 Ch 5 Analysis Chapters Investigating System Requirements Use Cases Domain Modeling

Use Case Modeling 2 Outlne Stakeholders SDLC Core Process 3 Analysis Discover & Understand Details 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 4 SDLC Phase: Analysis Core Process 3: Discover & understand details Ch2 - Investigating System Requirements covers all 5 tasks 5 Analysis Phase - outline Requirements Determination Gather Detailed Info

Information Gathering Techniques Formal vs Informal Systems Requirements Structuring Define Requirements Function vs Non-Functional Requirements FURPS Prioritize Requirements Develop UI Dialogs Evaluate Requirements with users Requirements Determination Analysis - Gather detailed info Information Gathering Techniques

Analysis - 1. Gather detailed info Why do we use different Techniques? A. Interviews Formal Systems documented, trained B. Questionnaires Informal Systems ___________ C. Observation of Business Processes D. Review of current system/software

Types of information to be discovered: Reasons for current system design E. Review of documents & procedures Rules for processing data F. Research vendor solutions Discrepancies, Redundancies G. User feedback Problems with existing system Opportunity to meet new need Special information processing circumstances

7 Requirements Determination Information Gathering TechniquesAnalysis - 1. Gather detailed info Interviews Interview users & other key stakeholders Effective way to understand business functions & 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 8 Requirements Determination Information Gathering TechniquesAnalysis - 1. Gather detailed info Interview cont. Checklist for Conducting an Interview Questionnaires Used with a large number of stakeholders Types of questions for both Interview & Questionnaires Closed-ended (Quantitative data ) Open-ended questions (Qualitative

data) 9 Requirements Determination Information Gathering TechniquesAnalysis - 1. Gather detailed info Observation of Business Processes Direct Observation Studying the business process Firsthand & objective Disadvantage People may change their normal operating behavior. Time-consuming 10 Requirements Determination

Information Gathering TechniquesAnalysis - 1. Gather detailed info Review of Current System/Software Features How it works Review of Documents & Procedures Existing business documents Forms, reports, work procedures Input & outputs 11 Requirements Determination Information Gathering TechniquesAnalysis - 1. Gather detailed info Research Vendor Solutions See what options are out there: build vs buy Look at what other companies have developed

+ research can provide new ideas + buying it may be cheaper, less risky - may purchase before understanding problem User Feedback Collecting feedback after initial testing Comments & suggestions 12 Requirements Structuring SDLC Phase: Analysis Analysis - 2. Define Requirements Define requirements System Requirements - (def) specifications that define the new system

Functional Requirements - activities the system must perform (& data required) Non-Functional Requirements - constraints and performance goals Functional Usability Reliability Performance Security + Business rules UI requirements Avail. reqs Responserequirements Access controls Design

time requirements requirements Encryption & processes & data Navigation Failure rate - real time requirements Help Doc. Backup & recovery - batch 13 Requirements Structuring SDLC Phase: Analysis

Analysis - 2. Define Requirements Define requirements cont. Create models of the requirements Model - a representation of some aspect of a system Textual model, Graphical models, Mathematical models 14 Requirements Structuring SDLC Phase: Analysis Analysis Steps 3-5

Prioritize requirements High vs. low priority Scope creep Develop UI Dialogs Prototype Can be better than an abstract model Evaluate Requirements with users 15

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