Phase 3 The Software Requirements Specification

After review of the customer’s System Spec. After educated analysis Preliminary design A technical, software “approach” Results in permission to detail-design and code

Customer Points-of-Contention Assumptions, Constraints, Limits Function Documentation – technical, user, and training manuals Training Maintenance / Enhancements Requirements Changes Status and Reviews

From the customer’s perspective How smart people are going to solve the problem that was stated in the System Spec. A “contract”, more or less Is it doable? ◦ Technically ◦ On time ◦ Under budget

Settles these issues: Software Architecture – Object Oriented? – Structured? – Database Oriented (Informational Flow)? – Event Driven Major Modules – to 2 or 3 levels of supervision – low level utilities if they touch hardware or the environment

Risk Assessment Technical Risks ◦ hardware / software / interfaces ◦ build vs. buy ◦ team expertise needed Schedule Risks ◦ budget ◦ calendar ◦ personnel – level of expertise required

Phase 3 Write PARTS OF an SRS ◦ Architectural Drawings ◦ Main User Screen(s) ◦ Integration Thread (also a Drawing) ◦ Change of Scope Form ◦ Cross Reference Listing

What is a module? Outputs Inputs Storage Processing Simple Block Diagram Form Arrows, of course, should be labeled

Data Flow Diagram Data Conversion DFD Standard Shapes Arrows, of course, should be labeled Temporary Storage Sink Source

Air Traffic Control DisplayDatabaseRadar AddRemoveEdit Disk Access Display Refresh UI RecordPlayback Sweep Data Conversion Data Interpretation

City Simulator

Talking Head

Talker

Data Flow Diagram - shows movement, conversion, and storage of data This is the "top" drawing of a $6 million, 45-person, 1 million LOC, 4 year project

Cloud Chart - (pre UML) object relationships