How Systems are Developed The Commercial Life Cycle Model Common form of the Software Life Cycle Used through the commercial, industrial, institutional government communities University of Houston Clear Lake Natural and Applied Science James C. Helm, Ph.D.,P.E.

Example Software Development Process This process illustrates the major steps and flow that might be typical of a DoD or major Government Contractor. The documents would be obtained from the DoD standard, MIL-STDs, or IEEE NASA Software Document Standard, Software Engineering Program, NASA-STD-2100-91

Example Software Development Process Completed Software System Requirements Analysis A B Engineering Change Control Formal SCCB C Example Software Development Process RR Allocated Baseline HDR IDR Architecture Design Interface Verification and Validation Test D Data Structure Algorithm Coding Unit Testing Component ENGINEERING BUILD Configuration Item Management Load Build Product TPR SCM Release Dr Jim Helm Metric Point Dictionary Cases DataBase Informal Test Data PDL Flowchart Package or Declaration SOFTWARE REQUIREMENTS ANALYSIS PRELIMINARY DESIGN DETAILED CODE CSU / CSC INTEGRATION TEST CSCI BLOCK TEST VALIDATION TEST Requirements Analysis Object Oriented Analysis Content Diagram Bound Limits Information Modeling Object Flow Diagram Object Specification State Transition Diagrams Structured Walkthroughs Requirements Comments Report Object Oriented Design Object Reuse Design Specification Decision Tables Object Activation Tables Prototypes Superior Refinement Structured Walkthrough Update Prototype Update Preliminary Desing into Test Case Design Structured Programming Package Reuse Structured Codes Walkthrough Structured Test Walkthrough Update Software Development Folders Update Requirements Matrix Execute White Box Testing Execute Black Box Testing Review Test Results CSU Integration Top-Down Bottom-Up Sandwich Code / Test data Walkthrough Execute Interface Tests Execute Black Box Tests Development Folder Update Requirements Matrix Execute Regression Tests CSCI Integration Test / Requirements Metrix Test Walkthrough Formal Test Execution Test Results Review Final Test Results CSCI Verification Formal Test Case Test Procedures Software Validation Test Reports

Requirement Phase Deals with all kinds of requirements system software hardware human system Interface human in the loop

Design Phase Normally consists of two parts Preliminary Design Detailed Design

Code Phase Implements the detailed design Some form of programming language Three possible coding options top-down bottom-up middle-out

Develop Large Driver to Stimulate System Establish/ Retain Required Databases TOP-DOWN Code Top Level CSC Then Next Level, etc. Final Integration is minimal Select Appropriate Compiler/ Assembler Test Whole System Each Time OPTION 1 Select Appropriate Programming Support Environment Develop Several Drivers to Stimulate Subsystems Code CSCs as functional threads Integration is moderate throughout Test Each Functional Thread MIDDLE-OUT OPTION 2 Determine Optimum Coding Strategy & Sequence Ready for I & t FROM DESIGN PHASE Initiate Appropriate Controls Follow Standards & Conventions OPTION 3 Develop many drivers to Stimulate CSUs Establish Software Library BOTTOM-UP Code CSUs separately Integration is Time Consuming Test Each CSU Extensively

Correlation Between Specifications and Test Match the kind of software being developed and the manner in which it is being implemented and integrated Specification hierarchy Test hierarchy

Integration and Testing Phase Major Activities shown on next slide Determine early the selection and specification of the optimum test strategy Select: tools, instrumentation, recording methods and SW drivers Select environment: hardware configuration and location of tests