OHT 11 1 Introduction The foundations of high

OHT 11. 1 • • Introduction The foundations of high quality maintenance • Foundation 1: software package quality • Foundation 2: maintenance policy Pre-maintenance software quality components • Maintenance contract review • Maintenance plan Maintenance software quality assurance tools • SQA tools for corrective maintenance • SQA tools for functionality improving maintenance • SQA infrastructure components for software maintenance • Managerial SQA tools for software maintenance Galin, SQA from theory to implementation © Pearson Education Limited 2004

OHT 11. 2 Software maintenance Corrective maintenance Adaptive maintenance Functionality improvement maintenance 17 -22% 23 -24% 54 -60% + User support service Galin, SQA from theory to implementation Perfective maintenance Preventive maintenance © Pearson Education Limited 2004

OHT 11. 3 Types of Maintenance q Corrective maintenance is concerned with fixing errors that are observed when the software is in use q Adaptive maintenance is concerned with the change in the software that takes place to make the software adaptable to new environment such as to run the software on a new operating system. q Perfective maintenance is concerned with the change in the software that occurs while adding new functionalities in the software. q Preventive maintenance involves implementing changes to prevent the occurrence of errors. Galin, SQA from theory to implementation © Pearson Education Limited 2004

OHT 11. 4 User’s difficulties • • Software failure Documentation failure Incomplete, vague or imprecise documentation User’s insufficient knowledge Galin, SQA from theory to implementation © Pearson Education Limited 2004

OHT 11. 5 Quality factor Corrective maintenance Adaptive maintenance Functionality improvement maintenance Correctness – Output High Correctness - Documentation High Correctness – Coding qualification High Reliability High Maintenability High Flexibility Testability High Portability High Interoperability High Galin, SQA from theory to implementation © Pearson Education Limited 2004

OHT 11. 6 • Version development policy – Sequential version policy – Tree version policy (branching and new version rules) • Change policy (permissive/balanced) Galin, SQA from theory to implementation © Pearson Education Limited 2004

OHT 11. 7 • Customer requirements clarification • Review of alternative approaches to maintenance provision • Review of estimates of required maintenance resources • Review of maintenance services to be provided by subcontractors and/or the customer • Review of maintenance costs estimates Galin, SQA from theory to implementation © Pearson Education Limited 2004

OHT 11. 8 Preparation of a • A list of the contracted maintenance services (external and internal customers) • A description of the maintenance team's organization • A list of maintenance facilities • A list of identified maintenance service risks • A list of required software maintenance procedures and controls • The software maintenance budget Galin, SQA from theory to implementation © Pearson Education Limited 2004

OHT 11. 9 SQA tools for corrective maintenance • Contractor-Subcontractor contract (for outsourcing maintenance services) - Procedures for handling maintenance calls - Full documentation of the service procedures - Availability of records - Certification for the contractor - Quality-related conditions Galin, SQA from theory to implementation © Pearson Education Limited 2004

OHT 11. 10 SQA tools for functionality improving maintenance • Project life cycle tools (reviews & testing) Tools are also implemented for large-scale adaptive maintenance tasks. Galin, SQA from theory to implementation © Pearson Education Limited 2004

OHT 11. 11 SQA infrastructure components for software maintenance • • • Maintenance procedure and work instruction Supporting quality devices Training and certification of maintenance teams Preventive and corrective actions Configuration management Maintenance documentation and quality record control Galin, SQA from theory to implementation © Pearson Education Limited 2004

OHT 11. 12 Managerial SQA tools for software maintenance • Performance controls for corrective maintenance services • Quality metrics for corrective maintenance • Cost of software maintenance quality Galin, SQA from theory to implementation © Pearson Education Limited 2004

OHT 11. 13 Cost of software maintenance quality • • • Cost of prevention Cost of appraisal Cost of managerial preparation and control Cost of internal failure Cost of external failure Cost of managerial failure Galin, SQA from theory to implementation © Pearson Education Limited 2004