Advanced S/w Eng - s/w productivity issues 1 Software Productivity Issues Why do software projects fail? Advanced Software Engineering COM360 University of Sunderland © 2001

Advanced S/w Eng - s/w productivity issues 2 Problems with Software Complexity Conformity Changeability Invisibility

Advanced S/w Eng - s/w productivity issues 3 Complexity Software is more complex than any other construct made by humans. A product becomes difficult to understand.

Advanced S/w Eng - s/w productivity issues 4 Conformity Generally, software must conform to interfaces with existing systems.

Advanced S/w Eng - s/w productivity issues 5 Changeability There is always pressure to change software.

Advanced S/w Eng - s/w productivity issues 6 Invisibility Software is difficult to visualise. DFDs etc. don’t tell the whole story.

Advanced S/w Eng - s/w productivity issues 7 The Phases of Software Production Requirements Specification Planning Design Implementation Integration Maintenance Retirement

Advanced S/w Eng - s/w productivity issues 8 Software Engineering Technology Methods –Analysis –Design –Coding –Testing –MaintenanceProcedures – Proj. Mngt. – SQA – SCM – Metrics – Tracking Tools – CASE

Advanced S/w Eng - s/w productivity issues 9 What is Software Productivity? Producing acceptable products (outputs) using the processes and people (inputs) at your disposal and within agreed-upon schedule.

Advanced S/w Eng - s/w productivity issues 10 Productivity Data The SEI has asked the following questions about productivity for over TEN years: how much effort is spent in each task? for each product item, what effort was devoted? what is the cost of defect removal by each inspection and test method, and by defect type?

Advanced S/w Eng - s/w productivity issues 11 Productivity - “it varies” Productivity varies dramatically between organisations... Organisations define lines of code and effort expended differently... Language variations have to be accounted for... Some organisations count reused code, some only count it if it’s modified...

Advanced S/w Eng - s/w productivity issues 12 Software Success Attributes Delivered on Time Delivered Within Budget Works Meets Requirements (Correct) Usable by Normal People Maintainable Documented and Supported

Advanced S/w Eng - s/w productivity issues 13 Laws of Project Management 1 No major project is ever installed on time, within budget, with the same staff Projects progress quickly until 90% complete; then stay 90% complete forever. With fuzzy project objectives you can avoid estimating the corresponding costs.

Advanced S/w Eng - s/w productivity issues 14 Laws of Project Management 2 When things go well, something will go wrong. When things can’t get worse, they will. If things improve, you have missed something. If project content changes, the rate of change will exceed rate of progress. Attempts to debug a system introduce new bugs that are harder to find.

Advanced S/w Eng - s/w productivity issues 15 Laws of Project Management 3 A badly planned project takes three times longer to complete that expected; A well planned project takes only twice as long. Project teams detest progress reporting because it vividly manifests their lack of progress.