Planning Iterative Software Development Projects Raj Agrawal, PMP Unisys

Synopsis  Iterative software development projects require a different approach to project planning as compared to traditional waterfall projects. This is especially true in areas such as estimation of effort, technical risk mitigation, schedule development, resource planning & scope management. Experiences, lessons learned and best practices derived in parametric estimation, iterative development of schedules, requirements development & analysis will be discussed.

Overview  Introduction  What is iterative development?  Reality – Requirements Change!  Why iterative development?  Challenges of iterative development  Estimation  Estimation techniques  Top down or bottom-up estimation?  Planning  Project Plan development  Resource Plan development  Scope management – iteration by iteration  Conclusion

What is Iterative Development?  Development methodology to improve software project delivery  Divides project into “mini waterfall projects” called iterations  Requirements per iteration are based on technical risk mitigation and business value  Iteration duration is typically 4-12 weeks  Iterations are timeboxed – fix end date and remove requirements if slippage  Each iteration delivers a partial working system  Requires continuous negotiation between scope, solution & project plan

Reality – Requirements Change! Source: “How to Fail with the Rational Unified Process: Seven Steps to Pain and Suffering”, Craig Larman, Philippe Kruchten, Kurt Bittner

Why Iterative Development?  Mitigates risk  Assumes requirements will change over project life  A tested partial solution enables feedback to align requirements and design  Provides early indication of project progress  Provides basis for early scope negotiations & management  Reduces Gold-plating & Requirements Creep

Challenges of Iterative Development  Cost estimation without a detailed WBS  Rolling Window Planning - Project Plan only detailed to next iteration  Requirements analysis during each iteration may lead to changes to baseline  Clients need to prioritize requirements  Architects need to identify and prioritize technical risks  Waterfall milestones such as SDR, PDR, CDR need to be mapped

Estimation Techniques  Top down estimation requires  A cost estimation tool  Measure of volume  Input for languages  Environment parameters  Bottom up estimation requires  A detailed WBS  Estimates for each lowest element of WBS

Top Down or Bottom Up Estimation?  They complement each other  Use top down estimation for application development  Bottom up estimation  Validation of top down estimate  Estimate each iteration and discipline within iteration  Add other items such as business modeling & system integration

Project Plan Development  Create high level plan based on estimate  Phase dates  Iteration plan  Iteration dates  Key milestones  Detail the first phase & first iteration  Develop next iteration plan mid-way through this iteration

Resource Plan Development  Use hours estimate from the cost model  Use hours by roles from cost model  Spread hours over the timeline  Assign staff to roles

Scope Management – Iteration by Iteration  Each iteration is time-boxed  Requirements dropped from an iteration move into next iteration  Only if requirements are prioritized  Architecture is defined  Technical risks are prioritized  Close stakeholder involvement is needed for scope management

Conclusion  Iterative development requires a different mindset – do the hard work first  Stakeholders need to involved closely  Estimation tools aid planning  Requirements should be prioritized  Architecture centric design  Iteration plan should mitigate risks  Leads to adaptive development