Dynamic Systems Development Method (DSDM)

1. Dynamic Systems Development Method (DSDM) • The DSDM Consortium is a non-profit organisation dedicated to defining, promoting and continuously evolving its de-facto world wide standard for developing business solutions within tight timeframes. • Non proprietary RAD method • Provides a framework for building and maintaining systems which meet tight time constraints through prototyping • Addresses all parties view of RAD • Pareto efficiency – Nothing is built perfectly first time

2. DSDM – Unsuitable applications • Safety critical applications • Why???? • Think of a business example

3. DSDM Critical Success Factors • Commitment of senior management to provide end user involvement • Easy access by developers to end users • Stability of the development team • Development team skills • Decision making powers of the users and developers in the development team

4. DSDM • Project control • Size of the development team

5. Explore the Method www.dsdm.org Please register on this site. Suggested reading : • White Papers • Case Studies • Process

6. DSDM Principles 1. Active user involvement is imperative DSDM is a user-centred approach. If users are not closely involved throughout the development lifecycle, delays will occur as decisions are made and users may feel that the final solution is imposed by the developers and/or their own management. 2. DSDM teams must be empowered to make decisions DSDM teams consist of both developers and users. They must be able to make decisions as requirements are refined and possibly changed. They must be able to agree that certain levels of functionality, usability, etc. are acceptable without frequent recourse to higher-level management. 3. The focus is on frequent delivery of products A product-based approach is more flexible than an activity-based one. The work of a DSDM team is concentrated on products that can be delivered in an agreed period of time. This enables the team to select the best approach to achieving the products required in the time available.

7. DSDM Principles 4. Fitness for business purpose is the essential criterion for acceptance of deliverables The focus of DSDM is on delivering the necessary functionality at the required time. Traditionally the focus has been on satisfying the contents of a requirements document and conforming to previous deliverables, even though the requirements are often inaccurate, the previous deliverables may be flawed and the business needs may have changed since the start of the project. 5. Iterative and incremental development is necessary to converge on an accurate business solution DSDM allows systems to grow incrementally. Therefore the developers can make full use of feedback from the users. Moreover partial solutions can be delivered to satisfy immediate business needs.

8. DSDM Principles 6. All changes during development are reversible Backtracking is a feature of DSDM. However in some circumstances it may be easier to reconstruct than to backtrack. This depends on the nature of the change and the environment in which it was made. The ability to reverse changes is limited to within the development of an increment. 7. Requirements are baselined at a high level Baselininghigh-level requirements means "freezing" and agreeing the purpose and scope of the system at a level that allows for detailed investigation of what the requirements imply. Further, more detailed baselines can be established later in the development, although the scope should not change significantly.

9. DSDM Principles 8. Testing is integrated throughout the lifecycle Testing is not treated as a separate activity. As the system is developed incrementally, it is also tested and reviewed by both developers and users incrementally to ensure that the development is moving forward not only in the right business direction but is technically sound 9. A collaborative and co-operative approach between all stakeholders is essential The nature of DSDM projects means that low-level requirements are not necessarily fixed when the developers are originally approached to carry out the work. Hence the short-term direction that a project takes must be quickly decided without recourse to restrictive change control procedures.

11. DSDM Lifecycle • There are 5 phases of development within DSDM • Feasibility study • Business study • Functional model iteration • System design and build iteration • Implementation

12. DSDM – Feasibility study • Objectives • High level feasibility study • Is the system feasible? • Could a system meet business requirements? • Possible technical solutions • First cut estimates of Timescale & Cost • Products • Feasibility report

13. DSDM – Business Study • Objectives • Business Functions to be supported • Prioritise functionality • Future development in terms of prototype deliverables • Basis for technical development to proceed

14. DSDM – Functional Model Iteration • Objectives – To demonstrate the required functionality using a functional model • All prototypes in DSDM are intended to evolve into the final system and are therefore built to be robust enough for operational use and to satisfy any relevant non-functional requirements, such as performance, security etc

15. DSDM – System Design & Build iteration • Focus is on ensuring that the prototypes are sufficiently well engineered for use in the operational environment. • Product • Fully Tested system • Design prototype review documents

16. DSDM - Implementation • Objectives – Place tested system in working environment • Train the users in the use of the system • Determine users future development requirements • Conduct a post implementation study • Products • Delivered system • Full set of documents • Post implementation review