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1、Other Methodologies,Classical methodologies, UP, RUP, AGILE.,Development,A software development process is a structure imposed on the development of a software product. AKA: software life cycle software process There are many models, each describing approaches to tasks or activities.,Waterfall,In th
2、e original waterfall model, the following phases are followed in order: Requirements specification Design Construction (AKA implementation or coding) Integration Testing and debugging (AKA validation) Installation Maintenance,Criticism,David Parnas, in “A Rational Design Process: How and Why to Fake
3、 It“, writes: “Many of the systems details only become known to us as we progress in the systems implementation. Some of the things that we learn invalidate our design and we must backtrack.” from: http:/web.cs.wpi.edu/gpollice/cs3733-b05/Readings/FAKE-IT.pdf The central idea here is sequential step
4、s and it does not work in practice,Iterative and Incremental development,The basic idea behind iterative development is to develop a software system incrementally: allows developers to learn during the development of earlier, incremental, deliverable versions of the system learning comes from both:
5、the development and use of the system Key steps in the process are: start with a simple implementation of a subset of the software requirements then iteratively enhance the evolving sequence of versions until the full system is implemented. At each iteration, design modifications are made and new fu
6、nctional capabilities are added.,UP,The Unified Process is an iterative and incremental development process. It is: Use Case Driven (to identify functional requirements) Architecture Centric (architecture is heart of the project) Risk Focused (address the most critical risks early ),UP phases,The Un
7、ified Process divides the project into four phases: Inception Elaboration Construction Transition Each phase produces a milestone document as its output.,UP phases: Inception,The Unified Process divides the project into four phases: Inception quite short! Establish a business case for the project Es
8、tablish the project scope and boundary conditions Outline the use cases and key requirements that will drive the design tradeoffs Outline one or more candidate architectures Identify risks Prepare a preliminary project schedule and cost estimate Output: Lifecycle Objective Milestone Elaboration Cons
9、truction Transition,UP phases: Elaboration,The Unified Process divides the project into four phases: Inception Elaboration capture most of the system requirements address known risk factors validate the system architecture via the implementation of an Executable Architecture Baseline, built in a ser
10、ies of small, timeboxed iterations Output: Lifecycle Architecture Milestone (a plan, including cost and schedule estimates, for the Construction phase ) Construction Transition,UP phases: Construction,The Unified Process divides the project into four phases: Inception Elaboration Construction the la
11、rgest! the rest of the system is built features are implemented in a series of short, timeboxed iterations Each iteration results in an executable release of the software Output: Initial Operational Capability Milestone Transition,UP phases: Transition,The Unified Process divides the project into fo
12、ur phases: Inception Elaboration Construction Transition system is deployed to the target users Feedback may result in refinements to be incorporated over the course of several Transition phase iterations it includes system conversions and user training Output: Product Release Milestone,Refinements,
13、Why? not everybody is happy with UP it can be ”customized” in different ways For the game-development community for example: http:/ Rational UP,The Rational Unified Process (RUP) is an iterative software development process framework created by the Rational Software Corporation, a division of IBM si
14、nce 2002. It was created to patch UP! Typical problems in UP projects are: Ad hoc requirements management Ambiguous and imprecise communication Brittle architecture Overwhelming complexity Undetected inconsistencies in requirements, designs, and implementations Insufficient testing Subjective assess
15、ment of project status Failure to attack risks Uncontrolled change propagation from http:/en.wikipedia.org/wiki/Rational_Unified_Process#Design ,Principles behind RUP,RUP has an underlying object-oriented model It is based on a set of six key principles for business-driven development (IBM): Adapt t
16、he process Balance stakeholder priorities Collaborate across teams Demonstrate value iteratively Elevate the level of abstraction Focus continuously on quality (ABCDEF ! ),RUP has short iterations,UP,RUP,RUP can be difficult to adopt, and needs customization before it works properly for a developpin
17、g team.,from: http:/ ,Another approach: be Agile!,Agile software development is a conceptual framework for undertaking software engineering projects - light-weight methodologies Predictive methods focus on planning the future in detail Adaptive methods focus on adapting quickly to changing realities
18、,Agile Values,From the Manifesto Individuals and interactions over processes and tools Working software over comprehensive documentation Customer collaboration over contract negotiation Responding to change over following a plan,from http:/www.agilemanifesto.org/ ,Agile principles,Agile principles (
19、.),Does it work?,Some advantages Easily adapting to changing requirements throughout the process More visibility into the actual progress of projects is available Can reduce the risks associated with software development Better addresses the business and customer needs,from http:/ ,Some numbers,A st
20、udy in the United Kingdom shows that of 1,027 projects, only 13% did not fail, and waterfall-style scope management was the “single largest contributing factor for failure, being cited in 82% of the projects as the number one problem.“ A 1995 study of over $37 billion USD worth of US Defense Departm
21、ent projects concluded that “46% of the systems so egregiously did not meet the real needs (although they met the specifications) that they were never successfully used, and another 20% required extensive rework“ to be usable. another study of 6,700 projects, it was found that four out of the five k
22、ey factors contributing to project failure were associated with and aggravated by the waterfall model, including inability to deal with changing requirements, and problems with late integration. And finally, another study of over 400 waterfall projects reported that only 10% of the developed code wa
23、s actually deployed, and of that, only 20% was actually used.,from http:/ ,from http:/ ,Links and further reading,Software development process http:/en.wikipedia.org/wiki/Software_development_process Iterative and Incremental development http:/en.wikipedia.org/wiki/Iterative_and_incremental_developm
24、ent UP: http:/en.wikipedia.org/wiki/Unified_Process A Managers Introduction to The Rational Unified Process (RUP) http:/ Agile Alliance http:/www.agilealliance.org/ Adaptive vs. Predictive: Is the end clear? http:/www.idea.org/adaptive.html The Agile Unified Process (AUP) http:/ Agile Modeling and the Rational Unified Process (RUP) http:/