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1、Topics,The nature of software development System planning Systems for three management levels Software development lifecycle,The essence of software development,Only one out of three software projects complete on-time and on-budget (The Standish Group report, 2003) The essence of software developmen
2、t: defined by the issues inherent in the software itself -software is a product of a creative act (not a result of a repetitive act of manufacturing) difficulties not amenable to breakthroughs or silver bullets - define software development invariants consequence of the inherent software complexity,
3、 complexity, conformity, conformity, changeability, and changeability, and invisibility,The accidents of software development,Accidental difficulties due to software production practices - amenable to human intervention attributed mostly to the fact that an information system is a social system must
4、 not be adding to the complexity and to the potential lack of supportability of the software product supportability = understandability + maintainability +scalability (extensibility) Related to: Stakeholders Process Modeling language and tools Will be discussed soon,Software development invariants,S
5、oftware in inherently complex function of interdependencies between components of which the software product is composed complexity in the wires Data intensive applications (enterprise information systems) are particularly complex Software must conform to: hardware/software platform on which it is b
6、uilt pre-existing information systems Software must be built to accommodate change Software is buried deeply in “invisible” programming statements, binary library code, and surrounding system software,Stakeholders,People who have a stake in a software project: Customers (users and system owners) Dev
7、elopers (analysts, designers, programmers, etc.) Information systems are social systems -developed by people (developers) for people (customers) The main causes of software failure can be traced to the stakeholder factor on the customer end, and on the developer end,Software process,Defines activiti
8、es and organizational procedures used in software production and maintenance A process model: states an order for carrying out activities; specifies what development artifacts are to be delivered and when; assigns activities and artifacts to developers; offers criteria for monitoring a projects prog
9、ress, for measuring the outcomes, and for planning future projects. Is not susceptible to standardization,Iterative and incremental process,An iterative process is one that involves managing a stream of executable releases. An incremental process is one that involves the continuous integration of th
10、e systems architecture to produce these releases, with each new release embodying incremental improvements over the other. (RUP) Some examples: the spiral model Rational Unified Process (RUP) Model Driven Architecture (MDA) the agile development process Iterative and incremental development must be
11、planned and controlled, and must conform to a pre-defined architectural design framework,Capability maturity model,Modeling language and tools,Modeling artifacts have to be communicated (language) and documented (tools) The Unified Modeling Language (UML) is a general-purpose visual modeling languag
12、e that is used to specify, visualize, construct, and document the artifacts of a software system. Computer-Assisted Software Engineering (CASE) tool enables storage and retrieval of models in a central repository and graphical and textual manipulation of models on a computer screen,CASE and process
13、improvement,Process improvement is much more than the introduction of new methods and techniques the introduction of new methods and techniques to organization at a low level of process maturity can bring more harm than good An integrated CASE tool can allow multiple developers to collaborate and sh
14、are design information in order to produce new design artifacts - the tool imposes processes on the development team - in “immature” organizations processes will not be followed (creating more mess than before) However, the same CASE methods and techniques would always bring personal productivity an
15、d quality improvements to individual developers,System planning,The question is: Which IS technologies and applications will return the most value to the business? System planning can be carried out in a number of different ways: SWOT Strengths, Weaknesses, Opportunities, Threats VCM Value Chain Mod
16、el BPR Business Process Reengineering Information System Architecture (ISA) All system planning approaches have an important common denominator they are concerned with effectiveness rather than efficiency,SWOT approach,VCM approach,The VCM (Value Chain Model) assesses competitive advantage by analyz
17、ing the full chain of activities in an organization from raw materials to final products sold and shipped to customers The question is: which value chain configurations will yield the greatest competitive advantage? The IS development projects can then target those segments, operations, distribution channels, marketing approaches, etc. that give the most competitive advantage Organizational functions are categorized into: primary activities they create or add value to a final product support activities they are essential but they do not enrich the product,
