chCurrentTrendsinSystemDevelopment实用学习教程.pptx

1.1 The Unified ProcessUnified Process(UP)defines a complete methodology that uses UML for system models and describes a new,adaptive system development life cycle.It is originally offered by Rational Software,which is now part of IBM.Developed by:Grady Booch,James Rumbaugh,Ivar Jacobsonwhich are the three pioneers behind the success of UML.19:52第1页/共39页A phase in the UP can be thought of as a goal or major emphasis for a particular portion of the project.UP phaseObjectiveInceptionDevelop an approximate vision of the system,make the business case,define the scope,and produce rough estimates for cost and schedule.ElaborationDefine the vision,identify and describe all requirements,finalize the scope,design and implement the core architecture and functions,resolve high risks,and produce realistic estimates for cost and schedule.ConstructionIteratively implement the remaining lower-risk,predictable,and easier elements and prepare for deployment.TransitionComplete the beta test and deployment so users have a working system and are ready to benefit as expected.第2页/共39页1.1 The Unified ProcessA UP discipline is a set of functionally related activities that contributes to one aspect of the development project.The disciplines can be divided into two main categories:System development activities(1)Business modeling,(2)Requirements,(3)Design,(4)Implementation,(5)Testing,(6)Deployment,Project management activities(7)Configuration and Change management,(8)Project management,and(9)Environment.Each iteration usually involves activities from all disciplines.19:52第3页/共39页19:52第4页/共39页1.2 Extreme ProgrammingExtreme Programming(XP)is an adaptive,agile development methodology that was created in the mid-1990s.The word extreme sometimes makes people think that this methodology is completely new and that developers who embrace XP are radicals.Extreme programming has these characteristics:Takes proven industry best practicesbest practices and focuses on them intenselyCombines those best practices(in their most intense forms)in a new way to produce a result that is greater than the sum of the parts第5页/共39页Four Core Values of XP1.CommunicationEffective communication involves not only documentation but also verbal discussion.2.Simplicity less is moreEven though developers have always advocated keeping solutions simple,they dont always follow their own advice.3.FeedbackAs with simplicity,getting frequent,meaningful feedback is recognized as a best practice of software development.4.Courage Developers always need courage to face the harsh choice of doing things right or throwing away bad code and starting over.第6页/共39页XP Practices:Planning XP embraces change.Change the changing.XP planning focuses on making a rough plan quickly and then refining it as things become clearer.The basis of an XP plan is a set of stories that users develop.A story describes what the system needs to do.XP doesnt use the term use case,but a user story and a use case express a similar idea.19:52第7页/共39页XP Practices:TestingEvery new piece of software requires testing,and every methodology includes testing.The developers write the unit tests,and the users write the acceptance tests.Before any code can be integrated intothe library of the growing system,it must pass the tests.By having the tests written first,XP automates their use and executes them frequently.Over time,a library of required tests is created,so when requirements change and the code needs to be updated,the tests can be rerun quickly and automatically.第8页/共39页XP Practices:Pair ProgrammingInstead of simply requiring one programmer to watch anothers work,pair programming divides up the coding work.1.First,one programmer might focus more on design and double-checking the algorithms while the other writes the code.2.Then,they switch roles;3.Thus,over time,they both think about design,coding,and testing.XP relies on comprehensive and continual code reviews.第9页/共39页XP Practices:Pair ProgrammingErrors are caught quickly and early,two people become familiar with every part of the system,all design decisions are developed by two brains,and fewer“quick and dirty”shortcuts are taken.The quality of the code is always higher in a pair-programming environment.Interestingly,Research has shown that pair programming is more efficient than programming alone.第10页/共39页XP Practices:Simple Designs Opponents say that XP neglects design,but that isnt true.XP conforms to the principles of Agile Modeling,for avoiding the“Big Design Up Front”approach.Instead,it views design as so important that it should be done continually,although in small chunks.19:52第11页/共39页XP Practices:Refactoring the Code Refactoring is the technique of improving the code without changing what it does.XP programmers continually refactor their code.Before and after adding any new functions,XP programmers review their code to see whether there is a simpler design or a simpler method of achieving the same result.19:52第12页/共39页XP Practices:Continuous Integration This practice embodies XPs idea of“growing”the software.Small pieces of code which have passed the unit tests are integrated into the system daily or even more often.Continuous integration highlights errors rapidly and keeps the project moving ahead.Small Releases A release is a point at which the new system can be turned over to users for acceptance testing and even for productive use.19:52第13页/共39页XP Practices:Pair ProgrammingOwning the Code Collectively In XP,everyone is responsible for the code.No one person can say“This is my code.”On-Site Customer As with all adaptive approaches,XP projects require continual involvement of users who can make business decisions about functionality and scope.19:52第14页/共39页XP Practices:Pair ProgrammingSystem MetaphorIt answers the questions 1.“How does the systemWork?”2.“What are its major components?”And it does it by having the developers identify a metaphor for the system.It can guide members toward a vision and help them understand the system.Forty-Hour Week and Coding Standards Developers should follow standards for coding and documentation.19:52第15页/共39页1.system(the outer ring),2.release(the middle ring),3.iteration(the inner ring).It is divided into three levels:第16页/共39页1.3 Scrum(争球)As a methodology,Scrum is responsive to a highly changing,dynamic environment in which users might not know exactly what is needed and might also change priorities frequently.Scrum focuses primarily on the team level.It is a type of social engineering that emphasizes individuals more than processes and describes how teams of developers can work together to build software in a series of short mini-projects.19:52第17页/共39页19:52第18页/共39页Product BacklogProduct backlog is a prioritized list of user requirements used to choose work to be done in a Scrum project,which includes user functions(such as use cases),features(such as security),and technology(such as platforms).19:52第19页/共39页1.3 ScrumThe three main organizational elements that affect a Scrum project are the product owner,the Scrum master,and the Scrum team or teams.19:52第20页/共39页1.3 ScrumThe product owner is the client,but he or she has additional responsibilities.In Scrum,the product owner maintains the product backlog list.Any request must first be approved and agreed to by the product owner.In traditional development projects,the project team initiates the interviews and other activities to identify and define requirements.In a Scrum project,the primary client controls the requirements.第21页/共39页1.3 Scrum PhilosophyScrum team is self-organizing and no overall project schedule exists.The Scrum master enforces Scrum practices and helps the team complete its work.The Scrum team is a small group of developers typically five to nine people who work together to produce the software.For projects that are very large,the work should be partitioned and delegated to smaller teams.第22页/共39页SprintThe basic work process is called a sprint,and all other practices are focused on supporting a sprint.A Scrum sprint is a firm 30-day period called a time box,with a specific goal or deliverable.At the beginning of a sprint,the team gathers for a one-day planning session.In this session,the team decides on the major goal for the sprint.The goal draws from several items on the prioritized product backlog list.19:52第23页/共39页SprintThe scope of that sprint is then frozen,and no one can change it neither the product owner nor any other users.If users do find new functions they want to add,they put them on the product backlog list for the next sprint.Every day during the sprint,the Scrum master holds a daily Scrum,which is a meeting of all members of the team.The objective is to report progress.第24页/共39页1.3 ScrumThe meeting(daily Scrum)is limited to 15 minutes or some other short time period.The purpose of this meeting is simply to report issues,not to solve them.One of the major responsibilities of the Scrum master is to note the impediments and see that they are removed.A good Scrum master clears impediments rapidly.The Scrum master also protects the team from any intrusions.19:52第25页/共39页1.3 ScrumThe team members are then free to accomplish their work.Team members do talk with users to obtain requirements,and users are involved in the sprints work.However,users cant change the items being worked on from the backlog list or change the intended scope of any item without putting it on the backlog list.第26页/共39页2.Trends in Technology InfrastructureClient Computing DevicesInternet and Telephone CommunicationsBack-End Computing19:52第27页/共39页Software as a Service(SAAS)Software as a service(SAAS)is a software delivery model similar to a utility,in which the application and its associated data are accessed via the Internet without locally installed programsA service is something that we purchase that does something for us.For example,we consider our utilities to be services.IAAS(infrastructure as a service)PAAS(platform as a service)19:52第28页/共39页3.1 Software as a Service(SAAS)19:52CostsPurchasing/owning softwareSAASSoftware licensesubstantialnot requiredDevelopment or customizingsubstantialnot requiredImplementation and installationsubstantialnot requiredUsage feesnot requiredas consumed or usedConfigurationnot requiredone time initialization IT support staffsubstantialnot requiredApplication support staffsubstantialnot requiredTraining of usersrequiredrequiredServers,networks,data storagesubstantialas consumed or usedInternet usagerequired(possibly)required第29页/共39页Open-Source SoftwareOpen-source software(OSS)is one of the truly remarkable phenomena in the recent growth of the software industry.Some OSI open-source criteria:1.Source code The source code must be open for distribution.2.Freely redistributable Recipients of the source code may also distribute it.3.Derived works The source code can be modified and distributed in its modified form.4.Distribution of license The open license should apply to all derived or modified software.5.No discrimination The license cant restrict who can receive or use the software.6.No related restrictions The license cant restrict other software that may be distributed in conjunction with the open-source software.19:52第30页/共39页Open-Source SoftwareThe business model for open-source software is also an interesting phenomenon.Because the software isnt sold or licensed for a fee,there has to be some other method for generating revenue.19:52第31页/共39页Open-Source Software19:52第32页/共39页Open-source software types of stakeholders19:52第33页/共39页3.3 The Web as an Application PlatformIn 2004,the term Web 2.0 was first usedAnother term for this type of Web site,which we will discuss later in this section,is Rich Internet Application(RIA).Types of Web Software Componentsplug-ins-a software component that adds specific capabilities to a larger software application19:52第34页/共39页3.3 The Web as an Application PlatformA widget is a type of plug-in,but it usually has a user interface component.In other words,it is a plug-in that can be placed on a Web page and is visible to the user.A gadget is another term that is used to describe a widget.Gadgets are most frequently used on a desktop,although some Web sites refer to their widgets as gadgets.A theme is a type of add-on that focuses on the look and feel of either the browser or the Web application.A toolbar is a type of add-on that can provide multiple capabilities to the Browser.Web mini-appssometimes referred to as Web apps19:52第35页/共39页Mashup ApplicationsMashup-a type of Web site that combines the functionality of several other Web sites through the use of predefined APIs19:52第36页/共39页3.4 Mashup Applications19:52第37页/共39页3.4 Mashup Applications19:52第38页/共39页感谢您的欣赏！第39页/共39页