软件工程课件：16-Internet

1、Outline1We are the WebService-Oriented ArchitectureSoftware-as-a-ServiceTen Years that Changed the WorldKevin Kelly, Wired Magazine, Aug. 200521972E-MailWorld Wide Web (Tim Berners-Lee)1991Time magazine, “It was not designed for doingcommerce, and it does not gracefully accommodatenew arrivals.”Nets

2、cape (Marc Andreesen, Jim clark)19941995Newsweek, “THE INTERNET? BAH!”the total number of Web pages exceeds 600 billion eBay Motors sold $11 billion worth of vehicles, 2001 auction of a $4.9 million private jet50 million blogs with a new one appearing every two seconds. 2005We are the WebKevin Kelly

3、, Wired, Aug. 2005“Not only did we fail to imagine what the Web would become, we still dont see it today! We are blind to the miracle it has blossomed into. And as a result of ignoring what the Web really is, we are likely to miss what it will grow into over the next 10 days. Any hope of discerning

4、the state of the Web in 2015 requires that we own up to how wrong we were 10 years ago. ”3美国著名连锁书店Borders因为不敌网络书店和电子书的强势竞争，向纽约的美国破产法院申请破产保护，重整债务。Borders成立于1971年，在上世纪90年代的书店扩张热潮中，Borders的店面覆盖了整个美国，旗下现有650家门市Borders未能预测到亚马逊和顾客消费习惯的变化带来的威胁，这些变化使实体书店走上下坡路。2001年4月，Borders将未盈利的互联网业务转让给亚马逊。当七年之后Borders重新推出

5、自己的网站时，亚马逊已经主导了蓬勃发展的在线书店市场。452012年3月， 1亿用户，433天。2012年9月， 2亿用户，6个月。2013年1月， 3亿用户，5个月。2014年6月，6亿用户，月活跃用户2.7亿6Generation YYoungsters born in the 1980s and came of age around the turn of millenium.Generation ZThe post-1990s generation that doesnt remember a world before the tech boom. Generation AlphaKi

6、ds born after 2010.Alpha kids will grow up with iPad in hand and never live without a smartphone and the ability to transfer a thought online in seconds. These massive technological change, among others, make Generation Alpha the most transformative generation ever.Web 1.0, 2.0, 3.0Web 1.0 Tim Berne

7、rs-Lee 1991Netscape 1994Read-only webWeb 2.0Time OReilly, 2004Read-Write WebWeb 3.0Dan Gillmor, Apr., 2005Read-Write-Execute Web7What is Web 2.0Design Patterns and Business Models for the next Generation of SoftwareTim OReilly, 9/30/2005 “Web 2.0” began with a conference brainstorming session betwee

8、n OReilly and MediaLive International. MediaLive International: Producer of technology tradeshows and conferences. Meaningless marketing buzzword? new conventional wisdom?“rich intelligent clients who share information across the web and deal with richer media (photos, sound, video).” (Adam Bosworth

9、, Google VP)“making global information available to local social contexts and giving people the flexibility to find, organize, share and create information in a locally meaningful fashion that is globally accessible.” (Danah Boyd)8What is Web 2.0“ Web 2.0 is the network as platform, spanning all con

10、nected devices; Web 2.0 applications are those that make the most of the intrinsic advantages of that platform: delivering software as a continually-updated service that gets better the more people use it. Consuming and remixing data from multiple sources, including individual users, while providing

11、 their own data and services in a form that allows remixing by others, creating network effects through an “architecture of participation,” and going beyond the page metaphor of Web 1.0 to deliver rich user experiences. ”Tim OReilly“Using the Web the way its meant to be used” - Paul Graham9Web 2.0 T

12、hemesThe Web As PlatformHarnessing Collective IntelligenceBlogging and the Wisdom of CrowdsData is the Next Intel InsideEnd of the Software Release CycleLightweight Programming ModelsSoftware Above the Level of a Single DeviceRich User Experiences10The Web As PlatformNetscape vs. GoogleNetscape: “we

13、btop”Google: not a desktop application but a serviceNo release, no licensing or sale, no installationDatabase management“The value of the software is proportional to the scale and dynamism of the data it helps to manage.”Collection of internet servers: a middleman between browser and search engine a

14、nd destination content server The “Long Tail”1112Cloud-based platform to build and deploy web apps. The Web As PlatformA platform beats an application every timeEarly PC era, MS played the platform card, trumping even the most dominant applications.Excel to Lotus 1-2-3, Word to WordPerfect, IE to Ne

15、tscapeThis time, clash between two platformsMonolithic: A single software provider, whose massive installed base and tightly integrated operating system and APIs give control over the programming paradigm.Architecture of Participation: A system without an owner, tied together by a set of protocols,

16、open standards and agreements for cooperation.13Harnessing Collective IntelligenceHyperlinking is the foundationYahoo! was born as an aggregation of the best work of thousands, then millions of web users.Googles PageRank uses the link structure to provide better search results.eBay is an enabler of

17、the collective activity of all its users: buyers and sellers.Amazon leads with “most popular” a real-time computation with an order of magnitude of user participation.14Harnessing Collective IntelligenceWikipedia, dynamic content creation: an entry can be added and edited by any web user“with enough

18、 eyeballs, all bugs are shallow” (Eric Raymond, open source software)Flickr, tagging, “folksonomy”, categorization of sites using freely chose keywords“viral marketing”, internet success dont advertise products but by recommendations propagating from one to anotherNetwork effects from user contribut

19、ions are the key to market dominance in the Web 2.0 era. 1516Blogging and the Wisdom of CrowdsThe Architecture of ParticipationThree ways to build large databaseYahoo!, Open Directory Project, NapsterSet inclusive defaults for aggregation user data and building value as a side-effect of ordinary use

20、 of the applicationA small core, well-defined extension mechanisms, and an approach that lets any well-behaved component be added by anyone, growing the router layer, “the onion”. 17Data is the Next Intel InsideWho own the data? Who control the data?“Maps copyright NavTeq, TeleAtlas”, “Images copyri

21、ght Digital Globe”A failure to understand the importance of owning an applications core data will eventually undercut its competitive positionMapQuest Yahoo! MS Google, licensing the same dataAmazon: “embraced and extended” their data suppliersMushup“.interactive Web applications that draw upon cont

22、ent retrieved from external data sources to create entirely new and innovative services.”18Web Mashup = API 1 + API 2 + API N/Mashup EditorsGoogle Mashup EditorMicrosoft PopflyYahoo pipesIBM Assemble ZeroWeb application from Yahoo! With GUI for building Mashup applicationsCombine many feeds into one

23、, then sort, filter and translate itGeocode favorite feeds and browse the items on an interactive map.Grab the output of any Pipes as RSS, JSON, KML, and other formatsYou can publish your pipes and share with others19Yahoo! Pipe : Example20Yahoo! Pipe : Example21Web Mashup genresMapping mashupsGoogl

24、e Maps, Yahoo Maps, Microsoft Virtual EarthVideo and photo mashups Flickr, YoutubeSearch and Shopping mashupseBay, AmazonNews mashups Diggdot.us= D + S + Del.icio.usExample: /22End of the Software Release CycleOperations must become a core competency: Dynamic systems that change constantlyThe softwa

25、re will cease to perform unless it is maintained on a daily basis. Users must be treated as co-developers“release early and release often” (open source) “the perpetual beta”“We put up two or three new features on some part of the site every day, and if users dont adopt them, we take them down. If th

26、ey like them, we roll them out to the entire site.”Flickr: deploy new builds up to every half hour. “Microsofts business model depends on everyone upgrading their computing environment every two to three years. Googles depends on everyone exploring whats new in their computing environment every day.

27、 ”23Lightweight Programming ModelsCase studyeBay: SOAP vs. REST (XML over HTTP, Representational State Transfer), REST 95%Google Maps, simple AJAX, leaving the data for the taking - creatively re-using the data) Lessons learnedSupport lightweight programming models that allow for loosely coupled sys

28、temsThink syndication, not coordinationDesign for “hackability” and remixabilityInnovation in Assembly24Software Above the Level of a Single DeviceSoftware in no longer limited to the PC platform one application that is used at multiple devicesiPod / iTuneTiVoYouTubeWhat applications become possible

29、 when our phones and our cars are not consuming data but reporting it?25Rich User Experience“Rich Internet Applications”26MS Silverlight showcase, http:/ Web application that has many of the characteristics of desktop applications.Visions for the Web“The web is and will be ubiquitous, have no centra

30、l authority, and consist of components that are heterogeneous and autonomous.”The “components”: Web pages programs“Dynamic”: content delivery service negotiation and interactions. 27Visions for the Web“. a goal of the Web was that, if the interaction between person and hypertext could be so intuitiv

31、e that the machine-readable information space gave an accurate representation of the state of peoples thoughts, interactions, and work patterns, then machine analysis could become a very powerful management tool, seeing patterns in our work and facilitating our working together through the typical p

32、roblems which beset the management of large organizations.”28- Tim Berners-Lee, The originator of WWW, 199129Visions for the WebOriginal Web CharacteristicsCurrent Web Characteristics Projected Web CharacteristicsDistributed Decentralized, Portal-centricDistributed nature competes with decentralizat

33、ionHigh Reliability Security vulnerabilitiesSpecialized subnetsFault tolerantSegments of Web are fault intolerantInternet hubs are fault vulnerableLow bandwidthExpanding bandwidthHigh bandwidthInformation display for humansInformation display for human, but business logic moved to specialized framew

34、ork serversSemantic Web services compete with proprietary server pages for business logic. Simple Markup LanguageeXtensible Markup LanguageMachine-readable information and semantics30Visions for the WebOriginal Web CharacteristicsCurrent Web Characteristics Projected Web CharacteristicsNo metadataLi

35、ttle metadataMachine-readable information and semantics Limited searchKeyword searchInference/semantic searchNo network logicLogic on serversLogic on WebOpen standardsOpen Web standards compete with proprietary frameworks serversOpen Web standards compete with proprietary frameworks serversEase of u

36、seMore accessMultimedia accessWeb 3.0 “Linked data”New ways of finding, integrating and analyzing data from diverse sources to achieve new information and insights never before possible. “Ubiquity of linked devices”New ways of connecting to the Web via a variety of machines, and of exchanging data b

37、etween machinesSemantic Web, Video on the Web, Mobile Web and Ubiquitous Web31Example: Wikipedia32Improving Wikipedia SearchDBPedia MobileService Oriented Architecture33Microsoft Robotic Studio34RobosoftWhiteBoxRoboticsRoboticsConnectionCoroware Web Services Architecture35RolesService providerServic

38、e requesterService discovery agencyInteractionsPublishFindBind36Service brokerRegistrationOrganization X Organization ZOrganization Y ComponentLibraryServicesFoundAuto-searchableApplication 1Application 2BusinessProcessThe SOA StoryRegistrationRegistrationDynamic Software ArchitectureSoftware archit

39、ectures evolve and change during run-timeBPELWSDLWSDLPartnerLinkPartnerLinkServiceProviderServiceProviderServiceProviderServiceProviderBindingBindingBindingBinding37BPEL: Business Process Execution LanguageTo compose services into business process WSDL: Web Services Description LanguageTo describe t

40、he service and its interface38ClientportTypeportTypeRetrieve the employeeTravel statusGet plane ticket offerFrom American AirlinesGet plane ticket offerFrom Delta AirlinesSelect the American Airlines ticketSelect the Delta Airlines ticketReturn the bestofferEmployTravelStatus WebServiceAmericaAirlin

41、esWebServicesDeltaAirlinesWebServices1. Request2. Request3. Reply4.1. Invoke4.2. Callback5.1. Invoke5.2. CallbackAmerican.price Delta.priceBPEL Process for Business Travels6. ReplyportTypeportType39processxmlns=/ws/2003/03/business-process/xmlns:print=/tptp/choreography/2004/engine/PrintHello World$

42、hello_world.valueDynamic Binding40Software-as-a-Service41Software is deadMark Benioff, CEO, SalesforceThe old-school view of software you buy it, you own it, and its your job to manage it thats coming to an end. Today, with Web 2.0 and pervasive computing coming on strong, were going to be seeing a

43、completely different generation of software. Itll be delivered via the Internet and will look exactly like its residing on each users computing device . But itll reside on a far-away server. Huge ResourcesThe illusion of infinite computing resources available on demand, thereby elmininating the need for cloud computing users to plan far ahead for proisioning No Commitment T