Architecture of the World Wide Web, Volume One W3C Recommendation 15 December 2004Presentation OrganizationWhere/What are the Other Volumes?Organization of the PaperWhat are: Principles, Constraints and Good Practices?Now into the gory detailsIntroductionAn Overview of How Scenario Bits and Pieces Fit TogetherStory Line SpecificsThings about URIsSample URIsYet more Things about URIsURI PersistenceIdentification of ResourcesInteraction StartsInteraction ContinuesDifficulties with any NegotiationsAn Abstract View of the Processes to this PointAn Example of Data that is Passed in the BackgroundData FormatsBinary and Textual Data FormatsBinary vs TextThe Perfect Language Design CaseVersioning and ExtensibilityVersioningExtensibilitySlide 27Composition of Data FormatsSeparation of Content, Presentation, and InteractionDemonstration of “Server does all” RecombineHypertextXML-Based Data FormatsGeneral Architecture PrinciplesOrthogonal SpecificationsSlide 35Error HandlingProtocol-Based InteroperabilityConclusionDiscussion QuestionsThe End.Principles, Constraints and Good PracticesPrinciplesConstraintsGood Practices (part one of six)Good Practices (part two of six)Good Practices (part three of six)Good Practices (part four of six)Good Practices (part five of six)Good Practices (part six of six)Architecture of the World Wide Web, Volume OneW3C Recommendation 15 December 2004Tim Berners-Lee (co-Chair, W3C), Tim Bray (Antarctica Systems), Dan Connolly (W3C), Paul Cotton (Microsoft Corporation), Roy Fielding (Day Software), Mario Jeckle (Daimler Chrysler), Chris Lilley (W3C), Noah Mendelsohn (IBM), David Orchard (BEA Systems), Norman Walsh (Sun Microsystems), and Stuart Williams (co-Chair, Hewlett-Packard). Presented by:Chuck CartledgeCarlton NorthernCS-791/891 Web Syndication Formats, ODU, Sping 2008 2Presentation Organization•A review of the paper taken from http://www.w3.org/TR/webarch/•Putting the paper into a context•The gore of the paper•The paper’s conclusion•“To everything there is a time and a season” and now it is time questions.•Practices and ideas applicable to other contextsCS-791/891 Web Syndication Formats, ODU, Sping 2008 3Where/What are the Other Volumes?•Not sure, perhaps this is similar to “Kill Bill, Volume 1” where the next volume came out a few months later. It has been a few years so maybe the Web architecture is still evolving?? Then again there is Mel Brookes movie of a similar name, or Sir Walter Raleigh’s book completed just before his execution.•The URI http://www.w3.org/TR/ has many reports that have the word architecture in the title, but none that address the Web in toto.CS-791/891 Web Syndication Formats, ODU, Sping 2008 4Organization of the Paper•Introduction–Who is the intended audience–Brings forth the ideas of:•Principle•Constraint•Good Practice•Identification–URIs with all their trials and trepidations–Uniqueness, collisions, persistence, commitments•Interaction–Access to a URI–Negotiation–Inconsistencies–Safe and unsafe actions•Data Formats–A discussion about the selection of data formats–Problems inherent with a multiplicity data formats–Attempts at Universal format•General Architectural Principles–Generally good things to keep in mind when building something that will be widely used•Glossary–Interesting and useful words•References–How many things of note are written with out references (aside from Einstein’s stuff)•Acknowledgements–Everyone gets their day in the sunCS-791/891 Web Syndication Formats, ODU, Sping 2008 5What are: Principles, Constraints and Good Practices?•Principle – a fundamental rule that applies to a large number of situations and variables•Constraint – many choices in design are somewhat arbitrary (‘:’ vice ‘*’, ‘p’ vice ‘paragraph’) and the results would probably have been the same. Other constraints may be imposed by technical, policy or design decisions.•Good practice – something that increases the value of the Web.CS-791/891 Web Syndication Formats, ODU, Sping 2008 6Now into the gory details (Sometimes you don’t want to know how its made, you just want to enjoy it.)CS-791/891 Web Syndication Formats, ODU, Sping 2008 7Introduction•The paper uses a scenario of Nadia planning a trip to Oaxaca, Mexico and sharing information with Dirk•The story follows the URI that Nadia gives to Dirk, how each of their agents (browsers) interprets the URI, how they interact with the serverCS-791/891 Web Syndication Formats, ODU, Sping 2008 8An Overview of How Scenario Bits and Pieces Fit TogetherWhat is this? How are the various parts used? Is it unique? How long is it viable?What is a resource? How do I get the one I want? What is the format of what I get?How is the resource presented to me? How do I communicate which version(s) of the resource I can accept?CS-791/891 Web Syndication Formats, ODU, Sping 2008 9Story Line Specifics•URI identification: (http://weather.example.com/oaxaca)•What is meant by each part of the HTTP URI–http: - HTTP scheme identifier–// - token separator–weather,example.com – host–oaxaca – absolute path to a resource•The interaction of the agents upon reception of this URI•How is the format of the data being returned determined•And, along the way: Principles, Constraints and Good Practices are identifiedCS-791/891 Web Syndication Formats, ODU, Sping 2008 10Things about URIs•A URI is an agreement about how the I’net community allocates names and associates them with a type of resource•One, or more URIs can be aliases for a different URI•URIs are “owned” by a social entity (someone or something under someone’s control) who agrees to live by the URI agreement•Separate URIs that are character by character the same, point to the same resource•Separate URIs that are not character by character the same, may point to the same thing (alias)CS-791/891 Web Syndication Formats, ODU, Sping 2008 11Sample URIs•ESGR – Employer Support of the Guard and Reserve, a volunteer advocacy group for mediation between employers and Guard and Reserve personnel -http://www.esgr.com/•www.esgr.com = 199.231.147.34•www.esgr.net = 199.231.147.34•www.esgr.mil = 131.84.1.94 –http://whois.domaintools.com/esgr.milCS-791/891 Web Syndication Formats, ODU, Sping 2008 12Yet more Things about URIs•You shouldn’t attempt to read too much into a URI–Just because a URI ends in