The%20Next%20Generation%20Web

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The Next Generation Web

• You see things and you say Why?But I dream
  things that never were and I say Why not?
• G. B. Shaw (Back to Methuselah)
• Michael B. Spring
• Department of Information Science and
  Telecommunications
• University of Pittsburgh
• spring_at_imap.pitt.edu
• http//www.sis.pitt.edu/spring

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Prelude

• When I try to explain the architecture now for
  the semantic web, I get the same distant look in
  peoples eyes as I did in 1989, when I tried to
  explain how global hypertext the world wide web
  would work.
• Tim Berners-Lee, Weaving the Web, pp.194-195

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Overview
SimpleConcepts

• Context
• Changing nature of documents
• The current state of the WWW
• The next generation web
• Conceptually
• Infrastructure
• Proposed Architectures
• Issues and conclusions

Ideas for aTechnicalSolution
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Context

• The Web is a critical environment for information
  exchange and is increasingly used by business
• Documents are changing in form and function
  computer mediation is making them more dynamic,
  more interactive, and more personal
• Powerful existing computing tools and
  infrastructure to support collaboration,
  distributed services, and agents are being
  retooled for a second generation web

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Artifacts and process

• Humans use documents as tools to accomplish
  different things
• Explanation of ideas
• Communication of design
• Specification of agreements
• In addition to their main message, documents
  provide ancillary information about work
  processes (feedback and feedthrough)
• The next generation web will embrace computer
  mediated and manipulable document forms

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Types of documents

• Classifying documents by scope captures many of
  the important distinctions between different
  types.
• Consider the difference in documents that are
• Personal
• Group
• Organizational
• Enterprise
• Archival

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Document Process matrix
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Digital Document Characteristics

• Digital documents have new features
• Components (charts, data sheets)
• Active links
• Versioning and commentary
• We work with digital documents differently
• Increased number of revisions, more copy and edit
• Outline and fill composition
• Computers can work with digital documents
• Automatic generation
• Agent based processing

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The Current State of the Web

• The web has begun to lose coherence -- locational
  association is not enough
• Disintermediated junk
• Unlinkable processes
• Insufficient inverted indices
• Classification is needed
• It requires a shared ontology
• It needs to be distributed
• It must be decentralized

2000
1990
Classification
300BC
Linking
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What the WWW is

• The web is distributed, decentralized and
  scalable system with
• A robust simple idempotent protocol (single
  request response)
• Based on a locational infrastructure (URLs and
  DNS)
• With an effective but costly envelop (TCP)
• And a growing ad hoc superstructure (server and
  client sides)

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What the WWW is not

• Stateful
• Cookies and server side session management
  struggle to provide a semblance of state
• Organized
• Search engines and portals are veneers that
  endeavor to provide organization
• Designed for processes
• http is connectionless and cannot support
  sessions
• HTML is inadequate for data interchange

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The Next Generation Is Here

• When a CGI program takes data from a DBMS to
  compose a web page with a form that is processed
  by another CGI, that is in essence a web service
• When a plug-in such as real-player accesses and
  plays streaming media, we are in essence using a
  web service
• Instant messaging and file sharing services such
  as Gnutella are better examples of services.
  More fully integrated in browsers, they are web
  services

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A Once and Future King

• The next generation is not really new --
  distributed computing, based on a client server
  model, has been with us for years.
• RPC and RMI approaches to distributed computing
  are multi-tiered, involve registration and
  lookup, and make use of shared interfaces.
• CORBA and DCOM provide process wrappers and
  distributed lookups.
• The next generation web is distributed computing
  dynamic, late binding, peer to peer
  architectures.

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The Next Generation WebConceptually

• Use the vast infrastructure of the web (millions
  of clients and servers using http) to access
  programs as well as static pages.
• Develop additional infrastructure that will allow
  highly distributed programs to operate securely
  and productively over the web.
• Build marketplaces that work.

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Infrastructure and Architecture

• The underlying infrastructure includes
• Component transaction monitors
• Abstract syntax
• Distributed directory services
• Security and authentication
• The architectural approaches are varied
• HPs E-service architectures (now absorbed)
• Suns JXTA (still emerging)
• Microsofts .NET (growing strong)
• W3Cs semantic web with its agent architectures
  (???)

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CTM Infrastructure

• Component Transaction Monitors (CTMs) are CGIs on
  steroids
• Early efforts moved beyond CGI to servlet runners
  and ASP/JSP with components/beans.
• CTM moves beyond managing threads to advertising,
  federation, transaction management, and security
  management.
• To deliver messages to components through http,
  an envelop is needed. The Simple Object Access
  Protocol (SOAP) is emerging as the protocol.

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XML Infrastructure

• Data Interchange
• In order to build documents that can be machine
  processed, we need more precise control over the
  structure of the document (we need to know there
  is an author element).
• We also need control over the content of the
  document (we need to control what goes in the
  author element).
• XML provides both of these capabilities

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XML Infrastructure(continued)

• Given a clear model of XML documents
• XPath defines the ability to obtain any set of
  nodes in a document
• XSLT allows the transformation of document trees
• DOM and SAX provide application program
  interfaces to these models
• Schema allow extensible and modular extension of
  definitions

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Directory Infrastructure

• Directories of objects are key to the
  infrastructure. They will be distributed and
  object oriented.
• The X.500 Directory Service is being used via
  LDAP(Lightweight Directory Access Protocols)
• The directories will be used to allow resources
  to advertise themselves so as to be discovered.
  The Universal Description, Discovery and
  Integration (UDDI) Protocol is emerging as a
  leader here
• There are a number of models for how directories
  will be related.

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Security and Authentication

• CTMs will implement secure pipes of various types
  between monitors to allow transactions that begin
  and end behind firewalls to move across the
  unprotected internet.
• Certificates will be used as the basis for the
  development of a web of trust that will allow for
  authentication and non-repudiation

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Approaches to Marketplaces

• Michael Dertouzous suggested that this
  environment we are moving toward most closely
  resembles and information marketplace
• HPs e-speak was an early contender
• SUNs JXTA has many similar characteristics, a
  tight coupling to Java, and a simple Unix like
  approach
• Microsofts .NET is focused on bringing
  Microsofts extensive resources to bear in easy
  to use ways
• The Semantic Web is a personal agent based view
  of how this new web might be used

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What is Espeak (1)

• Espeak is a component transaction monitor

ESpeak Services
Consumer
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What is ESpeak (2)

• ESpeak is a distributed service

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What is ESpeak (3)

• ESpeak is a system that provides support for
• Advertising and finding based on vocabularies
• Authentication
• Multiple access methods
• Security

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ESpeak Advertising and Authentication
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ESpeak Access and Security
Secure
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What is ESpeak (4)

• Espeak is an extensible system with
  decentralized control
• Vocabularies
• Attributes and values
• Combined and advertised
• Services
• Basic services
• Infrastructure services
• Support services

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Vocabularies and Metaservices
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A Mind Set

• Millions of machines
• Marketplace makers
• Competing service providers
• Dynamic offerings
• Distributed certificate authorities
• Intermediaries
• Smart devices
• Smart consumers

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E-Marketplaces
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JXTA

• Peer to peer P2P computing model
• JXTA comes from juxtapose the peer to peer
  model is juxtaposed against the traditional
  client server model.
• It consists of a federation of peers running JXTA
  cores
• The focus of this implementation is on truly ad
  hoc peers

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JXTA Architecture
JXTA Application
JXTA Service
Pipes
Network Services
Peers
Peer Groups
Services
Discovery
Pipe Binding
Access
Propagation
Rendezvous
Relay
Routing
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JXTA Components

• Peers are the fundamental entities in JXTA
• They offer and/or consume services
• They have a unique ID but may be mobile
• Pipes are used to connect peers
• They are late binding and dynamic
• They are considered one way and unreliable
• Services consist of both peer services and
  peer-group services which may be offered
  redundantly by all members of a peer group

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JXTA Services

• Discovery along with propagation and rendezvous
  are all related to the processes by which
  entities and services become known
• Advertisements are made by participants that are
  propagated, cached by rendezvous services, such
  that they might be discovered.
• Once discovered, services may be engaged through
  a series of messages

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JXTA Services (continued)

• The rendezvous service keeps track of known
  advertisements and other rendezvous services
  discovered services are cached. Queries, if not
  answerable locally are propagated.
• The router and relay services maintain
  information about routes to peers and translation
  between various transport services.
• There are also security and authentication
  services

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.NET

• Microsoft views the next generation web as a
  challenge to its control of the desktop
• .NET is Microsofts response
• .NET is a distributed peer to peer service
  environment built on top of a series of
  interfaces
• Microsoft is aggressively upgrading their
  existing software to include support for services
• Microsoft is very conscious of the need to
  promote this new environment via killer
  applications

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Microsofts .NET

• .NET is built by extending and creating new tools
  and services in three areas
• A set of servers both modified existing (SQL
  and Exchange) and new (BizTalk)
• A set of tools the wizards in VB and C are
  extended to encompass web services
• New foundation services advertising,
  notification, and security (Passport) that are a
  part of the CTM.

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The .NET Interfaces

• XML is the language or abstract syntax for
  protocols in .NET
• SOAP is the envelop which will be used to
  transmit the messages. It is used within an http
  POST request to send a UDDI request or get a WSDL
  interface.
• UDDI is the set of protocols to used to
  advertise, find, and combine services. It is
  written in XML.
• WSDL is the set of protocols used to define web
  services. It is written in XML.

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.NET Seduction

• Microsoft will help users see how this new
  environment will work by building new devices and
  services
• New devices that consume services
• Xbox
• Tablet PC
• Smart phone
• User experiences that promote the new environment
• Office will be .Net sensitive
• Microsoft Project will be .Net sensitive
• XP will be .Net sensitive

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The Semantic Web

• Tim Berners-Lee has described the next generation
  web as the semantic web.
• The semantic web would be manipulable by programs
• Like the current web, his vision is one that
• Is distributed and decentralized
• Must scale well and allow for imperfect
  contributions
• Must be such that the vast majority of the
  contributors to the web can participate easily

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The Components

• XML provides an extensible language for document
  and data interchange including
• Query
• Linking
• RDF provides a mechanism for developing
• Descriptions of resources
• Descriptions of the descriptions (schema)
• Inference engines (agents) would have the ability
  to discover resources based on schema analysis

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The Web Today
2. ObjectRequest
1. LocationLookup
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The Web with Descriptions
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Semantic Web
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Issues(1)

• A simple request could involve hundreds versus
  10s of network hops
• This would greatly increase bandwidth and the
  impact of network delays
• Preprocessing (DNS lookup pre LDAP) could reduce
  steps
• A component view could ease the burden by
  dynamically passing requests off
• Caching of information could greatly ease the
  burden
• Clients could cache schema and schema heads
• Schema servers could cache schema structures

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Issues(2)

• The appropriate level of logic and the
  distribution of processing will be critical
• What expressive power should be allowed (at what
  computational cost)
• Disjunction
• Negation
• What should the schema servers do?
• What can the directory servers do?
• What can the client do?

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Conclusions

• Infrastructure exists that can be used
• There are at least two visions operating
• A business service view -- .NET
• A personal agent view the semantic web
• JXTA appears capable of serving both visions
• It is not clear whether
• Any solution can be made simple enough
• A critical mass payoff can be achieved in
  reasonable time