Module 1 Introduction and Motivation

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Module 1Introduction and Motivation
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If I invent another programming language, its
name will contain the letter X.
(N. Wirth, Software Pioniere Konferenz, Bonn 2001)
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Google Indicator
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A history of Languge
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2 x (Descartes)
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lx.2x (Church)
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(LAMBDA (x) ( 2 x)) (McCarthy)
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W3C

• lt?xml version1.0gt
• ltlambda-termgt
• ltvarlistgt ltvargtxlt/vargtlt/varlistgt
• ltexpressiongt ltapplicationgt
• ltexprgtltconstgtlt/constgtlt/exprgt
• ltarg-listgtltexprgtltconstgt2lt/constgtlt/exprgt
• ltexprgtltvargtxlt/vargtlt/exprgt
• lt/arg-listgt
• lt/applicationgt lt/expressiongt
• lt/lambda-termgt

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What can the Web do for you?

• Download show HTML Documents
• Forms
• Pre-compiled point queries
• Updates in specific Web application
• Everywhere, any time, platform independent
• Simple keyword search (Google)
• Good for human-human, human-machine communication

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What the Web cannot do?

• Applications do not understand HTML
• Machine-Machine communication difficult
• Distributed Updates
• Long transactions (business processes)
• Powerful Queries
• Where can I find a used car for CHF 1000
• Scalability in the Millions of Machines

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Design Principles of W3C

• Everybody is autonomous
• Everybody can participate (open)
• All Standards are compatible
• All Standards are downwards compatible
• Platform- and vendor independance

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A little bit of history

• Database world
• 1970 relational databases
• 1990 nested relational model and object oriented
  databases
• 1995 semi-structured databases
• Documents world
• 1974 SGML (Structured Generalized Markup
  Language)
• 1990 HTML (Hypertext Markup Language)
• 1992 URL (Universal Resource Locator)

Data documents information 1996 XML (Extended
Markup Language) URI (Universal Resource
Identifier)
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What is XML?

• The Extensible Markup Language (XML) is the
  universal format for structured documents and
  data on the Web.
• Base specifications
• XML 1.0, W3C Recommendation Feb '98
• Namespaces, W3C Recommendation Jan '99

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XML Data Example

• ltbook year1967gt
• lttitlegtThe politics of experience
• lt/titlegt
• ltauthorgt
• ltfirstnamegtRonaldlt/firstnamegt
• ltlastnamegtLainglt/lastnamegt
• lt/authorgt
• lt/bookgt

Elements

• Syntax, no abstract model
• Documents, elements and attributes
• Tree-based, nested, hierarchically organized
  structure

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XML vs. relational data

• Relational data
• Invented as a mathematically clean abstract data
  model
• Philosophy schema first, then data
• Never had a standard syntax for data
• Strict rules for data normalization, flat tables
• Order is irrelevant, textual data supported but
  not primary goal
• XML
• First killer application publishing industry
• Invented as a syntax for data, only later an
  abstract data model
• Philosophy data and schemas should not be
  correlated, data can exist with or without
  schema, or with multiple schemas
• No data normalization, flexibility is a must,
  nesting is good
• Order may be very important, textual data support
  a primary goal

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Reasons for the XML success

• XML is a general data representation format
• XML is human readable
• XML is machine readable
• XML is internationalized (UNICODE)
• XML is platform independent
• XML is vendor independent
• XML is endorsed by the World Wide Web Consortium
  
• XML is not a new technology
• XML is not only a data representation format,
  its a full infrastructure of technologies

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XML as a family of technologies

• XML Information Set
• XML Schema
• XML Query
• The Extensible Stylesheet Transformation Language
  (XSLT)
• XLink, XPointer
• XML Forms
• XML Protocol
• XML Encryption
• XML Signature
• Others
• almost all the pieces needed for a good
  XML-based information hub

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Overview of XML Technologies

• W3C Standards
• Data XML, Namespaces, Infoset, Schema
• Communication SOAP, Encryption, WSDL, UDDI
• Processing Xpath, XSLT, Xquery, Xupdate, Xquery
  Text
• Integration RDF, OWL
• Other Standards
• Vertical domains RosettaNet, ebXML, ml
• Workflow BPEL
• Interfaces DOM, SAX, JAXP, SQL / XML

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Killer Applications for XML

• Data lives forever (longer than program code)
• legacy systems need to keep code to keep data
• huge IT infrastructures
• hello world program is very complex
• Model before Data (you need to know what you
  want)
• poor time to market, high cost
• SQL Objects are not enough
• middleware, data marshalling,
• No querying of objects, no encapsulation in SQL
• teure (five star guru) programmers needed
• XML Decouple Data and Schema!!!

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Killer XML advantages

• Code/schema/data independence
• Covers the continuous spectrum from totally
  structured data to documents
• from data management to information management
• Unique model for representing data, metadata and
  code

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Data metadata code

• Data (XML), schemas (XML Schemas) and code (XSLT,
  XQuery) they all have an XML syntax
• Easy to mix and match
• Data in the schemas (not yet)
• Data in code (already done)
• Code in schemas (not yet)
• Code in the data (not yet) dynamic data

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Misunderstanding about XML

• Data is self-describing.
• Tags dont hold semantics, they only hold the
  structure of the information
• The interpretation of the tags is in the
  application that handles the data, not in the
  tags themselves.

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XML handicaps

• Tree, and not a graph.
• Many limitations derive from here, and many
  complications in the XML processing languages.
• Difficulty in modeling NM relationships
• The notion of reference (e.g. XLink, XPointer)
  not well integrated in the XML stack
• Duplication of concepts
• Many ways to do the same thing
• Justification for a simpler data model like RDF
  
• Concepts that seem logically unnecessary
• PIs, comments, documents, etc
• Additional complexity factors
• xsinil, QName in content, etc

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Advantages and disadvantages

• 1. Handles the dual aspect of information
  lexical and binary 1 and 01
• Essential feature for the 21st century
  information management
• E.g. XML-based contract to be used in a legal
  procedure
• Lots of complexity derives from here
• XML Schema deals with both lexical and binary
  constraints
• XML Data Model has to include both the
  dmtyped-value and dmstring-value
• Processing language like XQuery and XSLT have to
  define their semantics for both aspects
• XML data storage and indexing heavily impacted

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Advantages and disadvantages

• 2. Data is context sensitive.
• We cannot do cut and paste in XML
• Certain aspects of the data depend on the context
  where the fragment of data occurs (base-URIs,
  namespaces,etc)
• Valuable feature for document management
• Very hard consequences on storing, indexing and
  processing XML
• Semantics of expressions also depends on the
  context where they appear
• Additional consequences on expression evaluation

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Sources of XML data ?

• Inter-application communication data (WS, Rest,
  etc)
• Mobile devices communication data
• Logs
• Blogs (RSS)
• Metadata (e.g. Schema, WSDL, XMP)
• Presentation data (e.g. XHTML)
• Documents (e.g. Word)
• Views of other sources of data
• Relational, LDAP, CSV, Excel, etc.
• Sensor data
• It would be interesting to know the pie-chart
  and the evolution of each branch !

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Some vertical application domains for XML

• HealthCare Level Seven http//www.hl7.org/
• Geography Markup Language (GML)
• Systems Biology Markup Language (SBML)
  http//sbml.org/
• XBRL, the XML based Business Reporting standard
  http//www.xbrl.org/
• Global Justice XML Data Model (GJXDM)
  http//it.ojp.gov/jxdm
• ebXML http//www.ebxml.org/
• e.g. Encoded Archival Description Application
  http//lcweb.loc.gov/ead/
• Digital photography metadata XMP
• An XML grammar for sensor data (SensorML)
• Real Simple Syndication (RSS 2.0)
  
• Basically everywhere.

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RosettaNet

• http//www.rosettanet.org
• Non-profit Organisation
• Sponsors IBM, Oracle, NEC, ...
• More than 400 additional members
• Goals
• Dynamic, flexible trading networks
• Operational efficiency (cost reduction)
• New business opportunities
• Technical Goals
• Common language, standard processesfor sharing
  of electronic business information

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RosettaNet

• PIPs Partner Interface Processes
• 8 Clusters
• Support
• Partner Product and Service Review
• Product Information
• Order Management
• Inventory Management
• Marketing Information Management
• Service and Support
• Manufacturing
• Segments wiht PIP Definitions in each Cluster

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3 Order Management

• Segment 3a Quote and Order Entry
• Segment 3b Transportation and Distribution
• Segment 3c Returns and Finance
• Segment 3d Product Configuration

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Quote and Order Entry
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Example DTD
lt!-- RosettaNet XML Message Schema
3A1_MS_R02_00_QuoteRequest.dtd (16-Apr-2001
1246) This document has been prepared by
Edifecs (http//www.edifecs.com/) based On
the Business Collaboration Framework from
requirements in conformance with the
RosettaNet methodology. --gt lt!ENTITY
common-attributes "id CDATA IMPLIED" gt
lt!ELEMENT Pip3A1QuoteRequest (
fromRole , GlobalDocumentFunctionCode
, Quote , thisDocumentGenerati
onDateTime , thisDocumentIdentifier ,
toRole ) gt
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Example DTD (ctd.)
lt!ELEMENT fromRole (
PartnerRoleDescription ) gt lt!ELEMENT
PartnerRoleDescription (
ContactInformation? ,
GlobalPartnerRoleClassificationCode ,
PartnerDescription ) gt lt!ELEMENT
ContactInformation ( contactName ,
EmailAddress , facsimileNumber?
, telephoneNumber ) gt lt!ELEMENT
contactName ( FreeFormText ) gt
lt!ELEMENT FreeFormText ( PCDATA )
gt lt!ATTLIST FreeFormText xmllang
CDATA IMPLIED gt
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Example DTD (ctd.)
lt!ELEMENT Quote ( comments? ,
financedBy? , GlobalGovernmentPriorityR
atingCode? , GlobalQuoteTypeCode ,
governmentContractIdentifier? ,
PriceCondition? , QuoteCustomerInformati
on? , QuoteLineItem ,
quoteRequestIdentifier ,
requestedResponseDate? ,
RequoteReference? , respondTo ,
submittedDate? , TaxExemptStatus? ,
transportedBy? ) gt
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ebXML

• http//www.ebxml.org
• OASIS Organization for the Advancement of
  Structured Information Standards
• Non profit, ... (like RosettaNet)
• Competition to RosettaNet
• ebXML Mission To provide an open XML based
  infrastructure enabling the global use of
  electronic business information in an
  interoperable, secure and consistent manner for
  all parties.
• Uses XML Schema (not DTDs)

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ebXML Example (SOAP)
ltSOAPEnvelope xmlnsSOAP"http//schemas.xmlsoap.
org/ xmlnsxsi"http//www.w3.org/2001/XMLSche
ma-instance" xsischemaLocation"http//schemas.
xmlsoap.org/gt ltSOAPHeader
xmlnseb"http//www.oasis-open.org/
xsischemaLocation"http//gt
ltebMessageHeader ...gt
... lt/ebMessageHeadergt lt/SOAPHeadergt ltSOAPBo
dy xmlnseb"http//www.oasis-open.org/
xsischemaLocation"http//gt ltebManifest
ebversion"2.0"gt ... lt/ebManifestgt lt/SOA
PBodygt lt/SOAPEnvelopegt
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ebXML Header Info (u.a.)

• Conversation ID
• ltebConversationIDgt2000-33-15-7lt/ebConversationID
  gt
• Sender and Recipient
• ltebFromgt
• ltebPartyId ebtype urndunsgt123lt/ebPartyI
  dgt
• ltebPartyId ebtype SCACgtRDWYlt/ebPartyIdgt
• ltebRolegthttp//rosettanet.org/roles/Buyerlt/eb
  Rolegt
• lt/ebFromgt
• ltebTogt
• ltebPartIdgtmailtojoe_at_example.comlt/ebPartIdgt
• ltebRolegthttp//rosettanet.org/roles/Sellerlt/eb
  Rolegt
• lt/ebTogt