XCube

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XCube

• XML For Data Warehouses
• By Sven Groot

2
Data warehouses

• Contains data drawn from several databases and
  external sources
• Provide a comprehensive view of all aspects of an
  enterprise
• Complemented by increased emphasis on powerful
  analysis tools
• SQL is inadequate
• OLAP OnLine Analytic Processing

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Data Warehousing
External Data Sources
Visualisation
Extract Clean Transform Load Refresh
OLAP
Serves
Metadata repository
Data Mining
Data Warehouse
Operational Databases
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OLAP

• Multidimensional data model

locid
8
10
10
13
20
30
50
pid
12
15
25
8
11
1
2
3
timeid
5
OLAP (contd)
Sales

• Multidimensional data as a relation

Locations
Products
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OLAP (contd)

• Dimension as hierarchies

PRODUCT
TIME
LOCATION
year
country
quarter
category
state
week
month
city
pname
date
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OLAP (contd)

• Typical OLAP queries
• Find the total sales
• Find total sales for each city
• Find total sales for each state
• Find the top five products ranked by total sales
• Possible to drill-down and roll-up on dimensions
• Pivoting

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eXtensible Markup Language

• Contains nodes that may be processing
  instructions, elements, attributes, CDATA
  sections or comments.
• Must be well-formed
• Format can be defined by a DTD or XSD.
• Multiple formats in one document using
  namespaces.
• Can be transformed using XSLT
• y.xsd
• Management Systems
• Second Edition

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Data Warehouses Reloaded

• Data warehousing occurs across departments all
  over the globe, and also across companies
• External datasources might include WWW and other
  data warehouses
• One flexible format for exchanging data cubes
  would be useful XCube

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XCube Scenarios

• Download

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XCube Scenarios (contd)

• Query

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XCube Scenarios (contd)

• Generating
• Conversion of any data into data cube
• Using data from a warehouse in data cube

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Requirements for online cubes

• Support for multidimensional data model.
• Support for conceptual distinction between
  schema, dimension and fact data.
• Transportable over the network.
• For flexibility and reuse linking and inclusion
  concepts needed
• Extensible to adapt to different data models or
  new concepts
• Easily convertible to and from various sources
  and formats
• Possibly allow OLAP processing to reduce data
  transfer

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XCube formats

• XCubeSchema

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XCube formats (contd)

• xmlns"http//www.xcube-open.org/V0_4/XCubeSch
  ema.xcsd"
• granularity"branch" /
• granularity"article" /

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XCube formats (contd)

• XCubeDimension

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XCube formats (contd)

• xmlns"http//www.xcube-open.org/V0_4/XCubeDim
  ension_base.xcsd"
• level"country" /
• level"country" /

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XCube formats (contd)

• XCubeFact

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• pen.org/V0_4/XCubeFact_base.xcsd"
• node"branch48" /
• /
• node"2003-07-24" /
• node"branch75" /
• /
• node"2003-07-24" /

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XCube extended formats

• XCubeText
• Adds textual description for nearly every
  element.
• Future version will allow separate files.
• Allows different levels of detail (short, medium,
  long, html)

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XCube extended formats (contd)

• XCubeQuery
• Organise interactive dialog between client and
  server
• Meant to facilitate more efficient exchange of
  data
• Consists of seven different query formats

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XCubeQuery

• List of available cubes
• Request /
• Responseid"purchase /

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XCubeQuery (contd)

• Getting the schema of a special cube
• Request idsale
• Responsexmlnsxshttp//www.w3.org/2001/XMLSchema
  
  
  
  
  
  id"revenue"/
  granularity"branch"/
  id"product" granularity"article"/
  
  stdLevel"true"/
  s/

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XCubeQuery (contd)

• Querying the Classification Schema
• Request
  
  idgeography/
• Response

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XCubeQuery (contd)

• chema"
• timeBase"quarter"
• stdLevel"true" /

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XCubeQuery (contd)

• Querying Classification Nodes
• Request levelbranch/
• Response id"branch48"
  level"city"/
  value"Meier"/
  id"branch75"
  level"city"/
  value"Bauer"/

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XCube extended formats (contd)

• XCubeFunction
• Still under development
• Query XCube server about its functionality

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XCube formats summary

• XCubeSchema
• XCubeDimension
• XCubeFact
• XCubeText
• XCubeQuery
• XCubeFunction

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Related work

• Common Warehouse Metamodel
• MetaCube-X
• XML for Analysis

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Where from here

• Basis for more complex and efficient
  infrastructure.
• Combination with XML Web Services
• Evolution of XCubeText
• Create new data warehouses with XCube standards.

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References

• Wolfgang Hümmer, Andreas Bauer Gunnar Hard
  XCube XML For Data Warehouses DOLAP03,
  November 7, 2003.
• http//www.xcube-open.org
• Raghu Ramakrishnan Johannes Gehrke Database
  Management Systems, second edition McGraw-Hill,
  2000
• T. Bray, J. Paoli, C.M. Sperberg-McQueen E.
  Maler Extensible Markup Language (XML) 1.0
  (Second Edition) W3C Recommendation 6 October
  2000http//www.w3.org/TR/REC-xml