native XML databases applications

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lt? native XML databases ?gtapplications
implications

• inls 258 db2
• alex vidas susan teague rector
• october 29, 2003

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What Are Native XML Databases (NXDs)?

• The XMLDB mailing list proposes that a native
  XML database
• Defines a (logical) model for an XML document --
  as opposed to the data in that document -- and
  stores and retrieves documents according to that
  model. At a minimum, the model must include
  elements, attributes, PCDATA, and document order.
  Examples of such models are the XPath data model,
  the XML Infoset, and the models implied by the
  DOM and the events in SAX 1.
• Has an XML document as its fundamental unit of
  (logical) storage, just as a relational database
  has a row in a table as its fundamental unit of
  (logical) storage.
• Is not required to have any particular underlying
  physical storage model. For example, it can be
  built on a relational, hierarchical, or
  object-oriented database, or use a proprietary
  storage format, such as indexed, compressed
  files.

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Architecture
Native XML Data Store
XML-RPC Interface
Database Engine
DBBroker Interface
Native Broker
XMLDB API
SOAP Interface
Relational Broker
RDBMS
XPath Engine
example depicting the eXist native XML database,
from Chaudhri, Akmal B., Rashid, Awais, Zicari,
Roberto. (2003). XML Data Management Native XML
and XML-Enabled Database Systems.
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History Why were NXDs Developed?

• "... the new paradigm is the XML document.
  Applications are slowly but steadily moving away
  from a data-centric point of view to a
  document-centric-oriented framework"
• Mable.
• Need ways of processing, storing and manipulating
  the semi-structured data, AND enabling a
  generation of the original document
• NXDs offer faster and more efficient alternatives
  for some of these tasks.

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NXD Features

• Document Collections
• Query Languages
• Updates and Deletes
• Transactions, Locking, and Concurrency
• Application Programming Interfaces (APIs
• Round-Tripping
• Remote Data
• Indexes
• External Entity Storage

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Document Centric Versus Data Centric

• Data-Centric Documents
• use XML as a data transport Bourret.
• like the data in RDBMSs
• designed for machine consumption and the fact
  that XML is used at all is usually superfluous
  Bourret.

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Document Centric Versus Data Centric

• Document-Centric Documents
• intended for a person to read rather than for an
  application process Mable.
• implicit ordering that allows little or no
  structure Mable
• Semi-structured in nature Bourret

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Sample of Document-Centric/Semi-Structured XML

• http//www.ibiblio.org/dickens/xml/
• from the Dickens Collection, courtesy of
  Documenting the
• American South Digitization Project

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Overview of Advantages/Disadvantages to Using NXD
Technology

• Main Advantages
• Superior Document-Centric/Semi-Structured Storage
  and Searching of XML
• Efficiency
• Similar features to those of a RDBMS
• Reuse Indexing Added Value
• Maintains the integrity of the document
• Schema-less in most cases
• Reduced workload for database professionals
• Quicker development to market time
• No complex mapping between the XML document and
  RDBMS
• Supports full-text searching and manipulation of
  recursive content

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Overview of Advantages/Disadvantages to Using NXD
Technology

• Main Disadvantages
• Extremely young, cutting-edge technology
• Has the stigma of becoming the next
  object-oriented database
• Organizations already have complex RDBMS models
  in place
• Lack of formatting options when retrieving data
  from the system
• No formal adoption of one query language
• Difficult to chose a system as there are so many
  on the market now
• Supports referential integrity, but is weak (with
  XML in general)
• Potential problems with redundancy

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Commercial Open Source NXDs

• key native xml databases
• eXist
• Xindice
• Tamino XML Database
• Berkeley DB
• db/XML
• GoXML DB Native XML database
• Ipedo XML Database
• X-Hive/DB
• Michigan's Digital Library Extension Service

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The Future of NXD Technology

• "Whether the future of databases is the
  traditional, relational and SQL model with XML
  technologies incorporated into it or a new
  XML-based model is a matter of debate"
• Krill

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Future, cont. Possibilities

• XML becomes dominant means of information
  interchange
• Modifications to relational database front-ends
  for XML
• Research into how to best index XML
• Defragmenting update abilities.
• Improved support for live remote data
• Changes or additions to Query languages
• Self-managing database technology
• Query processing changes
• Development of standards through standards bodies
  AND consortia
• Emergence of W3C XML Schema as the schema
  language of choice for NXDs?