What is an XML database?

The XML:DB initiative has defined three different types of XML database.
  1. Native XML Database (NXD)
    • a) 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 1.0.
    • b) 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.
    • c) 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.
  2. XML Enabled Database (XEDB) - A database that has an added XML mapping layer provided either by the database vendor or a third party. This mapping layer manages the storage and retrieval of XML data. Data that is mapped into the database is mapped into application specific formats and the original XML meta-data and structure may be lost. Data retrieved as XML is NOT guaranteed to have originated in XML form. Data manipulation may occur via either XML specific technologies(e.g. XPath, XSL-T, DOM or SAX) or other database technologies(e.g. SQL). The fundamental unit of storage in an XEDB is implementation dependent. The XML solutions from Oracle and Microsoft as well as many third party tools fall into this category.
  3. Hybrid XML Database (HXD) - A database that can be treated as either a Native XML Database or as an XML Enabled Database depending on the requirements of the application. An example of this would be Ozone.

Why are XML databases interesting?

There is a whole world of applications where an XML database is the best solution. For these applications an XML database will often far surpass a relational database in convenience, ease of development and performance. Applications where XML databases are often used consist of corporate information portals, membership databases, product catalogs, parts databases, patient information tracking, business to business document exchange as well as many many others. We hope that through the efforts of the XML:DB initiative that XML databases become widely accepted for all applications where the storage of XML data is necessary.

What is the XML:DB initiative for?

XML:DB has four primary goals.
  • Development of technology specifications for managing the data in XML Databases
  • Contribution of reference implementations of those specifications under an Open Source License
  • Formation of a community where XML database vendors and users can ask questions and exchange information to learn more about XML database technology and applications.
  • Evangelism of XML database products and technologies to raise the visibility of XML databases in the marketplace

Who is behind the organization?

XML:DB was formed by dbXML Group L.L.C, SMB GmbH and the OpenHealth Care Group and is currently supported by a growing list of companies. Please see the credits page for a list of all current supporters.

Why a new organization?

The founders of the XML:DB initiative felt that in order for XML databases to reach maturity within the marketplace a dedicated organization was necessary to bring all interested parties together. The XML:DB initiative is not designed as a replacement for the efforts of the W3C or any other organization. Our goal is to work together with those organizations while focusing on our unique area of interest around XML database technology.

What license is used for reference implementations?

All reference implementations will be licensed under an Apache style license.

What happens after the specifications are written?

When it makes sense to do so XML:DB will submit completed specifications to an appropriate standards body for international standardization.

How can you lay claim to the XML: namespace prefix?

The simple answer is we haven't. XML:DB is only the name of the organization and has no relation to the actual namespace prefixes used in our specifications.

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