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Oracle XML DB server


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Oracle XML DB server

HTTP, HTTPS, FTP, WebDAV including WebDAV Version Control

Oracle XML DB is not a separate server; it is an integral part of the Oracle database, providing all of the high-availability, scalability, reliability and unbreakable security features needed to run mission-critical applications.

You can use Enterprise Manager to manage and administer XML DB applications. The GUI in Enterprise Manager allows us to perform the following tasks.

Configuration

  • Configure XML DB including protocol server configuration
  • View and edit XML DB configuration parameters
  • Register XML schemas

Create Resources

  • Manage resource security such as ACL’s
  • Granting and revoking privileges
  • Creating and editing resource indexes
  • Viewing and navigating XML DB repository

Create XML schema-based tables and views

  • Create the storage structure based on XML schemas
  • Editing an XML schema
  • Creating XMLType columns and tables based on XMLType
  • Creating a view-based XML-schema
  • Creating function based indexes

Because the XML repository can be exposed as a WebDAV folder, getting access to the schema files is very straight forward. Creating XSD document and XSL transformations using Altova XML Spy for instance is especially easy.

The contents of the XML DB repository – usually XSD, XSL, XSLT and XML documents, but can also be JPG, DOCS or anything else you like – can be easily accessed directly over WebDAV or FTP from within the XMLSpy IDE.

Automatic bi-directional translation between client and database character sets

XML DB handles conversion of the files from/to oracle db on the fly. For instance when a WebDAV user opens a file in the repository, XML DB dynamically generates the file from data held in the oracle database.

When a schema-based XML document is loaded in the repository, XML DB will automatically recognise the document, shred it, and store it in the default table defined by the XML schema.

Storage options

Unstructured Storage

XML data is stored in a single field in a table as a Character Large Object (CLOB)

Advantages:

  • Throughput
  • Preserves fidelity of original document byte for byte, this may be important for some applications

Disadvantages:

  • When a row is updated, the entire XML document must be re-written to disk

Structured Storage

XML DB creates underlying oracle tables and objects to hold the XML data. These objects are created by referencing the required associated XSL document.

Advantages:

  • XQUERY / XPATH can be used to query and reference the data
  • Queries use the built-in standard oracle optimiser
  • Data can be streamed from/to the tables, reducing memory overhead when dealing with large document
  • Can use B-Tree indexes, Function-based indexes, Text based indexes
  • Can index on existsNode values etc…

Disadvantages:

  • All data must conform to a XSD schema (valid XML document) (also an advantage)
  • Extra processing required whilst ingesting and retrieving xml content

XSD Schemas

XSD schemas specify how to formally describe the elements in an Extensible Markup Language (XML) document. This description can be used to verify that each item of content in a document adheres to the description of the element in which the content is to be placed.

In general, a schema is an abstract representation of an object’s characteristics and relationship to other objects. An XML schema represents the interrelationship between the attributes and elements of an XML object (for example, a document or a portion of a document). To create a schema for a document, you analyze its structure, defining each structural element as you encounter it. For example, within a schema for a document describing a Web site, you would define a Web site element, a Web page element, and other elements that describe possible content divisions within any page on that site. Just as in XML and HTML, elements are defined within a set of tags.

An investment in an XML registry will, over time, allow projects to be more manageable and business driven allowing the business with the help of IS achieve its goals in a consistent and timely manner; which is, after all, the whole point of IS.

XMLTYPE

XMLType data type is a native Oracle type that contains XML data. It is stored internally as a CLOB column.

XMLType data type can be user like any other SQL data type in Oracle, including in Create Tables, Views, parameter passing or return types.

XMLType columns should contain well-formed XML documents.

Service oriented Architecture

Keywords: Abstraction, Granularity, Versioning, Internal dependencies

Web services provide easy access to remote content and application functionality using industry-standard mechanisms, without any dependency on the provider’s platform, the location, the service implementation, or the data format. For that reason, Web services are a principal means of achieving SEPA resource virtualisation, a key requirement for building enterprise scalable solutions.

The ability to turn the database into a Web services provider extends the database’s functionality to Web services client applications by allowing the execution of database operations and data retrieval through standard Web services mechanisms.

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