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Extending Informix®
Beyond standard relational database objects, HCL Informix® can be extended to handle specialized data types, access methods, routines, and other objects. Informix includes many built-in extensions that are fully integrated in the database server. Informix also provides DataBlade® modules, which are packages of extended database objects for a particular purpose and that are installed separately from the database server. Alternatively, you can create your own user-defined objects for Informix.
Informix® extensions and DataBlade® modules
These topics describe how to use built-in database extensions and separately installed DataBlade® modules.
Performing XML Publishing
The Informix® XML User's Guide includes information about using built-in functions for XML publishing with Informix.
Publishing SQL result sets in XML
Several functions let you publish XML from SQL queries.

Extending Informix®
Beyond standard relational database objects, HCL Informix® can be extended to handle specialized data types, access methods, routines, and other objects. Informix includes many built-in extensions that are fully integrated in the database server. Informix also provides DataBlade® modules, which are packages of extended database objects for a particular purpose and that are installed separately from the database server. Alternatively, you can create your own user-defined objects for Informix.
- Informix® extensions and DataBlade® modules
  These topics describe how to use built-in database extensions and separately installed DataBlade® modules.
  - Database Extensions User's Guide
    The Informix® Database Extensions User's Guide explains how to use the database extensions that come with HCL Informix: Large Object Locator, MQ messaging, binary data types, basic text search, node data type, and SQL packages.
  - Performing XML Publishing
    The Informix® XML User's Guide includes information about using built-in functions for XML publishing with Informix.
    - Publishing SQL result sets in XML
      Several functions let you publish XML from SQL queries.
      - XML publishing
        XML publishing provides a way to transform results of SQL queries into XML structures.
      - The idsxmlvp virtual processor class
        The XML functions that Informix® provides run in a virtual processor class named idsxmlvp.
      - Special characters in XML functions
        The XML functions of the database server automatically handle special characters.
      - The extract() and extractclob() XML functions
        Evaluates an XPATH expression on an XML column, document, or string. These functions are identical except that extractclob() returns a CLOB instead of LVARCHAR.
      - The existsnode() XML function
        Determines whether the XPath evaluation results in at least one XML element.
      - The extractvalue() and extractvalueclob() XML functions
        Returns the value of the XML node in contrast to extract(), which returns the XML node.
      - The genxml() and genxmlclob() XML functions
        Return rows of SQL results as XML elements. Use genxmlclob if the returned row is greater than LVARCHAR(32739).
      - The genxmlelem() and genxmlelemclob() XML functions
      - The genxmlqueryhdr() and genxmlqueryhdrclob() XML functions
        Returns the result set of a query in XML with the XML header.
      - The genxmlquery() and genxmlqueryclob() XML functions
        These functions take a SQL query as a parameter and return the result set in XML.
      - The genxmlschema() and genxmlschemaclob() XML functions
        These functions generate an XML schema and result in XML format.
      - The idsxmlparse() XML function
        Parse an XML document or fragment to determine whether it is well formed.
    - Transforming documents with XSLT functions
      Apply XSL stylesheets and transforms to XML documents.
  - Spatiotemporal Search for Moving Objects User's Guide
    The describes how to program applications to search data from moving objects in HCL Informix® databases using the spatiotemporal search extension.
  - TimeSeries Data User's Guide
    The Informix® TimeSeries Data User's Guide contains information to assist you in using the TimeSeries extension with HCL Informix.
  - Web DataBlade Module
    Use the Web DataBlade® module to create web applications that incorporate data that is retrieved dynamically from the HCL Informix® database.
- Creating extensions
  You can create user-defined data types, routines, access methods, and other database objects to suit your needs. You can use application programming interfaces to write user-defined routines and applications that access data in Informix® databases.

Publishing SQL result sets in XML

Several functions let you publish XML from SQL queries.

There are two of XML functions for each action depending on the size of total result set after adding all the tags necessary to publish it in XML format:

One that returns a maximum of LVARCHAR(32739)
One that returns a CLOB data type

The input XML must include every value inside an element, not as an attribute. For example:

<employee>
  <givenname>Roy</givenname>
  <familyname>Connor</familyname>
  <address>
    <address1>123 First Street</address1>
    <city>Denver</city>
    <state/>CO</state>
    <zipcode>80111</zipcode>
  </address>
  <phone>303-555-1212</phone>
</employee>

The XML functions are summarized in the following table.

Table 1. XML publishing functions
Action	Function	Comments
Return rows of SQL results as XML elements.	The genxml() and genxmlclob() XML functions	Similar to FOR XML RAW in Microsoft™ SQL Server
Return each column value as separate elements.	ids_xpgenxmlelem.html	Similar to FOR XML AUTO, ELEMENTS in Microsoft™ SQL Server
Return an XML schema and result in XML format.	The genxmlschema() and genxmlschemaclob() XML functions	Similar to FOR XML AUTO, XMLSCHEMA in Microsoft™ SQL Server
Returns the result set of a query in XML format.	The genxmlquery() and genxmlqueryclob() XML functions	These functions accept a SQL query as a parameter.
Returns the result set of a query in XML with the XML header.	The genxmlqueryhdr() and genxmlqueryhdrclob() XML functions	Every XML document must have a header. These functions provide a quick method of generating a header.
Evaluates an XPATH expression on an XML column, document, or string.	The extract() and extractclob() XML functions	Similar to the Oracle extract() function.
Returns the value of the XML node	The extractvalue() and extractvalueclob() XML functions	Similar to the Oracle extractvalue() function.
Verify whether a specific node exists in an XML document.	The existsnode() XML function	Similar to the Oracle exists() function.
Parse an XML document to determine whether it is well formed.	The idsxmlparse() XML function