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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.
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.
User-Defined Routines and Data Types Developer's Guide
The Informix® User-Defined Routines and Data Types Developer's Guide describes how to define new data types and enable user-defined routines (UDRs) to extend HCL Informix.
Develop a user-defined routine
Write the routine
Create a user-defined interface for XA data sources

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.
- 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.
  - DataBlade® API Programmer's Guide
    The Informix® DataBlade® API Programmer's Guide describes information about the DataBlade API, the C-language application programming interface (API) provided with HCL Informix.
  - DataBlade® API Function Reference
    The Informix® DataBlade® API Function Reference describes the DataBlade API functions and the subset of Informix ESQL/C functions that the DataBlade API supports.
  - DataBlade® Developers Kit
    The DataBlade® Developers Kit (DBDK) guides contain information about the tools you can use to develop and package DataBlade modules, which extend the functionality of HCL Informix® databases.
  - J/Foundation Developer's Guide
    The J/Foundation Developer's Guide describes how to write user-defined routines (UDRs) in the Java™ programming language for Informix®.
  - R-Tree Index User's Guide
    The Informix® R-Tree Index User's Guide describes the HCL Informix R-tree secondary access method and how to access and use its components.
  - User-Defined Routines and Data Types Developer's Guide
    The Informix® User-Defined Routines and Data Types Developer's Guide describes how to define new data types and enable user-defined routines (UDRs) to extend HCL Informix.
  - Virtual-Table Interface Guide
    The Informix® Virtual-Table Interface Programmer's Guide explains how to create a primary access method with the Virtual-Table Interface (VTI) so that users have a single SQL interface to HCL Informix tables and to data that does not conform to the storage scheme of HCL Informix.
  - Virtual-Index Interface Guide
    The Informix® Virtual-Index Interface Programmer's Guide explains how to create a secondary access method with the Virtual-Index Interface (VII) to extend the built-in indexing schemes of HCL Informix typically with a DataBlade® module.

Create a user-defined interface for XA data sources

The HCL Informix® Transaction Manager recognizes XA-compliant external data sources, which can participate in two-phase commit transactions. You can invoke support routines for each XA-compliant, external data source that participates in a distributed transaction at a particular transactional event, such as prepare, commit, or rollback. This interaction conforms to X/Open XA interface standards.

You can create user-defined support routines to provide data access mechanisms for external data from XA data sources. The interaction between Informix® and external data sources is through a set of purpose routines, such as xa_open( ), xa_start( ), xa_prepare( ), xa_rollback( ), xa_commit( ), xa_recover( ), xa_complete( ), xa_forget( ), xa_close( ), and xa_end( ) For more information these purpose functions, see the Informix® DataBlade® API Programmer's Guide.

You can create and drop XA-compliant data source types and instances of XA-compliant data sources. After you create an external XA-compliant data source, transactions can register and unregister the data source using the mi_xa_register_xadatasource( ) or ax_reg( ) and mi_xa_unregister_xadatasource( ) or ax_unreg( ) functions. For information about creating and dropping XA-compliant data source types and instances of XA-compliant data sources and information about the functions that transactions use to register and unregister the data source, see the Informix® DataBlade® API Programmer's Guide and the Informix® DataBlade® API Function Reference .

The MQ DataBlade® module is an example of a set of user-defined routines that provide data access mechanisms for external data from XA data sources and provides XA-support functions to provide transactional support for the interaction between HCL Informix® and WebSphere® MQ. For more information, see the Informix® Database Extensions User's Guide.