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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.
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.
Database access
Execute user-defined routines
This section provides information about how to call a user-defined routine (UDR).
Access MI_FPARAM routine-state information
When the routine manager calls a UDR, it passes the routine-state information as an extra argument, called the function-parameter structure, to the routine. This function-parameter structure, MI_FPARAM, holds the routine-state information for the C UDR with which it is associated.
Check routine arguments

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 overview
    - Data manipulation
    - Database access
      - Connection handling
        This section describes how to initialize, establish, and close connections.
      - Execute SQL statements
        One basic task of a DataBlade® API module is to send SQL statements to the database server for execution.
      - Execute user-defined routines
        This section provides information about how to call a user-defined routine (UDR).
        Access MI_FPARAM routine-state information
        When the routine manager calls a UDR, it passes the routine-state information as an extra argument, called the function-parameter structure, to the routine. This function-parameter structure, MI_FPARAM, holds the routine-state information for the C UDR with which it is associated.
        Check routine arguments
        Determine the data type of UDR arguments
        With the MI_FPARAM structure, you can write UDRs that operate over a type hierarchy, rather than on a single type. At run time, the routine can examine the MI_FPARAM structure to determine what data types were passed to the current invocation of the routine.
        Handling NULL arguments with MI_FPARAM
        By default, C UDRs do not handle SQL NULL values. A UDR is not executed if any of its arguments is NULL; the routine automatically returns a NULL value.
        Access return-value information
        Saving a user state
        The routine manager provides information about arguments and return values of a UDR in the MI_FPARAM structure that is associated with a UDR. In addition, you can store the address of private-state information, called user-state information, in a special field of the MI_FPARAM structure.
        Obtain additional routine information
        The MI_FPARAM structure of a C UDR provides additional information about a UDR.
        Call UDRs within a DataBlade® API module
        Call UDRs with the Fastpath interface
        With the DataBlade® API Fastpath interface, DataBlade API modules can directly invoke a UDR that was registered in the database. This interface bypasses the overhead associated with invoking a UDR through an SQL statement. This interface bypasses the query optimizer and executor, which are needed for an SQL statement. You can use this interface to execute any SQL routine.
        Obtain trigger execution information and HDR database server status
      - Exceptions and events
        This section describes exceptions and events, and explains how to handle them in DataBlade® API modules.
      - XA-compliant external data sources
    - Create user-defined routines
    - Appendix
      This section contains additional reference information.
  - 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.

Check routine arguments

The user state of a C UDR provides the following information about routine arguments:

Data type information about any arguments
Boolean value to indicate whether an argument is NULL

The following table lists the DataBlade® API accessor functions that obtain and set information about routine arguments in an MI_FPARAM structure.

Table 1. Argument information in an MI_FPARAM structure
Argument information	DataBlade® API accessor function
The number of arguments for the UDR with which the MI_FPARAM structure is associated	mi_fp_nargs() mi_fp_setnargs()
The type identifier of each argument that the MI_FPARAM structure contains	mi_fp_argtype() mi_fp_setargtype()
The length of each argument that the MI_FPARAM structure contains	mi_fp_arglen() mi_fp_setarglen()
The precision (total number of digits) of each argument that the MI_FPARAM structure contains	mi_fp_argprec() mi_fp_setargprec()
The scale of each argument that the MI_FPARAM structure contains	mi_fp_argscale() mi_fp_setargscale()
Whether each argument that the MI_FPARAM structure contains is an SQL NULL value	mi_fp_argisnull() mi_fp_setargisnull()