Home
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 extensionsYou 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 GuideThe Informix® DataBlade® API Programmer's Guide describes information about the DataBlade® API, the C-language application programming interface (API) provided with HCL Informix®.
Create user-defined routines
Develop a user-defined routineA C user-defined routine (UDR) is a UDR that is written in the C language and uses the server-side implementation of the DataBlade® API to communicate with the database server. C UDRs (functions and procedures) are implemented as C-language functions. DataBlade® modules often include C UDRs that are made available for use by registering them in the database.
Execute a UDR
The routine managerAfter the query parser has used routine resolution to determine which UDR to invoke, the query executor calls the routine manager to handle the UDR execution.
Push arguments onto the thread stackWhen the routine manager pushes arguments onto the thread stack, it pushes them as MI_DATUM values.
Argument promotionThe C compilers that accept Kernighan--Ritchie (K&R) syntax promote all arguments to the int data type when they are passed to a routine.

Argument promotion

The C compilers that accept Kernighan--Ritchie (K&R) syntax promote all arguments to the int data type when they are passed to a routine.

The size of this int data type is native for the computer architecture. ANSI C compilers permit arguments to be shorter than the native computer architecture size of an int. However, the routine manager uses K&R calling conventions when it pushes an MI_DATUM value onto the thread stack.

Tip: Many ANSI C compilers can use K&R calling conventions so code does work correctly across all platforms.

The routine manager cast promotes arguments with passed-by-value data types whose sizes are smaller than the size of the MI_DATUM data type to the size of MI_DATUM. When you obtain the smaller passed-by-value data type from the MI_DATUM structure, you must reverse the cast promotion to assure that your value is correct. For more information, see MI_DATUM in a C UDR (Server).

If you pass an argument smaller than an MI_DATUM structure, it is recommended that you pass a small by-value SQL type as an mi_integer value.

Rate this topic

5 stars 4 stars 3 stars 2 stars 1 star

Comment on this topic.

By clicking this box, you acknowledge that you are NOT a U.S. Federal Government employee or agency, nor are you submitting information with respect to or on behalf of one. HCL provides software and services to U.S. Federal Government customers through its partners immixGroup, Inc. Contact this team at https://hcltechsw.com/resources/us-government-contact. Do not include any personal data in this Comment box.