Informix DataBlade API Programmer's Manual Writing a User-Defined Routine

In This Chapter

Coding the User-Defined Routine

Defining Routine Parameters

For MI_DATUM Arguments

For the MI_FPARAM Argument

Obtaining Argument Values

Handling Character Arguments

Handling NULL Arguments

Modifying Argument Values

Defining a Return Value

Returning a Value

Returning Multiple Values

Coding the Routine Body

Choosing a Virtual Processor

Creating a Well-Behaved Routine

Preserving Concurrency

Writing Thread-Safe Code

Avoiding Unsafe Function Calls

Handling an Ill-Behaved Routine

Choosing the User-Defined VP Class

Defining the User-Defined VP

Assigning a C UDR to a User-Defined VP Class

Managing Virtual Processors

Adding and Dropping VPs

Monitoring Virtual Processors

Managing Memory

Managing User Memory

Allocating User Memory

Deallocating User Memory

Monitoring User Memory

Managing Stack Space

Managing Stack Usage

Increasing Stack Space

Accessing Operating-System Files

Opening a File

Specifying a Filename

Calling the Operating-System Open

Sharing Open Files

A Sample File-Access User-Defined Routine

Accessing the UDR Execution Environment

Accessing the Session Environment

Accessing the Server Environment