The C language user-defined node API consists of:
- A set of implementation functions that provide the functionality of the
user-defined node. These functions are invoked by the broker. The implementation
functions are mandatory, and if they are not supplied by the developer, an
exception is thrown at run time.
- A set of utility functions that create resources in the message broker,
or request a service of the broker. These utility functions are invoked by
a user-defined node.
Most of the utilities are shared by any type of node, however there are
a few that are specific to input nodes. These are marked in the text.