EvmCallback(5)							File Formats Manual						    EvmCallback(5)

NAME

       EvmCallback - Event Management callback function

SYNOPSIS

       void EventCB(
	       EvmConnection_t connection,
	       EvmCallbackArg_t callbackArg,
	       EvmCallbackData_t *callbackData)

DESCRIPTION

       An  EVM callback function is a function that you provide to allow your program to handle messages arriving on an EVM connection.  Most mes-
       sages will be incoming events or responses to requests you have made to the EVM daemon, but you may also get a callback for other reasons.

       You specify the name (EventCB) of the callback function in the callback parameter when you create an EVM connection with a response mode of
       callback.

       Your callback function is invoked by EvmConnDispatch(), which you must call whenever you detect activity pending on the connection.

       An EVM callback function must conform to the prototype shown.

   Callback function parameters:
       The  connection parameter contains the connection context pertaining to this callback.  This value was returned by EvmConnCreate() when the
       connection was created. If you have one callback function servicing multiple connections, you might test this to determine which connection
       a  particular  invocation  is handling.	The callbackArg parameter contains the value you specified as the callbackArg parameter to EvmCon-
       nCreate() when you created the connection. For example, you might use it to hold a pointer to your own context  data  for  the  connection.
       The callbackData parameter points to a structure containing the details of the callback.  The structure includes a callback reason code, an
       event, and a union containing data specific to each possible reason.  The event member may contain NULL if it is not applicable to the rea-
       son.   You may get these reasons: This callback reason indicates that the daemon was unable to deliver one or more events, probably because
       the client process had not finished processing earlier events, causing the connection buffer to overflow.  If necessary, you can  use  Evm-
       ConnControl(3)  to  increase  the  size of the receive buffer.  This callback reason indicates that an EVM event has been received from the
       daemon. The event is available in the callbackData structure.  You must use EvmEventDestroy(3) to free the event  when  you  have  finished
       with  it.   This  callback  reason indicates that a prior EvmEventPost() call has completed, usually with a response from the daemon if the
       responseMode was specified as EvmRESPONSE_CALLBACK when the connection was created. The posting status is  available  in  the  callbackData
       structure.  This callback reason indicates that a requested template has been delivered in response to an EvmConnRegistrationGet() request.
       You must use EvmEventDestroy(3) to free the template when you have  finished  with  it.	 This  callback  reason  indicates  that  a  prior
       EvmEventSubscribe() call has completed, usually with a response from the daemon.  This callback reason indicates that event template infor-
       mation has been delivered in response to an EvmConnTemplateScan() request.  The template is available in the callbackData  structure.   You
       must use EvmEventDestroy(3) to free the template when you have finished with it.

       See the Common Desktop Environment: Programmer's Guide for examples of callback functions.

FILES

       Header file that contains the event declaration, structures, and prototype for the callback function

SEE ALSO

       Routines: EvmConnCreate(3), EvmConnCheck(3), EvmConnSubscribe(3), EvmEventPost(3)

       Event Management: EVM(5)

       Event Connection: EvmConnection(5)

       EVM Events: EvmEvent(5)

       Common Desktop Environment: Programmer's Guide delim off

																    EvmCallback(5)