EvmConnCreate(3) Library Functions Manual EvmConnCreate(3)
NAME
EvmConnCreate(), EvmConnCreatePoster(), EvmConnCreateSubscriber(), EvmConnDestroy(), EvmConnFdGet() - establish or destroy connection with
the EVM daemon
SYNOPSIS
Library
EVM Support Library
Parameters
type Establishes the function of the connection. Possible values are as follows:
Creates a connection for use by posting clients.
Creates a connection for use by subscribing clients.
The responseMode operand must be set to
responseMode Establishes the behavior of certain connection-oriented API functions when requests are made to the EVM daemon. If a func-
tion call results in such a request, the function returns a response according to the value of this operand, as follows:
The function returns without waiting for the daemon's response.
In this mode, any return status other than indicates that a problem was detected in preliminary validation. A
response of signifies only that the request was sent to the daemon. An response cannot determine if the request was
received or accepted.
The function does preliminary validation, returning a status
reflecting any error it finds. If the function finds no error, it passes the request to the EVM daemon and blocks
until a response is received from the daemon. The status returned by the function may result either from preliminary
validation or from validation by the daemon. If no error is returned by the function, the request has been accepted
by the daemon.
The function returns without waiting for a response.
Any return status other than indicates that a problem was detected in preliminary validation.
If no error is found, the function passes the request to the EVM daemon, and returns immediately with a status of The
calling process must use or a related function to watch for I/O activity on the connection, and then invoke to handle
the activity. In most cases, the connection's callback function is invoked to handle incoming messages.
This response mode must be used for listening connections.
transport Specify the type of connection to be made to the daemon. Because EVM currently supports only local connection the daemon,
this argument must always be set to NULL. If this argument is not NULL, an error occurs.
callback A pointer to a routine that is to be called by to process an incoming message. The routine is declared as described in the
EvmCallback(5) manpage. If the response mode is not this operand is NULL.
callbackArg This argument is supplied each time the callback routine is invoked by See EvmCallback(5). The calling process uses this
argument to pass its own context data for the connection to the callback function. If no context data is required, this op-
erand is NULL.
connection For connection is the return operand for the new connection. For the other routines described on this manpage, connection is
the EVM connection to be processed.
fd The return operand for the file number associated with the supplied connection.
DESCRIPTION
The routine establishes a connection between a client process and the EVM daemon. If the connection is successful, a pointer to a new con-
nection context is returned in the connection argument.
The routine is a macro that establishes a posting connection to the local daemon. Using this macro is equivalent to calling with type set
to responseMode set to and transport, callback,and callbackArg are all set to NULL.
The routine is a macro that establishes a subscribing connection to the local daemon. Using this macro is equivalent to calling with type
set to responseMode set to and transport set to NULL.
The routine returns the file number associated with the connection. This file number can be used by a client application, which handles
multiple I/O sources, for use in a call to to determine when there is activity on the connection. The program must call to handle the
activity. It must not close the file descriptor, nor perform any direct I/O on it.
The routine destroys the connection and frees any resources associated with it. This routine must be called to destroy the connection.
RETURN VALUE
The operation completed without error.
One of the arguments to the function is invalid.
A value in a structure member is invalid.
An operation failed because an attempt to acquire heap memory failed.
A read error occurred while reading from the EVM daemon connection.
A write error occurred while writing to the EVM daemon connection.
An error occurred while attempting to connect to the EVM daemon.
An error occurred on the EVM connection.
Invoke to destroy the connection.
The current operation was interrupted by receipt of a signal.
ERRORS
The value of is not set.
FILES
Default pathname for the domain socket.
SEE ALSO
Commands
evmget(1), evmpost(1), evmwatch(1).
Functions
connect(2), select(2), socket(2).
Routines
EvmConnControl(3), EvmConnDispatch(3), EvmConnWait(3).
Event Management
EVM(5).
Event Callback
EvmCallback(5).
Event Connection
EvmConnection(5).
EVM Events
EvmEvent(5).
EvmConnCreate(3)