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EvmConnCreate(3)
NAME
EvmConnCreate, EvmConnFdGet, EvmConnDestroy - Establishes or destroys
connection with the EVM daemon
LIBRARY
EVM Support Library (libevm.so, libevm.a)
SYNOPSIS
#include <evm/evm.h>
EvmStatus_t EvmConnCreate(
EvmConnectionType_t type,
EvmResponseMode_t responseMode,
const EvmTransport_t transport,
EvmCallback_t callback,
EvmCallbackArg_t callbackArg,
EvmConnection_t *connection);
EvmStatus_t EvmConnFdGet (
EvmConnection_t connection,
EvmFd_t *fd);
EvmStatus_t EvmConnDestroy(
EvmConnection_t connection);
OPERANDS
type This parameter establishes the function of the connection. Possible
values are the following:
EvmCONNECTION_POST
Creates a connection for use by posting clients.
EvmCONNECTION_LISTEN
Creates a connection for use by subscribing clients. The
responseMode parameter must be set to EvmRESPONSE_CALLBACK.
EvmCONNECTION_SERVICE
Creates a service connection. This mode is not currently
supported for general use.
responseMode
This parameter establishes the behavior of certain connection-
oriented API functions when requests are made to the EVM daemon. If
a function call results in such a request, the function will return a
response according to the value of this parameter, as follows:
EvmRESPONSE_IGNORE
The function returns without waiting for the daemon's response.
In this mode, any return status other than EvmERROR_NONE
indicates that a problem was detected in preliminary validation.
A response of EvmERROR_NONE signifies only that the request was
sent to the daemon; you cannot establish whether it was received
or accepted.
EvmRESPONSE_WAIT
The function does preliminary validation, returning a status
reflecting any error it finds. If it 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.
EvmRESPONSE_CALLBACK
The function returns without waiting for a response. Any return
status other than EvmERROR_NONE 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 EvmERROR_NONE.
The calling process must use EvmConnWait(3) or a related function
to watch for I/O activity on the connection, and then invoke
EvmConnDispatch(3) to handle the activity. In most cases, this
will result in the connection's callback function being invoked
to handle incoming messages.
This response mode must be used for listening connections.
transport
This specifies the type of connection to be made to the daemon. You
usually should set this argument to NULL for the default connection
to the local daemon. For remote connection, set it to the address of
an EvmTransport_t structure, transport, initialized in the following
manner:
transport.type = EvmTRANSPORT_TCPIP;
transport.data.tcpip.portNumber = -1; /* -1 for default port */
transport.data.tcpip.hostName = "remote_system_address";
callback
A pointer to a routine that will be called by EvmConnDispatch() to
process an incoming message. The routine must be declared as
described in the EvmCallback(5) reference page. This parameter
should be NULL if the response mode is not EvmRESPONSE_CALLBACK.
callbackArg
The argument that will be supplied as the callbackArg argument each
time the callback routine is invoked by EvmConnDispatch(). See the
EvmCallback(5) reference page. The calling process should use this
argument to pass its own context data for the connection to the
callback function. This parameter should be NULL if no context data
is required.
connection
For EvmConnCreate() this is the return parameter for the new
connection. For the other routines described on this page it is the
connection to be processed.
fd The return parameter for the file number associated with the supplied
connection.
DESCRIPTION
The EvmConnCreate() routine establishes a connection between a client
process and the EVM daemon. If the connection is successful, a pointer to
a new connection context is returned in the connection argument.
The EvmConnFdGet() 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 select(2) to determine
when there is activity on the connection. The program must call
EvmConnDispatch() to handle the activity. It must not close the file
descriptor, nor perform any direct I/O on it.
The EvmConnDestroy() routine destroys the connection and frees any
resources associated with it. This routine must be called to destroy the
connection.
RETURN VALUES
EvmERROR_NONE
The operation was completed without error.
EvmERROR_INVALID_ARGUMENT
One of the arguments to the function was invalid.
EvmERROR_INVALID_VALUE
A value in a structure member is invalid.
EvmERROR_NO_MEMORY
An operation failed because an attempt to acquire heap memory failed.
EvmERROR_READ
A read error occurred while reading from the EVM daemon connection.
EvmERROR_WRITE
A write error occurred while writing to the EVM daemon connection.
EvmERROR_CONNECT
An error occurred while attempting to connect to the EVM daemon.
EvmERROR_SELECT
An error occurred on the EVM connection. Invoke EvmConnDestroy() to
destroy the connection.
EvmERROR_SIGNAL
The current operation was interrupted by receipt of a signal.
ERRORS
None
FILES
/var/evm/sockets/evmd
Default pathname for the domain socket.
SEE ALSO
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)
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Index for
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Alphabetical
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