Index for Section 3

Alphabetical listing for E

Bottom of page

EvmConnCreate(3)
NAME
  EvmConnCreate, EvmConnCreatePoster, EvmConnCreateSubscriber, EvmConnFdGet,
  EvmConnDestroy - Establish or destroy connection with the EVM daemon

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 EvmConnCreatePoster(
	  EvmConnection_t *connection );

  EvmStatus_t EvmConnCreateSubscriber(
	  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 operand 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 operand must be set to EvmRESPONSE_CALLBACK.

      EvmCONNECTION_SERVICE
	      Creates a service connection. This mode is not currently
	      supported for general use.

  responseMode
      This operand 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 operand, 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 operand 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
      EvmCallback(5).  The calling process should use this argument to pass
      its own context data for the connection to the callback function. This
      operand should be NULL if no context data is required.

  connection
      For EvmConnCreate() this is the return operand for the new connection.
      For the other routines described on this page, it is the connection to
      be processed.

  fd  The return operand 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 EvmConnCreatePoster() routine is a macro that establishes a posting
  connection to the local daemon. Using this macro is equivalent to calling
  EvmConnCreate() with type set to EvmCONNECTION_POST, responseMode set to
  EvmRESPONSE_WAIT, and transport, callback and callbackArg all set to NULL.

  The EvmConnCreateSubscriber() routine is a macro that establishes a
  subscribing connection to the local daemon. Using this macro is equivalent
  to calling EvmConnCreate() with type set to EvmCONNECTION_LISTEN,
  responseMode set to EvmRESPONSE_CALLBACK, and transport set to NULL.

  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

LIBRARY
  EVM Support Library (libevm.so, libevm.a)

FILES
  /var/evm/sockets/evmd
      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)

  Files: kevm(7)

  Event Management: EVM(5)

  Event Callback: EvmCallback(5)

  Event Connection: EvmConnection(5)

  EVM Events: EvmEvent(5)

  Programmer's Guide

Index for Section 3

Alphabetical listing for E

Top of page