ppsService.open()

Open a PPS object file for read, write, or both

Signature

ppsService.open(path, flags, mode, errorlistener);

Arguments

Argument	Type	Description
`path`	String	The pathname of a PPS object file to open. Required. You can append any of the following pathname open options to the PPS object path: OPTION_DELTA — Open in delta mode OPTION_NATIVE — Open in native mode OPTION_NOPERSIST — Open as nonpersistent object OPTION_SERVER — Open as server object OPTION_VERBOSE — Be verbose For information on the native-mode option, see the Description, below. For information on all other pathname open options, see the Persistent Publish/Subscribe Developer's Guide.
`flags`	Integer	Open the PPS object file, using the specified access modes. Required. You can specify any of the following constants: FLAG_RDONLY — Read only FLAG_WRONLY — Write only FLAG_RDWR — Read-write FLAG_CREAT — Open with file create FLAG_TRUNC — Open with truncation You can also specify flags defined in the QNX system header file fcntl.h.
`mode`	Integer	Use the specified owner, group, other access permissions for the newly created PPS object file. Required. Specify a mode in this argument only if you specify FLAG_CREAT in the `flags` argument; otherwise, pass 0. You can specify any of the following constants: Owner MODE_IRWXU — Read, write, execute/search MODE_IRUSR — Read MODE_IWUSR — Write MODE_IXUSR — Execute/search Group MODE_IRWXG — Read, write, execute/search MODE_IRGRP — Read MODE_IWGRP — Write MODE_IXGRP — Execute/search Other MODE_IRWXO — Read, write, execute/search MODE_IROTH — Read MODE_IWOTH — Write MODE_IXOTH — Execute/search You can also specify any permissions defined the QNX OS header file fcntl.h.
`errorlistener`	Function	The callback function that gets called if an error occurs. Required. See errorListener() for details.

Description

The ppsService.open() method is a JavaScript wrapper of the QNX native open() function. It has the same usage as open(), except for its extra errorlistener argument. See open() in the QNX Neutrino RTOS Library Reference for more information, including details of the various access modes.

The JavaScript PPS API has an exclusive “native” pathname open option. When you append this option to the PPS path (i.e. pps_path?native or pps_path?ppsService.OPTION_NATIVE), the PPS data received by calling ppsService.read() or ppsService.watch() on the file descriptor will be in PPS native format. See dataListener() for signature information.

See the QNX Persistent Publish/Subscribe Developer's Guide for more information on pathname open options.

Returns

On success, a positive number that represents the file descriptor; otherwise, 0 or a negative number.

Examples

var PATH = '/pps/person';

var errorHandler = function(fd, errorID, errorMessage) {
   // handle the error
   console.log('FD: %d, Error ID: %d, Message: %s.', fd, errorID, errorMessage);
}

// open for write, create the file if it does not exist.
var fd_wr = ppsService.open(PATH, ppsService.FLAG_WRONLY | ppsService.FLAG_CREAT, 
                                  ppsService.MODE_IRWXU | ppsService.MODE_IRWXG | 
                                  ppsService.MODE_IRWXO, errorHandler);
if (fd_wr < 1) {
   console.log('Open for write failed.');
}

// open for read
var fd_r = ppsService.open(PATH, ppsService.FLAG_RDONLY, 0, errorHandler);
if (fd_r < 1) {
   console.log('Open for read failed.');
}

// open for read in delta mode
var fd_r_delta = ppsService.open(PATH + '?delta', ppsService.FLAG_RDONLY, 0, errorHandler);
if (fd_r_delta < 1) {
   console.log('Open for read in delta mode failed.');
}

// open for read in raw data format
var fd_r_raw = ppsService.open(PATH + '?native', ppsService.FLAG_RDONLY, 0, errorHandler);
if (fd_r_raw < 1) {
   console.log('Open for read in raw data format failed.');
}

// open for read and write
var fd_rw = ppsService.open(PATH, ppsService.FLAG_RDWR, 0, errorHandler);
if (fd_rw < 1) {
   console.log('Open for read and write failed.');
}