File locking considerations

The flat file transport strategy uses the Java 1.5 File Channel feature to facilitate locking the events file when writing events. This strategy allows for external programs to adopt a file locking strategy when accessing this file.

Since the java.nio.FileChannel and java.nio.FileLock classes make use of native system concurrent file access capabilities, the external programs can make use of system-level, concurrent access methods, without concern as to whether these are compatible with the locking used by the FlatFile transport.

For those programs that are Java-centric, the java.nio.FileChannel and java.nio.FileLock classes are recommended when reading events from the event file.

The following code fragment illustrates a suggested approach.

. . .
FileOutputStream fos = new FileOutputStream("<eventfilename>");
DataOutputStream dos = new DataOutputStream(new BufferOutputStream(fos));
FileChannel channel = fos.getChannel();
FileLock lock = channel.lock();
try {
    . . . read and/or write data . . .
} catch (Exception e) {
    . . . handle exceptions . . .
} finally {
    lock.release();
}
. . .