File system Connector

The file system Connector is a transport Connector that requires a Parser to operate. The file system Connector reads and writes files available on the system it runs on. Concurrent usage of a file can be controlled by means of a locking mechanism.

This Connector can only be used in Iterator or AddOnly mode, or for the equivalent operations in Passive state.

Configuration

The Connector needs the following parameters:

File Path

The name of the file to read or write.

Timeout (in seconds)

When this parameter is specified as a positive number, the Connector waits for available data when reading from a file (that is, the Connector is in Iterator mode). Specify 0 (zero) to wait forever, or any other number which specifies the number of seconds to wait before signalling end of file. Setting this parameter to 0 (zero) causes the Connector to simulate the UNIX-style tail -f command.

If we have requested a lock on the file (using the Lock File parameter), the Timeout parameter instead specifies how long to wait to acquire the lock. An unspecified or negative number means "wait forever".

Append on Output

If set, the Connector appends instead of overwriting when the file is opened for writing.

Lock file

When writing, acquire an exclusive lock on the file being written. When reading, acquire a shared lock.

The lock is acquired when the Connector is initialized, and released when the Connector is closed.

If one Connector (A) has acquired an exclusive lock on a file, and another Connector (B) tries to open it, then Connector B will either wait for he lock to be released, or an error will be thrown. If Connector B has checked the exclusive Lock parameter, it will wait; if Connector B has not checked the exclusive Lock parameter, an error will be thrown.

The locking mechanism is Operating System dependent. Note that file locking can cause deadlocks, especially if more than one file is locked per AssemblyLine.

For more information, see http://java.sun.com/j2se/1.5.0/docs/api/java/nio/channels/FileChannel.html#lock()

Detailed Log

If this parameter is checked, more detailed log messages are generated.

Parser

In the Parser tab, we can configure the name of a Parser to access the contents of the file by selecting a Parser in the "Inherit from:" button.

See also

URL Connector.