VFS Transport

VFS (Virtual File System) transport implementation is a module which belongs to the Apache Synapse project. The following classes implement the listener and sender APIs.

org.apache.synapse.transport.vfs.VFSTransportListener
org.apache.synapse.transport.vfs.VFSTransportSender

The necessary classes can be found in the synapse-vfs-transport.jar file. Unlike the transports described previously, VFS transport does not have any global parameters to be configured. Rather, it has a set of service level parameters that needs to be specified for each service. VFS transport implementation is mainly used and mostly effective in the WSO2 ESB.

Starting from Carbon version 4.0.0, VFS transport supports the FTPS protocol. Configuration is identical to other protocols with the only difference being the URL prefixes.

The VFS transport implementation is based on Apache Commons VFS implementation. Therefore commons-vfs.jar file should be included in the Carbon classpath to enable the VFS transport.

Since VFS transport deals with file operations, there are instances that these can fail due to unavailability of some resource. In such an instance, the VFS transport is equipped with the following fault-handling mechanism.

When a failure occurs in a file object, that will be marked as a fail record and will be moved to location (configured by the user) where move error file objects are kept. The failed record will be maintained inside a text file (file name is configurable) and the location of that file will be provided by the user. When the next polling iteration is going on, it will check the file against the failed record and if the file is a failed record, it will skip processing and schedule a move task to move that file (the retry duration of the file move task can be configured). It's handled this way because it is a random failure in the move operation.

VFS Service Level Parameters

Tip

In transport parameter tables, literals displayed in italic mode under the "Possible Values" column should be considered as fixed literal constant values. Those values can be directly put in transport configurations.

Parameter Name	Description	Required	Possible Values	Default Value
transport.vfs. FileURI	The file URL from where the input files should be fetched.	Yes	A valid file URL of the form file:// file://<path>
transport.vfs. ContentType	Content type of the files transferred over the transport.	Yes	A valid content type for the files (eg: text/xml)
transport.vfs. FileName Pattern	If the VFS listener should read only a subset of all the files available in the specified file URI location, this parameter can be used to select those files by name using a regular expression.	No	A regular expression to select files by name (eg:.*\.xml)
transport. PollInterval	The polling interval in milliseconds for the transport receiver to poll the file URI location.	No	A positive integer
transport.vfs. ActionAfter Process	Action to perform over the files after processed by the transport.	No	MOVE, DELETE	DELETE
transport.vfs. ActionAfter Failure	Action to perform over the files after processed by the transport.	No	MOVE, DELETE	DELETE
transport.vfs. MoveAfter Process	The location to move the files after processing.	Required if ActionAfterProcess is MOVE	A valid file URI
transport.vfs. MoveAfter Failure	The location to move the files after a failure occurs.	Required if ActionAfterFailure is MOVE	A valid file URI
transport.vfs. ReplyFileURI	The location to which reply files should be written by the transport.	No	A valid file URI
transport.vfs. ReplyFile Name	The name for reply files written by the transport.	No	A valid file name	response.xml
transport.vfs. Move Timestamp Format	The pattern/format of the timestamps added to file names as prefixes when moving files (See the API documentation of `java.text.` `SimpleDateFormat` for details).	No	A valid timestamp pattern (eg: yyyy-MM- dd'T'HH:mm :ss.SSSZ)
transport.vfs. Streaming	If files should be transferred in streaming mode or not.	No	true, false	false
transport.vfs. Reconnect Timeout	Reconnect timeout value in seconds to be used in case of an error when transferring files.	No	A positive integer	30 sec
transport.vfs. MaxRetry Count	Maximum number of retry attempts to carry out in case of errors.	No	A positive integer	3
transport.vfs. Append	When writing the response to a file, if the response should be appended to the response file this parameter should be set to true. By default the response file will be completely overwritten.	No	true, false	false
transport.vfs. MoveAfter FailedMove	New destination to move the failed file.	No	A valid file URI
transport.vfs. Failed Records FileName	The file name to maintain the list of failure files.	No	A valid file name	vfs-move- failed- records. properties
transport.vfs. Failed Records File Destination	The destination of the failed file.	No	A folder URI	repository /conf/
transport.vfs. Move Failed Record Timestamp Format	When adding a record to the failed file, entries are logged as: `file_name` `time_stamp`. This will configure the time stamp format.	No	A valid timestamp pattern (eg: yyyy- MM-dd'T'HH:mm: ss.SSSZ)	dd-MM- yyyy HH:mm :ss
transport.vfs. Failed Record Next Retry Duration	The time in milli second for the move task to wait until next retry.	No	A positive integer	3000 milli seconds

You can find a VFS transport implementation in this tutorial: http://wso2.org/library/tutorials/2011/01/sftp-file-transer-wso2-esb