The protocol bridge

The protocol bridge enables your WebSphere® MQ File Transfer Edition (WMQFTE) network to access files stored on a file server outside your WMQFTE network. This file server can use the FTP, FTPS (if you have enabled the Version 7.0.4.1 function), or SFTP network protocols. Each file server needs at least one dedicated agent. The dedicated agent is known as the protocol bridge agent.

The protocol bridge is available as part of the Server component. You can have multiple dedicated agents on a single system running WebSphere MQ File Transfer Edition Server that connect to different file servers.

All agents involved in a transfer that includes a protocol file server must be at Version 7.0.1 or later. The protocol bridge agent must be at Version 7.0.2 or later. If the source agent is at Version 7.0.1 and the destination protocol bridge agent is at Version 7.0.2, the transfer log message generated by the source agent does not include the information that the destination agent is a protocol bridge agent.

If you enable the Version 7.0.4.1 function, you can use a protocol bridge agent to transfer files to multiple endpoints simultaneously. WMQFTE provides a file called ProtocolBridgeProperties.xml that you can edit to define the different protocol file servers that you want to transfer files to. The fteCreateBridgeAgent command adds the details of the default protocol file server to ProtocolBridgeProperties.xml for you. This file is described in Protocol bridge properties file format.

You can use the protocol bridge agent to perform the following actions:
  • Upload files from the WMQFTE network to an FTP, FTPS, or SFTP server
  • Download files from an FTP, FTPS, or SFTP server to the WMQFTE network
Note: The protocol bridge agent can support only FTP, FTPS, or SFTP servers that allow files to be accessed by their absolute file path. Those protocol servers that allow access to files based on the current directory are not supported by the protocol bridge agent.

The diagram shows two departments: Accounts, which uses FTP, and Payroll, which uses WebSphere MQ File Transfer Edition. An FTP server is on the boundary between these two departments. This FTP server communicates with two FTP clients in the Accounts department. The FTP server also communicates with a protocol bridge agent in the Payroll department, which in turn communicates with two WMQFTE agents.

The diagram shows a main FTP server that located between the Accounts department, which uses FTP, and the Payroll department, which uses WebSphere MQ File Transfer Edition. The FTP server is used to exchange files between the two departments. The protocol bridge agent is between the FTP server and the rest of the WMQFTE network and is configured to communicate with three different FTP servers.

Ensure that you have another agent in your WMQFTE network in addition to the protocol bridge agent. The protocol bridge agent is a bridge to the FTP, FTPS, or SFTP server only and does not write transferred files to the local disk. If you want to transfer files to or from the FTP, FTPS, or SFTP server you must use the protocol bridge agent as the destination or source for the file transfer (representing the FTP, FTPS, or SFTP server) and another standard agent as the corresponding source or destination.

When you transfer files using the protocol bridge, the bridge must have permission to read the source or destination directory containing the files you want to transfer. For example, if you want to transfer files from the directory /home/fte/bridge that has execute permissions (d--x--x--x) only, any transfers you attempt from this directory fail with the following error message:
BFGBR0032E: Attempt to read filename from the protocol file server has failed with server error 550
Failed to open file.

Configuring a protocol bridge agent

A protocol bridge agent is like a standard WMQFTE agent. Create a protocol bridge agent by using the fteCreateBridgeAgent command. If you have enabled the Version 7.0.4.1 function, you can configure a protocol bridge agent using the ProtocolBridgeProperties.xml file, which is described in Protocol bridge properties file format. If you are using an earlier version, configure the agent using the specific protocol bridge properties described in Advanced agent properties. For all versions, you can also configure a credential mapping as described in Mapping credentials for a file server. After you have configured a protocol bridge agent for a particular protocol file server, you can then use that agent for that purpose only.

Protocol bridge recovery

If the protocol bridge agent is unable to connect to the file server because the file server is unavailable, all file transfer requests are queued until the file server becomes available. If the protocol bridge agent is unable to connect to the file server because the agent is using the wrong credentials, the transfer fails and the transfer log message reflects this error. If the protocol bridge agent is ended for any reason, all requested file transfers are retained and continue when the protocol bridge is restarted.

During file transfer, files are typically written as temporary files at the destination and are then renamed when the transfer is complete. However, if the transfer destination is a protocol file server that is configured as limited write (users can upload files to the protocol file server but cannot change those uploaded files in any way; effectively users can write once only), transferred files are written to the destination directly. This means that if a problem occurs during the transfer, the partially written files remain on the destination protocol file server and WebSphere MQ File Transfer Edition cannot delete or edit these files. In this situation, the transfer fails.


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Timestamp icon Last updated: Tuesday, 30 January 2018
http://www.ibm.com/support/knowledgecenter/SSEP7X_7.0.4/com.ibm.wmqfte.doc/protocol_bridge.htm