The file message system

SQL Remote can be used even if you do not have a message system in place, by using the file message system.

Addresses in the file message system

The file message system is a simple file-sharing system. A file address for a remote user is a subdirectory into which all their messages are written. To retrieve messages from their "inbox", an application reads the messages from the directory containing the user's files. Return messages are sent to the address (written to the directory) of the consolidated database.

When running as a Windows service make sure that the account under which the Message Agent is running has permissions to read and write all necessary directories. This is often a problem when accessing network drives.

Root directory for addresses

The file system addresses are typically subdirectories of a shared directory that is available to all SQL Remote users, whether by modem or on a local area network. Each user should have a registry entry, initialization file entry, or SQLREMOTE environment variable pointing to the shared directory.

You can also use the file system to put the messages in directories on the consolidated and remote machines. A simple file transfer mechanism can then be used to exchange the files periodically to effect replication.

FILE message control parameters

The FILE message system uses the following control parameters:

  • Directory   This is set to the directory under which the messages are stored. The setting is an alternative to the SQLREMOTE environment variable.

  • Debug   This is set to either YES or NO, with the default being NO. When set to YES, all file system calls made by the FILE link are displayed.

  • Encode_dll   If you have implemented a custom encoding scheme, you must set this to the full path of the custom encoding DLL that you created. See Encoding and compressing messages.

  • invalid_extensions   A comma-separated list of file extensions that you do not want dbremote to use when generating files in the messaging system.

  • Unlink_delay   This is the number of seconds to wait before attempting to delete a file if the previous attempt to delete the file failed. If no value is defined for unlink_delay, then the default behavior is to pause for 1 second after the first failed attempt, 2 seconds after the second failed attempt, 3 seconds after the third failed attempt, and 4 seconds after the fourth failed attempt.

Windows Mobile and ActiveSync

For the file link, dbremote looks in \My Documents\Synchronized Files. On the desktop computer, the SQLREMOTE environment variable or directory message link parameter for the FILE link should be set to the following:

%SystemRoot%\Profiles\userid\Personal\Windows-mobile-device-name\Synchronized Files

where userid and Windows-mobile-device-name are set to the appropriate values. With this setup, ActiveSync automatically synchronizes the message files between the desktop and Windows Mobile system.

Check Mobile Devices » Tools » ActiveSync Options to ensure that file synchronization is activated.

For information on setting message link parameters, see The file message system.

See also