Synchronizing over the Internet or an Intranet

When a replica has been placed on an Internet or intranet server and the Synchronizer has been configured correctly, users can synchronize by using a standard HTTP connection. Note, however, that you cannot schedule synchronization over the Internet or an intranet with Replication Manager, because Replication Manager cannot control the communication link to your Internet service provider. As an alternative, you can write DAO code to link to your Internet service provider, execute a synchronization, and then drop the communications link.

You need three things to use synchronization over the Internet or an intranet: a client computer with a replica, an Internet or intranet server that is also configured as a Microsoft Jet replication Synchronizer, and a second replica on the same computer as the Internet server.

The client computer starts synchronization by doing the following:

• Identifying the changes to be sent to the replica on the Internet or intranet server and bundling them in a message.
  
  
• Connecting to the Internet or intranet server and getting the address of the server’s FTP folder.
  
  
• Sending the bundled changes to the FTP address.

Once the changes are stored on the server, the server continues the synchronization by notifying the Synchronizer that there is data in the FTP folder. The Synchronizer then takes the following actions:

• Picks up the data in the FTP folder and applies it to the replica on the Internet or intranet server.
  
  
• Queries the replica on the Internet or intranet server to see if there is any data to send back to the replica on the client computer.

If there are no changes to send to the replica on the client computer, the synchronization is complete. If there are changes to send back to the replica on the client computer, the following process occurs:

• The Synchronizer places the data in the FTP folder and notifies the Internet or intranet server that there is data for the client computer.
  
  
• The server sends a message to the client computer that there is data to collect.
  
  
• The client computer collects the data and applies it to the client replica.

Internet or intranet synchronization works only between replicas on different machines. If you attempt to synchronize two replicas — one managed with an Internet Synchronizer and one unmanaged — on the same machine, you will get a message saying that the exchange was unsuccessful because the Internet is slow or because there is a problem with the Internet or intranet server. However, if you have the same two replicas on two different computers, the Internet or intranet exchange succeeds.