Delphi - Folder Synchronization over network

I have an application that connects to a database and can be used in multi-user mode, whereby multiple computers can connect the the same database server to view and modify data. One of the clients is always designated to be the 'Master' client. This master also receives text information from either RS232 or UDP input and logs this data every second to a text file on the local machine.

My issue is that the other clients need to acces开发者_运维百科s this data from the Master client. I am just wondering the best and most efficient way to proceed to solve this problem. I am considering two options:

1. Write a folder synchronize class to synchronize the folder on the remote (Master) computer with the folder on the local (client) computer. This would be a threaded, buffered file copying routine.
2. Implement a client/server so that the Master computer can serve this data to any client that connects and requests the data. The master would send the file over TCP/UDP to the requesting client.

The solution will have to take the following into account:

a. The log files are being written to every second. It must avoid any potential file locking issues.

b. The copying routine should only copy files that have been modified at a later date than the ones already on the client machine.

c. Be as efficient as possible

d. All machines are on a LAN

e. The synchronization need only be performed, say, every 10 minutes or so.

f. The amount of data is only in the order of ~50MB, but once the initial (first) sync is complete, then the amount of data to transfer would only be in the order of ~1MB. This will increase in the future

Which would be the better method to use? What are the pros/cons? I have also seen the Fast File Copy post which i am considering using.

If you use a database, why the "master" writes data to a text file instead of to the database, if those data needs to be shared?

Why invent the wheel? Use rsync instead. Package for windows: cwrsync.

For example, on the Master machine install rsync server, and on the client machines install rsync clients or simply drop files in your project directory. Whenever needed your application on a client machine shall execute rsync.exe requesting to synchronize necessary files from the server.

In order to copy open files you will need to setup Windows Volume Shadow Copy service. Here's a very detailed description on how the Master machine can be setup to allow copying of open files using Windows Volume Shadow Copy.

Write a web service interface, so that the clients an connect to the server and pull new data as needed. Or, you could write it as a subscribe/push mechanism so that clients connect to the server, "subscribe", and then the server pushes all new content to the registered clients. Clients would need to fully sync (get all changes since last sync) when registering, in case they were offline when updates occurred.

Both solutions would work just fine on the LAN, the choice is yours. You might want to also consider those issues related to the technology you choose:

• Deployment flexibility. Using file shares and file copy requires file sharing to work, and all LAN users might gain access to the log files.
• Longer term plans: File shares are only good on the local network, while IP based solutions work over routed networks, including Internet.
• The file-based solution would be significantly easier to implement compared to the IP solution.