>Anyone would know of something similar than then SyncLock of .NET in VFP?

Mutexes will work but can be a pain from FoxPro as they require Win32 structures. You can also use .NET to call and do the locking.

But - you might be able to use simpler solutions using files that can be locked. Dump a file to disk when you access a task and hold it open while the task you want to block is running. Another machine that tries to access that same task then can try to get a lock on the file and if it can't has to wait for it to become available. It's pretty trivial to implement this sort of semaphore locking. Likewise you can a similar locking strategy for FIFO queueing by letting one application getting a lock on a file while the second tries to find an available file to process the next transaction.

The latter is essentially how Web Connection's file mode works and it's proven super reliable over the last 20 years even under heavy load :-)

The nice thing about a fox solution is that you can control it to minute details. If something goes wrong with a mutex your app will lock up pretty much, Additionally using files works across multiple machines, while Mutexes are limited to inter machine operations.

+++ Rick ----