In a network environment, an MFS should expect to receive calls that involve record and file locks. As with other aspects of the system, however, an MFS programmer must understand the underlying technology of locking in order to take full advantage of this group of calls.
Lock Semaphores
In order to remain compatible with the variety of networks supported in OpenInsight, the system uses a standard protocol for the establishment of locks. This is based on lock semaphores.
When an BASIC+ LOCK statement is executed, the system uses the file handle and record key information (if locking a record) to create a lock semaphore. In order to accommodate all potential network locking schemes, the semaphore is simplified by hashing the file and record information into a reduced eight-byte format.
