Logical Serialization (Magic xpa 4.x)

Quite often there are processes which are important enough to the integrity of the system, that only one user should be allowed to access it at any given time. Any other user who tries to access this process will have to wait their turn. Let us take our happy couple as an example. They were discussing the fact that perhaps they needed a line of credit for their Checking account. So while Wilma was at the bank, she went to see the bank manager and discussed this with him. The bank manager agreed to provide $1000 in credit and began to update the system. At the same time, Fred is at another branch (or even at the same branch) and is discussing matters with the Credit Manager who agrees to provide only $750. If both of these transactions were allowed to go through, the actual line of credit would be $1750. In order to overcome this problem, you can use the Magic xpa internal function Lock for this program. By using this function in the Task Prefix of the Credit Line program (and UnLock in the Task Suffix), then once the Bank Manager loads the program, the Credit Manager would not be able to load it until the Bank Manager finishes.