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Who's responsible for locking and concurrency?

 
Ronnie Phelps
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Should all locking responsibilities be controlled by the Data Base Server and all Concurrent access be controled by the NetworkProtocol?
 
Michael Morris
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Hi Ronnie,

Should all locking responsibilities be controlled by the Data Base Server and all Concurrent access be controled by the NetworkProtocol?

I'm not real sure what your getting at here. First of all are you using RMI or sockets? In my implementation, concurrent access (in regards to modification) of the Data object was ultimately controlled by the remote connection object. When the client called dataAccess.modify(), the remote connection object first called lockManager.isRecordLocked(this, record) before calling data.modify(). If isRecordLocked() returned false then the remote object threw a DatabaseException. So really I suppose the LockManager and the remote object worked in concert to protect Data from concurrent modification.
Hope this helps,
Michael Morris
 
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