This week's book giveaways are in the iOS and Features new in Java 8 forums. We're giving away four copies each of Barcodes with iOS: Bringing together the digital and physical worlds and Core Java for the Impatient and have the authors on-line! See this thread and this one for details.
Data concurrency is a complex subject and usually it is achieved through specific database technologies and transaction isolation levels. However there are other vendor specific strategies. WebLogic for example has four concurrency strategies:
The default is the database concurrency strategy, which will delegate the responsibility of data locking to the underlying database system. The optimistic strategy enforces concurrency using the classic client/server approach of ensuring that the data have not been changed by other clients during the transaction. This of course works only with CMP and for each update the container will issue a query like this: