One solution is to use optimistic locking to detect if a user tries to edit data that has already been edited by a different user. What you do once you have detected that situation depends on your app and your requirements. You have to define your conflict solving strategy.
With optimistic locking nearly each table will have a column "version" and you increment the version whenever you edit a row. User A now has a specific version of the DB data and if User A tries to save changes then the database must still contain the same version for that row. If it does not then User B has already changed the row and User A has outdated data. Alternatively you could provide a totally different workflow that circumvent such a situation. For example all your data could be read-only by default in your UI and you have to click an "Edit" button. Once User A clicks on "edit" the data will be locked and no one else can also "edit" that data until User A has saved that data again. But as said the strategy you choose greatly depends on your app and requirements. -- J. -- You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/google-web-toolkit. For more options, visit https://groups.google.com/d/optout.
