title: Pessimistic offline locking using Entity framework
body: <p>First I'd like to describe the mechanism of a locking solution I'd like to implement. Basically an item can be opened in read or write mode. However if an user opens the item in write mode, no other user should be able to open it in edit mode. The item means a case in a customer service application.</p>
  
  <p>In order to to this I came up with the following: The table will contain a flag which indicates if an item is checked out for edit, and an 'end time', while this flag is valid. The default value for it is 3 minutes, if no user interaction happens during this time, the flag can be ignored next time when an user tries to open the same item.</p>
  
  <p>On the UI side, I use jQuery to monitor if an user is active. If he or she is, a periodic AJAX call extends his or her time frame so he or she can continue working on the item. When the user saves the item, the flag will be removed. The end time is necessary to handle situations when the browser crashes or when the user goes to drink a coffee and leaves the item open for an hour.</p>
  
  <p>So, the question. :) If an user opens the item in edit mode first I have to read the flag &amp; time values for the time item, and if I find these valid (flag is not set, or set but not valid because of the time) and I have to update them with new values. 
  What kind of transaction level should I use for this in EF, if any? Or should I write stored procedures to handle the select &amp; update in a transaction? If so, what kind of locking method should I use?</p>