Concurreny help - flagging a record "being used" in client server environment

[vanvee]

Hi

I am trying to program a VB.Net Windows application (in a client server
environment with multiple users) and am seeking some help about a
possible technique to handle concurreny issues. I am using ADO.Net,
typed datasets, and data binding through code. Is there any way that
when a user pulls out a record (and this user could only pull one
record at a time) into his local dataset, that a flag can be sent back
to the server for that record, which will then in turn give a message
to any other user that "this file is being modified by another user"
and then allow them to view the record but make it read-only? I'm
thinking this could prevent any "after the fact" concurrency issues.
At the same time though, I realize it is only the user who pulls the
record who's machine knows that the record is being modified. Could I
perhaps write to another table a key field that the other computers
check? ....or maybe insert (the flag), then do a select again (but
this seems like a lot of unnecessary processing)...any thought on how
one might pull off such a system?

Thanks so much for any help!

 

[Cor Ligthert]

VanVee,

Have a look at optimistic an pesimistic concurrency. Because ADONET is
disconnected is pesimistic concurrency as you describe here (classic name
recordlocking) not easy to do.

You can have a look at these pages about this.

http://msdn.microsoft.com/library/d...skPerformingOptimisticConcurrencyChecking.asp

I hope this helps?

Cor

 

[vanvee]

Thank you Cor! You have been so helpful! How much do I owe you?

 

[Cor Ligthert]

Thank you Cor! You have been so helpful! How much do I owe you?

Nothing more than these words.

HTH

Cor