Concurrency in RIA

Question

This'll be my first question on this platform. I've done lots of development using Flex, WebORB and ASP.NET. We have solved Concurrency problems with messaging (Pessimistic Concurrency Control). This works pretty good but it also makes the whole application dependent of the messaging. No messaging, no concurrency control. I know that ASP.NET has version control in DataSets, but how would you go and use that if you are working on a RIA. It seems hard to go and store each dataset in the session of the client... So, if the Client would like need all products, I would need to store the dataset in the session of the client. When the client would change something to a product and save the product, I could then update the dataset (stored in the session) and try to save it... Seems a lot of work and a lot of memory that will be used (because those products will be kept in the memory of the client, so the dataset needs to be kept on the server side session). I think the most easy way would be to provide all DTO's with a version number. If the client would try to save a DTO, I could compare the version number with the one in the database.

Lieven Cardoen

Answer 1

This is something I've done before - as the original data was coming from an SQL Server database we just used a rowversion typed column in each DTO to determine if it had changed while the user was working on it.

At this point you can either barf on the error or try and figure out a way to merge the changes, but at least you can tell that it's changed underneath you :)