I'm not sure what you mean by "concurrency" here, but how about returning a 409 (Conflict) status code instead of 500?
http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.4.10 500 means "internal server error", i.e. something the client cannot do anything about. -- You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.
