The client context identifier is typically a globally unique character string. For performance, the maximum length of the string should be less than 36 characters. The client context identifier can also be a blank ("") value or the unknown value (?).
The following code fragment shows a recommended ABL assignment statement for generating a unique value for the client context identifier:
This is only one of the methods you can use to generate a client context identifier, but it does generate a globally unique value.
The default method of generating the client context identifier is to allow the AppServer clients (ABL, Java, and .NET) to automatically generate the value and send it to the AppServer. Optionally, the AppServer client or the AppServer agent can create their own client context identifier for advanced application logic.
For example, the client context identifier in an ABL session needs to be reset in order to indicate the end of the client user login session. This is typically done when the server invalidates the current client login session by invoking the
LOGOUT( ) method on the client-principal object that maintains the session, and by removing the client login context from the context store. The server then typically sets the
ClientContextId property on the appropriate
Progress.Lang.OERequestInfo class instance (available through the
CURRENT-RESPONSE-INFO attribute on the
SESSION handle) to the unknown value (
?). This tells the client that its current login session has been terminated, and any subsequent (presumably invalid) requests from the client to the same AppServer connection will contain a client context identifier with the unknown value (
?). For more information on client-principal objects and using the
ClientContextId property to manage context for user login sessions, see
Implementing multi-tier security models in this manual and the sections on authenticating the user identity for multi-tier applications in
OpenEdge Development: Programming Interfaces.
