The present invention provides a method, apparatus and computer program product which enables a target service to provide operations which behave, on a per operation basis, in a way appropriate to the type of client that requested the operation to be performed. As a result the target service can provide operations which behave differently for different clients. Further the client can obtain details of the behavior characteristics of the operations, according to its type, at runtime and act appropriately in the event of the request being timed out or resulting in a communication failure. For example, the client middleware can take action to re-issue a timed out request if the behavior characteristic for that operation indicates that multiple invocations of the operation will yield the same result.