Called by Lightstreamer Kernel through the Remote Server to end a previous request of data for an Item. After the call has returned, no more ItemEvents for the item should be sent to the listener until requested by a new subscription for the same item. 

The method can be blocking, but, as the Proxy Adapter implements subscribe and unsubscribe asynchronously, subsequent subscribe-unsubscribe-subscribe-unsubscribe requests can still be issued by Lightstreamer Server to the Proxy Adapter. When this happens, the requests may be queued on the Remote Adapter, hence some Subscribe calls may be delayed. 

void Unsubscribe(string itemName);

void Unsubscribe(string itemName);

Function Unsubscribe(itemName As string) As void