Conformance Units for Subscription Services and Monitored Item Services have been constructed to allow Server to scale depths of queues and number of items. This allows Server to configure these features to match functional requirements of server while limiting memory usage. What cannot be limited under current specification is the size of the item being monitored. The Client could select a large item to monitor, such as : String, Array or Structure. Providing memory on Entry-Level Devices to support monitoring and queueing based on largest item in Address Space is prohibitive. Additionally, flexibility to allow monitoring and queueing of a large number of small items vs a small number of large items is probably appropriate for many application domains.
I proposed these changes to profiles/conformance units:
• For “Monitor Items 2” Conformance Unit, replace existing text with, “Support at least 2 MonitoredItems per Subscription where the size of the MonitoredItem is less than or equal to size of Double”.
• For “Monitor Item 10” Conformance Unit, replace existing text with, “Support at least 10 MonitoredItems per Subscription where the size of the MonitoredItem is less than or equal to size of Double”.