COAS — GCPR Issue: Event Interface Enhancements

The EventSupplier interface in COAS has one simple call for a client to receive events: subscribe. This operation allows a client to specify a sequence of subscriptions which are structures that include data on who and what the client is interested in. According to the specification, calling this operation will replace any current subscriptions made by a previous invocation. Thus this operation is not additive. We recommend that an additional operation be added which would allow subscriptions to additive - not replacing the current subscriptions but adding new ones. Conversely the ability to remove specific subscriptions would be required as well. GCPR will want to keep a cache of patient data up to date. The event interfaces may be useful for this purpose. As new patients are added to cache, servers could be notified of the new subscriptions. Without additive subscriptions, the client would have to resend the same subscription information on current patients already in cache each time a new subscription was needed.