[OpenSER-Users] presence caching and retrieval

Hi, I was wondering, when a SIP user publishes his presence to the openser presence module, is this presence data cached in memory by the server or is this immediately stored in the database? Is this somehow configurable? If the presence data is cached in memory, is there an interface available for an external server to query the presence of one or more resources? In particular, we are looking for a performant way to query the presence of multiple users (for example 20). We would like to avoid the overhead of creating a SIP subscription for each resource: - to avoid traffic overhead - we only need to know the current presence of the resource(s) and are not interested in future presence changes. Do you have any suggestions on if/how this can be achieved with openser? kind regards, Sigrid Thijs