I have Orion working seamlessly, saving entities and retrieving them.
But I'd like to know which is the recommended way to insert (and/or retrieving) a sequence of values for an entity, not updating its value, but adding a new value to the entity, so later I can retrieve all values stored for an specific entity ID and "draw" the evolution in a graph.
Updated: I've seen that it may be posible to do it subscribing to a Cosmos instance. Is this the recommended way?
Thanks!
The recommended way for creating historics in FIWARE is through the Cygnus tool. It is a connector that, taking advantage of the subscription-notification mechanism, subscribes to an Orion instance in order to be notifed each time certain entities' attributes change.
Cygnus has been designed for persisting the data in several storages: HDFS (Cosmos file system is a HDFS), MySQL, CKAN, MongoDB, Kafka, STH/Comet... (and more to come). For each one of them, a particular configurable module (sink, if using the Flume technology jargon) has been created. Just choose the most convenient storage for your application logic.