Replicated Entities Protocol Note that while this protocol provides support for replicated entities, the data types sent across the protocol are not replicated entities themselves. It is the responsibility of the Kalix proxy to implement the replicated entities, merge functions, vector clocks etc, not the user service. The user service need only hold the current value in memory, and this protocol sends deltas to the user service to update its in memory value as necessary. These deltas have no way of dealing with conflicts, hence it is important that the Kalix proxy always knows what the state of the user service's in memory value is before sending a delta. If the Kalix proxy is not sure what the value is, eg because it has just sent an operation to the user service which may have updated its value as a result, the proxy should wait until it gets the result of the operation back, to ensure its in memory value is in sync with the user service so that it can calculate deltas that won't conflict. The user service is expected to update its value both as the result of receiving deltas from the proxy, as well as when it sends deltas. It must not update its value in any other circumstance, updating the value in response to any other stimuli risks the value becoming out of sync with the Kalix proxy. The user service will not be sent back deltas as a result of its own changes. An invocation of handle is made for each entity being handled. It may be kept alive and used to handle multiple commands, and may subsequently be terminated if that entity becomes idle, or if the entity is deleted. Shutdown is typically done for efficiency reasons, unless the entity is explicitly deleted, and a terminated handle stream does not mean the proxy has stopped tracking the state of the entity in its memory. Special care must be taken when working with maps and sets. The keys/values are google.protobuf.Any, which encodes the value as binary protobuf, however, serialized protobufs are not stable, two semantically equal objects could encode to different bytes. It is the responsibility of the user service to ensure that stable encodings are used.