initial virtual sensor with protobuf

sensor.proto

@@ -0,0 +1,44 @@
+syntax = "proto3";
+
+message Energy {
+    uint32 mAh = 1;
+}
+message TimePoint {
+    uint64 millis_since_epoch = 1;
+}
+message Duration {
+    uint32 millis = 1;
+}
+message Temperature {
+    double celsius = 1;
+}
+
+message StatusRequest {}
+message SensorStatus {
+    string name = 1;
+    TimePoint online_since = 2;
+    Energy battery_charge = 3;
+    Energy battery_capacity = 4;
+    Duration max_sampling_period = 5;
+    Duration cur_sampling_period = 6;
+    uint32 max_chunk_size = 7;
+    uint32 cur_chunk_size = 8;
+    uint32 n_chunk_capacity = 9;
+    uint32 n_full_data_chunks = 10;
+    uint32 n_empty_data_chunks = 11;
+}
+
+message DataChunkRequest {}
+message DataChunk {
+    TimePoint begin = 1;
+    Duration period = 2;
+    repeated Temperature data = 3;
+}
+
+message SetSamplingPeriodResult {}
+
+service Sensor {
+    rpc get_status (StatusRequest) returns (SensorStatus) {}
+    rpc set_sampling_period (Duration) returns (SetSamplingPeriodResult) {}
+    rpc pop_data_chunk (DataChunkRequest) returns (DataChunk) {}
+}