What is Suripu

Suripu is composed of three parts:

1. The service which listens for incoming data over HTTP / Protobuf and stores it.
2. The Oauth2 API which provides a way to access the data
3. The factory which exposes an HTTP endpoint to store public key generated at the factory level.

Protobuf

We have chosen Protobuf as a serialization protocol for exchanging information over the wire. The main benefits are small footprint, extensibility and built-in documentation.

message SimpleSensorBatch {
    message GpsInfo {
        optional float latitude = 1;
        optional float longitude = 2;
        optional float accuracy = 3;
        optional float speed = 4;
        optional string provider = 5;
    }

    message SimpleSensorSample {
        optional int64 timestamp = 1;
        optional float ambient_temperature = 2; // deprecated
        optional float ambient_humidity = 3; // deprecated
        optional float ambient_light = 4; // deprecated
        optional float ambient_decibels = 5;
        optional float ambient_air_quality = 6; // deprecated
        optional bytes device_data = 7;   //
        optional bytes device_data_signature = 8;
        optional float sound_amplitude = 9;

        optional GpsInfo gps = 10;
        optional int32 offset_millis = 11;
    }

    optional string device_id = 1;
    repeated SimpleSensorSample samples = 2;

}

A SimpleSensorBatch message contains a list of SimpleSensorSample collected from device, phone and/or both. The GPS information, is for instance, only available on the phone, whereas the air quality is only collected on the device.

SimpleSensorSample contains a free form byte payload optional bytes device_data = 7; for which, there is no spec yet. The current implementation is as follows:

final LittleEndianDataInputStream dataInputStream = new LittleEndianDataInputStream(inputStream);

int temp, light, humidity, airQuality;
long timestamp;

timestamp = dataInputStream.readLong();
temp = dataInputStream.readInt();
light = dataInputStream.readInt();
humidity = dataInputStream.readInt();
airQuality = dataInputStream.readInt();

HTTP Framework

Dropwizard/Jersey is used for the HTTP framework on top of which suripu is built, for both receiving data – the service – and processing API requests.