{"id":2784,"date":"2020-05-18T08:38:00","date_gmt":"2020-05-18T06:38:00","guid":{"rendered":"https:\/\/www.basyskom.de\/?p=2784"},"modified":"2020-05-29T11:01:50","modified_gmt":"2020-05-29T09:01:50","slug":"protobuf-for-iot","status":"publish","type":"post","link":"https:\/\/www.basyskom.de\/en\/protobuf-for-iot\/","title":{"rendered":"Protobuf for IoT: Sending cost-optimized into the cloud (Part 2 of 4)"},"content":{"rendered":"\t\t
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Introduction<\/h2>

IoT devices for industrial use are often deployed in places without an ethernet or WiFi connection and have to use a mobile broadband connection. To reduce traffic costs, it is required to keep the amount of data that has to be transmitted as low as possible.<\/p>

Cloud providers also calculate in data blocks of a certain size for billing, so a small message size combined with batching can save money for the cloud side too.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Protobuf<\/h2>\n\"Protobuf\"Protobuf<\/a>\u00a0is a serialization method for structured data developed by Google which offers a compact binary wire format and built-in mechanisms which make it easy to remain forward and backward compatible when updating the messages.\n\nIt uses an interface description language to specify the structured data and the Protobuf compiler to generate code for serialization, deserialization and message handling for C++, Java, Python, Objective-C, C#, JavaScript, Ruby, Go, PHP and Dart.\n\nThe compact wire format and the compatibility related features make Protobuf very interesting for the usage in IoT systems. The wide range of supported languages enables the creation of a heterogeneous processing infrastructure for Protobuf encoded device messages.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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Using Protobuf in an IoT example<\/h2>

To show the workflow with Protobuf, let\u2018s define the Protobuf messages for an environment data sensor device in the current proto3 format. The device measures temperature, pressure, humidity and CO2<\/sub> level and generates events if certain threshold values are exceeded or if a sensor fails.<\/p>

An important key to understanding why the messages have been designed like this is that there is no way to recognize the message type from the serialized data.\u00a0 We don’t want to send an identifier in addition to the serialized data, so there must be a single point of entry for all message types we are going to send.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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syntax = "proto3";\n\npackage iotexample;\n\nmessage EnvironmentData {\n  double temperature = 1;\n  double pressure = 2;\n  double humidity = 3;\n  double co2_level = 4;\n}\n\nenum ErrorLevel {\n  UNSPECIFIED = 0;\n  ERROR = 1;\n  WARNING = 2;\n  INFO = 3;\n}\n\nmessage Event {\n  int32 event_number = 1;\n  ErrorLevel error_level = 2;\n  string message = 3;\n}\n\nmessage TelemetryMessage {\n  uint64 timestamp = 1;\n  oneof payload {\n    EnvironmentData environment_data = 2;\n    Event event = 3;\n  }\n}\n\nmessage DeviceMessages {\n  repeated TelemetryMessage telemetry_messages = 1;\n} <\/code><\/pre>