Network Survey Messaging

Readme Contents

• What is it?
• Why?
• Some Details
• Why are there protobuf files?
• Build and development instructions
• Generating Go Code
• Change log
• Contact

What is it?

The Network Survey Messaging API defines a set of messages that can be used for sending wireless network survey messages between two applications.

The latest version of the API is published here.

Why?

The original purpose for this API was to facilitate sending LTE survey messages from the Network Survey Android App to a remote server via gRPC. However, it has been expanded not only to support additional protocols such as GSM, CDMA, UMTS and 802.11, but has also been expanded to allow for its use outside the original Android application by any system wanting to share wireless protocol data, or send wireless signal events.

Some Details

The messages in this API are defined using AsyncAPI. All the messages are in JSON format. In addition to the messages this API defines, it also defines the topics the messages can be sent on. For the most part, the topic is close to the message name, but the idea is that these messages can be sent over transports such as MQTT or Kafka. If they are, then the topic name in MQTT, Kafka, or any other system should follow the "channel" defined in this API. For example, the Network Survey Android App has a feature that sends out the GSM, CDMA, UMTS, LTE, 802.11, and Bluetooth JSON messages defined in this API. In doing so, it publishes them to the MQTT topic that follows the channel name in this API. Therefore, anyone wanting to consume survey records from that app simply needs to subscribe the the pre-defined topic/channel name and consume the JSON messages.

Why are there protobuf files?

Protobuf was originally used at the IDL, and gRPC was used as the RPC framework / transport. However, to allow the survey messages to flow over tools such as Kafka and be consumed more easily without requiring a protobuf library to deserialize the binary messages, the actual messages were sent in JSON instead. That being said, it is really easy to construct a protobuf object and use the Protobuf JsonFormat.Printer to convert a protobuf object to JSON. Therefore, proto definitions matching the JSON messages are provided as a convenient way to generate the JSON message strings.

In other words, the protobuf files and gRPC SDKs are provided as convenience libraries only and are not an official part of the Network Survey Messaging API. The API is instead only the JSON message schema and channel/topic names for the messages.

As a result, if a gRPC setup is of interest to a user of these messages, then the generated library can be employed to send the protobuf messages over gRPC. The build produces a Java library with all the messages for use by the client and server software respectively.

More information about protobuf is available here. More information about gRPC is available here.

Of note, the protobuf definitions were changed between version 0.1.3 and 0.2.0. The old definitions have been left for backwards compatibility, but the new ones in the com.craxiom.messaging package should be leveraged instead.

Sample usage

The gRPC website has tutorials for utilizing gRPC + protobuf for Android and Java.

Getting Started

Add Network Survey Messaging to your project

The Network Survey Messaging protobuf library is available via mavenCentral

dependencies {
    implementation 'com.craxiom:network-survey-messaging:1.6.0'
}

Build and development instructions

Prerequisites

To build the AsyncAPI files you need to have npm installed. For macOS, it can be installed via brew

• brew install node

Then install the html template generator

• npm install -g @asyncapi/generator
• npm install -g @asyncapi/html-template

Additional AsyncAPI generators can be found here: https://github.com/asyncapi/generator#list-of-official-generator-templates

There is also an option to use a docker container for running the AsyncAPI commands instead of running locally. More information can be found here.

An example command: docker run --rm -it -v ${PWD}/src/main/asyncapi/network_survey_messaging.yaml:/app/network_survey_messaging.yaml -v ${PWD}/builddocs:/app/output asyncapi/generator:1.17.25 /app/network_survey_messaging.yaml @asyncapi/[email protected] -o /app/output --force-write

Building the HTML content from the AsyncAPI file

• Execute ag src/main/asyncapi/network_survey_messaging.yaml @asyncapi/html-template -o build/network-survey-messaging-html
• The HTML content will be located in the directory specified after the -o option.

To publish a new version of the Network Survey Messaging API HTML page, use the following command

• ag src/main/asyncapi/network_survey_messaging.yaml @asyncapi/html-template -o docs

This will overwrite the current HTML content from the docs directory with the last API definition from the yaml file.

Building the protobuf Java library

The Java library is built and published with Java 8 to support older Android versions, however it can be built with Java 11 if needed.

• Execute gradlew build in the root directory to produce the Java library with the protobuf messages.
• Execute gradlew publishToMavenLocal in the root directory to publish the artifacts to the local Maven cache.

Generated code is here:

• Java: build/generated/source/proto/main/java/com/craxiom/messaging
• Python: build/generated/source/proto/main/python/com/craxiom/messaging

Generating Go code

The Go code is generated using the protoc compiler.

The Go code is generated using the following command: - protoc --go_out=go/ --go_opt=paths=source_relative --go-grpc_out=go/ --go-grpc_opt=paths=source_relative src/main/proto/*.proto

More specifically, I used the following commands:

cd src/main
mkdir output
rm -r proto/craxiom
find ./proto -name "*.proto" | xargs protoc -I=./proto --go_out=./output --go-grpc_out=./output

Example gRPC Server written in Go

If you want to see how to use the generated Go code to create a gRPC server, check out the code at https://github.com/christianrowlands/ns-messaging-go-grpc-server

The server does not do anything useful, but serves as an example of how one might be created in GoLang.

Change log

See the change log for details about each release: CHANGELOG.md

Contact

Christian Rowlands [email protected]