transitdata-apc-protobuf-json-transformer

Transform APC messages from Protobuf back to JSON.

For internal use at HSL, we need to redeliver the expanded and combined APC messages back to the MQTT broker. First the messages need to be transformed from Protobuf back to original APC JSON.

This project depends indirectly on transitdata-common project for its Protobuf proto definition files though the files have been slightly modified.

Development

1. Install the build dependencies for the Apache Pulsar C++ client.

2. Create a suitable .env file for configuration. Check below for the configuration reference.

3. Install dependencies:

   npm install

4. Run linters and tests and build:

   npm run check-and-build

5. Load the environment variables:

   set -a
   source .env
   set +a

6. Run the application:

   npm start

Docker

You can use the Docker image hsldevcom/transitdata-apc-protobuf-json-transformer:edge. Check out the available tags.

Configuration

Environment variable	Required?	Default value	Description
HEALTH_CHECK_PORT	❌ No	8080	Which port to use to respond to health checks.
PINO_LOG_LEVEL	❌ No	info	The level of logging to use. One of "fatal", "error", "warn", "info", "debug", "trace" or "silent".
PULSAR_BLOCK_IF_QUEUE_FULL	❌ No	true	Whether the send operations of the producer should block when the outgoing message queue is full. If false, send operations will immediately fail when the queue is full.
PULSAR_COMPRESSION_TYPE	❌ No	LZ4	The compression type to use in the topic PULSAR_PRODUCER_TOPIC. Must be one of Zlib, LZ4, ZSTD or SNAPPY.
PULSAR_CONSUMER_TOPIC	✅ Yes		The topic to consume APC Protobuf messages from.
PULSAR_SUBSCRIPTION	✅ Yes		The name of the subscription for reading messages from PULSAR_CONSUMER_TOPIC.
PULSAR_PRODUCER_TOPIC	✅ Yes		The topic to send APC JSON messages to.
PULSAR_SERVICE_URL	✅ Yes		The service URL.