WebSocket adapter

WebSocket adapter provides an WebSocket API for sending and receiving messages through the platform.

Configuration

The service is configured using the environment variables presented in the following table. Note that any unset variables will be replaced with their default values.

Variable	Description	Default
MF_WS_ADAPTER_PORT	Service WS port	8190
MF_BROKER_URL	Message broker instance URL	nats://localhost:4222
MF_WS_ADAPTER_LOG_LEVEL	Log level for the WS Adapter	error
MF_WS_ADAPTER_CLIENT_TLS	Flag that indicates if TLS should be turned on	false
MF_WS_ADAPTER_CA_CERTS	Path to trusted CAs in PEM format
MF_JAEGER_URL	Jaeger server URL for distributed tracing. Leave empty to disable tracing.
MF_THINGS_AUTH_GRPC_URL	Things service Auth gRPC URL	localhost:8183
MF_THINGS_AUTH_GRPC_TIMEOUT	Things service Auth gRPC request timeout in seconds	1s

Deployment

The service is distributed as Docker container. Check the ws-adapter service section in docker-compose to see how the service is deployed.

Running this service outside of container requires working instance of the message broker service. To start the service outside of the container, execute the following shell script:

# Download the latest version of the service
git clone https://github.com/MainfluxLabs/mainflux

cd mainflux

# compile the ws
make ws

# Copy binary to bin
make install

# set the environment variables and run the service
MF_Broker_URL=[Message broker instance URL] \
MF_WS_ADAPTER_PORT=[Service WS port] \
MF_WS_ADAPTER_LOG_LEVEL=[WS adapter log level] \
MF_WS_ADAPTER_CLIENT_TLS=[Flag that indicates if TLS should be turned on] \
MF_WS_ADAPTER_CA_CERTS=[Path to trusted CAs in PEM format] \
MF_JAEGER_URL=[Jaeger server URL] \
MF_THINGS_AUTH_GRPC_URL=[Things service Auth gRPC URL] \
MF_THINGS_AUTH_GRPC_TIMEOUT=[Things service Auth gRPC request timeout in seconds] \
$GOBIN/mainfluxlabs-ws

Usage

Authentication is provided via the Authorization header or query parameters for browser clients that cannot set headers:

• Thing key: Authorization: Thing <thing_key> or ?key=<key>&keyType=<type>
• User bearer token: Authorization: Bearer <user_token> or ?token=<user_token>

Publishing messages

Connect to /messages or /messages/<subtopic> using a thing key:

ws://localhost:8190/messages?key=<thing_key>&keyType=<key_type>
ws://localhost:8190/messages/sensors/temperature?key=<thing_key>&keyType=<key_type>

Once connected, each message sent over the socket is published to the platform.

Sending commands

Connect to /things/<thing_id>/commands or /groups/<group_id>/commands using a thing key or user bearer token:

ws://localhost:8190/things/<thing_id>/commands?key=<thing_key>&keyType=<key_type>
ws://localhost:8190/groups/<group_id>/commands?token=<user_token>

Both endpoints support an optional subtopic:

ws://localhost:8190/things/<thing_id>/commands/firmware
ws://localhost:8190/groups/<group_id>/commands/config/network

Once connected, each message sent over the socket is published as a command to the target thing or group.