ws

README

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	localhost:6831
MF_THINGS_AUTH_GRPC_URL	Things service Auth gRPC URL	localhost:8181
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

For more information about service capabilities and its usage, please check out the WebSocket paragraph in the Getting Started guide.

Documentation

Index

• Variables
• type Client
  • func NewClient(c *websocket.Conn) *Client
  • func (c *Client) Cancel() error
  • func (c *Client) Handle(msg messaging.Message) error
• type Service
  • func New(things mainflux.ThingsServiceClient, pubsub messaging.PubSub) Service

Variables

var (
	// ErrFailedMessagePublish indicates that message publishing failed.
	ErrFailedMessagePublish = errors.New("failed to publish message")

	// ErrFailedSubscription indicates that client couldn't subscribe to specified channel
	ErrFailedSubscription = errors.New("failed to subscribe to a channel")

	// ErrFailedUnsubscribe indicates that client couldn't unsubscribe from specified channel
	ErrFailedUnsubscribe = errors.New("failed to unsubscribe from a channel")

	// ErrFailedConnection indicates that service couldn't connect to message broker.
	ErrFailedConnection = errors.New("failed to connect to message broker")

	// ErrInvalidConnection indicates that client couldn't subscribe to message broker
	ErrInvalidConnection = errors.New("nats: invalid connection")

	// ErrUnauthorizedAccess indicates that client provided missing or invalid credentials
	ErrUnauthorizedAccess = errors.New("missing or invalid credentials provided")

	// ErrEmptyTopic indicate absence of thingKey in the request
	ErrEmptyTopic = errors.New("empty topic")

	// ErrEmptyID indicate absence of channelID in the request
	ErrEmptyID = errors.New("empty id")
)

Types

type Client

type Client struct {
	// contains filtered or unexported fields
}

Client handles messaging and websocket connection

func NewClient

func NewClient(c *websocket.Conn) *Client

NewClient returns a new Client object

func (*Client) Cancel

func (c *Client) Cancel() error

Cancel handles the websocket connection after unsubscribing

func (*Client) Handle

func (c *Client) Handle(msg messaging.Message) error

Handle handles the sending and receiving of messages via the broker

type Service

type Service interface {
	// Publish Message
	Publish(ctx context.Context, thingKey string, msg messaging.Message) error

	// Subscribe  subscribes to a channel with specified id.
	Subscribe(ctx context.Context, thingKey, chanID, subtopic string, client *Client) error

	// Unsubscribe method is used to stop observing resource.
	Unsubscribe(ctx context.Context, thingKey, chanID, subtopic string) error
}

Service specifies web socket service API.

func New

func New(things mainflux.ThingsServiceClient, pubsub messaging.PubSub) Service

New instantiates the WS adapter implementation