Mainflux.mainflux/twins

Twins

Service twins is used for CRUD and update of digital twins. Twin is a semantic representation of a real world entity, be it device, application or something else. It holds the sequence of attribute based definitions of a real world thing and refers to the time series of definition based states that hold the historical data about the represented real world thing.

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_TWINS_LOG_LEVEL	Log level for twin service (debug, info, warn, error)	error
MF_TWINS_HTTP_PORT	Twins service HTTP port	9021
MF_TWINS_SERVER_CERT	Path to server certificate in PEM format
MF_TWINS_SERVER_KEY	Path to server key in PEM format
MF_JAEGER_URL	Jaeger server URL
MF_TWINS_DB_NAME	Database name	mainflux
MF_TWINS_DB_HOST	Database host address	localhost
MF_TWINS_DB_PORT	Database host port	27017
MF_TWINS_SINGLE_USER_EMAIL	User email for single user mode (no gRPC communication with users)
MF_TWINS_SINGLE_USER_TOKEN	User token for single user mode that should be passed in auth header
MF_TWINS_CLIENT_TLS	Flag that indicates if TLS should be turned on	false
MF_TWINS_CA_CERTS	Path to trusted CAs in PEM format
MF_TWINS_MQTT_URL	Mqtt broker URL for twin CRUD and states update notifications	tcp://localhost:1883
MF_TWINS_THING_ID	ID of thing representing twins service & mqtt user
MF_TWINS_THING_KEY	Key of thing representing twins service & mqtt pass
MF_TWINS_CHANNEL_ID	Mqtt notifications topic
MF_NATS_URL	Mainflux NATS broker URL	nats://127.0.0.1:4222
MF_AUTHN_GRPC_PORT	Authn service gRPC port	8181
MF_AUTHN_TIMEOUT	Authn gRPC request timeout in seconds	1
MF_AUTHN_URL	Authn service URL	localhost:8181

Deployment

The service itself is distributed as Docker container. The following snippet provides a compose file template that can be used to deploy the service container locally:

version: "3"
services:
  twins:
    image: mainflux/twins:[version]
    container_name: [instance name]
    ports:
      - [host machine port]:[configured HTTP port]
    environment:
      MF_TWINS_LOG_LEVEL: [Twins log level]
      MF_TWINS_HTTP_PORT: [Service HTTP port]
      MF_TWINS_SERVER_CERT: [String path to server cert in pem format]
      MF_TWINS_SERVER_KEY: [String path to server key in pem format]
      MF_JAEGER_URL: [Jaeger server URL]
      MF_TWINS_DB_NAME: [Database name]
      MF_TWINS_DB_HOST: [Database host address]
      MF_TWINS_DB_PORT: [Database host port]
      MF_TWINS_SINGLE_USER_EMAIL: [User email for single user mode]
      MF_TWINS_SINGLE_USER_TOKEN: [User token for single user mode]
      MF_TWINS_CLIENT_TLS: [Flag that indicates if TLS should be turned on]
      MF_TWINS_CA_CERTS: [Path to trusted CAs in PEM format]
      MF_TWINS_MQTT_URL: [Mqtt broker URL for twin CRUD and states]
      MF_TWINS_THING_ID: [ID of thing representing twins service]
      MF_TWINS_THING_KEY: [Key of thing representing twins service]
      MF_TWINS_CHANNEL_ID: [Mqtt notifications topic]
      MF_NATS_URL: [Mainflux NATS broker URL]
      MF_AUTHN_GRPC_PORT: [Authn service gRPC port]
      MF_AUTHN_TIMEOUT: [Authn gRPC request timeout in seconds]
      MF_AUTHN_URL: [Authn service URL]

To start the service outside of the container, execute the following shell script:

# download the latest version of the service
go get github.com/mainflux/mainflux

cd $GOPATH/src/github.com/mainflux/mainflux

# compile the twins
make twins

# copy binary to bin
make install

# set the environment variables and run the service
MF_TWINS_LOG_LEVEL: [Twins log level] MF_TWINS_HTTP_PORT: [Service HTTP port] MF_TWINS_SERVER_CERT: [String path to server cert in pem format] MF_TWINS_SERVER_KEY: [String path to server key in pem format] MF_JAEGER_URL: [Jaeger server URL] MF_TWINS_DB_NAME: [Database name] MF_TWINS_DB_HOST: [Database host address] MF_TWINS_DB_PORT: [Database host port] MF_TWINS_SINGLE_USER_EMAIL: [User email for single user mode] MF_TWINS_SINGLE_USER_TOKEN: [User token for single user mode] MF_TWINS_CLIENT_TLS: [Flag that indicates if TLS should be turned on] MF_TWINS_CA_CERTS: [Path to trusted CAs in PEM format] MF_TWINS_MQTT_URL: [Mqtt broker URL for twin CRUD and states] MF_TWINS_THING_ID: [ID of thing representing twins service] MF_TWINS_THING_KEY: [Key of thing representing twins service] MF_TWINS_CHANNEL_ID: [Mqtt notifications topic] MF_NATS_URL: [Mainflux NATS broker URL] MF_AUTHN_GRPC_PORT: [Authn service gRPC port] MF_AUTHN_TIMEOUT: [Authn gRPC request timeout in seconds] MF_AUTHN_URL: [Authn service URL] $GOBIN/mainflux-twins

Usage

Starting twins service

The twins service publishes notifications on an mqtt topic of the format channels/<MF_TWINS_CHANNEL_ID>/messages/<twinID>/<crudOp>, where crudOp stands for the crud operation done on twin - create, update, delete or retrieve - or state - save state. In order to use twin service, one must inform it - via environment variables - about the Mainflux thing and channel used for mqtt notification publishing. You can use an already existing thing and channel - thing has to be connected to channel - or create new ones.

To set the environment variables, please go to .env file and set the following variables:

MF_TWINS_THING_ID=
MF_TWINS_THING_KEY=
MF_TWINS_CHANNEL_ID=

with the corresponding values of the desired thing and channel. If you are running mainflux natively, than do the same thing in the corresponding console environment.

For more information about service capabilities and its usage, please check out the API documentation.