PubSub
In the world of microservice architecture, the event driven approach is indistinguishable and zero framework has built-in support for the accessing the message queue systems.
At times the app we develop has to rely on external service signal through API call and through events and let us decide the state of the data/action.
Alike, other built-in solutions, the PubSub clients will be automatically added to container once the needed service configurations available.
zero app tries to connect, captures the ping status and attaches to the app life-time, otherwise app explicitly calls the PubSub is disabled.
ctx.KF.publish(ctx, "topic", "message-key", "payload"); #publishes message to a topic on the subscribed client
app.addKafkaSubscription("topic", subscriberHandler); #listens for upcoming event and injects into subscriber handler for further actions.ctx.MQ.publish("topic"); #publishes message to a topic on the subscribed client
app.addSubscription("topic", subscriber-handler); #listens for upcoming event and injects into subscriber handler for further actions.Support
zero framework supports following brokers to publish and subscriber to.
| Message Broker | Support |
|---|---|
| Kafka | ✅ |
| MQTT | ✅ |
Configurations
This list of configurations help the developer to prefer either Kafka or MQTT pubsub per instance.
| kafka config | Remarks | Default* / Others | Required |
|---|---|---|---|
| PUBSUB_BACKEND | Choose kafka or mqtt as pubsub mq | None (KAFKA / MQTT) | Yes |
| PUBSUB_BROKER | Set the addresses of the Kafka cluster | localhost:9092 [one or multiple host address] | Yes |
| PUBSUB_OFFSET | Allow the subscription to begin from | None | No |
| CONSUMER_ID | Unique identifier of the subscribing group | None | No |
| KAFKA_BATCH_SIZE | Number of messages added in one messageSet | 100* | No |
| KAFKA_BATCH_BYTES | The overall size of the messageSet that includes one or more message | 1048576* | No |
| KAFKA_BATCH_TIMEOUT | MessageSet flush timeout | 1000* | No |
| KAFKA_SECURITY_PROTOCOL | Protocol used to communicate with kafka cluster | plaintext*,ssl,sasl_plaintext, sasl_ssl | No |
| KAFKA_SASL_MECHANISM | SASL Authentication mechanism | plain* | No |
| KAFKA_SASL_USERNAME | SASL Authentication username | Applicable only with sasl plain mode | No |
| KAFKA_SASL_PASSWORD | SASL Authentication password | Applicable only with sasl plain mode | No |
| KAFKA_TLS_CERT_FILE | Path to client's public key (PEM) used for authentication. | None | No |
| KAFKA_TLS_KEY_FILE | Path to client's private key (PEM) used for authentication. | None | No |
| KAFKA_TLS_CA_CERT_FILE | Path to client's CA cert (PEM) used for authentication. | None | No |
| KAFKA_TLS_INSECURE_SKIP_VERIFY | Skip client certificate verifications | true*, false | No |
| MQTT config | Remarks | Default* / Others | Required |
|---|---|---|---|
| MQTT_PROTOCOL | Protocol used to communicate with MQTT server | tcp* | Yes |
| MQTT_HOST | IP Address of the MQTT Server | None | Yes |
| MQTT_PORT | Port of the MQTT Server | None | Yes |
| MQTT_CLIENT_ID_SUFFIX | Client ID name for the debug messages | None | No |