Crate svc_agent[][src]

Expand description


svc-agent is a library implementing common MQTT agent messaging pattern conventions and abstracting out the protocol’s specifics to enable building microservices with full-duplex communication.

On the broker side its counterpart is mqtt-gateway plugin for VerneMQ.

Key concepts

svc-agent is about exchanging messages between agents using pub-sub model.

An agent is a service or end user who can publish and subscribe to messages. Each agent has a unique AgentId.

Message can be of three types:

  1. Requests that end users send to services. Services may call other services too.
  2. Responses that services send back.
  3. Events that just may happen in services and it pushes a notification to subscribers.

Each outgoing message has a Destination and each incoming message has a Source which can also be of three types:

  1. Broadcast that is being received by each of the subscribed agents.
  2. Multicast that is being received by only one agent of a SharedGroup of subscribers.
  3. Unicast that is intended for a specific agent.


pub use self::error::Error;



Agent identifier.

A group of agents which shares a subscription. Commonly used for balancing requests over a group of instances of some service.

Messages subscription builder.


Message destination.

Message source.


Something that can be addressed as agent.