[][src]Crate libp2p_swarm

High level manager of the network.

A Swarm contains the state of the network as a whole. The entire behaviour of a libp2p network can be controlled through the Swarm. The Swarm struct contains all active and pending connections to remotes and manages the state of all the substreams that have been opened, and all the upgrades that were built upon these substreams.

Initializing a Swarm

Creating a Swarm requires three things:

  1. A network identity of the local node in form of a PeerId.
  2. An implementation of the Transport trait. This is the type that will be used in order to reach nodes on the network based on their address. See the transport module for more information.
  3. An implementation of the NetworkBehaviour trait. This is a state machine that defines how the swarm should behave once it is connected to a node.

Network Behaviour

The NetworkBehaviour trait is implemented on types that indicate to the swarm how it should behave. This includes which protocols are supported and which nodes to try to connect to. It is the NetworkBehaviour that controls what happens on the network. Multiple types that implement NetworkBehaviour can be composed into a single behaviour.

Protocols Handler

The ProtocolsHandler trait defines how each active connection to a remote should behave: how to handle incoming substreams, which protocols are supported, when to open a new outbound substream, etc.


pub use protocols_handler::IntoProtocolsHandler;
pub use protocols_handler::KeepAlive;
pub use protocols_handler::ProtocolsHandler;
pub use protocols_handler::ProtocolsHandlerEvent;
pub use protocols_handler::ProtocolsHandlerUpgrErr;
pub use protocols_handler::SubstreamProtocol;



Once a connection to a remote peer is established, a ProtocolsHandler negotiates and handles one or more specific protocols on the connection.




Dummy implementation of NetworkBehaviour that doesn't do anything.


Contains the state of the network, plus the way it should behave.


Implementation of IntoProtocolsHandler that combines two protocols into one.


Implementation of ProtocolsHandler that opens a new substream for each individual message.


Implementation of ProtocolsHandler that combines two protocols into one.


Parameters passed to poll(), that the NetworkBehaviour has access to.



An action that a NetworkBehaviour can trigger in the Swarm in whose context it is executing.


Event generated by the Swarm.



A behaviour for the network. Allows customizing the swarm.


When deriving NetworkBehaviour this trait must be implemented for all the possible event types generated by the inner behaviours.


Parameters passed to poll(), that the NetworkBehaviour has access to.

Type Definitions


Substream for which a protocol has been chosen.


Contains the state of the network, plus the way it should behave.