[][src]Module libp2p::request_response

Generic request/response protocols.

General Usage

RequestResponse is a NetworkBehaviour that implements a generic request/response protocol or protocol family, whereby each request is sent over a new substream on a connection. RequestResponse is generic over the actual messages being sent, which are defined in terms of a RequestResponseCodec. Creating a request/response protocol thus amounts to providing an implementation of this trait which can then be given to RequestResponse::new. Further configuration options are available via the RequestResponseConfig.

Requests are sent using RequestResponse::send_request and the responses received as RequestResponseMessage::Response via RequestResponseEvent::Message.

Responses are sent using RequestResponse::send_response upon receiving a RequestResponseMessage::Request via RequestResponseEvent::Message.

Protocol Families

A single RequestResponse instance can be used with an entire protocol family that share the same request and response types. For that purpose, RequestResponseCodec::Protocol is typically instantiated with a sum type.

One-Way Protocols

The implementation supports one-way protocols that do not have responses. In these cases the RequestResponseCodec::Response can be defined as () and RequestResponseCodec::read_response as well as RequestResponseCodec::write_response given the obvious implementations. Note that RequestResponseMessage::Response will still be emitted, immediately after the request has been sent, since RequestResponseCodec::read_response will not actually read anything from the given I/O stream. RequestResponse::send_response need not be called for one-way protocols, i.e. the ResponseChannel may just be dropped.

Limited Protocol Support

It is possible to only support inbound or outbound requests for a particular protocol. This is achieved by instantiating RequestResponse with protocols using ProtocolSupport::Inbound or ProtocolSupport::Outbound. Any subset of protocols of a protocol family can be configured in this way. Such protocols will not be advertised during inbound respectively outbound protocol negotiation on the substreams.



Limit the number of requests peers can send to each other.



The ID of an inbound or outbound request.


A request/response protocol for some message codec.


The configuration for a RequestResponse protocol.


A channel for sending a response to an inbound request.


A wrapper around RequestResponse which adds request limits per peer.



Possible failures occurring in the context of receiving an inbound request and sending a response.


Possible failures occurring in the context of sending an outbound request and receiving the response.


The level of support for a particular protocol.


The events emitted by a RequestResponse protocol.


An inbound request or response.



Types serving as protocol names.


A RequestResponseCodec defines the request and response types for a RequestResponse protocol or protocol family and how they are encoded / decoded on an I/O stream.