# Request-Response Protocol
The first protocol implemented for Airnode is request–response. An Airnode serving the request–response protocol listens for requests, makes the API call specified by the request, and finally makes the response transaction back on chain.
This sections briefly describes the structure of the request response protocol contracts. You can find more information in the source files on github (opens new window).
The request–response protocol is implemented as a single permissionless contract
that all Airnodes interact with, which is named
AirnodeRrp.sol. This base
contract has the following inheritance tree that compartmentalizes the aspects
of the protocol.
This contract has two key responsibilities:
- It is used by requesters to make requests.
- It is used by Airnodes to fulfill requests.
However, this contract is shared for all requesters and Airnodes on a particular chain. This means that neither Airnode operators nor requesters need to deploy this contract themselves. Instead, API3 will deploy this contract once per chain and you simply connect your Airnode or requester contract to that deployed contract. See the Airnode contract addresses for reference.
is a CLI tool used to interact with
AirnodeRrp.sol and perform administrative
IAirnodeRrp.sol (opens new window)
interface describes all functions and events of the
which implements this interface.
This interface inherits:
- IAuthorizationUtils.sol (opens new window)
- IWithdrawalUtils.sol (opens new window)
- ITemplateUtils.sol (opens new window)