Common Quote Oracle
Video
Original
Abstract
The following allows for the implementation of a standard API for data feeds providing the relative value of assets, forcing compliant contracts to use explicit token amounts instead of price factors. This approach has been shown to lead to better security and time-to-market outcomes.
Motivation
The information required to value assets is scattered over a number of major and minor sources, each one with their own integration API and security considerations. Many protocols over the years have implemented oracle adapter layers for their own use to abstract this complexity away from their core implementations, leading to much duplicated effort.
This specification provides a standard API aimed to serve the majority of use cases. Preference is given to ease of integration and serving the needs of product teams with less knowledge, requirements and resources.
Specification
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 and RFC 8174.
Definitions
- base asset: The asset that the user needs to know the value for (e.g: USDC as in "I need to know the value of 1e6 USDC in ETH terms").
- quote asset: The asset in which the user needs to value the
base
(e.g: ETH as in "I need to know the value of 1e6 USDC in ETH terms"). - value: An amount of
base
inquote
terms (e.g. Thevalue
of 1000e6 USDC in ETH terms is 283,969,794,427,307,000 ETH, and thevalue
of 1000e18 ETH in USDC terms is 3,521,501,299,000 USDC). Note that this is an asset amount, and not a decimal factor.
Methods
getQuote
Returns the value of baseAmount
of base
in quote
terms.
MUST round down towards 0.
MUST revert if the value of baseAmount
of base
in quote
terms would overflow in a uint256.
- name: getQuote type: function stateMutability: view inputs: - name: baseAmount type: uint256 - name: base type: address - name: quote type: address outputs: - name: quoteAmount type: uint256
Special Addresses
Some assets under the scope of this specification don't have an address, such as ETH, BTC and national currencies.
For ETH, the address will be 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE
as per ERC-7528.
For BTC, the address will be 0xbBbBBBBbbBBBbbbBbbBbbbbBBbBbbbbBbBbbBBbB
.
For assets without an address, but with an ISO 4217 code, the code will be used (e.g. address(840)
for USD).
Rationale
The use of getQuote
doesn't require the consumer to be aware of any decimal partitions that might have been defined
for the base
or quote
and should be preferred in most data processing cases.
The spec doesn't include a getPrice
function because it is rarely needed on-chain, and it would be a decimal number of
difficult representation. The popular option for representing prices can be implemented for ERC-20 with decimals as
`oracle.getQuote(base, quote, 10**base.decimals()) and will give the value of a whole unit of base in quote terms.
Backwards Compatibility
Most existing data feeds related to the relative value of pairs of assets should be representable using this standard.
Security Considerations
This specification purposefully provides no methods for data consumers to assess the validity of the data they receive. It is expected of individual implementations using this specification to decide and publish the quality of the data that they provide, including the conditions in which they will stop providing it.
Consumers should review these guarantees and use them to decide whether to integrate or not with a data provider.
Copyright
Copyright and related rights waived via CC0.
Adopted by projects
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