Push-Based Oracle

A push-based oracle initiates data transmission without requiring a request from the smart contract. The oracle network monitors predefined conditions (e.g., a price feed update or a specific time interval) and pushes the data onto the blockchain, triggering contract execution.

• Contrast with Pull Models: Unlike pull-based oracles, which wait for a contract to request data, push models enable event-driven automation.
• Use Case: Ideal for limit orders, liquidation engines, and scheduled payments that must execute automatically when conditions are met.

In a push-based model, the entity operating the oracle (or the dApp subsidizing it) pays the gas fees for broadcasting the data transaction to the blockchain. This shifts the cost burden off the end-user's contract call.

• Economic Model: Costs are often covered by protocol treasuries, subscription fees, or relayer networks.
• Implication: Enables complex, gas-intensive update logic without impacting user transaction costs, but requires the oracle operator to manage gas economics carefully.

Push oracles can deliver data based on real-time triggers or fixed schedules.

• Event-Driven: Pushes data immediately when an off-chain event occurs (e.g., a sports match ends, an API reports a new value).
• Time-Driven: Pushes data at regular intervals (e.g., a price feed updated every block or every 10 seconds).
• Key Benefit: Provides deterministic freshness and guarantees that contracts have the latest state required for critical functions like collateral valuation.

To ensure data integrity and censorship resistance, robust push-based oracles aggregate data from multiple, independent node operators or data sources. Consensus mechanisms (like medianizing reports) are performed off-chain before the final value is pushed on-chain.

• Security Model: Reduces reliance on any single point of failure.
• Example: A price feed oracle might collect data from 30+ independent nodes, discard outliers, and push the median value. This process mitigates risks of data manipulation or provider downtime.

While the aggregation logic often occurs off-chain for efficiency, the final data payload pushed on-chain can include cryptographic proofs or be verifiable against a known set of oracle node addresses.

• Proof of Inclusion: Some designs attach signatures from a threshold of oracle nodes, allowing contracts to verify the data's origin.
• Transparency: All historical pushes are permanently recorded on the blockchain, providing an auditable trail of all data supplied to contracts.

Push-based oracle services often implement subscription models or whitelisting to control which smart contracts can receive data pushes. This manages resource allocation and prevents spam.

• Mechanism: Contracts may need to be registered or hold a specific NFT or token to be eligible for updates.
• Example: A DeFi protocol might pay a monthly fee to an oracle service to have price feeds pushed to its liquidation contract every block.

A data delivery model where on-chain contracts actively request (pull) data from an oracle network, which then responds with a transaction. This is the inverse of a push-based model.

• Key Difference: The smart contract initiates the data update, often via a function call, rather than receiving unsolicited updates.
• Use Case: Suited for less time-sensitive data where gas costs for updates are borne only when needed, such as fetching a user's credit score or a historical price.

A network of independent node operators that collectively source, aggregate, and deliver data to smart contracts, providing security and reliability.

• Core Function: Mitigates single points of failure and data manipulation by using multiple independent data sources and node operators.
• Relation to Push: A push-based oracle is typically implemented using a DON. The network's nodes collaboratively decide when and what data to push on-chain.

A continuously updated stream of specific data (e.g., ETH/USD price) published on-chain by an oracle. A push-based oracle is the mechanism that maintains and updates these feeds.

• Components: Includes the on-chain aggregator contract (holding the current value) and the off-chain infrastructure that updates it.
• Example: Chainlink Data Feeds are canonical examples of push-based oracles delivering high-frequency price data for DeFi.

The two primary triggers for a push-based oracle update.

• Heartbeat: A time-based trigger (e.g., every hour) that ensures data freshness even if the price is stable.
• Deviation Threshold: A price-movement-based trigger (e.g., update if price moves >0.5%) that ensures accuracy during volatility.
• Combined Use: These parameters allow a push oracle to optimize for both gas efficiency (fewer unnecessary updates) and data precision.

The process by which a smart contract cryptographically verifies the authenticity and consensus of data delivered by an oracle before accepting it.

• Mechanism: For push oracles, this often involves checking digitally signed reports from a threshold of node operators in a DON.
• Security Role: Prevents a single malicious node from unilaterally pushing incorrect data, as the contract's verification logic will reject invalid submissions.

The economic considerations of who pays for on-chain transactions in an oracle system.

• Push Model Cost: The oracle service (or its node operators) typically pays the gas to push updates, bundling the cost into service fees.
• Pull Model Cost: The end-user or dApp contract pays the gas to request data.
• Incentive Alignment: In push-based systems, node operators are incentivized to update reliably to maintain the feed's utility and earn rewards.