Who uses index values published onchain?

Index and benchmark providers that license indices to tokenized funds, onchain markets and structured products.

Goldsky

Index values published onchain

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What are index values published onchain?

Index values published onchain are the levels of a benchmark or reference index written to a contract on the chain, so tokenized funds, structured products and markets that track the index can read it; the contract is often called an index oracle.

Index providers publish them because a product can only settle against the index on the chain it runs on, and each chain has to show the same value.

A Goldsky Compose task reads each new value from your API on a schedule and writes it to every chain you serve; calculating the index stays with you.

How index values get onchain

The diagram follows one index value from your calculation engine to the products that read it on each chain, and shows who does each step. Your setup may differ.

Calculate the indexYour index engine produces a new value

ComposeFetch the valueYour task reads your API on schedule

ComposePublish to each chainThe same value on every chain you serve

Products read the indexFunds and markets tracking it update

Goldsky

Calculate the index
The index value comes from your methodology, and only your calculation engine produces it.
Your engine calculates each new value and makes it available through your API with the time it applies to. A value published without its time can’t be told apart from the one before it.
Set up a contract for the index value on each chain
Apps can only read the index value from a contract on their own chain, so each chain needs one that stores it.
Deploy a contract on each chain that stores the latest index value and its date, and lets only your publishing wallet update it. If anyone can write to it, anyone can change the index value the apps read.
Fetch the value on schedule
Handled by Goldsky Compose
The chain shows the index only when someone writes it there, so a job has to pick up each new value.
The job runs as often as products need the index refreshed and has to cope with your API being briefly unavailable. If a run fails and nobody is alerted, products keep settling against an old value.
With Goldsky, a Compose task with a cron trigger reads your API through context.fetch, which retries a failed call with backoff.
Call external APIs from a task (opens in a new tab)
Publish the same value to each chain
Handled by Goldsky Compose
A product on one chain and a product on another should settle against the same index value.
Each chain is written separately, so a failing chain doesn’t hold up the rest, and the next run catches it up. Every chain gets the same value and timestamp.
Compose sends one wallet.writeContract call per chain from the same task, run together with Promise.allSettled, and with onReorg set to replay it resends an update a reorg drops.
Handle confirmations and reorgs (opens in a new tab)
Keep a record of every update
Handled by Goldsky Compose
If an app or an auditor asks why a value was on the chain, the answer has to come from records of what was read and written.
The record ties each value on the chain to the source response it came from, the time it was read and the transaction that wrote it. Without it, rebuilding one update means searching logs on each side by hand.
Every call a Compose task makes, including each fetch from your source and each transaction it sends, is logged for auditing. If a run is interrupted, calls that already finished aren’t repeated, so a write isn’t sent twice.
How Compose logs each call (opens in a new tab)
Products read the index
Funds, markets and structured products that track the index read it from the contract on their chain.
Each product reads the latest value and its time and applies its own rules. Products should treat a value older than they expect as stale.