Chainlink Data Streams Consumer

This package can authenticate to the Chainlink Data Streams API, fetch reports from feeds, and decode them to a format that is usable in a JavaScript environment.

In Node.js, it can also subscribe to the corresponding WebSocket API, and receive low-latency updates. For now, the latter is unavailable in browsers, because the header-based authentication used by the Chainlink for WebSockets does not seem to be usable in Web browsers.

To consume real-time feeds in browsers, it's recommended to proxy them through a backend service.

Installing

This package is not published in NPM yet. You can add it to your project like this:

npm i --save git+https://github.com/hackbg/chainlink-datastreams-consumer.git

Connecting

Use your authentication credentials to instantiate the default export of the module.

import ChainlinkDatastreamsConsumer from '@hackbg/chainlink-datastreams-consumer'

const api = new ChainlinkDatastreamsConsumer({
  hostname:     '...',
  wsHostname:   '...',
  clientID:     '...',
  clientSecret: '...',
})

Fetching data from feeds

Use the fetchFeed method to pull the data from one feed for a given point in time. This asynchronously returns an instance of the Report object, which combines the fields from the SingleReport, FullReport, and ReportBlob types.

const report = await api.fetchFeed({
  timestamp: '1694212245',
  feed: '0x0002F18A75A7750194A6476C9AB6D51276952471BD90404904211A9D47F34E64',
})

Use the fetchFeeds method to pull the data from multiple feeds for a given point in time. This asynchronously returns a Record<FeedId, Report>.

const reports = await api.fetchFeeds({
  timestamp: '1694212245',
  feeds: [
    '0x00023496426b520583ae20a66d80484e0fc18544866a5b0bfee15ec771963274',
    '0x0002f18a75a7750194a6476c9ab6d51276952471bd90404904211a9d47f34e64'
  ] 
})

Subscribing to feeds

In Node.js, you can also use the WebSocket-based API.

The optional feeds parameter allows you to connect and subscribe in a single expression. Use the instance's on, once and off methods to set up event handling.

import ChainlinkDatastreamsConsumer from '@hackbg/chainlink-datastreams-consumer'

const api = new ChainlinkDatastreamsConsumer({
  hostname: '...',
  wsHostname: '...',
  clientID: '...',
  clientSecret: '...',
  feeds: [ '0x...', '0x...', '0x...', ]
}).on('report', report => {
  console.log(report)
})

It's recommended to keep a single SDK instance per credential set, and use the asynchronous subscribeTo and unsubscribeFrom methods to change the set of feeds to which the SDK is listening.

await api.subscribeTo('0x...')

await api.subscribeTo([
  '0x...',
  '0x...'
])

await api.unsubscribeFrom('0x...')

await api.unsubscribeFrom([
  '0x...',
  '0x...'
])

The underlying WebSocket is automatically closed and reopened when the list of feeds changes; when there are 0 feeds, it remains closed.

The IDs of currently subscribed feeds are available on the feeds property, as a read-only Set.