Stream and Decode reports using the Go SDK (WebSocket)

Guide Versions

This guide is available in multiple versions. Choose the one that matches your needs.

In this guide, you'll learn how to use the Data Streams SDK for Go to stream and decode DataLink feeds from the Aggregation Network. You'll set up your Go project, listen for real-time reports, decode them, and log their attributes.

Requirements

Git: Make sure you have Git installed. You can check your current version by running git --version in your terminal and download the latest version from the official Git website if necessary.
Go Version: Make sure you have Go version 1.22.4 or higher. You can check your current version by running go version in your terminal and download the latest version from the official Go website if necessary.
API Credentials: Access to DataLink requires API credentials to connect to the Aggregation Network. If you haven't already, contact us to request access.

Guide

Set up your Go project

Create a new directory for your project and navigate to it:
```
mkdir my-datalink-project
cd my-datalink-project
```
Initialize a new Go module:
```
go mod init my-datalink-project
```

Install the Data Streams SDK:

go get github.com/smartcontractkit/data-streams-sdk/go

Understanding Report Schema Versions

Data Providers may use different report schema versions. The schema version determines the structure of the data returned by the feed and affects how you should decode the report.

Import the appropriate schema version in your code (e.g., v4).
Use that version when decoding the report with report.Decode[v4.Data]().

Different schema versions have different fields and structures.

In this example, we're using report schema v4 for the EUR/USD feed, but your implementation should match the schema version specified by your Data Provider.

Establish a WebSocket connection and listen for real-time reports

Create a new Go file, stream.go, in your project directory:
```
touch stream.go
```

Insert the following code example and save your stream.go file:

package main

import (
  "context"
  "fmt"
  "os"
  "time"

  streams "github.com/smartcontractkit/data-streams-sdk/go"
  feed "github.com/smartcontractkit/data-streams-sdk/go/feed"
  report "github.com/smartcontractkit/data-streams-sdk/go/report"
  v4 "github.com/smartcontractkit/data-streams-sdk/go/report/v4" // Import the v4 report schema.
)

func main() {
  if len(os.Args) < 2 {
  fmt.Println("Usage: go run stream.go [StreamID1] [StreamID2] ...")
  os.Exit(1)
  }

  // Set up the SDK client configuration
  cfg := streams.Config{
  ApiKey:    os.Getenv("API_KEY"),
  ApiSecret: os.Getenv("API_SECRET"),
  WsURL: "wss://ws.testnet-dataengine.chain.link",
  Logger: streams.LogPrintf,
  }

  // Create a new client
  client, err := streams.New(cfg)
  if err != nil {
  cfg.Logger("Failed to create client: %v\n", err)
  os.Exit(1)
  }

  // Parse the feed IDs from the command line arguments
  var ids []feed.ID
  for _, arg := range os.Args[1:] {
  var fid feed.ID
  if err := fid.FromString(arg); err != nil {
    cfg.Logger("Invalid stream ID %s: %v\n", arg, err)
    os.Exit(1)
  }
  ids = append(ids, fid)
  }

  ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
  defer cancel()

  // Subscribe to the feed(s)
  stream, err := client.Stream(ctx, ids)
  if err != nil {
  cfg.Logger("Failed to subscribe: %v\n", err)
  os.Exit(1)
  }

  defer stream.Close()
  for {
    reportResponse, err := stream.Read(context.Background())
    if err != nil {
      cfg.Logger("Error reading from stream: %v\n", err)
      continue
    }

    // Log the contents of the report before decoding
    cfg.Logger("Raw report data: %+v\n", reportResponse)

      // Decode each report as it comes in
      decodedReport, decodeErr := report.Decode[v4.Data](reportResponse.FullReport)
      if decodeErr != nil {
        cfg.Logger("Failed to decode report: %v\n", decodeErr)
        continue
      }

        // Log the decoded report
        cfg.Logger("\n--- Report Stream ID: %s ---\n" +
          "------------------------------------------\n" +
          "Observations Timestamp : %d\n" +
          "Benchmark Price        : %s\n" +
          "Valid From Timestamp   : %d\n" +
          "Expires At             : %d\n" +
          "Link Fee               : %s\n" +
          "Native Fee             : %s\n" +
          "Market Status          : %d\n" +
          "------------------------------------------\n",
          reportResponse.FeedID.String(),
          decodedReport.Data.ObservationsTimestamp,
          decodedReport.Data.BenchmarkPrice.String(),
          decodedReport.Data.ValidFromTimestamp,
          decodedReport.Data.ExpiresAt,
          decodedReport.Data.LinkFee.String(),
          decodedReport.Data.NativeFee.String(),
          decodedReport.Data.MarketStatus,
        )

        // Also, log the stream stats
        cfg.Logger("\n--- Stream Stats ---\n" +
        stream.Stats().String() + "\n" +
        "--------------------------------------------------------------------------------------------------------------------------------------------\n",
        )
  }
}

Download the required dependencies and update the go.mod and go.sum files:
```
go mod tidy
```
Set up the SDK client configuration within stream.go with your API credentials and the WebSocket URL:
```
cfg := streams.Config{
    ApiKey:    os.Getenv("API_KEY"),
    ApiSecret: os.Getenv("API_SECRET"),
    WsURL: "wss://ws.testnet-dataengine.chain.link",
    Logger: streams.LogPrintf,
}
```
- Set your API credentials as environment variables:
```
export API_KEY="<YOUR_API_KEY>"
export API_SECRET="<YOUR_API_SECRET>"
```
  Replace <YOUR_API_KEY> and <YOUR_API_SECRET> with your API credentials.
- WsURL is the WebSocket URL for the Data Streams Aggregation Network. Use wss://ws.testnet-dataengine.chain.link for the testnet environment.
See the SDK Reference page for more configuration options.

For this example, you'll subscribe to the EUR/USD DataLink feed on testnet. This feed ID is 0x0004b9905d8337c34e00f8dbe31619428bac5c3937e73e6af75c71780f1770ce.

Execute your application:

go run stream.go 0x0004b9905d8337c34e00f8dbe31619428bac5c3937e73e6af75c71780f1770ce

Expect output similar to the following in your terminal:

2025-06-03T11:00:21-05:00 Raw report data: {"fullReport":"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","feedID":"0x0004b9905d8337c34e00f8dbe31619428bac5c3937e73e6af75c71780f1770ce","validFromTimestamp":1748966421,"observationsTimestamp":1748966421}

2025-06-03T11:00:21-05:00
--- Report Stream ID: 0x0004b9905d8337c34e00f8dbe31619428bac5c3937e73e6af75c71780f1770ce ---
------------------------------------------
Observations Timestamp : 1748966421
Benchmark Price        : 1137352500000000000
Valid From Timestamp   : 1748966421
Expires At             : 1751558421
Link Fee               : 22305691203008313
Native Fee             : 121845225708415
Market Status          : 2
------------------------------------------

2025-06-03T11:00:21-05:00
--- Stream Stats ---
accepted: 1, deduplicated: 0, total_received 1, partial_reconnects: 0, full_reconnects: 0, configured_connections: 1, active_connections 1
--------------------------------------------------------------------------------------------------------------------------------------------

2025-06-03T11:00:22-05:00 Raw report data: {"fullReport":"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","feedID":"0x0004b9905d8337c34e00f8dbe31619428bac5c3937e73e6af75c71780f1770ce","validFromTimestamp":1748966422,"observationsTimestamp":1748966422}

2025-06-03T11:00:22-05:00
--- Report Stream ID: 0x0004b9905d8337c34e00f8dbe31619428bac5c3937e73e6af75c71780f1770ce ---
------------------------------------------
Observations Timestamp : 1748966422
Benchmark Price        : 1137402500000000000
Valid From Timestamp   : 1748966422
Expires At             : 1751558422
Link Fee               : 22305954748885486
Native Fee             : 121840244594291
Market Status          : 2
------------------------------------------

2025-06-03T11:00:22-05:00
--- Stream Stats ---
accepted: 2, deduplicated: 0, total_received 2, partial_reconnects: 0, full_reconnects: 0, configured_connections: 1, active_connections 1
--------------------------------------------------------------------------------------------------------------------------------------------

2025-06-03T11:00:23-05:00 Raw report data: {"fullReport":"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","feedID":"0x0004b9905d8337c34e00f8dbe31619428bac5c3937e73e6af75c71780f1770ce","validFromTimestamp":1748966423,"observationsTimestamp":1748966423}

2025-06-03T11:00:23-05:00
--- Report Stream ID: 0x0004b9905d8337c34e00f8dbe31619428bac5c3937e73e6af75c71780f1770ce ---
------------------------------------------
Observations Timestamp : 1748966423
Benchmark Price        : 1137402500000000000
Valid From Timestamp   : 1748966423
Expires At             : 1751558423
Link Fee               : 22305689648183859
Native Fee             : 121844427871698
Market Status          : 2
------------------------------------------

2025-06-03T11:00:23-05:00
--- Stream Stats ---
accepted: 3, deduplicated: 0, total_received 3, partial_reconnects: 0, full_reconnects: 0, configured_connections: 1, active_connections 1
--------------------------------------------------------------------------------------------------------------------------------------------

[...]

Decoded report details

The decoded report details include:

Attribute	Value	Description
`Feed ID`	`0x0004b9905d8337c34e00f8dbe31619428bac5c3937e73e6af75c71780f1770ce`	The unique identifier for the feed. In this example, the feed is for EUR/USD.
`Observations Timestamp`	`1748966423`	The timestamp indicating when the data was captured.
`Benchmark Price`	`1137402500000000000`	The observed price in the report, with 18 decimals. For readability: `1.1374025` USD per EUR.
`Valid From Timestamp`	`1748966423`	The start validity timestamp for the report, indicating when the data becomes relevant.
`Expires At`	`1751558423`	The expiration timestamp of the report, indicating the point at which the data becomes outdated.
`Link Fee`	`22305689648183859`	The fee to pay in LINK tokens for the onchain verification of the report data. With 18 decimals. For readability: `0.022305689648183859` LINK. Note: This example fee is not indicative of actual fees.
`Native Fee`	`121844427871698`	The fee to pay in the native blockchain token (e.g., ETH on Ethereum) for the onchain verification of the report data. With 18 decimals. For readability: `0.000121844427871698` ETH. Note: This example fee is not indicative of actual fees.
`Market Status`	`2`	The current market status. `2` indicates the market is `Open`.

Payload for onchain verification

In this guide, you log and decode the full_report payload to extract the report data. In a production environment, you should verify the data to ensure its integrity and authenticity. Refer to the Verify report data onchain guide.

Adapting code for different report schema versions

When working with different DataLink providers, you'll need to adapt your code to handle the specific report schema version they use:

Import the correct schema version module. Examples:

For v4 schema (as used in this example):

v4 "github.com/smartcontractkit/data-streams-sdk/go/report/v4"

For v3 schema:

v3 "github.com/smartcontractkit/data-streams-sdk/go/report/v3"

Update the decode function to use the correct schema version. Examples:

For v4 schema (as used in this example):

decodedReport, decodeErr := report.Decode[v4.Data](reportResponse.FullReport)

For v3 schema:

decodedReport, decodeErr := report.Decode[v3.Data](reportResponse.FullReport)

Access fields according to the schema version structure.

Explanation

Establishing a WebSocket connection and listening for reports

Your application uses the Stream function in the Data Streams SDK's client package to establish a real-time WebSocket connection with the Data Streams Aggregation Network.

Once the WebSocket connection is established, your application subscribes to one or more streams by passing an array of feed.IDs to the Stream function. This subscription lets the client receive real-time updates whenever new report data is available for the specified streams.

Decoding a report

As data reports arrive via the established WebSocket connection, they are processed in real-time:

Reading streams: The Read method on the returned Stream object is continuously called within a loop. This method blocks until new data is available, ensuring that all incoming reports are captured as soon as they are broadcasted.
Decoding reports: For each received report, the SDK's Decode function parses and transforms the raw data into a structured format (v4.Data for this example). This decoded data includes data such as the benchmark price.

Handling the decoded data

In this example, the application logs the structured report data to the terminal. However, this data can be used for further processing, analysis, or display in your own application.

Stream and Decode reports using the Go SDK (WebSocket)

Guide Versions

Get the latest Chainlink content straight to your inbox.