Fetch and decode V3 reports using the Rust SDK

Guide Versions

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

Rust SDK - V3 reports for Crypto streams

Go SDK - V3 reports for Crypto streams Go SDK - V4 reports for RWA streams Rust SDK - V3 reports for Crypto streams Rust SDK - V4 reports for RWA streams

In this guide, you'll learn how to use Chainlink Data Streams with the Streams Direct implementation and the Data Streams SDK for Rust to fetch and decode V3 reports for Crypto streams from the Data Streams Aggregation Network. You'll set up your Rust project, retrieve 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.
• Rust: Make sure you have Rust installed. You can install Rust by following the instructions on the official Rust website.
• API Credentials: Access to the Streams Direct implementation requires API credentials. If you haven't already, contact us to request mainnet or testnet early access.

Guide

You'll start with the set up of your Rust project. Next, you'll fetch and decode reports for crypto streams and log their attributes to your terminal.

Set up your Rust project

1. Create a new directory for your project and navigate to it:

   mkdir my-data-streams-project && cd my-data-streams-project
   

2. Initialize a new Rust project:

   cargo init
   

3. Add the Data Streams SDK to your Cargo.toml:

   [dependencies]
   data-streams-sdk = { git = "https://github.com/smartcontractkit/data-streams-sdk.git", subdir = "rust/crates/sdk" }
   data-streams-report = { git = "https://github.com/smartcontractkit/data-streams-sdk.git", subdir = "rust/crates/report" }
   tokio = { version = "1.4", features = ["full"] }
   hex = "0.4"
   

Fetch and decode a report with a single stream

1. Replace the contents of src/main.rs with the following code:

   use data_streams_report::feed_id::ID;
   use data_streams_report::report::{decode_full_report, v3::ReportDataV3};
   use data_streams_sdk::client::Client;
   use data_streams_sdk::config::Config;
   use std::env;
   use std::error::Error;
   
   #[tokio::main]
   async fn main() -> Result<(), Box<dyn Error>> {
       // Get feed ID from command line arguments
       let args: Vec<String> = env::args().collect();
       if args.len() < 2 {
           eprintln!("Usage: cargo run [FeedID]");
           std::process::exit(1);
       }
       let feed_id_input = &args[1];
   
       // Get API credentials from environment variables
       let api_key = env::var("API_KEY").expect("API_KEY must be set");
       let api_secret = env::var("API_SECRET").expect("API_SECRET must be set");
   
       // Initialize the configuration
       let config = Config::new(
           api_key,
           api_secret,
           "https://api.testnet-dataengine.chain.link".to_string(),
           "wss://api.testnet-dataengine.chain.link/ws".to_string(),
       )
       .build()?;
   
       // Initialize the client
       let client = Client::new(config)?;
   
       // Parse the feed ID
       let feed_id = ID::from_hex_str(feed_id_input)?;
   
       // Fetch the latest report
       let response = client.get_latest_report(feed_id).await?;
       println!("\nRaw report data: {:?}\n", response.report);
   
       // Decode the report
       let full_report = hex::decode(&response.report.full_report[2..])?;
       let (_report_context, report_blob) = decode_full_report(&full_report)?;
       let report_data = ReportDataV3::decode(&report_blob)?;
   
       // Print decoded report details
       println!("\nDecoded Report for Stream ID {}:", feed_id_input);
       println!("------------------------------------------");
       println!("Observations Timestamp: {}", response.report.observations_timestamp);
       println!("Benchmark Price       : {}", report_data.benchmark_price);
       println!("Bid                   : {}", report_data.bid);
       println!("Ask                   : {}", report_data.ask);
       println!("Valid From Timestamp  : {}", response.report.valid_from_timestamp);
       println!("Expires At            : {}", report_data.expires_at);
       println!("Link Fee              : {}", report_data.link_fee);
       println!("Native Fee            : {}", report_data.native_fee);
       println!("------------------------------------------");
   
       Ok(())
   }
   

2. Set up 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.

3. For this example, you will read from the ETH/USD crypto stream. This stream ID is 0x000359843a543ee2fe414dc14c7e7920ef10f4372990b79d6361cdc0dd1ba782. See the Stream Addresses page for a complete list of available crypto assets.

   Build and run your application:

   cargo run -- 0x000359843a543ee2fe414dc14c7e7920ef10f4372990b79d6361cdc0dd1ba782
   

   Expect output similar to the following in your terminal:

   Raw report data: Report { feed_id: 0x000359843a543ee2fe414dc14c7e7920ef10f4372990b79d6361cdc0dd1ba782, valid_from_timestamp: 1734124400, observations_timestamp: 1734124400, full_report: "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" }
   
   
   Decoded Report for Stream ID 0x000359843a543ee2fe414dc14c7e7920ef10f4372990b79d6361cdc0dd1ba782:
   ------------------------------------------
   Observations Timestamp: 1734124400
   Benchmark Price       : 3904011708000000000000
   Bid                   : 3903888333211164500000
   Ask                   : 3904628100124598400000
   Valid From Timestamp  : 1734124400
   Expires At            : 1734210800
   Link Fee              : 3574678975954600
   Native Fee            : 25614677280600
   ------------------------------------------
   

Decoded report details

The decoded report details include:

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.

Explanation

Initializing the API client and configuration

The API client is initialized in two steps:

1. Config::new creates a configuration with your API credentials and endpoints. This function:

   • Validates your API key and secret
   • Sets up the REST API endpoint for data retrieval
   • Configures optional settings like TLS verification

2. Client::new creates the HTTP client with your configuration. This client:

   • Handles authentication automatically
   • Manages HTTP connections
   • Implements retry logic for failed requests

Fetching reports

The SDK provides several methods to fetch reports through the REST API:

1. Latest report: get_latest_report retrieves the most recent report for a feed:

   • Takes a feed ID as input
   • Returns a single report with the latest timestamp
   • Useful for applications that need the most current data

2. Historical report: get_report fetches a report at a specific timestamp:

   • Takes both feed ID and timestamp
   • Returns the report closest to the requested timestamp
   • Helpful for historical analysis or verification

Each API request automatically:

• Generates HMAC authentication headers
• Includes proper timestamps
• Handles HTTP response status codes
• Deserializes the JSON response into Rust structures

Decoding reports

Reports are decoded in three stages:

1. Hex decoding: The full_report field comes as a hex string prefixed with "0x":

   let full_report = hex::decode(&response.report.full_report[2..])?;
   

2. Report separation: decode_full_report splits the binary data:

   • Extracts the report context (metadata)
   • Isolates the report blob (actual data)
   • Validates the report format

3. Data extraction: ReportDataV3::decode parses the report blob into structured data:

   • Benchmark price (18 decimal places)
   • Bid and ask prices for liquidity-weighted pricing
   • Fee information for onchain verification
   • Timestamp information

Error handling

The example demonstrates Rust's robust error handling:

1. Type-safe errors:

   • Uses custom error types for different failure scenarios
   • Implements the Error trait for proper error propagation
   • Provides detailed error messages for debugging

2. Error propagation:

   • Uses the ? operator for clean error handling
   • Converts errors between types when needed
   • Bubbles up errors to the main function

3. Input validation:

   • Checks command-line arguments
   • Validates environment variables
   • Verifies feed ID format

The decoded data can be used for further processing, analysis, or display in your application. For production environments, you must verify the data onchain using the provided full_report payload.