Fetch and Decode reports using the Rust SDK

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Fetch and decode reports using the Rust SDK

Fetch and decode reports using the Go SDK Fetch and decode reports using the Rust SDK

In this guide, you'll learn how to use the Data Streams SDK for Rust to fetch and decode DataLink feeds from the Aggregation Network. You'll set up your Rust project, retrieve a report, decode it, and log its attributes.

Requirements

• Rust: Make sure you have Rust installed. You can install Rust by following the instructions on the official Rust website.
• 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

You'll start with the set up of your Rust project. Next, you'll fetch and decode a report and log its attributes to your terminal.

Set up your Rust project

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

   mkdir my-datalink-project && cd my-datalink-project
   

2. Initialize a new Rust project:

   cargo init
   

3. Add the following dependencies to your Cargo.toml file:

   [dependencies]
   chainlink-data-streams-sdk = "1.0.0"
   chainlink-data-streams-report = "1.0.0"
   tokio = { version = "1.4", features = ["full"] }
   hex = "0.4"
   

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.

1. Import the appropriate schema version in your code (e.g., v4).
2. 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.

Fetch and decode a report with a single stream

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

   use chainlink_data_streams_report::feed_id::ID;
   use chainlink_data_streams_report::report::{ decode_full_report, v4::ReportDataV4 };
   use chainlink_data_streams_sdk::client::Client;
   use chainlink_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 = ReportDataV4::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.price);
      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!("Market Status         : {}", report_data.market_status);
      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 EUR/USD DataLink feed. This feed ID is 0x0004b9905d8337c34e00f8dbe31619428bac5c3937e73e6af75c71780f1770ce.

   Build and run your application:

   cargo run -- 0x0004b9905d8337c34e00f8dbe31619428bac5c3937e73e6af75c71780f1770ce
   

   Expect output similar to the following in your terminal:

   Raw report data: Report { feed_id: 0x0004b9905d8337c34e00f8dbe31619428bac5c3937e73e6af75c71780f1770ce, valid_from_timestamp: 1748966929, observations_timestamp: 1748966929, full_report: "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" }
   
   
   Decoded Report for Stream ID 0x0004b9905d8337c34e00f8dbe31619428bac5c3937e73e6af75c71780f1770ce:
   ------------------------------------------
   Observations Timestamp: 1748966929
   Benchmark Price       : 1137940000000000000
   Valid From Timestamp  : 1748966929
   Expires At            : 1751558929
   Link Fee              : 22354237602048880
   Native Fee            : 122218105848518
   Market Status         : 2
   ------------------------------------------
   

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.

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:

1. Import the correct schema version module. Examples:

   • For v4 schema (as used in this example):

      use chainlink_data_streams_report::report::{ decode_full_report, v4::ReportDataV4 };
     

   • For v3 schema:

     use chainlink_data_streams_report::report::{ decode_full_report, v3::ReportDataV3 };
     

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

   • For v4 schema (as used in this example):

     let report_data = ReportDataV4::decode(&report_blob)?;
     

   • For v3 schema:

     let report_data = ReportDataV3::decode(&report_blob)?;
     

3. Access fields according to the schema version structure.

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: ReportDataV4::decode parses the report blob into structured data:

   • Feed ID (unique identifier for the feed)
   • Observations timestamp (when the data was captured)
   • Benchmark price (18 decimal places)
   • Validity timestamps (valid from and expires at)
   • Fee information for onchain verification (LINK and native token fees)
   • Market status (0=Unknown, 1=Closed, 2=Open, 3=Suspended)

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.