The integration with Solana enhances the Messaging Layer’s capabilities for payment processing and authorization, offering a decentralized solution for paid device usage. This integration ensures transaction security and automates payment workflows.
Payment Validation: The system uses Solana’s RPC interface to verify user payment eligibility. For instance, before a device transitions to a working state, it checks if the user has prepaid sufficient funds. This ensures fairness and economic incentives for service usage.
State-Payment Linkage: Device state changes (e.g., from “available” to “working”) trigger corresponding payment actions. When a device starts working, the system locks the user’s prepaid funds; upon completion, the actual cost is settled and transferred. This linkage is driven by messaging events, minimizing manual intervention.
Fault Tolerance and Error Handling: If a payment operation fails (e.g., due to insufficient funds), the system automatically reverts the device state and notifies stakeholders. This design enhances robustness, preventing inconsistencies due to payment issues.
Scalability: Solana’s high throughput and low transaction costs make it ideal for managing payments across a large device network. The Messaging Layer leverages this to support extensive deployments without performance bottlenecks.
In your application, this integration manifests as collaboration between device controllers and servers: controllers initiate state change requests, while servers validate payments and confirm updates, all seamlessly connected via the messaging layer.
Hello World (Integrate Solana)!
Prerequisites
Before you begin, ensure you have the following installed:
Step 1: Update the Workspace Dependencies
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[workspace]
members = ["subscriber", "publisher"]
[dependencies]
nostr-sdk = "0.38.0"
nostr = "0.38.0"
solana-sdk = "2.2.2"
solana-client = "2.2.6"
serde_json = "1.0.140"
serde = "1.0.219"
tokio = { version = "1.38.0", features = ["full"] }
Step 2: Update the Publisher
Edit publisher/Cargo.toml to use workspace dependencies:
Replace the contents of subscriber/src/main.rs with this code to subscribe to events and request a Solana airdrop:
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use nostr::{key::Keys, types::{SingleLetterTag, Timestamp}, Kind};
use nostr_sdk::{Client, Filter, RelayPoolNotification};
use serde::Deserialize;
use solana_client::rpc_client::RpcClient;
use solana_sdk::pubkey::Pubkey;
use std::str::FromStr;
#[derive(Deserialize)]
struct Message {
greeting: String,
solana_pubkey: String,
}
const MENTION_TAG: SingleLetterTag = SingleLetterTag::lowercase(nostr::Alphabet::P);
const SESSION_TAG: SingleLetterTag = SingleLetterTag::lowercase(nostr::Alphabet::S);
#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
// Initialize the Nostr client
let keys: Keys = Keys::generate();
let client_opts = nostr_sdk::Options::default();
let client = Client::builder()
.signer(keys.clone())
.opts(client_opts)
.build();
client.add_relay("wss://dev-relay.xephy.dev").await?;
client.connect().await;
// Define a filter for "Hello World" events
let filter = Filter::new()
.kind(Kind::Custom(1573))
.since(Timestamp::now())
.custom_tag(SESSION_TAG, ["hello_session"])
.custom_tag(MENTION_TAG, ["receiver_pubkey"]);
// Subscribe to the filter
client.subscribe(vec![filter], None).await?;
println!("Subscribed events on wss://dev-relay.xephy.dev");
// Initialize Solana testnet client
let solana_client = RpcClient::new("https://api.devnet.solana.com".to_string());
// Handle notifications asynchronously
client
.handle_notifications(|notification| async {
match notification {
RelayPoolNotification::Event { event, .. } => {
println!("Received {}", event.content);
// Parse the JSON content
if let Ok(message) = serde_json::from_str::<Message>(&event.content) {
// Request airdrop to the solana_pubkey
if let Ok(pubkey) = Pubkey::from_str(&message.solana_pubkey) {
match solana_client.request_airdrop(&pubkey, 1_000_000_000) {
Ok(signature) => {
println!(
"Airdrop requested for {}. Signature: {}",
pubkey, signature
);
if let Ok(confirmed) =
solana_client.confirm_transaction(&signature)
{
if confirmed {
println!("Airdrop confirmed for {}", pubkey);
}
}
}
Err(e) => println!("Airdrop failed: {:?}", e),
}
} else {
println!("Invalid Solana pubkey: {}", message.solana_pubkey);
}
} else {
println!("Failed to parse message content");
}
}
_ => {} // Ignore other notification types
}
Ok(false) // Keep listening (false means don't stop)
})
.await?;
Ok(())
}
Step 4: Compile and Run
Run the Subscriber (in one terminal):
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cargo run -p subscriber
Run the Publisher (in a new terminal):
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cargo run -p publisher
Expected Output:
Subscriber terminal:
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Subscribed events on wss://dev-relay.xephy.dev
Publisher terminal:
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Published 'Hello World' event to wss://dev-relay.xephy.dev
Airdrop request for [ ... ]
Subscriber terminal:
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Received: {"greeting":"Hello World","solana_pubkey":"..."}
Airdrop requested for ... Signature: ...
Airdrop confirmed for ...
Next Steps
This example demonstrates a basic integration between Messaging Layer and Solana. You could extend this further by:
Deploying a Solana smart contract (program) to handle more complex interactions
Using Nostr events to trigger contract calls
Implementing payment verification or other blockchain-based logic
Adding error handling and retry mechanisms for airdrop requests
This simple integration opens the door to building decentralized applications that combine messaging capabilities with Solana's high-performance blockchain.
