RelayService SDK - Relay Core

Overview

The RelayService class enables service providers to:

Register services with pricing and metadata
Handle payments via x402 protocol
Prove delivery with cryptographic evidence
Track reputation based on outcomes

Design Philosophy: Explicit service definition, proof-first delivery, reputation as first-class.

Installation

npm install @relaycore/sdk ethers

Quick Start

import { RelayService } from '@relaycore/sdk';
import { ethers } from 'ethers';

// Initialize service
const service = new RelayService({
  wallet: new ethers.Wallet(privateKey, provider),
  network: 'cronos-testnet',
  apiUrl: 'https://api.relaycore.xyz'
});

// Register service
const registered = await service.register({
  name: 'Pyth Price Oracle',
  description: 'Real-time price feeds from Pyth Network',
  category: 'oracle',
  price: '100000', // 0.1 USDC per call
  inputSchema: {
    type: 'object',
    properties: {
      symbol: { type: 'string' }
    },
    required: ['symbol']
  },
  outputSchema: {
    type: 'object',
    properties: {
      price: { type: 'number' },
      timestamp: { type: 'number' }
    }
  }
});

// Handle payments
service.handlePayment<{ symbol: string }, { price: number; timestamp: number }>(
  async (ctx) => {
    // Execute service logic
    const price = await getPythPrice(ctx.input.symbol);
    
    // Deliver result with proof
    await ctx.deliver({
      result: {
        price: price.value,
        timestamp: price.timestamp
      },
      proof: price.signature,
      latencyMs: Date.now() - ctx.timestamp.getTime()
    });
  }
);

Core Methods

`constructor(config: ServiceConfig)`

Initialize the service provider. Parameters:

interface ServiceConfig {
  wallet: ethers.Signer;  // Wallet for receiving payments
  network?: Network;       // 'cronos-testnet' | 'cronos-mainnet'
  apiUrl?: string;         // API endpoint
}

`register(definition: ServiceDefinition): Promise<RegisteredService>`

interface ServiceDefinition {
  name: string;
  description?: string;
  category: string;              // e.g., 'oracle', 'trading', 'data'
  price: string;                 // Price per call (base units)
  endpoint?: string;             // Service endpoint URL
  inputSchema?: JsonSchema;      // JSON Schema for input validation
  outputSchema?: JsonSchema;     // JSON Schema for output validation
  inputType?: string;            // Human-readable input type
  outputType?: string;           // Human-readable output type
  tags?: string[];               // Searchable tags
  capabilities?: string[];       // Service capabilities
  version?: string;              // Service version
}

Returns:

interface RegisteredService {
  id: string;                    // Service ID
  ownerAddress: string;          // Provider wallet address
  registeredAt: Date;
  isActive: boolean;
}

Example:

const service = await provider.register({
  name: 'DEX Quote Aggregator',
  description: 'Aggregate quotes from 6 perpetual DEX venues',
  category: 'trading',
  price: '10000', // 0.01 USDC
  inputSchema: {
    type: 'object',
    properties: {
      pair: { type: 'string' },
      side: { type: 'string', enum: ['long', 'short'] },
      leverage: { type: 'number', minimum: 1, maximum: 50 },
      sizeUsd: { type: 'number', minimum: 100 }
    },
    required: ['pair', 'side', 'leverage', 'sizeUsd']
  },
  outputSchema: {
    type: 'object',
    properties: {
      entryPrice: { type: 'number' },
      liquidationPrice: { type: 'number' },
      fundingRate: { type: 'number' },
      bestVenue: { type: 'string' }
    }
  },
  tags: ['dex', 'perpetuals', 'aggregator'],
  capabilities: ['multi-venue', 'best-execution'],
  version: '1.0.0'
});

console.log('Service registered:', service.id);

`handlePayment<TInput, TOutput>(handler: (ctx: PaymentContext<TInput>) => Promise<void>): void`

Set payment handler for incoming requests. Parameters:

interface PaymentContext<TInput> {
  paymentId: string;             // Unique payment ID
  txHash: string;                // On-chain transaction hash
  amount: string;                // Amount paid (base units)
  payerAddress: string;          // Payer wallet address
  input: TInput;                 // Service input data
  timestamp: Date;               // Payment timestamp
  
  // Delivery methods
  deliver: <TOutput>(proof: DeliveryProof<TOutput>) => Promise<void>;
  fail: (reason: string, retryable?: boolean) => Promise<void>;
}

Delivery Proof:

interface DeliveryProof<T> {
  result: T;                     // Service output
  proof?: string;                // Cryptographic proof (optional)
  evidence?: Record<string, unknown>; // Additional evidence
  latencyMs?: number;            // Execution latency
}

Example:

service.handlePayment<QuoteInput, QuoteOutput>(async (ctx) => {
  const startTime = Date.now();
  
  try {
    // Validate input
    if (!ctx.input.pair || !ctx.input.side) {
      return await ctx.fail('Invalid input: missing required fields', false);
    }
    
    // Execute service logic
    const quote = await aggregateQuotes({
      pair: ctx.input.pair,
      side: ctx.input.side,
      leverage: ctx.input.leverage,
      sizeUsd: ctx.input.sizeUsd
    });
    
    // Deliver with proof
    await ctx.deliver({
      result: {
        entryPrice: quote.entryPrice,
        liquidationPrice: quote.liquidationPrice,
        fundingRate: quote.fundingRate,
        bestVenue: quote.bestVenue
      },
      proof: quote.signature, // Optional cryptographic proof
      evidence: {
        sources: quote.sources,
        timestamp: Date.now()
      },
      latencyMs: Date.now() - startTime
    });
    
    console.log('Quote delivered:', ctx.paymentId);
    
  } catch (error) {
    // Report failure
    await ctx.fail(
      `Service error: ${error.message}`,
      true // retryable
    );
  }
});

`getReputation(): Promise<ProviderReputation>`

Get current reputation score and metrics. Returns:

interface ProviderReputation {
  reputationScore: number;       // Score 0-100
  successRate: number;           // Success rate percentage
  totalDeliveries: number;       // Total successful deliveries
  avgLatencyMs: number;          // Average latency
  trend: 'improving' | 'stable' | 'declining';
  rank?: number;                 // Rank among all providers
  percentile?: number;           // Percentile ranking
}

Example:

const reputation = await service.getReputation();

console.log('Reputation Score:', reputation.reputationScore);
console.log('Success Rate:', reputation.successRate, '%');
console.log('Avg Latency:', reputation.avgLatencyMs, 'ms');
console.log('Trend:', reputation.trend);
console.log('Rank:', reputation.rank, '(top', reputation.percentile, '%)');

`getMetrics(): Promise<ServiceMetrics>`

Get detailed service performance metrics. Returns:

interface ServiceMetrics {
  timestamp: Date;
  reputationScore: number;
  successRate: number;
  avgLatencyMs: number;
  totalCalls: number;
  totalPayments: number;
  totalRevenue: string;          // Total revenue in base units
}

Example:

const metrics = await service.getMetrics();

console.log('Total Calls:', metrics.totalCalls);
console.log('Total Revenue:', (parseInt(metrics.totalRevenue) / 1e6).toFixed(2), 'USDC');
console.log('Success Rate:', metrics.successRate, '%');

`deactivate(): Promise<void>`

Deactivate the service (stop accepting new requests). Example:

await service.deactivate();
console.log('Service deactivated');

Reputation System

How Reputation is Calculated

reputationScore = (successRate * 0.7) + (latencyScore * 0.2) + (volumeScore * 0.1)

where:
  successRate = (successfulDeliveries / totalDeliveries) * 100
  latencyScore = max(0, 100 - (avgLatencyMs / 10))
  volumeScore = min(100, (totalDeliveries / 100) * 100)

Reputation Updates

Reputation updates after each delivery:

// On successful delivery
await ctx.deliver(proof);
// → Increments successfulDeliveries
// → Updates avgLatencyMs
// → Recalculates reputationScore

// On failure
await ctx.fail(reason, retryable);
// → Increments failedDeliveries
// → Decreases reputationScore

Reputation Trends

interface ReputationTrend {
  'improving': reputationScore increased > 5 points in last 7 days
  'stable': reputationScore changed < 5 points in last 7 days
  'declining': reputationScore decreased > 5 points in last 7 days
}

Payment Events

Listen to payment events for logging and analytics:

service.on('payment:received', (event: PaymentEvent) => {
  console.log('Payment received:', event.paymentId);
  console.log('Amount:', event.amount);
  console.log('Payer:', event.payerAddress);
});

service.on('payment:settled', (event: PaymentEvent) => {
  console.log('Payment settled:', event.txHash);
});

service.on('payment:failed', (event: PaymentEvent) => {
  console.error('Payment failed:', event.error);
});

Advanced Usage

SLA Enforcement

service.handlePayment<Input, Output>(async (ctx) => {
  const startTime = Date.now();
  const SLA_MAX_LATENCY = 5000; // 5 seconds
  
  try {
    const result = await executeService(ctx.input);
    const latency = Date.now() - startTime;
    
    if (latency > SLA_MAX_LATENCY) {
      // SLA violated - refund
      await ctx.fail(
        `SLA violation: latency ${latency}ms exceeds ${SLA_MAX_LATENCY}ms`,
        false
      );
      return;
    }
    
    await ctx.deliver({
      result,
      latencyMs: latency,
      evidence: { slaCompliant: true }
    });
  } catch (error) {
    await ctx.fail(error.message, true);
  }
});

Cryptographic Proof

import { ethers } from 'ethers';

service.handlePayment(async (ctx) => {
  const result = await executeService(ctx.input);
  
  // Generate cryptographic proof
  const message = JSON.stringify({
    paymentId: ctx.paymentId,
    result,
    timestamp: Date.now()
  });
  
  const signature = await wallet.signMessage(message);
  
  await ctx.deliver({
    result,
    proof: signature,
    evidence: {
      message,
      signer: await wallet.getAddress()
    }
  });
});

Rate Limiting

const rateLimiter = new Map<string, number>();
const RATE_LIMIT = 10; // requests per minute

service.handlePayment(async (ctx) => {
  const count = rateLimiter.get(ctx.payerAddress) || 0;
  
  if (count >= RATE_LIMIT) {
    return await ctx.fail(
      'Rate limit exceeded: max 10 requests per minute',
      true
    );
  }
  
  rateLimiter.set(ctx.payerAddress, count + 1);
  setTimeout(() => {
    rateLimiter.delete(ctx.payerAddress);
  }, 60000);
  
  // Execute service...
});

Best Practices

1. Always Provide Proof

// ❌ Bad: No proof
await ctx.deliver({ result });

// ✅ Good: With proof and evidence
await ctx.deliver({
  result,
  proof: signature,
  evidence: { sources, timestamp },
  latencyMs: executionTime
});

2. Handle Errors Gracefully

try {
  const result = await executeService(ctx.input);
  await ctx.deliver({ result });
} catch (error) {
  await ctx.fail(
    error.message,
    error.code !== 'INVALID_INPUT' // retryable if not input error
  );
}

3. Track Latency

const startTime = Date.now();
const result = await executeService(ctx.input);
const latencyMs = Date.now() - startTime;

await ctx.deliver({ result, latencyMs });

4. Validate Input

service.handlePayment(async (ctx) => {
  // Validate against schema
  if (!validateInput(ctx.input, inputSchema)) {
    return await ctx.fail('Invalid input schema', false);
  }
  
  // Execute service...
});

Monetization

Pricing Strategies

// Fixed price per call
await service.register({
  price: '10000' // 0.01 USDC
});

// Dynamic pricing based on input
service.handlePayment(async (ctx) => {
  const basePrice = 10000;
  const complexityMultiplier = ctx.input.leverage / 10;
  const actualPrice = basePrice * complexityMultiplier;
  
  // Verify payment amount
  if (parseInt(ctx.amount) < actualPrice) {
    return await ctx.fail('Insufficient payment', false);
  }
  
  // Execute service...
});

Revenue Tracking

const metrics = await service.getMetrics();
const revenueUSDC = parseInt(metrics.totalRevenue) / 1e6;

console.log('Total Revenue:', revenueUSDC.toFixed(2), 'USDC');
console.log('Avg Revenue per Call:', (revenueUSDC / metrics.totalCalls).toFixed(4), 'USDC');

Next Steps

Agent SDK

Build agents that use your service

Session Management

Accept session-based payments

x402 Protocol

Understanding payment flow

Build Service Guide

Complete tutorial

SDK Documentation

​Overview

​Installation

​Quick Start

​Core Methods

​constructor(config: ServiceConfig)

​register(definition: ServiceDefinition): Promise<RegisteredService>

​handlePayment<TInput, TOutput>(handler: (ctx: PaymentContext<TInput>) => Promise<void>): void

​getReputation(): Promise<ProviderReputation>

​getMetrics(): Promise<ServiceMetrics>

​deactivate(): Promise<void>

​Reputation System

​How Reputation is Calculated

​Reputation Updates

​Reputation Trends

​Payment Events

​Advanced Usage

​SLA Enforcement

​Cryptographic Proof

​Rate Limiting

​Best Practices

​1. Always Provide Proof

​2. Handle Errors Gracefully

​3. Track Latency

​4. Validate Input

​Monetization

​Pricing Strategies

​Revenue Tracking

​Next Steps

Agent SDK

Session Management

x402 Protocol

Build Service Guide

Overview

Installation

Quick Start

Core Methods

`constructor(config: ServiceConfig)`

`register(definition: ServiceDefinition): Promise<RegisteredService>`

`handlePayment<TInput, TOutput>(handler: (ctx: PaymentContext<TInput>) => Promise<void>): void`

`getReputation(): Promise<ProviderReputation>`

`getMetrics(): Promise<ServiceMetrics>`

`deactivate(): Promise<void>`

Reputation System

How Reputation is Calculated

Reputation Updates

Reputation Trends

Payment Events

Advanced Usage

SLA Enforcement

Cryptographic Proof

Rate Limiting

Best Practices

1. Always Provide Proof

2. Handle Errors Gracefully

3. Track Latency

4. Validate Input

Monetization

Pricing Strategies

Revenue Tracking

Next Steps