Arvo - A toolkit for event driven applications (arvo-core)

The foundational package of, Arvo, a TypeScript toolkit for building event-driven applications that are distributed system-compliant. Arvo Core provides CloudEvents-compliant event primitives, type-safe contract validation, and OpenTelemetry observability without infrastructure lock-in.

This package gives you three essential building blocks for event-driven architecture:

ArvoEvent - CloudEvents-compliant event primitives with built-in validation, tracing, and execution cost tracking.

ArvoContract - Type-safe service interfaces with semantic versioning. Define what events your services accept and emit with automatic runtime validation and compile-time type inference.

ArvoEventFactory - Contract-bound factories that create validated events with full IntelliSense support and OpenTelemetry integration.

Installation

npm install arvo-core zod@3

Quick Start

import { createArvoContract, createArvoEventFactory } from 'arvo-core';
import { z } from 'zod';

// Define a contract
const userContract = createArvoContract({
  uri: '#/contracts/user',
  type: 'user.create',
  versions: {
    '1.0.0': {
      accepts: z.object({
        email: z.string().email(),
        name: z.string()
      }),
      emits: {
        'evt.user.create.success': z.object({
          userId: z.string(),
          timestamp: z.string()
        })
      }
    }
  }
});

// Create events with type safety
const factory = createArvoEventFactory(userContract.version('1.0.0'));

const event = factory.accepts({
  source: 'api/users',
  data: {
    email: 'user@example.com',
    name: 'John Doe'
  }
});

Why Arvo?

Arvo abstracts infrastructure concerns from your business logic. Write application code once and deploy it anywhere - Node.js servers, serverless functions, browsers, or distributed clusters. Your business logic encapsulated in event handlers and contracts remain unchanged while you swap infrastructure integrations.

The same primitives work for simple request-response services, complex multi-service workflows, AI agent systems, and everything in between. No framework lock-in, no mandatory infrastructure, just clean event-driven code that integrates with your existing stack.

What is arvo-core?

The arvo-core is one of the two foundational packages in the Arvo ecosystem, alongside arvo-event-handler. Together, they provide the complete foundation for building event-driven applications that are distributed system-compliant. Explore additional tools and integrations in the @arvo-tools namespace.

Learn more at the official Arvo website: https://www.arvo.land/

Documentation

Complete guides, API reference, and tutorials at https://www.arvo.land/

License

MIT - See LICENSE.md

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