apollo-reference-architecture

# Apollo Reference Architecture

## Overview
Production-ready reference architecture for Apollo.io integrations covering system design, data flows, and integration patterns.

## Architecture Diagram

```
+------------------+     +------------------+     +------------------+
|   Frontend       |     |   API Gateway    |     |   Apollo API     |
|   (React/Vue)    |---->|   (Express)      |---->|   (External)     |
+------------------+     +------------------+     +------------------+
                                |                        |
                                v                        |
                    +------------------+                 |
                    |   Apollo Service |<----------------+
                    |   (Business Logic)|
                    +------------------+
                          |    |    |
            +-------------+    |    +-------------+
            v                  v                  v
    +------------+     +------------+     +------------+
    |   Cache    |     |  Database  |     |   Queue    |
    |   (Redis)  |     | (Postgres) |     |   (Bull)   |
    +------------+     +------------+     +------------+
```

## Project Structure

```
src/
├── lib/
│   └── apollo/
│       ├── client.ts          # Apollo API client
│       ├── cache.ts           # Caching layer
│       ├── rate-limiter.ts    # Rate limiting
│       ├── errors.ts          # Custom errors
│       └── types.ts           # TypeScript types
├── services/
│   └── apollo/
│       ├── search.service.ts  # People/org search
│       ├── enrich.service.ts  # Enrichment logic
│       ├── sequence.service.ts # Email sequences
│       └── sync.service.ts    # Data synchronization
├── jobs/
│   └── apollo/
│       ├── enrich.job.ts      # Background enrichment
│       ├── sync.job.ts        # Periodic sync
│       └── cleanup.job.ts     # Cache cleanup
├── routes/
│   └── api/
│       └── apollo/
│           ├── search.ts      # Search endpoints
│           ├──