AWS AppSync GraphQL + Event API Example

This project demonstrates a complete serverless backend using AWS AppSync with both GraphQL API and Event API capabilities, deployed with AWS SAM.

Architecture

The application consists of:

• GraphQL API: Traditional GraphQL operations (queries, mutations) for CRUD operations
• Event API: Real-time event streaming for live notifications and updates
• DynamoDB: NoSQL database for data persistence
• Lambda Functions: Serverless compute for business logic and event publishing
• Authentication: Lambda-based auth for both APIs

Features

GraphQL API

• Create and fetch stories
• Add comments to stories
• Query stories with comments
• External API proxy functionality

Event API

• Real-time event publishing
• WebSocket connections for live updates
• Channel-based event routing
• API key authentication

Integration

• GraphQL mutations automatically publish events
• Real-time notifications when data changes
• Consistent authentication across both APIs

Prerequisites

• AWS CLI configured with appropriate permissions
• Node.js 22+ and npm
• AWS SAM CLI
• Git

Deployment

1. Clone and install dependencies:

   git clone <repository-url>
   cd appsync-sam-example
   cd backend && npm install

2. Build the application:

   make

3. Deploy to AWS:

   sam deploy --profile your-aws-profile --region us-east-1

   Replace your-aws-profile with your actual AWS CLI profile name.

API Endpoints

After deployment, you'll get these outputs:

• GraphQL API URL: AppSyncGraphQLUrl
• Event API HTTP URL: EventApiHttpURL
• Event API WebSocket URL: EventApiWebSocketURL
• Event API Key: EventApiKey

Usage Examples

GraphQL Operations

The project includes Bruno collections with ready-to-use GraphQL queries and mutations:

Available Operations:

• Queries (docs/appsync-sam-example/queries/):

  • fetchStories.bru - Fetch paginated stories
  • getStory.bru - Get single story with comments
  • getUrlHttpDataSource.bru - Test HTTP data source
  • getUrlLambdaDataSource.bru - Test Lambda data source

• Mutations (docs/appsync-sam-example/mutations/):

  • createStory.bru - Create a new story
  • createStoryComment.bru - Add comment to story

To use the Bruno collections:

1. Install Bruno
2. Open the docs/appsync-sam-example/ directory in Bruno
3. Configure the environment with your GraphQL API URL and auth headers
4. Run the requests to test the API

Event API

Connect via WebSocket:

wss://your-event-api-url/event/realtime

Subscribe to Events:

// Subscribe to story events
const subscription = client.subscribe({
  channel: 'default/stories'
});

// Subscribe to comment events
const commentSub = client.subscribe({
  channel: 'default/stories/story-id/comments'
});

Project Structure

├── backend/
│   ├── src/
│   │   ├── graphql/
│   │   │   ├── schema.graphql
│   │   │   ├── modules/        # TypeScript resolvers
│   │   │   └── resolvers/      # Compiled JS resolvers
│   │   └── lambdas/            # Lambda functions
│   └── package.json
├── template.yaml                # SAM template
├── Makefile                     # Build automation
└── README.md

Development

• Linting: npm run lint
• Building: make build
• Testing: Deploy and test with GraphQL client or Event API client

Architecture Benefits

1. Real-time Updates: Event API provides live notifications
2. Scalable: Serverless architecture auto-scales
3. Secure: Lambda-based authentication
4. Integrated: GraphQL mutations trigger events automatically
5. Cost-effective: Pay-per-use pricing

Technologies Used

• AWS AppSync (GraphQL + Event APIs)
• AWS Lambda (Node.js/TypeScript)
• Amazon DynamoDB
• AWS SAM
• TypeScript
• GraphQL