> ## Documentation Index
> Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Event Patterns Scheduled Events and Pipes

> This guide explores core components of event-driven architectures in AWS EventBridge, including Event Patterns, Scheduled Events, and Pipes for efficient event response.

In this guide, we’ll explore three core components of event-driven architectures in AWS EventBridge: Event Patterns, Scheduled Events, and Pipes. Mastering these concepts helps you build reliable, maintainable, and scalable systems that respond to events efficiently.

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***

## 1. Event Patterns

Event Patterns filter incoming events based on specific criteria so you only process what matters.

### Why Use Event Patterns

* Focus on critical events (e.g., `DatabaseTimeout`).
* Minimize alert noise and unnecessary processing.
* Improve system performance by discarding irrelevant events.

<Callout icon="triangle-alert" color="#FF6B6B">
  Overly broad patterns can flood your pipeline with unwanted events. Too narrow patterns risk missing important alerts.
</Callout>

### Key Pattern Attributes

| Attribute   | Description                        | Example                                |
| ----------- | ---------------------------------- | -------------------------------------- |
| source      | Originating service or application | `["com.myapp.database"]`               |
| detail-type | Event category                     | `["Error"]`                            |
| detail      | JSON object with custom filters    | `{ "errorCode": ["DatabaseTimeout"] }` |

### Example: Match a Database Timeout

```json theme={null}
{
  "source": ["com.myapp.database"],
  "detail-type": ["Error"],
  "detail": {
    "errorCode": ["DatabaseTimeout"]
  }
}
```

This pattern only matches events where:\
• `source` = `com.myapp.database`\
• `detail-type` = `Error`\
• `detail.errorCode` = `DatabaseTimeout`

***

## 2. Scheduled Events (Schedulers)

Scheduled Events let you trigger rules on a fixed schedule, using either **rate** or **cron** expressions.

### Rate Expressions

Use `rate()` to fire at regular intervals—perfect for heartbeats and metrics.

```json theme={null}
{
  "ScheduleExpression": "rate(1 hour)",
  "State": "ENABLED"
}
```

This rule runs every hour for tasks like health checks or rolling metrics.

### Cron Expressions

Use `cron()` for precise timing—ideal for backups, reports, and maintenance windows.

```json theme={null}
{
  "ScheduleExpression": "cron(0 2 * * ? *)",
  "State": "ENABLED"
}
```

This fires daily at 2:00 AM UTC.

| Schedule Type | Expression          | Use Case                        |
| ------------- | ------------------- | ------------------------------- |
| Rate          | `rate(1 hour)`      | Hourly health checks            |
| Cron          | `cron(0 2 * * ? *)` | Nightly backups/reports at 2 AM |

***

## 3. Pipes

Pipes connect an event source to a target, optionally transforming the data in transit. Think of them as an assembly line:

1. **Source**: AWS service or custom producer (e.g., SQS, Kinesis).
2. **Transformation**: Filter or enrich payloads using `InputTemplate`.
3. **Target**: AWS service or HTTP endpoint (e.g., Lambda, SNS).

<Callout icon="lightbulb" color="#1CB2FE">
  Pipes simplify data flow and reduce the need for custom glue code by handling filtering, mapping, and retry logic automatically.
</Callout>

### Example: Redacting Sensitive Fields

```yaml theme={null}
Source:
  Arn: arn:aws:sqs:us-east-1:123456789012:my-queue
  Type: SQS
Target:
  Arn: arn:aws:lambda:us-east-1:123456789012:function:process-events
  Type: LAMBDA
InputTemplate: |
  {
    "userId": <$.detail.userId>,
    "action": <$.detail.action>,
    "timestamp": <$.time>
  }
```

Here, the pipe:

* Reads messages from an SQS queue.
* Discards sensitive fields (e.g., `$.detail.password`).
* Invokes a Lambda function with sanitized event data.

***

These three building blocks—Event Patterns, Scheduled Events, and Pipes—form the backbone of event-driven solutions in AWS EventBridge. Use them together to create efficient, scalable, and maintainable event workflows.

***

## Links and References

* [AWS EventBridge Documentation](https://docs.aws.amazon.com/eventbridge/latest/userguide/)
* [Scheduling Expressions in EventBridge](https://docs.aws.amazon.com/eventbridge/latest/userguide/scheduled-events.html)
* [EventBridge Pipes Overview](https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-pipes.html)

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