content-distribution

What this skill does

# AEM Cloud Service Content Distribution

> **Beta Skill**: This skill is in beta and under active development.
> Results should be reviewed carefully before use in production.
> Report issues at https://github.com/adobe/skills/issues

Programmatic content publishing and distribution monitoring using official AEM Cloud Service APIs.

## When to Use This Skill

Use this skill collection for:
- **Programmatic publishing**: Publish content via `Replicator` API
- **Distribution monitoring**: Track distribution lifecycle events
- **Automated workflows**: Integration with workflow process steps
- **Event handling**: React to distribution events (failures, completions)
- **Custom publishing logic**: Bulk operations, Preview tier publishing

## Sub-Skills

This is a parent skill that routes to specialized sub-skills based on your task:

| Task | Sub-Skill | File |
|------|-----------|------|
| Programmatically publish/unpublish content | Replication API | [replication/SKILL.md](./replication/SKILL.md) |
| Monitor distribution events and lifecycle | Sling Distribution Events | [sling-distribution/SKILL.md](./sling-distribution/SKILL.md) |

## Quick Decision Guide

**Choose Replication API** when you need to:
- Publish content from custom OSGi services
- Integrate publishing into workflow steps
- Perform bulk publishing operations
- Publish to Preview tier for review
- Check replication status programmatically

**Choose Sling Distribution Events** when you need to:
- Monitor distribution lifecycle (created, queued, distributed, imported)
- React to distribution failures
- Trigger post-distribution actions (cache warming, notifications)
- Audit distribution operations
- Track distribution metrics

## Official APIs

Both skills use official, supported AEM Cloud Service APIs:

1. **Replication API**: `com.day.cq.replication`
   - **Javadoc**: https://developer.adobe.com/experience-manager/reference-materials/cloud-service/javadoc/com/day/cq/replication/package-summary.html
   - **Main Classes**: `Replicator`, `ReplicationOptions`, `ReplicationStatus`, `ReplicationActionType`

2. **Sling Distribution API**: `org.apache.sling.distribution`
   - **Javadoc**: https://developer.adobe.com/experience-manager/reference-materials/cloud-service/javadoc/org/apache/sling/distribution/package-summary.html
   - **Main Packages**: `org.apache.sling.distribution.event` (event topics and properties)

## Architecture Overview

```
┌──────────────────────────────────────────────────┐
│ Replication API (Your Code)                     │
│ com.day.cq.replication.Replicator                │
│                                                  │
│ replicator.replicate(session, ACTIVATE, path)   │
└────────────────────┬─────────────────────────────┘
                     ↓
┌──────────────────────────────────────────────────┐
│ Sling Distribution (Underlying Transport)       │
│ org.apache.sling.distribution                    │
│                                                  │
│ [AGENT_PACKAGE_CREATED]   ← Distribution events │
│          ↓                   fire at each stage  │
│ [AGENT_PACKAGE_QUEUED]                          │
│          ↓                                       │
│ [AGENT_PACKAGE_DISTRIBUTED]                     │
│          ↓                                       │
│ Adobe Developer Pipeline Service                │
│          ↓                                       │
│ [IMPORTER_PACKAGE_IMPORTED]                     │
└──────────────────────────────────────────────────┘
                     ↓
         Content live on Publish/Preview
```

### How It Works

1. **Your code** calls `Replicator.replicate()` to publish content
2. **Sling Distribution** packages content and fires `AGENT_PACKAGE_CREATED` event
3. Package is **queued** and `AGENT_PACKAGE_QUEUED` event fires
4. Package is **sent** to Adobe Developer pipeline and `AGENT_PACKAGE_DISTRIBUTED` event fires
5. Target tier **imports** content and `IMPORTER_PACKAGE_IMPORTED` event fires
6. Content is **live** on target tier (Publish or Preview)

## Common Patterns

### Pattern 1: Publish and Monitor

Publish content and track when it goes live:

```java
// Step 1: Publish using Replication API
@Reference
private Replicator replicator;

public void publishContent(Session session, String path) throws ReplicationException {
    replicator.replicate(session, ReplicationActionType.ACTIVATE, path);
}

// Step 2: Monitor completion using Distribution Events
@Component(service = EventHandler.class, property = {
    org.osgi.service.event.EventConstants.EVENT_TOPIC + "=" + 
        DistributionEventTopics.IMPORTER_PACKAGE_IMPORTED
})
public class PublishCompletionHandler implements EventHandler {
    
    @Override
    public void handleEvent(Event event) {
        String[] paths = (String[]) event.getProperty(
            DistributionEventProperties.DISTRIBUTION_PATHS
        );
        
        LOG.info("Content is now live: {}", String.join(",", paths));
        // Trigger post-publish actions (cache warming, notifications, etc.)
    }
}
```

### Pattern 2: Preview-First Workflow

Publish to Preview for approval, then to Publish:

```java
// Workflow Step 1: Publish to Preview
public void publishToPreview(Session session, String path) throws ReplicationException {
    ReplicationOptions options = new ReplicationOptions();
    options.setFilter(agent -> "preview".equals(agent.getId()));
    
    replicator.replicate(session, ReplicationActionType.ACTIVATE, path, options);
}

// Workflow Step 2: After approval, publish to Publish tier
public void publishToProduction(Session session, String path) throws ReplicationException {
    ReplicationOptions options = new ReplicationOptions();
    options.setFilter(agent -> "publish".equals(agent.getId()));
    
    replicator.replicate(session, ReplicationActionType.ACTIVATE, path, options);
}
```

### Pattern 3: Auto-Publish with Failure Handling

Auto-publish content and alert on failures:

```java
// Publish handler
@Component(service = EventHandler.class, property = {
    org.osgi.service.event.EventConstants.EVENT_TOPIC + "=" + 
        SlingConstants.TOPIC_RESOURCE_CHANGED
})
public class AutoPublishHandler implements EventHandler {
    
    @Reference
    private Replicator replicator;
    
    @Override
    public void handleEvent(Event event) {
        String path = (String) event.getProperty(SlingConstants.PROPERTY_PATH);
        
        if (shouldAutoPublish(path)) {
            try (ResourceResolver resolver = getServiceResolver()) {
                Session session = resolver.adaptTo(Session.class);
                replicator.replicate(session, ReplicationActionType.ACTIVATE, path);
            } catch (Exception e) {
                LOG.error("Auto-publish failed", e);
            }
        }
    }
}

// Failure monitoring
@Component(service = EventHandler.class, property = {
    org.osgi.service.event.EventConstants.EVENT_TOPIC + "=" + 
        DistributionEventTopics.AGENT_PACKAGE_DROPPED
})
public class FailureAlertHandler implements EventHandler {
    
    @Reference
    private AlertService alertService;
    
    @Override
    public void handleEvent(Event event) {
        String packageId = (String) event.getProperty(
            DistributionEventProperties.DISTRIBUTION_PACKAGE_ID
        );
        
        alertService.sendAlert("Distribution failed", packageId);
    }
}
```

## Rate Limits and Constraints

| Constraint | Limit | Impact |
|-----------|-------|--------|
| Paths per API call (recommended) | 100 | Transactional guarantee; system auto-splits above this |
| Payload size | 10 MB | Excluding binaries |

> **Note**: `ReplicationOptions.setUseAtomicCalls()` is `@Deprecated` / "no longer required" per the Cloud Service Javadoc — the system handles auto-bucketing automatically for >100 paths.

**Best Practice**: For large hierarchical content trees, use the Tree Activation workflow step instead of custom code.

## Key Differences from AEM 6.x

| Feature