adobe/content-distribution

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 | | Monitor distribution events and lifecycle | Sling Distribution Events | 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:

// 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:

// 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:

// 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 | AEM 6.x | AEM Cloud Service | |---------|---------|-------------------| | Replication API | com.day.cq.replication.Replicator | ✅ Same API | | Replication agents | Manual configuration | ✅ Automatic (managed by Adobe) | | Transport mechanism | Direct JCR replication | ✅ Sling Distribution via Adobe pipeline | | Preview tier | Not available | ✅ Available (requires agent filtering) | | Distribution events | Limited | ✅ Full lifecycle via org.apache.sling.distribution.event | | Agent configuration | Manual OSGi config | ❌ Not exposed (managed by Adobe) |

When NOT to Use These Skills

Use UI workflows instead when:

• Publishing small amounts of content manually
• One-off publishing operations
• Content authors can use Quick Publish or Manage Publication

Use Tree Activation workflow when:

• Publishing large hierarchical content trees
• Bulk operations across hundreds of paths and no custom logic is needed

Quick Reference

Replication API Basics

// Inject service
@Reference
private Replicator replicator;

// Publish single page
replicator.replicate(session, ReplicationActionType.ACTIVATE, "/content/mysite/page");

// Unpublish
replicator.replicate(session, ReplicationActionType.DEACTIVATE, "/content/mysite/page");

// Bulk publish (≤100 for transactional guarantee)
replicator.replicate(session, ReplicationActionType.ACTIVATE, 
    new String[]{"/content/page1", "/content/page2"}, null);

// Publish to Preview
ReplicationOptions options = new ReplicationOptions();
options.setFilter(agent -> "preview".equals(agent.getId()));
replicator.replicate(session, ReplicationActionType.ACTIVATE, "/content/page", options);

// Check status
ReplicationStatus status = replicator.getReplicationStatus(session, "/content/page");
boolean isPublished = status != null && status.isActivated();

Distribution Event Handling Basics

// Listen for distribution events
@Component(service = EventHandler.class, property = {
    org.osgi.service.event.EventConstants.EVENT_TOPIC + "=" + 
        DistributionEventTopics.AGENT_PACKAGE_CREATED,
    org.osgi.service.event.EventConstants.EVENT_TOPIC + "=" + 
        DistributionEventTopics.AGENT_PACKAGE_DISTRIBUTED,
    org.osgi.service.event.EventConstants.EVENT_TOPIC + "=" + 
        DistributionEventTopics.AGENT_PACKAGE_DROPPED,
    org.osgi.service.event.EventConstants.EVENT_TOPIC + "=" + 
        DistributionEventTopics.IMPORTER_PACKAGE_IMPORTED
})
public class DistributionMonitor implements EventHandler {
    
    @Override
    public void handleEvent(Event event) {
        String topic = event.getTopic();
        String packageId = (String) event.getProperty(
            DistributionEventProperties.DISTRIBUTION_PACKAGE_ID
        );
        String[] paths = (String[]) event.getProperty(
            DistributionEventProperties.DISTRIBUTION_PATHS
        );
        
        // Handle event based on topic
        if (DistributionEventTopics.AGENT_PACKAGE_DROPPED.equals(topic)) {
            LOG.error("Distribution failed: {}", packageId);
        } else if (DistributionEventTopics.IMPORTER_PACKAGE_IMPORTED.equals(topic)) {
            LOG.info("Content is live: {}", String.join(",", paths));
        }
    }
}

Best Practices

1. Use the right API: Replication API for publishing, Distribution events for monitoring
2. Respect rate limits: ≤100 paths for transactional guarantee
3. Handle failures: Always catch ReplicationException, monitor AGENT_PACKAGE_DROPPED events
4. Use service users: Never use admin credentials
5. Filter events appropriately: Only listen to events you need
6. Validate permissions: Call replicator.checkPermission() before replication
7. Publish only what's needed: Avoid unnecessary bulk operations

Troubleshooting

Replication Issues

| Issue | Solution | |-------|----------| | ReplicationException | Check service user has crx:replicate permission | | Content not on target tier | Verify agent filter, check replication status | | "Too many paths" error | Use ≤100 paths for transactional guarantee, or pass all paths — system auto-splits |

Event Handling Issues

| Issue | Solution | |-------|----------| | Event handler not firing | Verify event topic constant matches exactly | | Missing event properties | Always null-check event properties | | Handler slowing distribution | Use async job processing, don't block |

Detailed Documentation

For detailed examples, code samples, and advanced usage:

• Replication API: See replication/SKILL.md
• Sling Distribution Events: See sling-distribution/SKILL.md

References

• Replication Javadoc: https://developer.adobe.com/experience-manager/reference-materials/cloud-service/javadoc/com/day/cq/replication/package-summary.html
• Sling Distribution Javadoc: https://developer.adobe.com/experience-manager/reference-materials/cloud-service/javadoc/org/apache/sling/distribution/package-summary.html
• Adobe Documentation: https://experienceleague.adobe.com/docs/experience-manager-cloud-service/content/operations/replication.html
• Sling Distribution: https://sling.apache.org/documentation/bundles/content-distribution.html
• Service Users / Repo Init: https://experienceleague.adobe.com/en/docs/experience-manager-cloud-service/content/implementing/developing/aem-project-content-package-structure#repo-init