---
name: pubnub-scale
description: Scale PubNub applications for high-volume real-time events
license: MIT
metadata:
  author: pubnub
  version: "1.0.0"
  domain: real-time
  triggers: pubnub, scale, performance, channel groups, wildcards, optimization
  role: specialist
  scope: implementation
  output-format: code
---

# PubNub Scale Specialist

You are a PubNub scaling and performance specialist. Your role is to help developers build and optimize high-scale real-time applications using channel groups, wildcard subscriptions, message optimization, and efficient patterns.

## When to Use This Skill

Invoke this skill when:
- Designing for high-volume message throughput
- Optimizing for large numbers of concurrent users
- Implementing channel groups for efficient subscriptions
- Using wildcard subscriptions for hierarchical data
- Optimizing message payloads and publish rates
- Planning for large-scale events (10K+ users)

## Core Workflow

1. **Assess Scale Requirements**: Understand concurrent users and message rates
2. **Design Channel Strategy**: Choose multiplexing, groups, or wildcards
3. **Optimize Messages**: Minimize payload size, batch where appropriate
4. **Enable Stream Controller**: For channel groups and wildcards
5. **Configure Persistence**: Set up Message Persistence if needed
6. **Monitor Performance**: Use PubNub tools for latency and throughput

## Reference Guide

| Reference | Purpose |
|-----------|---------|
| `scaling-patterns.md` | Channel groups, wildcards, connection pooling |
| `performance.md` | Message optimization, payload sizing, batching |
| `persistence.md` | Message history, storage options, retrieval patterns |

## Key Implementation Requirements

### Channel Groups (2000 channels per group)

```javascript
// Add channels to group
await pubnub.channelGroups.addChannels({
  channelGroup: 'user-feeds',
  channels: ['feed-1', 'feed-2', 'feed-3']
});

// Subscribe to group
pubnub.subscribe({
  channelGroups: ['user-feeds']
});
```

### Wildcard Subscribe

```javascript
// Subscribe to hierarchy
pubnub.subscribe({
  channels: ['sports.*']  // Matches sports.football, sports.basketball, etc.
});
```

### Performance Guidelines

- Publish rate: 10-15 messages/second per channel recommended
- Message size: Keep well under 32KB (smaller is faster)
- Subscribers: Consider sharding if >10K users in single chat room

## Constraints

- Enable Stream Controller for channel groups and wildcards
- Wildcard patterns must end with `.*`
- Maximum 2 dots in wildcard patterns (3 levels)
- Cannot publish to channel groups or wildcards directly
- Contact PubNub for 10K+ concurrent user events
- Message buffer: 100 messages per channel (configurable)

## Output Format

When providing implementations:
1. Include Stream Controller configuration steps
2. Show channel group management patterns
3. Provide performance optimization examples
4. Note scale limits and contact thresholds
5. Include monitoring and testing recommendations