/messaging

name: messaging
description: Message queues, events, and async communication patterns
category: skill
allowed-tools: Read, Write, Glob, Grep, Bash
user-invocable: true
context: inject
version: 1.0.0

Messaging Skills

Overview

Asynchronous communication patterns for building scalable, decoupled distributed systems. Messaging enables services to communicate without direct coupling, improving reliability and scalability.

Messaging Types

| Type | Description | Use Case | Examples | |------|-------------|----------|----------| | **Point-to-Point** | One sender, one receiver | Task distribution | RabbitMQ, SQS | | **Pub/Sub** | One sender, many receivers | Event broadcasting | Kafka, Redis Pub/Sub | | **Request/Reply** | Synchronous over async | RPC-style calls | RabbitMQ RPC | | **Event Streaming** | Ordered, replayable log | Event sourcing | Kafka, Kinesis |

Delivery Guarantees

| Guarantee | Description | Trade-off | |-----------|-------------|-----------| | **At-most-once** | Fire and forget | May lose messages | | **At-least-once** | Retry until acknowledged | May have duplicates | | **Exactly-once** | Deduplicated delivery | Complex, higher latency |

When to Use Messaging

Use Messaging For

• Decoupling services
• Async task processing
• Event-driven architectures
• Load leveling and buffering
• Cross-service communication

Avoid Messaging When

• Simple request/response is sufficient
• Strong consistency is required
• Real-time response is critical
• System complexity isn't justified

Categories

Fundamentals

Core messaging concepts:

• **Messaging Patterns** - Common communication patterns
• **Sync vs Async** - When to use each approach
• **Message Types** - Commands, events, and queries

Queues

Message queue implementations:

• **RabbitMQ** - Feature-rich message broker
• **Redis Queues** - Simple Redis-based queues
• **AWS SQS** - Managed queue service
• **BullMQ** - Node.js job queue

Events

Event-driven patterns:

• **Event-Driven Architecture** - EDA fundamentals
• **Apache Kafka** - Event streaming platform
• **Event Sourcing** - State as event log
• **Pub/Sub** - Publish-subscribe patterns

Patterns

Distributed system patterns:

• **Saga Pattern** - Distributed transactions
• **Outbox Pattern** - Reliable event publishing
• **Retry Strategies** - Handling failures
• **Dead Letter Queue** - Failed message handling

Reliability

Ensuring message delivery:

• **Delivery Guarantees** - At-most/least/exactly-once
• **Idempotency** - Safe message reprocessing
• **Message Ordering** - Maintaining sequence

Best Practices

Production considerations:

• **Message Design** - Schema and versioning
• **Error Handling** - Failure management
• **Monitoring** - Observability and alerting

Quick Reference

Message Broker Comparison

| Feature | RabbitMQ | Kafka | SQS | Redis | |---------|----------|-------|-----|-------| | Model | Queue | Log | Queue | Queue/Pub-Sub | | Ordering | Per-queue | Per-partition | FIFO option | Per-queue | | Persistence | Durable | Always | Always | Optional | | Replay | No | Yes | No | No | | Throughput | High | Very High | High | Very High | | Latency | Low | Low | Medium | Very Low |

Common Patterns

Producer → Queue → Consumer (Point-to-Point)
Producer → Exchange → Queue → Consumer (RabbitMQ)
Producer → Topic → Partition → Consumer Group (Kafka)
Publisher → Channel → Subscribers (Pub/Sub)

Integration with F5

# In f5-config.yaml
messaging:
  broker: rabbitmq
  queues:
    - name: orders
      durable: true
      dlq: orders-dlq
  events:
    - topic: order.placed
      retention: 7d

Related Skills

• [Architecture](/skills/architecture/) - System design patterns
• [Database](/skills/database/) - Transactional outbox
• [DevOps](/skills/devops/) - Message broker deployment