EventDispatch

EventDispatch is an event-driven notification orchestration service built with Clojure, Kafka, and Datomic. It exposes a REST API to create and manage notifications, publishes events to Kafka for asynchronous processing, and persists an immutable delivery history in Datomic for auditing and analytics.

Overview

EventDispatch handles high-volume event streams by:

• Receiving events from multiple producers
• Distributing them through load balancers
• Processing them asynchronously via Kafka
• Storing an immutable history in Datomic

Architecture

EventDispatch follows the Hexagonal Architecture (Ports & Adapters) pattern, which promotes decoupling and testability:

graph LR
    subgraph external [External World]
        HTTPClient([HTTP Clients])
        KafkaBrokerExt([Kafka Broker])
        DatomicDB[(Datomic DB)]
    end

    subgraph boundary [Boundary Layer]
        HTTPDiplomat["HTTP Diplomat<br/>(Wire Format)"]
        KafkaDiplomat["Kafka Diplomat<br/>(Wire Format)"]
        HTTPAdapter["HTTP Adapter<br/>(Inbound)"]
        KafkaAdapter["Kafka Adapter<br/>(Outbound)"]
        DatomicAdapter["Datomic Adapter<br/>(Outbound)"]
    end

    subgraph domain [Domain Core]
        Controllers["Controllers<br/>(notification_controller)"]
        Logic["Logic Layer<br/>(notification_logic)"]
        Models["Models<br/>(notification, event)"]
    end

    HTTPClient -->|REST| HTTPDiplomat
    HTTPDiplomat -->|Serialize/Deserialize| HTTPAdapter
    HTTPAdapter -->|Request| Controllers
    Controllers -->|Business Rules| Logic
    Logic -->|Data| Models
    
    Logic -->|Event| KafkaAdapter
    KafkaAdapter -->|Kafka Diplomat| KafkaDiplomat
    KafkaDiplomat -->|Message| KafkaBrokerExt
    
    Logic -->|Persist| DatomicAdapter
    DatomicAdapter -->|Query| DatomicDB

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Design Principles

• Models: Pure domain entities representing business concepts
• Logic: Business rules and orchestration logic
• Controllers: Application entry points that coordinate logic
• Diplomats: Handle serialization/deserialization of wire formats
• Adapters: Implement ports to communicate with external systems
• Ports: Protocols that define contracts between domain and adapters

Getting Started

Prerequisites

• Java 11 or higher
• Clojure 1.10+
• Kafka 2.8+
• Datomic

Installation

git clone https://github.com/Ryanditko/EventDispatch.git
cd EventDispatch
lein deps

Development

lein run

License

This project is licensed under the MIT License.