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iii Architecture is very modular. Composed of a few Layers: Engine, Modules, Adapters. Let’s break down each layer:
  • Engine: The core of iii. It is the engine that powers the iii architecture.
  • Modules: The core modules that make up the iii architecture.
  • Adapters: The adapters that connect the iii architecture to the outside world. See Adapters for details.

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Engine

The engine is the orchestration layer. Responsible for connecting the modules to the workers.

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Core Modules

Built with Rust for exceptional speed and memory efficiency, Core Modules deliver top-tier performance. Examples of Modules:
  • HTTP Module: Expose functions as HTTP endpoints.
  • Stream Module: Durable streams for real-time data subscriptions.
  • Queue Module: Topic-based message queuing with retries and DLQ.
  • PubSub Module: Topic-based publish/subscribe for real-time events.
  • Cron Module: Schedule functions with cron expressions.
  • Observability Module: Traces, metrics, logs, and alerts (OpenTelemetry).
Within these modules, there’s an Adapter Layer, where we can configure external services to be used as their backend. For example: in the Queue Module, you can configure Redis or RabbitMQ to manage queues.

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How to configure the Engine

Let’s use the Stream Module as an example. The following file is the main configuration file for iii. Add it to your project as iii-config.yaml and iii will automatically load the modules and adapters. 
modules:
  - class: modules::stream::StreamModule
    config:
      port: ${STREAM_PORT:3112}
      host: 0.0.0.0
      adapter:
        class: modules::stream::adapters::RedisAdapter
        config:
          redis_url: ${REDIS_URL:redis://localhost:6379}
In the example above, we’re configuring only the Stream Module in the Engine. We can configure the port to listen on and the host to listen on. We’re also configuring the adapter to use for the Stream Module. In this case, we’re using the modules::stream::adapters::RedisAdapter. We can configure the Redis URL to use for the RedisAdapter.