Services & IO

Panopticon pipelines can interact with the outside world through services. The PipelineServices struct bundles two categories of functionality:

• PipelineIO - Send notifications and prompt for user input
• EventHooks - React to pipeline lifecycle events (compilation, execution, completion)

Services are optional. A pipeline without services runs silently, which is often what you want for batch processing or automated workflows. When you need feedback or interactivity, services provide a clean abstraction.

Attaching Services to a Pipeline

Use Pipeline::with_services() to attach a PipelineServices instance:

#![allow(unused)]
fn main() {
use panopticon_core::prelude::*;

let services = PipelineServices::defaults();
let mut pipeline = Pipeline::with_services(services);
}

Using PipelineIO

The PipelineIO trait provides two methods for interacting with users:

• notify(message) - Display a message (fire-and-forget)
• prompt(message) - Display a message and wait for a response

Commands access these through the ExecutionContext:

#![allow(unused)]
fn main() {
// Inside a command's execute method
ctx.services().notify("Processing started...").await?;

if let Some(answer) = ctx.services().prompt("Continue? (y/n)").await? {
    if answer.to_lowercase() == "y" {
        // proceed
    }
}
}

Multiple IO services can be registered. When you call notify, all registered services receive the message. When you call prompt, services are tried in order until one returns a response.

Event Hooks

Event hooks let you observe pipeline lifecycle events without modifying command logic. Hooks fire at key moments:

• Draft phase: After namespaces/commands are added, before/after compilation
• Ready phase: Before/after pipeline, namespace, and command execution
• Completed phase: When results are being collected

This is useful for logging, metrics, progress reporting, or custom debugging.

Default Services

PipelineServices::defaults() behaves differently based on build mode:

In debug builds, you get console output and lifecycle logging out of the box. In release builds, services start empty for maximum control.

To start with no services regardless of build mode:

#![allow(unused)]
fn main() {
let services = PipelineServices::new();
}

Implementing Custom Services

This guide covers using services. For implementing your own PipelineIO or EventHooks:

See the Extend guide: Implementing Services

The Extend guide covers:

• Implementing the PipelineIO trait for custom notification channels
• Implementing EventHooks for lifecycle callbacks
• Available hook events and their payloads
• Registering multiple services with add_io() and add_hook()