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Microsoft Agent Framework Workflows Core Concepts - Events

This document provides an in-depth look at the Events system of Workflows in the Microsoft Agent Framework.

Overview

There are built-in events that provide observability into the workflow execution.

Built-in Event Types

// Workflow lifecycle events
WorkflowStartedEvent    // Workflow execution begins
WorkflowCompletedEvent  // Workflow reaches completion
WorkflowErrorEvent      // Workflow encounters an error

// Executor events
ExecutorInvokeEvent     // Executor starts processing
ExecutorCompleteEvent   // Executor finishes processing
ExecutorFailureEvent    // Executor encounters an error

// Superstep events
SuperStepStartedEvent   // Superstep begins
SuperStepCompletedEvent // Superstep completes

// Request events
RequestInfoEvent        // A request is issued

# Workflow lifecycle events
WorkflowStartedEvent    # Workflow execution begins
WorkflowOutputEvent     # Workflow produces an output
WorkflowErrorEvent      # Workflow encounters an error

# Executor events
ExecutorInvokeEvent     # Executor starts processing
ExecutorCompleteEvent   # Executor finishes processing

# Request events
RequestInfoEvent        # A request is issued

Consuming Events

using Microsoft.Agents.Workflows;

await foreach (WorkflowEvent evt in run.WatchStreamAsync())
{
    switch (evt)
    {
        case ExecutorInvokeEvent invoke:
            Console.WriteLine($"Starting {invoke.ExecutorId}");
            break;

        case ExecutorCompleteEvent complete:
            Console.WriteLine($"Completed {complete.ExecutorId}: {complete.Data}");
            break;

        case WorkflowCompletedEvent finished:
            Console.WriteLine($"Workflow finished: {finished.Data}");
            return;

        case WorkflowErrorEvent error:
            Console.WriteLine($"Workflow error: {error.Exception}");
            return;
    }
}

from agent_framework import (
    ExecutorCompleteEvent,
    ExecutorInvokeEvent,
    WorkflowOutputEvent,
    WorkflowErrorEvent,
)

async for event in workflow.run_stream(input_message):
    match event:
        case ExecutorInvokeEvent() as invoke:
            print(f"Starting {invoke.executor_id}")
        case ExecutorCompleteEvent() as complete:
            print(f"Completed {complete.executor_id}: {complete.data}")
        case WorkflowOutputEvent() as output:
            print(f"Workflow produced output: {output.data}")
            return
        case WorkflowErrorEvent() as error:
            print(f"Workflow error: {error.exception}")
            return

Custom Events

Users can define and emit custom events during workflow execution for enhanced observability.

using Microsoft.Agents.Workflows;
using Microsoft.Agents.Workflows.Reflection;

internal sealed class CustomEvent(string message) : WorkflowEvent(message) { }

internal sealed class CustomExecutor() : ReflectingExecutor<CustomExecutor>("CustomExecutor"), IMessageHandler<string>
{
    public async ValueTask HandleAsync(string message, IWorkflowContext context)
    {
        await context.AddEventAsync(new CustomEvent($"Processing message: {message}"));
        // Executor logic...
    }
}

from agent_framework import (
    handler,
    Executor,
    WorkflowContext,
    WorkflowEvent,
)

class CustomEvent(WorkflowEvent):
    def __init__(self, message: str):
        super().__init__(message)

class CustomExecutor(Executor):

    @handler
    async def handle(self, message: str, ctx: WorkflowContext[str]) -> None:
        await ctx.add_event(CustomEvent(f"Processing message: {message}"))
        # Executor logic...

Next Steps