Implementation:Microsoft Semantic kernel AddStepFromProcess

Knowledge Sources	Semantic Kernel Semantic Kernel Docs
Domains	Process_Orchestration, Composite_Pattern
Last Updated	2026-02-11 19:00 GMT

Overview

Pattern for nesting processes within processes using AddStepFromProcess and WhereInputEventIs to create modular, reusable workflow compositions.

Description

AddStepFromProcess is a method on ProcessBuilder that adds a child ProcessBuilder as a step within a parent process. The child process is treated as a single step from the parent's perspective, but internally contains its own graph of steps and event routes. The WhereInputEventIs method on the returned sub-process builder maps parent-level events to the child's declared input events, creating the event boundary bridge between the two scopes.

When a child process is added, the builder marks it with HasParentProcess = true, signaling that the child's lifecycle is managed by the parent. The child process's entry steps become accessible through the WhereInputEventIs method, which returns a ProcessFunctionTargetBuilder scoped to the parent process, allowing seamless routing from parent events to child input events.

Usage

Use AddStepFromProcess whenever you want to embed a reusable sub-workflow within a larger process. Define the child process independently using its own ProcessBuilder, then add it as a step to the parent and map events using WhereInputEventIs.

Code Reference

Source Location

• Repository: semantic-kernel
• Sample: dotnet/samples/GettingStartedWithProcesses/Step02/Step02b_AccountOpening.cs:L30-31

Key Signatures

// On ProcessBuilder - adds a child process as a step
public ProcessBuilder AddStepFromProcess(
    ProcessBuilder kernelProcess,
    IReadOnlyList<string>? aliases = null);

// On the returned ProcessBuilder - maps parent events to child input events
public ProcessFunctionTargetBuilder WhereInputEventIs(string eventId);

Import

using Microsoft.SemanticKernel;

I/O Contract

AddStepFromProcess Inputs

Name	Type	Required	Description
kernelProcess	ProcessBuilder	Yes	The child process builder to add as a step. Its HasParentProcess is set to true.
aliases	IReadOnlyList<string>?	No	Previous step names for backward compatibility with saved state.

AddStepFromProcess Output

Name	Type	Description
return	ProcessBuilder	The child process builder, now registered as a step. Use WhereInputEventIs to map events.

WhereInputEventIs Inputs

Name	Type	Required	Description
eventId	string	Yes	The input event Id declared by the child process via OnInputEvent. Must match exactly.

WhereInputEventIs Output

Name	Type	Description
return	ProcessFunctionTargetBuilder	A target builder scoped to the parent process that routes events into the child's input event.

Usage Examples

Defining a Reusable Child Process

A child process is defined independently as a static factory method. It has its own steps, its own OnInputEvent entry points, and its own internal routing.

public static class NewAccountVerificationProcess
{
    public static ProcessBuilder CreateProcess()
    {
        ProcessBuilder process = new("AccountVerificationProcess");

        var creditCheckStep = process.AddStepFromType<CreditScoreCheckStep>();
        var fraudDetectionStep = process.AddStepFromType<FraudDetectionStep>();

        // Child process declares its input events
        process
            .OnInputEvent(AccountOpeningEvents.NewCustomerFormCompleted)
            .SendEventTo(new ProcessFunctionTargetBuilder(
                creditCheckStep,
                functionName: CreditScoreCheckStep.ProcessStepFunctions.DetermineCreditScore,
                parameterName: "customerDetails"))
            .SendEventTo(new ProcessFunctionTargetBuilder(
                fraudDetectionStep,
                functionName: FraudDetectionStep.ProcessStepFunctions.FraudDetectionCheck,
                parameterName: "customerDetails"));

        // Internal routing between child steps
        creditCheckStep
            .OnEvent(AccountOpeningEvents.CreditScoreCheckApproved)
            .SendEventTo(new ProcessFunctionTargetBuilder(
                fraudDetectionStep,
                functionName: FraudDetectionStep.ProcessStepFunctions.FraudDetectionCheck,
                parameterName: "previousCheckSucceeded"));

        return process;
    }
}

Adding Child Processes to a Parent

The parent process adds child processes as steps and maps its events to the child's input events using WhereInputEventIs.

ProcessBuilder process = new("AccountOpeningProcessWithSubprocesses");

// Add atomic steps
var formStep = process.AddStepFromType<CompleteNewCustomerFormStep>();
var userInputStep = process.AddStepFromType<UserInputStep>();
var mailServiceStep = process.AddStepFromType<MailServiceStep>();

// Add child processes as steps
var accountVerificationStep =
    process.AddStepFromProcess(NewAccountVerificationProcess.CreateProcess());
var accountCreationStep =
    process.AddStepFromProcess(NewAccountCreationProcess.CreateProcess());

// Route a parent event to multiple child processes simultaneously
formStep
    .OnEvent(AccountOpeningEvents.NewCustomerFormCompleted)
    .SendEventTo(
        accountVerificationStep.WhereInputEventIs(
            AccountOpeningEvents.NewCustomerFormCompleted))
    .SendEventTo(
        accountCreationStep.WhereInputEventIs(
            AccountOpeningEvents.NewCustomerFormCompleted));

// Route transcript to the creation subprocess
formStep
    .OnEvent(AccountOpeningEvents.CustomerInteractionTranscriptReady)
    .SendEventTo(
        accountCreationStep.WhereInputEventIs(
            AccountOpeningEvents.CustomerInteractionTranscriptReady));

Routing Child Process Output Events to Parent Steps

Events emitted by child processes with Public visibility bubble up to the parent. The parent routes them like any other step event.

// Child process emits public events that the parent can capture
accountVerificationStep
    .OnEvent(AccountOpeningEvents.CreditScoreCheckRejected)
    .SendEventTo(new ProcessFunctionTargetBuilder(mailServiceStep));

accountVerificationStep
    .OnEvent(AccountOpeningEvents.FraudDetectionCheckFailed)
    .SendEventTo(new ProcessFunctionTargetBuilder(mailServiceStep));

accountVerificationStep
    .OnEvent(AccountOpeningEvents.FraudDetectionCheckPassed)
    .SendEventTo(
        accountCreationStep.WhereInputEventIs(
            AccountOpeningEvents.NewAccountVerificationCheckPassed));

// Child process output leads to parent process completion
accountCreationStep
    .OnEvent(AccountOpeningEvents.WelcomePacketCreated)
    .SendEventTo(new ProcessFunctionTargetBuilder(mailServiceStep));

mailServiceStep
    .OnEvent(AccountOpeningEvents.MailServiceSent)
    .StopProcess();

Related Pages

Implements Principle

• Principle:Microsoft_Semantic_kernel_Subprocess_Composition