Tutorials Microservices with .NET

Publish-Subscribe Pattern — Complete Guide

Publish-Subscribe Pattern — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of Microservices with .NET on Toolliyo Academy.

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Microservices with .NET · Lesson 33 of 120

Orchestration Saga

Beginner ✓IntermediateAdvancedProfessional

Intermediate · 2 — Building services · ~6 min · Module 4: Saga and Distributed Transactions

What is this?

Orchestration Saga is a key part of ShopNest Cloud-Native — your .NET microservices learning project. In plain terms: it helps Identity Service work correctly in a distributed system where each app deploys and scales on its own.

Why should you care?

You care about this when one business action spans Order, Payment, and Inventory — and you cannot use one SQL transaction across three databases.

See it live — copy this example

Create a Web API project (dotnet new webapi), paste the code, then run dotnet run.

public class PlaceOrderStateMachine : MassTransitStateMachine<PlaceOrderState>
{
    public State AwaitingPayment { get; private set; }
    // PaymentSucceeded → ReserveInventory → Completed
    // PaymentFailed → Compensate (cancel order)
}

Run Example »

Edit the code and click Run — like W3Schools Try it Yourself.

Code
Result

What happened?

  • The example shows Orchestration Saga wired into Identity Service.
  • Read each line, run it locally, then change one setting and observe what breaks or improves.
  • That is how teams learn in production too — small experiments, not big bang rewrites.

Try it yourself

  1. Open or create the ShopNest project area for Identity Service.
  2. Apply the Orchestration Saga pattern from the lesson example.
  3. Run dotnet build && dotnet run (or docker compose up when the lesson uses containers).
  4. Change a string or number in the example and run again — predict the output first.
  5. Break the code on purpose (remove a semicolon), read the compiler error, then fix it.

Remember

Orchestration Saga connects to Identity Service in ShopNest Cloud-Native. Practice by editing the example yourself — do not only read. Move on when you can explain this topic in your own words without looking.

Real-world: Swiggy order → restaurant → rider flow

When a customer confirms food order, events notify restaurant prep and rider dispatch. No single 30-second HTTP chain.

Outcome: Restaurant promos deploy without taking down payment processing.

Interview prep for this lesson

Practice these questions aloud after reading—each links to a full structured answer.

Senior PDF Detailed
Saga Pattern: As mentioned earlier, this is the preferred way to manage distributed?
Short answer: transactions in microservices without locking resources or requiring a distributed transaction manager. Sagas break a transaction into smaller, manageable steps, with each microservice handling its own loca…
Mid PDF Detailed
Publish Events: A service publishes an event when a significant action or state?
Short answer: change occurs, such as creating a new order or processing a payment. The event is typically sent to a message broker like Kafka or RabbitMQ. Real-world example (ShopNest) After payment succeeds, ShopNest pu…
Mid PDF Detailed
Circuit Breaker Pattern: As described, this prevents system overloads by stopping?
Short answer: calls to failing services. Real-world example (ShopNest) After payment succeeds, ShopNest publishes OrderPaid . Inventory and Notification services react independently—no giant distributed transaction. Say…
Mid PDF Detailed
Event Producer (Publisher): A service that emits events (e.g., "Order Created",?
Short answer: &quot;Payment Processed&quot;) and publishes them to a message broker. Real-world example (ShopNest) After payment succeeds, ShopNest publishes OrderPaid . Inventory and Notification services react independ…
Mid PDF Detailed
Circuit Breaker Pattern:?
Short answer: A circuit breaker monitors failures and trips (opens) if a service experiences repeated failures, preventing further calls to the failing service and giving it time to recover. Tools: Hystrix, Resilience4j.…
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Microservices with .NET
Course syllabus

Microservices with .NET Tutorial

Module 1: Foundations and Fundamentals
Module 2: Building User Microservice
Module 3: ShopNest Services and Integration
Module 4: RabbitMQ and Messaging
Module 5: Saga and Distributed Transactions
Module 6: API Gateway
Module 7: gRPC, CQRS, and GraphQL
Module 8: Resiliency and Fault Tolerance
Module 9: DevOps and Cloud-Native
Module 10: Git and GitHub
Module 11: CI/CD Pipelines
Module 12: Observability and Testing
Module 13: Advanced Topics
Module 14: Real-World Enterprise Projects
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