Máquinas de estados para orquestração
Aplique conceitos de máquinas de estados para criar orquestradores Saga robustos e previsíveis que acompanhem o progresso das transações.
Máquinas de estados para orquestração é uma aula grátis de Microservices Communication Patterns (Saga, Circuit Breaker) no CoddyKit. Esta é a aula 2 de 4. Você pode ler a aula completa abaixo gratuitamente — depois pratica ao vivo no navegador com um editor de código integrado e um tutor de IA 24/7. Faz parte do caminho de aprendizado de Microservices Communication Patterns (Saga, Circuit Breaker), e seu progresso é sincronizado entre a web e o app CoddyKit. O curso de Microservices Communication Patterns (Saga, Circuit Breaker) inclui 4 aulas no total.
Partes desta aula ainda não foram traduzidas e aparecem em inglês.
State Machines for Sagas
Welcome to this lesson on using state machines to build robust saga orchestrators!
Orchestration sagas manage complex distributed transactions by keeping track of the overall process. State machines are a powerful tool for this.
Why State Machines?
A saga orchestrator needs to know the exact status of a business process at any given moment. This allows it to:
- Decide the next action to take.
- Handle failures and trigger compensation.
- Ensure consistency across multiple services.
State machines provide a clear, structured way to model this complex logic.
State Machine Basics
At its core, a state machine consists of three main concepts:
- States: Represent different phases or conditions of the saga (e.g.,
OrderCreated,PaymentPending). - Events: Occurrences that trigger changes in the saga (e.g.,
PaymentSuccessful,ShipmentFailed). - Transitions: Rules that define how an event causes the saga to move from one state to another.
Example: Order Processing Saga
Let's consider a common scenario: an online order processing saga.
This saga might involve several services:
- Order Service
- Payment Service
- Shipping Service
The orchestrator needs to coordinate these steps.
Defining Saga States
For our order processing saga, we can define states like:
ORDER_CREATED: Initial state.PAYMENT_PENDING: Waiting for payment confirmation.PAID: Payment successful.SHIPPING_PENDING: Waiting for shipment to be initiated.SHIPPED: Item has been shipped.CANCELLED: Order cancelled (due to failure or user action).
Defining Saga Events
And the events that can occur:
ORDER_PLACED: Customer places an order.PAYMENT_SUCCESS: Payment service confirms payment.PAYMENT_FAILED: Payment service reports failure.SHIPMENT_SUCCESS: Shipping service confirms shipment.SHIPMENT_FAILED: Shipping service reports an issue.ORDER_CANCELLED_REQUEST: User requests cancellation.
State Transition Logic
The core of a state machine is its transition logic: Current State + Event = New State (and possibly an action).
For example:
- If in
ORDER_CREATEDstate andORDER_PLACEDevent occurs, transition toPAYMENT_PENDING. - If in
PAYMENT_PENDINGstate andPAYMENT_SUCCESSevent occurs, transition toPAID.
This defines the predictable flow of your saga.
Code: Simple State Transition
Here's a simplified Java example demonstrating how states and events can drive transitions in an orchestrator.
Try running it to see the state changes!
public class SimpleSagaState {
public enum SagaStepState {
STARTED,
PROCESSING_PAYMENT,
PAYMENT_COMPLETE,
FAILED
}
private SagaStepState currentState;
public SimpleSagaState() {
this.currentState = SagaStepState.STARTED;
}
public SagaStepState getCurrentState() {
return currentState;
}
public void processEvent(String event) {
System.out.println("Event: " + event);
switch (currentState) {
case STARTED:
if ("OrderCreated".equals(event)) {
currentState = SagaStepState.PROCESSING_PAYMENT;
}
break;
case PROCESSING_PAYMENT:
if ("PaymentSuccess".equals(event)) {
currentState = SagaStepState.PAYMENT_COMPLETE;
} else if ("PaymentFailed".equals(event)) {
currentState = SagaStepState.FAILED;
}
break;
case PAYMENT_COMPLETE:
// After payment, might go to shipping, etc.
break;
case FAILED:
System.out.println("Saga already failed.");
break;
}
System.out.println("New State: " + currentState);
}
public static void main(String[] args) {
SimpleSagaState saga = new SimpleSagaState();
System.out.println("Initial State: " + saga.getCurrentState());
saga.processEvent("OrderCreated");
saga.processEvent("PaymentSuccess");
saga.processEvent("ShipmentInitiated"); // This event won't change state in this simplified example
System.out.println("Final State: " + saga.getCurrentState());
}
}Compensation with States
One of the biggest advantages of using state machines for sagas is how they simplify compensation logic.
If a service fails, the orchestrator receives a 'failed' event. Based on the current state, the state machine can determine which compensation actions need to be triggered to reverse previous successful steps.
For example, if in PAID state and SHIPMENT_FAILED occurs, the state machine can transition to CANCELLED and trigger a refund.
State Transition Question
Consider an order saga using a state machine. The order is currently in the PAYMENT_PENDING state.
If the orchestrator receives a PAYMENT_FAILED event, what is the most appropriate next state for the saga, typically indicating compensation?
Recap: States for Orchestration
In this lesson, we explored how state machines are crucial for building robust saga orchestrators.
- They provide a clear model for tracking saga progress.
- States, Events, and Transitions define the saga's flow.
- They simplify handling complex logic, especially for compensation.
By explicitly defining states and transitions, you create predictable and resilient distributed transactions.
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Perguntas Frequentes
A aula “Máquinas de estados para orquestração” é grátis?
Sim — o texto completo de “Máquinas de estados para orquestração” é grátis para ler aqui na web. Para praticá-la interativamente (um editor de código integrado e um tutor de IA 24/7) e desbloquear o restante do curso de Microservices Communication Patterns (Saga, Circuit Breaker), atualize para CoddyKit PRO. O curso de Microservices Communication Patterns (Saga, Circuit Breaker) inclui 4 aulas no total.
O que vou aprender em “Máquinas de estados para orquestração”?
Aplique conceitos de máquinas de estados para criar orquestradores Saga robustos e previsíveis que acompanhem o progresso das transações. Você pratica Microservices Communication Patterns (Saga, Circuit Breaker) com código prático que executa diretamente no navegador, e um tutor de IA 24/7 responde suas dúvidas enquanto trabalha na aula.
Preciso ter experiência prévia para começar Microservices Communication Patterns (Saga, Circuit Breaker)?
Nenhuma experiência prévia é necessária. Microservices Communication Patterns (Saga, Circuit Breaker) no CoddyKit é estruturado para alunos iniciantes até avançados, então você pode começar aqui ou desde o início e aprender no seu ritmo. Esta é a aula 2 de 4.
Quanto tempo leva a aula “Máquinas de estados para orquestração”?
A maioria das aulas CoddyKit leva cerca de 5–10 minutos. Cada uma é compacta e interativa, então você faz progresso constante e retoma exatamente de onde parou entre web e app.
Posso escrever e executar código nesta aula de Microservices Communication Patterns (Saga, Circuit Breaker)?
Sim. Cada aula de Microservices Communication Patterns (Saga, Circuit Breaker) inclui um editor de código integrado, então você escreve e executa código real direto no navegador e recebe feedback de IA instantaneamente — nenhuma configuração local necessária.
Todas as aulas deste curso
- Conceção de orquestradores Saga
- Máquinas de estados para orquestração
- Implementação com um motor de fluxos de trabalho
- Testes de sagas orquestradas