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In this section, we are going to do hands on lap, which is the saga pattern for orchestrate distributed

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transactions using a step functions.

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So let's start with fundamentals of this section.

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Topic with remembering microservices and communications is enough that microservices are organized around

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business capabilities with a separate database per microservices.

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Microservices are loosely coupled and they use asynchronous messaging to communicate with each other.

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Microservices are independently deployable.

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So let's think microservices on ecommerce domain, you can see the image on the slide.

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Basically, this is the order fulfillment process and we will implement these order fulfillment process

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with orchestration using a list step functions.

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Let me explain the steps.

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One by one, the customer is placed an order using frontend channels and API gateway invoke to order

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microservices and the order fulfillment process is started.

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So order is going to check if the item is available in the inventory or not.

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If the inventory is available, it is basically the dock item in the inventory database and it calls

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the payment microservices.

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If the payment is successfully done with third party integration, it starts with the delivery microservices.

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And when the delivery is done, the order status will be completed.

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If one of these steps are not successful, it should be rolled back the steps and return back to the

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previous status.

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For example, we should return back to the inventory database table and we should return back to the

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payment microservices and order microservices and so on.

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And we will set the status as a fail status.

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So all these rollback statements should be handled by the orchestrator.

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So how we can set up these workflow in microservice architectures of course with using saga pattern.

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So now it is good to understand what is a pattern.