outbox

State management with outbox

Sample info

Attribute	Details
Dapr runtime version	v1.12.0
Dapr .NET SDK	v1.12.0
Language	C#
Environment	Local

Overview

In this sample, you'll run applications to demonstrate Dapr's state management outbox pattern. One application generates orders to save data in a state store which then transactionally sends pub/sub messages to a listening notification application. See How-To: Enable the transactional outbox pattern to understand when this pattern is a good choice for your architecture.

Note: This example leverages the Dapr client SDK.

This quickstart includes two applications:

• A .NET client application order-processor which creates orders, saves and deletes them to a state store.
• A .NET notification application order-notification which receives pub/sub messages for topics from a message broker when the state store is updated.

Run apps with multi-app run

You can run both applications using a multi-app run template file with dapr run -f .

1. Open a new terminal window and run the order-processor and the order-notification apps using the multi app run template defined in dapr.yaml:

2. Run the applications:

  dapr run -f .

When orders are created and saved to the state store you see a corresponding notification message topic.

== APP - order-processor == Saving Order: Order { orderId = 1 }
== APP - order-notification == Order notification received : {"orderId":1}

When orders are deleted you also see a corresponding notifications message.

== APP - order-processor == Deleting Order: Order { orderId = 2 }
== APP - order-notification == Order notification received : {"orderId":2}

3. Switch from Redis to MySQL

Redis is not a true transactional store, however it is easy to switch the underlying state store from Redis to MySQL. You can read about how to use the Dapr MySQL component here

• Install MySQL as a container image using the password mysecret for the root user.

docker run --name mysql -d \
   -p 3306:3306 \
   -e MYSQL_ROOT_PASSWORD=mysecret \
   --restart unless-stopped \
   mysql:8

• Change the Program.cs code in order-processor directory to use the statestoresql state store.

string DAPR_STORE_NAME = "statestoresql";

• Run the applications again with the dapr run -f . command

4. Stop and clean up the application processes either with CTRL+C command or running dapr stop -f . from another terminal window.

    dapr stop -f .

Observing the messages

You can install a viewer for the messages and state store. For example if you are using Redis you can install the Redis weijan.vscode-redis-client