DynamoDb Configuration

DynamoDB is a fully managed NoSQL database provided by AWS. Setting it up as a SagaRepository is simple, but do note that it requires implementing the ISagaVersion interface that requires a Version property for optimistic concurrency:

public class OrderState :
    SagaStateMachineInstance,
    ISagaVersion
{
    public Guid CorrelationId { get; set; }
    public int Version { get; set; }
    public string CurrentState { get; set; }
    public DateTime? OrderDate { get; set; }
}

Configure the saga repository

To configure DynamoDB as a saga repository, use the AddMassTransit container extension:

builder.Services.AddMassTransit(cfg =>
{
    cfg.AddSagaStateMachine<OrderStateMachine, OrderState>()
        .DynamoDbRepository(config =>
        {
            // required
            config.TableName = "Orders";
             // required. Refer to AWS SDK docs for how to create a context.
            config.ContextFactory(provider => new DynamoDBContext(dynamoDbClient));
        });
});

The code above configures the repository to store saga instances in a table named Orders. A DynamoDBContext must be created from an existing AmazonDynamoDBClient instance. For example, if a local dynamodb instance is used, the code creating a client could look like this:

var dynamoDbClient = new AmazonDynamoDBClient(new AmazonDynamoDBConfig { ServiceURL = "http://localhost:4566" });