This sample shows a client/server scenario using non-transactional saga persistence.
Prerequisites
Ensure that an instance of the latest Azure Cosmos DB Emulator is running.
Projects
SharedMessages
The shared message contracts used by all endpoints.
Client
- Sends the
StartOrdermessage toServer. - Receives and handles the
OrderCompletedevent.
Server projects
- Receive the
StartOrdermessage and initiate anOrderSaga. OrderSagarequests a timeout with an instance ofCompleteOrderwith the saga data.OrderSagapublishes anOrderCompletedevent when theCompleteOrdertimeout fires.
Persistence config
Configure the endpoint to use Cosmos DB Persistence.
var endpointConfiguration = new EndpointConfiguration("Samples.CosmosDB.Simple.Server");
var persistence = endpointConfiguration.UsePersistence<CosmosPersistence>();
var connection = Environment.GetEnvironmentVariable("COSMOS_CONNECTION_STRING")
?? @"AccountEndpoint=https://localhost:8081/;AccountKey=C2y6yDjf5/R+ob0N8A7Cgv30VRDJIWEHLM+4QDU5DE2nQ9nDuVTqobD4b8mGGyPMbIZnqyMsEcaGQy67XIw/Jw==";
persistence.DatabaseName("Samples.CosmosDB.Simple");
persistence.CosmosClient(new CosmosClient(connection));
persistence.DefaultContainer("Server", "/id");
In the non-transactional mode, the saga id is used as a partition key, and thus, the container needs to use / as the partition key path.
Order saga data
public class OrderSagaData :
ContainSagaData
{
public Guid OrderId { get; set; }
public string OrderDescription { get; set; }
}
Order saga
public class OrderSaga(ILogger<OrderSaga> logger) :
Saga<OrderSagaData>,
IAmStartedByMessages<StartOrder>,
IHandleTimeouts<CompleteOrder>
{
protected override void ConfigureHowToFindSaga(SagaPropertyMapper<OrderSagaData> mapper)
{
mapper.MapSaga(saga => saga.OrderId).ToMessage<StartOrder>(msg => msg.OrderId);
}
public Task Handle(StartOrder message, IMessageHandlerContext context)
{
var orderDescription = $"The saga for order {message.OrderId}";
Data.OrderDescription = orderDescription;
logger.LogInformation($"Received StartOrder message {Data.OrderId}. Starting Saga");
var shipOrder = new ShipOrder
{
OrderId = message.OrderId
};
logger.LogInformation("Order will complete in 5 seconds");
var timeoutData = new CompleteOrder
{
OrderDescription = orderDescription,
};
return Task.WhenAll(
context.SendLocal(shipOrder),
RequestTimeout(context, TimeSpan.FromSeconds(5), timeoutData)
);
}
public Task Timeout(CompleteOrder state, IMessageHandlerContext context)
{
logger.LogInformation($"Saga with OrderId {Data.OrderId} completed");
MarkAsComplete();
var orderCompleted = new OrderCompleted
{
OrderId = Data.OrderId
};
return context.Publish(orderCompleted);
}
}