This sample shows a client/server scenario using a dynamic table configuration for certain saga types with a fallback to the default table.
Prerequisites
Ensure that an instance of the latest Azure Storage Emulator or 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. OrderSagasends aShipOrdercommand toShipOrderSagaShipOrderSagarequests a timeout with an instance ofCompleteOrderwith the saga data.ShipOrderSagareplies withCompleteOrderwhen theCompleteOrdertimeout fires.OrderSagapublishes anOrderCompletedevent when theCompleteOrdermessage arrives.
Persistence config
Configure the endpoint to use Azure Table Persistence.
var endpointConfiguration = new EndpointConfiguration("Samples.AzureTable.Table.Server");
var useStorageTable = true;
var persistence = endpointConfiguration.UsePersistence<AzureTablePersistence>();
var connection = useStorageTable ? "UseDevelopmentStorage=true" :
"TableEndpoint=https://localhost:8081/;AccountName=AzureTableSamples;AccountKey=C2y6yDjf5/R+ob0N8A7Cgv30VRDJIWEHLM+4QDU5DE2nQ9nDuVTqobD4b8mGGyPMbIZnqyMsEcaGQy67XIw/Jw==";
var tableServiceClient = new TableServiceClient(connection);
persistence.UseTableServiceClient(tableServiceClient);
persistence.DefaultTable("OrderSagaData");
In the non-transactional mode the saga id is used as a partition.
Behaviors
For all messages destined to go to the ShipOrderSaga the table is overridden at runtime to use ShipOrderSagaData table.
class BehaviorProvidingDynamicTable : Behavior<IIncomingLogicalMessageContext>
{
public override Task Invoke(IIncomingLogicalMessageContext context, Func<Task> next)
{
if (context.Message.Instance is ShipOrder ||
context.Headers.TryGetValue(Headers.SagaType, out var sagaTypeHeader) && sagaTypeHeader.Contains(nameof(ShipOrderSaga)))
{
Log.Info($"Message '{context.Message.MessageType.FullName}' destined to be handled by '{nameof(ShipOrderSaga)}' will use 'ShipOrderSagaData' table.");
context.Extensions.Set(new TableInformation("ShipOrderSagaData"));
}
else
{
Log.Info($"Message '{context.Message.MessageType.FullName}' destined to be handled by '{nameof(OrderSaga)}' will the default table.");
}
return next();
}
static readonly ILog Log = LogManager.GetLogger<BehaviorProvidingDynamicTable>();
}
The behavior needs to be registered in the pipeline
endpointConfiguration.Pipeline.Register(new BehaviorProvidingDynamicTable(), "Provides a non-default table for sagas started by ship order message");
Order saga data
public class OrderSagaData :
ContainSagaData
{
public Guid OrderId { get; set; }
public string OrderDescription { get; set; }
}
Order saga
public class OrderSaga :
Saga<OrderSagaData>,
IAmStartedByMessages<StartOrder>,
IHandleMessages<CompleteOrder>
{
static ILog log = LogManager.GetLogger<OrderSaga>();
protected override void ConfigureHowToFindSaga(SagaPropertyMapper<OrderSagaData> mapper)
{
mapper.MapSaga(saga => saga.OrderId)
.ToMessage<StartOrder>(msg => msg.OrderId)
.ToMessage<CompleteOrder>(msg => msg.OrderId);
}
public Task Handle(StartOrder message, IMessageHandlerContext context)
{
Data.OrderId = message.OrderId;
Data.OrderDescription = $"The saga for order {message.OrderId}";
log.Info($"Received StartOrder message {Data.OrderId}. Starting Saga");
var shipOrder = new ShipOrder
{
OrderId = message.OrderId
};
return context.SendLocal(shipOrder);
}
public Task Handle(CompleteOrder message, IMessageHandlerContext context)
{
log.Info($"Saga with OrderId {Data.OrderId} completed");
MarkAsComplete();
var orderCompleted = new OrderCompleted
{
OrderId = Data.OrderId
};
return context.Publish(orderCompleted);
}
}
ShipOrder saga data
public class ShipOrderSagaData :
ContainSagaData
{
public Guid OrderId { get; set; }
}
ShipOrder saga
public class ShipOrderSaga :
Saga<ShipOrderSagaData>,
IAmStartedByMessages<ShipOrder>,
IHandleTimeouts<CompleteOrder>
{
static ILog log = LogManager.GetLogger<ShipOrderSaga>();
protected override void ConfigureHowToFindSaga(SagaPropertyMapper<ShipOrderSagaData> mapper)
{
mapper.MapSaga(saga => saga.OrderId).ToMessage<ShipOrder>(msg => msg.OrderId);
}
public Task Handle(ShipOrder message, IMessageHandlerContext context)
{
log.Info($"Order Shipped. OrderId {message.OrderId}");
Data.OrderId = message.OrderId;
log.Info("Order will complete in 5 seconds");
var timeoutData = new CompleteOrder();
return RequestTimeout(context, TimeSpan.FromSeconds(5), timeoutData);
}
public Task Timeout(CompleteOrder state, IMessageHandlerContext context)
{
log.Info($"Saga with OrderId {Data.OrderId} about to complete");
MarkAsComplete();
state.OrderId = Data.OrderId;
return ReplyToOriginator(context, state);
}
}