# RabbitMQ Transport Upgrade Version 4 to 5


## Mandatory routing topology selection

Specifying a routing topology is now mandatory. For backwards compatibility, the recommendation is to use the conventional routing topology, which was the previous default.

See [routing topology](/transports/rabbitmq/routing-topology.md) for further details.


## Direct routing topology changes

The convention for overriding the name of the exchange used when publishing events has changed. The address and the event type are no longer passed to the `exchangeNameConvention` parameter of the [UseDirectRoutingTopology](/transports/rabbitmq/routing-topology.md#direct-routing-topology-enabling) method.

```csharp
// For RabbitMQ Transport version 5.x
var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
transport.UseDirectRoutingTopology(
    routingKeyConvention: type => "myroutingkey",
    exchangeNameConvention: () => "MyTopic");

// For RabbitMQ Transport version 4.x
var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
transport.UseDirectRoutingTopology(
    routingKeyConvention: type => "myroutingkey",
    exchangeNameConvention: (address, eventType) => "MyTopic");
```


## Custom routing topology changes

The following changes have been made to the interfaces used to create custom routing topologies.


### IDeclareQueues removed

The `IDeclareQueues` interface added in Version 4.2 has been removed. The two address parameters on the interface's `DeclareAndInitialize` method have been added to the `Initialize` method of the `IRoutingTopology` interface. Implementations of the `Initialize` method are now responsible for creating any queues required by the topology.


### ISupportDelayedDelivery removed

The `ISupportDelayedDelivery` interface added in Version 4.3 has been removed. The `BindToDelayInfrastructure` method is now part of the `IRoutingTopology` interface.


## Exchange and queue durability

Exchange and queue durability is no longer controlled by the [global message durability settings](/nservicebus/messaging/non-durable-messaging_core_7.md#enabling-non-durable-messaging-global-for-the-endpoint) specified for the endpoint. The routing topologies provided by the transport now create durable exchanges and queues by default. The `UseDurableExchangesAndQueues` setting has been introduced to control durability:

```csharp
// For RabbitMQ Transport version 8.x
var topology = RoutingTopology.Conventional(QueueType.Quorum, useDurableEntities: false);

var transport = new RabbitMQTransport(topology, "host=localhost");

endpointConfiguration.UseTransport(transport);

// For RabbitMQ Transport version 7.x
var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
transport.DisableDurableExchangesAndQueues();

// For RabbitMQ Transport version 6.x
var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
transport.DisableDurableExchangesAndQueues();

// For RabbitMQ Transport version 5.x
var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
transport.UseDurableExchangesAndQueues(false);

// For RabbitMQ Transport version 5.x
var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
transport.UseDurableExchangesAndQueues(false);
```

If `DisableDurableMessages` has been called, the transport will throw an exception unless `UseDurableExchangesAndQueues` is also called:

```csharp
// For RabbitMQ Transport version 5.x
var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
endpointConfiguration.DisableDurableMessages();
transport.UseDurableExchangesAndQueues(true);

// For RabbitMQ Transport version 5.x
var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
endpointConfiguration.DisableDurableMessages();
transport.UseDurableExchangesAndQueues(true);
```


## Delayed Delivery

The timeout manager is no longer enabled by default, so the `DisableTimeoutManager` API has been deprecated. If an endpoint still has undelivered messages stored in its persistence database, the new `EnableTimeoutManager` API can be used to ensure those messages are delivered.

```csharp
// For RabbitMQ Transport version 7.x
var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
var delayedDelivery = transport.DelayedDelivery();
delayedDelivery.EnableTimeoutManager();

// For RabbitMQ Transport version 6.x
var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
var delayedDelivery = transport.DelayedDelivery();
delayedDelivery.EnableTimeoutManager();

// For RabbitMQ Transport version 5.x
var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
var delayedDelivery = transport.DelayedDelivery();
delayedDelivery.EnableTimeoutManager();

// For RabbitMQ Transport version 5.x
var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
var delayedDelivery = transport.DelayedDelivery();
delayedDelivery.EnableTimeoutManager();
```