# Azure Service Bus Transport (Legacy) Upgrade Version 7 to 8



## Forwarding topology number of entities in bundle removed

In Versions 8 and above the API to configure bundle prefix and number of entities in a bundle has been removed:

```csharp
var transport = endpointConfiguration.UseTransport<AzureServiceBusTransport>();
var forwardingTopology = transport.UseForwardingTopology();

forwardingTopology.BundlePrefix("my-prefix");
forwardingTopology.NumberOfEntitiesInBundle(3);
```

The bundle is set to one entity. For existing endpoints running with multiple entities in a bundle, the transport automatically picks up previously configured entities. The default topic name for bundle is set to `bundle-1`.


## Controlling entity creation

Controlling entity creation has been simplified. Instead of having to provide a full implementation of `DescriptionFactory` where all settings on the description object had to be provided, a customizer (`DescriptionCustomizer`) has been introduced where only the customized properties can be changed. `DescriptionCustomizer` can be found on the `Queues`, `Topics` and `Subscriptions` API extension points.


## Queue and Subscription MaxDeliveryCount

In version 7 the transport sets `MaxDeliveryCount` to match immediate retries specified by each endpoint to ensure messages are not dead-lettered accidentally.

In version 8 and above, `MaxDeliveryCount` is set to `int.MaxValue` to ensure messages are not dead-lettered accidentally and to remove the dependency on the endpoints' immediate retries configuration.

Customization of `MaxDeliveryCount` is strongly discouraged, yet can be performed using `DescriptionCustomizer` API for queues and topics.

## BrokeredMessage conventions

Due to complexity, and resultant risk, of implementation, the API to specify how the `BrokeredMessage` body is stored and retrieved by overriding the default conventions is obsoleted and the following methods were deprecated:

```csharp
var transport = endpointConfiguration.UseTransport<AzureServiceBusTransport>();
transport.UseBrokeredMessageToIncomingMessageConverter<CustomIncomingMessageConversion>();
```

```csharp
var transport = endpointConfiguration.UseTransport<AzureServiceBusTransport>();
transport.UseOutgoingMessageToBrokeredMessageConverter<CustomOutgoingMessageConversion>();
```


## Serialization is mandatory

In Versions 7 and below, the transport was setting the default serialization. In Versions 8 and above, the transport is no longer sets the default serialization. Instead, it should be configured.

For backwards compatibility, `NServiceBus.Newtonsoft.Json` serializer should be used.

```csharp
// For Azure Service Bus Transport (Legacy) version 10.x
endpointConfiguration.UseSerialization<NewtonsoftJsonSerializer>();

// For Azure Service Bus Transport (Legacy) version 9.x
endpointConfiguration.UseSerialization<NewtonsoftJsonSerializer>();

// For Azure Service Bus Transport (Legacy) version 8.x
endpointConfiguration.UseSerialization<NewtonsoftJsonSerializer>();
```


## Send/publish namespaces caching

In Version 7 to control sending/publishing namespaces caching, the transport must provide an implementation of two contracts.

```csharp
// For Azure Service Bus Transport (Legacy) version 10.x
public class CustomNamespacePartitioningStrategy :
    INamespacePartitioningStrategy
{
    ReadOnlySettings settings;

    public CustomNamespacePartitioningStrategy(ReadOnlySettings settings)
    {
        this.settings = settings;
    }

    public IEnumerable<RuntimeNamespaceInfo> GetNamespaces(PartitioningIntent partitioningIntent)
    {
        throw new NotImplementedException();
    }

    public bool SendingNamespacesCanBeCached { get; }
}

// For Azure Service Bus Transport (Legacy) version 9.x
public class CustomNamespacePartitioningStrategy :
    INamespacePartitioningStrategy
{
    ReadOnlySettings settings;

    public CustomNamespacePartitioningStrategy(ReadOnlySettings settings)
    {
        this.settings = settings;
    }

    public IEnumerable<RuntimeNamespaceInfo> GetNamespaces(PartitioningIntent partitioningIntent)
    {
        throw new NotImplementedException();
    }

    public bool SendingNamespacesCanBeCached { get; }
}

// For Azure Service Bus Transport (Legacy) version 8.x
public class CustomNamespacePartitioningStrategy :
    INamespacePartitioningStrategy
{
    ReadOnlySettings settings;

    public CustomNamespacePartitioningStrategy(ReadOnlySettings settings)
    {
        this.settings = settings;
    }

    public IEnumerable<RuntimeNamespaceInfo> GetNamespaces(PartitioningIntent partitioningIntent)
    {
        throw new NotImplementedException();
    }

    public bool SendingNamespacesCanBeCached { get; }
}

// For Azure Service Bus Transport (Legacy) version 7.x
public class MyNamespacePartitioningStrategyWithControlledCaching :
    INamespacePartitioningStrategy, ICacheSendingNamespaces
{
    ReadOnlySettings settings;

    public MyNamespacePartitioningStrategyWithControlledCaching(ReadOnlySettings settings)
    {
        this.settings = settings;
    }

    public IEnumerable<RuntimeNamespaceInfo> GetNamespaces(PartitioningIntent partitioningIntent)
    {
        throw new NotImplementedException();
    }

    public bool SendingNamespacesCanBeCached { get; } = false;
}
```

From Versions 8 and above, only a single contract is required.

```csharp
// For Azure Service Bus Transport (Legacy) version 10.x
public class MyNamespacePartitioningStrategy :
    INamespacePartitioningStrategy
{
    public IEnumerable<RuntimeNamespaceInfo> GetNamespaces(PartitioningIntent partitioningIntent)
    {
        throw new System.NotImplementedException();
    }

    public bool SendingNamespacesCanBeCached { get; }
}

// For Azure Service Bus Transport (Legacy) version 9.x
public class MyNamespacePartitioningStrategy :
    INamespacePartitioningStrategy
{
    public IEnumerable<RuntimeNamespaceInfo> GetNamespaces(PartitioningIntent partitioningIntent)
    {
        throw new System.NotImplementedException();
    }

    public bool SendingNamespacesCanBeCached { get; }
}

// For Azure Service Bus Transport (Legacy) version 8.x
public class MyNamespacePartitioningStrategy :
    INamespacePartitioningStrategy
{
    public IEnumerable<RuntimeNamespaceInfo> GetNamespaces(PartitioningIntent partitioningIntent)
    {
        throw new System.NotImplementedException();
    }

    public bool SendingNamespacesCanBeCached { get; }
}
```