Why use a QueueClient vs MessageFactory?

Azure Service Bus provides different way to send/receive messages.

• You can use the QueueClient to send and receive message to/from a queue.
• You can use the TopicClient to send message to a topic
• And you can use the SubscriptionClient to receive message from a subscription.

Using MessageSender and MessageReceiver, you create sender and receiver that are entity type invariant:

var factory = MessagingFactory.CreateFromConnectionString("MyConnectionString");

• A MessageSender can send messages to both topic or queue:

  var sender = factory.CreateMessageSender("Queue ou topic path");

• A MessageReceiver ca receive messages from both queue and subscription:

  var receiver = factory.CreateMessageReceiver("Queue ou subscription path");

Theses abstractions can give you more flexibility if you need to switch from a queue to a topic or vice versa because you just need to change the path of the service bus entity (This could be in your configuration file) so no code change needed. Using QueueClient, TopicClient, SubscriptionClient, you'll have to change your code if you want to move from a queue to a topic.

So my advice is to always use a MessageReceiver/MessageSender when you have to send/receive message from/to a an Azure ServiceBus queue topic/subscription.

NOTE: This does not apply for Eventhub which has a different implementation.