Difference Between Windows Azure Service Bus and Windows Azure Virtual Network

Question

I want to connect to On-Premises database from Azure. Basically i will be hosting my web Application on azure and will be using Database from On-Premises.

According to www.WindowsAzure.com both Azure Service Bus and Windows Azure Virtual Network are used for connecting to On-Premises database. But what is the difference between these two and which of them should be used according to different situation ?

Answer 1

There is a big difference between both approaches: Service Bus is connectivity on application or messaging level. Here you will have two options:

• Service Bus Relay : here you have to expose a web service (that connects to your local database) over the Relay binding. This will make a publically reachable service in a firewall friendly way. This is mostly a synchronous approach.
• Service Bus messaging: you will have to have a local process that listens on messages / events that you put on a queue or a topic/subscription from your application. This is mostly an asynchronous approach.

Virtual Networking: here you can set up connectivity on network level and you would be able to connect to your database as if he is on the same network as your cloud based application. The advantage here is that your code would not have to change, compared to a standard application (except for connectivity retries)

Both approaches are totally different, but can be valid, depending on your preference of architecture. (web service oriented, network level connectivity, or asynchronous processing).

Hope this helps.