Q17. What is AppFabric?

Windows azure AppFabric is nothing but a set of Connecting Services - a set of middleware services for applications running in the cloud or on premise.

AppFabric resides on top of the operating system and is a set of services. It includes :
Service Bus
Access Control Services

Service Bus

Service Bus is a message-oriented-middleware technology. It is a messaging service used for connecting applications. It connects the different components of a cloud application or establishes a connection between the cloud and on-premise applications by enabling them to exchange messages in a loosely coupled way.

service bus

Note that we have to install AppFabric SDK to develop applications which use AppFabric services.

How many types of messaging patterns Service Bus provides?

Service bus allows a developer to use different communication and messaging protocols in his application. Service Bus provides two types of messaging patterns “relayed” and “brokered” and these two messaging patterns are widely used to connect on-premise and cloud applications.

What is Relayed Messaging Pattern in AppFabric ServiceBus?

The Relayed messaging pattern supports direct one-way messaging, request/response messaging, and peer-to-peer messaging.

relay service

What is Brokered Messaging Pattern

The Brokered messaging pattern supports message queuing and publish/subscribe messaging. It provides asynchronous communication between a service and the consumer. The components of the Brokered messaging system are Queues, Topics and Subscriptions.

Important words:


A middleware is a piece of software which connects different components of software. In this context, the Service Bus is a middle ware.

loosely coupled

loosely coupled refers to a system which can connect when required and stay disconnected when not required.

Asynchronous communication

Asynchronous communication in this context refers to exchange of messages whenever required.