Key features

Routing

If different clients are sending messages to ESB, ESB will decide to which server the message should be routed. Routing can be based on headers, content of message.

Filtering

According to the content, can filter and then decide whether sending to back end or discarding the messages.

Transformation

Client has their own format of sending messages but back end services has their own defined format. So ESB get the message from client and change to the format the back end can understand give it then get the response from back end then send it to client.

Transformation is using XSLT.

Protocol Switching

Client will communicate with the ESB with SOAP or HTTP protocol but the back end service is deployed with Fix protocol. So ESB is used to transform from HTTP protocol to Fix protocol.

Load balancing

When multiple messages coming into the ESB, some of the messages routed to different servers.

QOS (quality of services)

when service is deployed into wso2 ESB , client will communicate with ESB with a security token.But back end has no authentication mechanism. So the non secure back end service can be secured through wso2 ESB secure mechanism.