HTTP Pass Through Transport over HTTP NIO Transport

when request message comes from client to the ESB as we know initially it hits the transport so when we go deep into the transport there we know there are two interfaces implemented namely TransportListener and TransportSender. So TransportListener is responsible to receive and process the client request and TransportSender is responsible for process and send response back to the client.wso2 ESB support no of transport in order to do establish better communication between client and the back-end service

One of the Two Transports Supported wso2 ESB are

• HTTP Pass Through Transport
• HTTP NIO Transport

In Wso2 ESB 5.0.0 the default transport is HTTP Pass Through the reason is when comparing HTTP Pass Through Transport and HTTP NIO Transport, HTTP Pass Through provided high performence.

So why to use HTTP Pass Through Transport over HTTP NIO Transport?

1.What is happen when we use HTTP NIO Transport ?

In HTTP NIO Transport the transport listener is HTTPCoreNIO.When request message comes, It write the message content to a input buffer. Then the message builder which is in axis2Engine read the content from the input buffer and build a object model which is XML based. This model is used in entire flow through the synapse mediation engine. Once the message reach to message formatter in axis2Engine it write that XML based object model as stream of byte in to a output buffer. Then the transport Sender in HTTP NIO Transport HttpCoreNIOSender read the content from the output buffer and send to backend server. Since there are two buffers engaged in this is called as duel buffer architecture.

2.What is the Drawback when we use HTTP NIO Transport ?

Since In HttpNIOTransport each and every client message request is writing to buffer in message building and formatting it affect to the performance of the ESB.

3.What is the solution?

Solution is HTTPPassThrough Transport since it based on single buffer and obviously it has been improve the performance of the ESB.The output buffer has been removed from the architecture and single shared buffer is using there.

4.What is happen when we use HTTP Pass Through Transport ?

PassThroughHttpListener create SourceHandler to receive client requests.Then it read only the request headers not the body. Then by looking at the headers of the request Simply route the message.That is only the overview of HttpPassThrough Transport in deep there are several components involve to route the message to the correct destination.

When message comes to the HttpPassThroughTransport It hits the PassThroughHttpListener it check whether the artifact is content aware or not if it is content aware then the message writes to the buffer and send to message builder in axis2Engine to create XML based object model and pass the request through the mediation engine and next to message formatter and then on demand it create output buffer dynamically and message formatter write the message to the buffer. Then Transport Sender read the message from the buffer and send it to the back-end server.

If the artifact is not contain any mediators which support content awareness then client request message should not be build and formatted then it skip the message builder and formatter then message directly go through the mediation engine and send to the back-end server.

5.How to switch from HTTP NIO Transport to HTTP Pass Through Transport?

We have to edit axis2.xml file configuration in order to switch