difference between various methods for sending an outbound message using apache camel exchange

What is the difference between the following methods for sending an outbound message using camel exchange :

   e.getIn().setBody(body)开发者_运维技巧
   e.getOut().setBody(body)
   e.setOut(out);

and what exactly does the InOut Exchange pattern do ? i mean i know it's the default ExchangePattern and the caller expects a reply ..how do i set the reply..i am little vague about this . The APi javadocs are of little help :(

thank you

See the FAQ http://camel.apache.org/using-getin-or-getout-methods-on-exchange.html