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How WSO2 ESB implements the EIP
The Architecture section in WSO2 ESB documentation describes how the ESB processes a message it receives. When a message arrives before it is sent through the pipes for mediation, it will be transformed to a SOAP envelop using message builders. This way, the message will be of a standard format for the message mediation engine to do the processing. Once the response is ready to be sent back to the receiver, it will be changed back to its original format through message formatters.