1. A computer-implemented method for transmitting a message from a sending application through an application integration system, the method comprising: determining, at a routing module of an application integration system that is implemented on one or more processors, an identity of a receiving application of the message, the application integration system utilizing an application integration system file format; determining, at a mapping module of the application integration system, a receiving application file format used by the receiving application; sending the identity, of the receiving application of the message and the file format used by the receiving application to the sending application in response to a polling received from the sending application at the application integration system; wrapping, at the application integration system, the message in a markup language file envelope if the receiving application file format is identical to a sending application file format used by the sending application, the wrapping comprising adding a message header in the application integration system file format while leaving the message content unchanged and without mapping or converting the message content according to the application integration system file format; converting, at the application integration system, the message to the application integration system file format if the receiving application file format differs from the sending application file format; and routing either the markup language file envelope with the message or the converted message through the application integration system to the receiving application; wherein the markup language corresponds to extensible markup language (XML).