1. A method for converting items for exchange between heterogeneous applications, the method comprising: storing metadata to configure instructions for performing one or more conversion operations on individual items in a plurality of items, individual items in the plurality of items being transmitted between two or more heterogeneous applications in a plurality of applications; identifying at least a first item in the plurality of items being transmitted from a first application in the plurality of applications for delivery to one or more other applications in the plurality of applications; and using the metadata to perform a sequence of conversion operations on the first item in order to convert the first item from a format of the first application to a plurality of intermediate formats and then to a format of each of the one or more other applications, the sequence of conversion operations including at least a first syntax conversion operation to convert the first item to a first intermediate format in the plurality of intermediate formats, and at least a first semantic conversion operation to convert the item to a second intermediate format in the plurality of intermediate formats.