6. The method of claim 2 wherein applying the selected at least one markup language transformation to the tagged pre-transform data portions to transform the tagged pre-transform data portions in the message to tagged post-transform data portions in the message according to at least one transformation function associated with the at least one markup language transformation comprises: configuring a message parser with a set of search tags associated with a transformation in the sequence of transformations to be applied to the tagged pre-transform data portions in the message, each search tag capable of being matched to a tagged data portion of the message that is to be transformed according to a transformation function of the transformation in the sequence of transformations; using the parser, parsing the message to identify, within the message, at least one start search tag of the set of search tags that indicates a start of tagged pre-transform data in the message; in response to identifying a start search tag, applying the at least one transformation function to pre-transform message data in the message, beginning at the start of the tagged pre-transform data in the message and continuing until the parser identifies an end search tag in the message that indicates the end of the tagged pre-transform data in the message, application of the transformation function producing post-transform data; and integrating the post transform data into a transformed message to replace the tagged pre-transform data originally received in the message.
17. The method of claim 6 wherein the transformation functions specified by transformations in the sequence of transformations defined by the rule set that are to be applied to tagged message data include functions to perform metadata transformation operations within the message data by the markup language processing device such that the message forwarded to the recipient computerized device contains metadata that is different than metadata within the message received, the metadata transformations including modification of data values within at least one of: hypertext transport protocol data (HTTP); secure sockets layer data (SSL); and transmission control protocol data (TCP/IP).