There was also a version that would automatically turn JSON into XML and vice versa. When REST started pushing out SOAPy stuff, we actually had a meeting where the sales guy (at the behest of our XML loving CTO) showed us a diagram that was roughly this:

Web ------------- Premisis

JSON ---> || ---> XML

JSON <--- || <--- XML

Price was $9,600 for the 2U appliance that makes all your non-enterprisy JSON into something fitting of today's modern enterprise, circa 2001. To this day, I laugh when I think about it.

How does such a thing work? Parsing XML is full of branches and dynamic allocations that general purpose CPUs are good at.

I would assume it works by encoding primarily a strict, predictable format. And when decoding, primarily accelerating the stricter, more predictable parts, and including some regular CPUs for the difficult bits.