[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: Creating a Complex System using XSLT. Step 1: CreateFeedb
The missing part of the amplifier analogy is one or several microphones/pickups that get that signal on output and route it back to the amplifier. That alone produces the feedback. Something listens and routes. To be more complete, because the environment (the room acoustics) shapes the signal, feedback can occur because the room is sensitive to a given frequency and reflects it back intensely. One should look for both known couplers and surprise couplers. Equalization is used to tune out the second kind (at the mics); the palm of the hand can be used to dampen feedback into the guitar pickup. Also, mic grouping, mic choice (eg, SM57s are bad a bad sound but insensitive to feedback), and so on. Given a pipeline (your supervisor) with multiple documents being dynamically created and merged, one could indeed simulate feedback driven systems where the XSLT stylesheet acts as the filter (the equalizer) and the schema acts like the palm of a hand. len From: Thomas B. Passin [mailto:tpassin@c...] Roger L. Costello wrote: > > That leads me to another question - is feedback generally applied to the > "data" or to the "process"? > Feedback is part of the processing of the data. Think of an electronic amplifier. The unmodified input signal is the data, the amplifier provides a transformation of that signal to create the output. Thus, the stylesheet would be analogous to the amplifier (or other electronic circuit). With feedback, a part of the input signal is taken from the output. If the feedback adds linearly to the input, and the feedback portion of the output is linear, the system is a lot easier to analyze than if there is non-linearity. Thinking about an xslt transformation, its functional design should prevent feeding back part of the output to the input. Once the input has been read, it cannot be changed so far as the particular transformation is concerned. Thus, xslt operates somewhat analgously (is that a word??) to an open loop amplifier. So it would seem that to simulate fedback behavior using xslt, you would need some kind of supervisor sitting outside the stylesheet, capable of routing both its output and the original input to another transformation. Could that supervisor also be a stylesheet? I doubt it but maybe someone else could be clever enough.
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