Re: [MEXT] Binary Filters and the nature of MIP Re: binary filtersdraft 0

["Glen Zorn" <gwz at net-zen.net>]

Hannes Tschofenig [mailto://Hannes.Tschofenig at gmx.net] writes:

> Sorry to be unclear.
> 
> There are two aspects:
> 
> 1) How do you encode filters on the wire, i.e., when carried in your
> favorite mobility protocol (or other protocol; does not really matter
> that
> much).
> 
> 2) How are these filters implemented in a particular node?
> 
> Now, for item (2) folks have come up with quite sophisticated
> mechanisms
> (typically dedicated languages that have an assembler like syntax) over
> time
> that are (a) highly efficient and (b) quite compact in the encoding. I
> provide a reference to the BSD packet filter system but the work
> obviously
> did not stop in 1992.
> 
> Now, ideally you would want to select a format for (1) that allows easy
> conversion to the format used with (2).
> 
> The problem now is that different implementations use different
> languages.
> So, it is quite likely that you will have to convert the stuff you get
> via
> (1) anyway to (2).
> 
> So, my conclusion is that the format for (1) does not really matter
> unless
> you get to pick a format that is extremely close or equal to the format
> used
> by (2) for most of the implementations.
> 
> This only matters if the translation from (1) to (2) is performance-
> wise an
> issue. I am not sure it really is and in that case you could as well
> toss a
> coin since it does not matter at all for the format for (1) is.
> 
> Does this description make any sense?

Total sense.  I'd just add that if we are to worry about performance issues
at all they should be issues that we have some control over (i.e.,
efficiency on the wire) rather than those we do not (for example, the
algorithms used at either end to create or process the filters).

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