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General question about the header of EXI

Anonymous
2017-04-27
2017-04-27
  • Anonymous

    Anonymous - 2017-04-27

    I am (partially) writing a customized Schema Informed C/C++ EXI encoder and decoder for several schemas, and I have a general question about the header.
    The first byte is 0x80 (no EXI cookier, [10] for distinguishing bits, [0] no presence bit for EXI options, [0_0000] format version of 1)
    But what follows after that is something I can't find in the spec and it doesn't appear to be actual EXI data yet.  Depending on what schema I'm using, I get a different set of bits so I assume it's something to indicate what schema is being used.  How is this calculated?  Where is it specified in the specification?  (https://www.w3.org/TR/exi/).
    Currently, I just skip over these bits for decode, and blindly write them for encode.  Can somebody here tell me what these are?  Have I just missed a portion of the EXI?

    Thank you,-Rich

     
    • Anonymous

      Anonymous - 2017-04-28

      Nevermind, I figured it out.  The XML can have something like 90 different ways to begin start, these are what the bits are, it selects which production is being made, even though only two really exist in practical use for my project.

      On Thursday, April 27, 2017 2:48 PM, Richard Wicks <rich_wicks@yahoo.com> wrote:
      

      I am (partially) writing a customized Schema Informed C/C++ EXI encoder and decoder for several schemas, and I have a general question about the header.
      The first byte is 0x80 (no EXI cookier, [10] for distinguishing bits, [0] no presence bit for EXI options, [0_0000] format version of 1)
      But what follows after that is something I can't find in the spec and it doesn't appear to be actual EXI data yet.  Depending on what schema I'm using, I get a different set of bits so I assume it's something to indicate what schema is being used.  How is this calculated?  Where is it specified in the specification?  (https://www.w3.org/TR/exi/).
      Currently, I just skip over these bits for decode, and blindly write them for encode.  Can somebody here tell me what these are?  Have I just missed a portion of the EXI?

      Thank you,-Rich

       
  • Rumen Kyusakov

    Rumen Kyusakov - 2017-05-08

    Hi,

    Sorry for late response. What bits follow in this case is ruled by the Schema-informed Document Grammar (https://www.w3.org/TR/exi/#informedDocGrammars)

    Good luck!
    Rumen

     

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