RCCS Index

Message and Index Design Notes

Again, as part of the design for compact structures, the individual components were designed to fit efficiently into 32 bit words and 512 byte blocks. Messages were blocked rather than variable length for faster access and faster rebuilding if needed.

Clearly, other choices are possible.

Messages:

1 or more 128 byte blocks, in sequence. First block starts with std header, then first (128-SHL) bytes of message. Subsequent blocks contain 128 bytes of message, no other control.

Chr msg length is in header. Unix CR only, no LF.

Header Codes/Types:
  1. Area Definition
  2. Conference Def
  3. Subject Definition
  4. Tree hdr
  5. Index hdr
  6. Message hdr
  7. Unused
  8. "
  9. "
  10. Member Def
  11. Admin Def
  12. Reserved
Standard msg header:

Std Hdr Length: 24 bytes

  1. 24 bits "BII" Start ID for recovery
  2. 08 b "6" Code for message header type
  3. 32 b Dt/Ti Date/Time submitted in GMT
  4. 32 b User # User ID number
  5. 32 b Sect # 128by Sect # where msg starts
  6. 16 b A/C/S Area/Conf/Subj numbers
  7. 16 b Tree # Tree in subject number
  8. 16 b link # Msg # of referred msg
  9. 16 b Chr len Length of message in bytes

Standard index header: SHL: 24 bytes

  1. 24 bits "BII" Start ID for recovery
  2. 08 b "5" Code for message header type
  3. 16 b A/C/S
  4. 16 b Msg #
  5. 16 b Tree #
  6. 16 b ChrSec Chr len of message
  7. 32 b TrSec Sector/offset in tree(29/3)
  8. 32 b Reserved

All content on this site is Copyright 2001 and 2002 by Bill Nicholls