********************************************************************** FTSC FIDONET TECHNICAL STANDARDS COMMITTEE ********************************************************************** Publication: FSP-1032 Revision: 1 Title: Binkp optional protocol extension Dataframe Compression Authors: Alex Shakhaylo Issue Date: 03 Feb 2004 Review Date: 03 Feb 2005 -+-------------------------------------------------------------------- Contents: 1. Binkp Dataframe Compression A. References B. History -+-------------------------------------------------------------------- Status of this document -+--------------------- This document is a Fidonet Standards Proposal (FSP). This document specifies an optional Fidonet standard protocol for the Fidonet community, and requests discussion and suggestions for improvements. This document is released to the public domain, and may be used, copied or modified for any purpose whatever. 1. Binkp Dataframe Compression -+---------------------------- A session is in PLZ mode in case the both sides set "PLZ" flag in any of M_NUL "OPT" packets. This extension may be used in both binkp/1.0 and binkp/1.1 protocol versions. To compress dataframes in PLZ mode ZLib library (by Jean-loup Gailly and Mark Adler) is used. It is assumed that in PLZ mode any dataframe withing the regular data exchange may be compressed with 'compress' or 'compress2' methods of ZLib library. Compressed dataframes are indicated by setting the second high bit of the high byte of the frame header. Thus the biggest dataframe in PLZ mode cannot exceed 00111111 11111111 = 0x3FFF = 16383 bytes. At any moment during a session any side may swith off PLZ mode by sending M_GET command with additional parameter 'NZ' (for example: M_GET "config.sys 125 2476327846 100 NZ", this command requests to switch off PLZ mode and to resend "config.sys" file from offset 100). A position of 'NZ' additional parameter in M_GET command is not fixed, because of other optional extensions which can also use additional parameters. A. References -+----------- [FSP-1018] Binkp 1.0 Protocol specification. B. History -+-------- Rev.1, 20042501: First release.