Overview
========

   RFE 6209091 NL7C (Network Layer 7 Cache) proposes to complete the
   integration of NCA, LSARC/1998/373 Solaris Network Cache and Accelerator,
   into the kernel with a patch/micro release binding.

   Note, the integration of NCA into the kernel was started as part of the
   FireEngine project, PSARC/2002/433, with the implementation of NCA's
   protocol stack framework and IP/TCP design.

   NL7C completes the integration of NCA into the kernel by porting NCA's
   HTTP layer and object cache into the sockfs kernel module.

   NL7C maintains all of NCA's configuration, administration, and APIs such
   that the user will experience little change from previous releases with
   the stability level of the NCA interfaces remaining the same (Evolving).

   NL7C is targeted for an update of S10.

   NL7C's main benefit is the reduction of code as NL7C relies on the core
   protocol IP/TCP stack instead of a dedicated and duplicate stack. Note,
   the NCA protocol stack is removed.

   NL7C interposes on the sockfs/AF_INET/tcp control and data paths such
   that coordination with other projects in the sockfs space will be done
   as necessary, e.g. Clearwater (2003/146), Yellowdart (2003/182), and
   SDP (2004/298).

   NL7C does not have feature interactions with IPsec, IPMP, routing,
   or other basic networking components.  It operates as a cache
   logically at the application layer.  A socket is a socket.

   Like NCA, NL7C works only in the global zone, and this is enforced
   by the driver interfaces.  A future project should address the
   Zones limitation.


Ndd
===

   The nca kmod and driver remain for servicing of ndd ioctl()s from either
   ndd(1M) or other application ioctl() cals.

   Only the nca specific variables are serviced while all others "tcp_*" and
   "ip_*" variables return an obsoleted message referring the user to use the
   appropriate "/dev/tcp" or "/dev/ip" ndd variable.


Alternative Designs
===================

   Alternatives to installing into sockfs were considered, e.g. as
   part of Clearwater an interpose on the fly could've been done, but
   as Clearwater was shelved.  This would have taken NCA's http/tcp/ip
   design and implementing an http layer as part of the current
   FireEngine tcp/ip kmod.

   The welding of NCA functionality to sockfs was chosen as the best
   place to support an L7 cache.  If in a future sockfs were socket
   interpose can be done the small amount of code used to do the weld
   can be replaced with the appropriate interpose code.

   There are about 300 lines of code changes such that if NCA is
   disabled (the default), then no change to control/data flow of a
   socket. If NCA is enabled then, based on the NCA configuration
   (/etc/nca/ncaport.conf) specified ipaddr/port pairs or if the
   listen() socket is of AF_NCA, then NL7C will interpose.

   An accept()ing socket is marked for NL7C interpose, subsequent
   read-side data is http parsed for cache lookup, in the case of a
   cache hit the response is generated without application
   interaction.

   In the case of a miss, the socket is marked for cache fill and the
   request passed up to the application and subsequent write-side data
   is cached while being processed as normal by the sockfs code.

   In the case of a miss but not a request that NL7C is interested in
   then the socket NL7C state is cleared and the request/response is
   handled by the application.


Future
======

   Support for NCAS (NCA SSL, Secure Socket Layer) functionality as part of
   the Greyhoung project, PSARC/2002/557.

   Tentative plans call for additional L7 protocol support, e.g. ftp, to
   be explored. PSARC case(s) to be filed.

   NL7C configuration, administration, and programmatic interfaces, at which
   time NCA can be depreciated.  NL7C should be enhanced to use SMF.

   NL7C should support web servers running in zones other than the
   global zone.


Supporting Documentation
========================

   See http://NL7C.eng.Sun.COM for additional details.  (None of this
   material is normative for the case.)