NAME

       nns_intro - Name service facility, introduction

DESCRIPTION

       nns (short for nano nameservice) is a facility built for the package comm, adding a simple
       name service to it.  It is also built on top  of  comm,  using  it  for  the  exchange  of
       messages between the client and server parts.

       This  name  service  facility  has  nothing  to do with the Internet's Domain Name System,
       otherwise known as DNS. If the reader is looking for a package dealing  with  that  please
       see either of the packages dns and resolv, both found in Tcllib too.

       Tcllib  provides  2  applications  and  4  packages which are working together and provide
       access to the facility at different levels.

APPLICATIONS

       The application nnsd provides a simple name server which can be run by anybody anywhere on
       their  system,  as  they  see  fit.   It  is also an example on the use of the server-side
       package nameserv::server.

       Complementing this server is the nns client application.  A possible, but no very sensible
       use  would be to enter name/port bindings into a server from a shell script. Not sensible,
       as shell scripts normally do not provide a comm-based service.

       The only case for this to make some sense would be in a shell script wrapped around a  Tcl
       script  FOO which is using comm, to register the listening port used by FOO.  However even
       there it would much more sensible to extend FOO to use the nameservice  directly.  And  in
       regard  on  how  to that nns can be used as both example and template.  Beyond that it may
       also be useful to perform nameservice queries from shell scripts.

       The third application, nnslog is a stripped down form of the nns client application. It is
       reduced  to  perform  a  continuous search for all changes and logs all received events to
       stdout.

       Both  clients  use  the  nameserv::auto  package  to  automatically  hande  the  loss  and
       restoration of the connection to the server.

PACKAGES

       The  two  main  packages  implementing the service are nameserv and nameserv::server, i.e.
       client and server. The latter has not much of an API, just  enough  to  start,  stop,  and
       configure it. See the application nnsd on how to use it.

       The  basic  client, in package nameserv, provides the main API to manipulate and query the
       service. An example of its use is the application nns.

       The second client package, nameserv::auto is API  compatible  to  the  basic  client,  but
       provides  the  additional functionality that it will automatically restore data like bound
       names when the connection to the name service was lost and  then  reestablished.  I.e.  it
       automatically  detects the loss of the server and re-enters the data when the server comes
       back.

       The package nameserv::common is of no  interest  to  users.  It  is  an  internal  package
       containing code and definitions common to the packages nameserv and nameserv::server.

       All packages use the uevent package for the reporting of special circumstances via events,
       and reserve the uevent-tag nameserv for their exclusive use.  All  their  events  will  be
       posted to that tag.

INTERNALS

       The  document Name service facility, client/server protocol specifies the protocol used by
       the packages nameserv and nameserv::server to talk to each other. It is of no interest  to
       users of either the packages or applications.

       Developers  wishing  to  modify  and/or  extend or to just understand the internals of the
       nameservice facility however are strongly advised to read it.

BUGS, IDEAS, FEEDBACK

       This document, and the package it describes,  will  undoubtedly  contain  bugs  and  other
       problems.    Please   report  such  in  the  category  nameserv  of  the  Tcllib  Trackers
       [http://core.tcl.tk/tcllib/reportlist].  Please also report any ideas for enhancements you
       may have for either package and/or documentation.

SEE ALSO

       nameserv(3tcl),  nameserv::auto(3tcl),  nameserv::common(3tcl),  nameserv::protocol(3tcl),
       nameserv::server(3tcl), nnsd(3tcl), nss(3tcl)

KEYWORDS

       client, name service, server

CATEGORY

       Networking

COPYRIGHT

       Copyright (c) 2008 Andreas Kupries <andreas_kupries@users.sourceforge.net>