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nns_intro(n)                                Name service facility                               nns_intro(n)



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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 ser-vice service
       vice 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 sys-tem, system,
       tem,  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 nor-mally normally
       mally 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 pack-ages packages
       ages 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, will undoubtedly contain bugs and other problems.  Please report such in the  category
       nameserv  of  the  Tcllib  SF Trackers [http://sourceforge.net/tracker/?group_id=12883].  Please also
       report any ideas for enhancements you may have for either package and/or documentation.  Please  also
       report any ideas for enhancements you may have.

SEE ALSO
       nameserv(n),   nameserv::auto(n),  nameserv::common(n),  nameserv::protocol(n),  nameserv::server(n),
       nnsd(n), nss(n)

KEYWORDS
       client, name service, server

CATEGORY
       Networking

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




nns                                                  1.0                                        nns_intro(n)