nns_intro(3)



nns_intro(3tcl)              Name service facility             nns_intro(3tcl)

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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 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 re-
       solv, both found in Tcllib too.

       Tcllib  provides  2  applications  and 4 packages which are working to-
       gether 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 exam-
       ple 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 sen-
       sible 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  name-
       serv::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 manipu-
       late and query the service. An example of its use  is  the  application
       nns.

       The  second client package, nameserv::auto is API compatible to the ba-
       sic client, but provides the additional functionality that it will  au-
       tomatically  restore  data  like bound names when the connection to the
       name service was lost and then reestablished. I.e. it automatically de-
       tects  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  in-
       ternal  package  containing code and definitions common to the packages
       nameserv and nameserv::server.

       All packages use the uevent package for the reporting of  special  cir-
       cumstances  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.

       When proposing code changes, please provide unified diffs, i.e the out-
       put of diff -u.

       Note further that  attachments  are  strongly  preferred  over  inlined
       patches.  Attachments  can  be  made  by  going to the Edit form of the
       ticket immediately after its creation, and  then  using  the  left-most
       button in the secondary navigation bar.

SEE ALSO
       nameserv(3tcl),   nameserv::auto(3tcl),  nameserv::common(3tcl),  name-
       serv::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>

tcllib                                1.0                      nns_intro(3tcl)

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