


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 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 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.




nns                            1.0                              1





nns_intro(n)          Name service facility          nns_intro(n)


       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  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,  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 docu-
       mentation.  Please also report any ideas for enhancements you may have.

SEE ALSO
       nameserv(n), nameserv::auto(n),  nameserv::common(n),  nameserv::proto-
       col(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                              2


