


nameserv::protocol(n) Name service facility nameserv::protocol(n)


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NAME
       nameserv::protocol - Name service facility, client/server protocol

SYNOPSIS
       Bind name data

       Release

       Search pattern

       ProtocolVersion

       ProtocolFeatures

       Search/Continuous/Start tag pattern

       Search/Continuous/Stop tag

       Search/Continuous/Change tag add|remove response

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DESCRIPTION
       The packages nameserv::server, nameserv, and nameserv::common provide a
       simple unprotected name service facility for use in small trusted envi-
       ronments.

       Please read Name service facility, introduction first.

       This  document contains the specification of the network protocol which
       is used by client and server to talk to each other, enabling  implemen-
       tations of the same protocol in other languages.

NANO NAME SERVICE PROTOCOL VERSION 1
       This  protocol  defines  the basic set of messages to be supported by a
       name service, also called the Core feature.

   BASIC LAYER
       The basic communication between client and server  is  done  using  the
       remote-execution protocol specified by the Tcl package comm.  The rele-
       vant document specifying its  on-the-wire  protocol  can  be  found  in
       comm_wire.

       All the scripts exchanged via this protocol are single commands in list
       form and thus can be interpreted as plain messages instead  of  as  Tcl
       commands.  The  commands/messages specified in the next section are the
       only commands understood by the server-side. Command and variable  sub-
       stitutions  are not allowed within the messages, i.e. arguments have to
       be literal values.

       The protocol is synchronous. I.e. for each message sent a  response  is
       expected, and has to be generated. All messages are sent by the client.



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nameserv::protocol(n) Name service facility nameserv::protocol(n)


       The server does not sent messages, only responses to messages.

   MESSAGE LAYER
       Bind name data
              The client sends this message when it registers  itself  at  the
              service  with a name and some associated data. The server has to
              send an error response if the name is already in use.  Otherwise
              the response has to be an empty string.

              The server has to accept multiple names for the same client.

       Release
              The  client  sends  this  message  to unregister all names it is
              known under at the service. The response  has  to  be  an  empty
              string, always.

       Search pattern
              The  client  sends  this message to search the service for names
              matching the glob-pattern. The response has to be  a  dictionary
              containing  the  matching names as keys, and mapping them to the
              data associated with it at Bind-time.

       ProtocolVersion
              The client sends this message to query the service for the high-
              est  version  of  the  name  service  protocol  it supports. The
              response has to be a positive integer number.

              Servers supporting only Nano Name  Service  Protocol  Version  1
              have to return 1.

       ProtocolFeatures
              The  client sends this message to query the service for the fea-
              tures of the name service protocol it supports. The response has
              to be a list containing feature names.

              Servers  supporting  only  Nano  Name Service Protocol Version 1
              have to return {Core}.


NANO NAME SERVICE PROTOCOL EXTENSION: CONTINUOUS SEARCH
       This protocol defines an extended set of messages to be supported by  a
       name  service,  also called the Search/Continuous feature. This feature
       defines additional messages between client and server, and is otherwise
       identical  to  version  1 of the protocol. See the last section for the
       details of our foundation.

       A  service  supporting  this  feature  has  to  put  the  feature  name
       Search/Continuous  into  the  list  of features returned by the message
       ProtocolFeatures.

       For this extension the protocol is asynchronous. No direct response  is
       expected  for  any  of  the  messages in the extension. Furthermore the
       server will  start  sending  messages  on  its  own,  instead  of  only
       responses  to  messages,  and the client has to be able to handle these



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nameserv::protocol(n) Name service facility nameserv::protocol(n)


       notifications.

       Search/Continuous/Start tag pattern
              The client sends this message to start searching the service for
              names  matching  the  glob-pattern.   In contrast to the regular
              Search request this one asks the server to continuously  monitor
              the  database  for  the addition and removal of matching entries
              and to notify the client of all  such  changes.  The  particular
              search is identified by the tag.

              No  direct response is expected, rather the clients expect to be
              notified of changes via explicit  Search/Continuous/Result  mes-
              sages generated by the service.

              It  is  further  expected  that  the  tag  information is passed
              unchanged to the Search/Continuous/Result messages. This tagging
              of  the  results  enables clients to start multiple searches and
              distinguish between the different results.

       Search/Continuous/Stop tag
              The client sends this message  to  stop  the  continuous  search
              identified by the tag.

       Search/Continuous/Change tag add|remove response
              This  message is sent by the service to clients with active con-
              tinuous searches to transfer found changes. The first such  mes-
              sage for a new continuous search has to contains the current set
              of matching entries.

              To ensure this a service has to generate an add-message with  an
              empty response if there were no matching entries at the time.

              The  response  has  to  be  a dictionary containing the matching
              names as keys, and mapping them to the data associated  with  it
              at Bind-time.  The argument coming before the response tells the
              client whether the names in the response were added  or  removed
              from the service.


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       SF       Trackers       [http://source-
       forge.net/tracker/?group_id=12883].  Please also report any  ideas  for
       enhancements you may have for either package and/or documentation.

SEE ALSO
       comm_wire(n), nameserv(n), nameserv::server(n)

KEYWORDS
       comm, name service, protocol

CATEGORY
       Networking



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nameserv::protocol(n) Name service facility nameserv::protocol(n)


COPYRIGHT
       Copyright (c) 2007-2008 Andreas Kupries <andreas_kupries@users.sourceforge.net>























































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