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
       environments.

       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
       implementations 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
       relevant 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
       substitutions 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.
       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
              highest 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
              features 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
       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
              messages 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
              continuous searches to transfer found changes. The first such
              message 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://sourceforge.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

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




nns                                   0.1                nameserv::protocol(n)
