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







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








Bind name data


Release


Search pattern


ProtocolVersion


ProtocolFeatures


Search/Continuous/Start tag pattern


Search/Continuous/Stop tag


Search/Continuous/Change tag
    add|remove response












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.








This protocol defines the basic set of messages to be supported by
    a name service, also called the Core feature.






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.









  

  
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.

  

  

  
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.

  
  
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.

  

  
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.

  

  

  
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}.

  












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.



  

  
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.

  

  

  
The client sends this message to stop the continuous search identified by
      the tag.

  

  
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.

  










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.








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








comm, name service, protocol








Networking








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








  

    0.1
    nns