nns_auto(3)



nameserv::auto(3tcl)         Name service facility        nameserv::auto(3tcl)

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NAME
       nameserv::auto - Name service facility, Client Extension

SYNOPSIS
       package require Tcl  8.4

       package require nameserv::auto  ?0.3?

       package require nameserv

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DESCRIPTION
       Please read the document Name service facility, introduction first.

       This  package  provides  the  exact  same API as is provided by package
       nameserv, i.e. the regular name service client.  It  differs  from  the
       former  by taking measures to ensure that longer-lived data, i.e. bound
       names, continuous and unfullfilled async searches, survive the loss  of
       the connection to the name server as much as is possible.

       This  means  that the bound names and continuous and unfullfilled async
       searches are remembered client-side and automatically  re-entered  into
       the  server  when  the  connection comes back after its loss. For bound
       names there is one important limitation to such restoration: It is pos-
       sible  that a name of this client was bound by a different client while
       the connection was gone. Such names are fully lost, and  the  best  the
       package can and will do is to inform the user of this.

API
       The  user-visible API is mainly identical to the API of nameserv and is
       therefore not described here. Please read the  documentation  of  name-
       serv.

       The  differences  are  explained  below,  in  the  sections OPTIONS and
       EVENTS.

OPTIONS
       This package supports all the options of  package  nameserv,  plus  one
       more.  The additional option allows the user to specify the time inter-
       val between attempts to restore a lost connection.

       -delay milliseconds
              The value of this option is an integer value > 0 which specifies
              the  interval to wait between attempts to restore a lost connec-
              tion, in milliseconds. The default value is 1000, i.e. one  sec-
              ond.

EVENTS
       This  package generates all of the events of package nameserv, plus two
       more. Both events are generated for the tag nameserv.

       lost-name
              This event is generated when a bound name is  truly  lost,  i.e.
              could not be restored after the temporary loss of the connection
              to the name server. It indicates that a  different  client  took
              ownership of the name while this client was out of contact.

              The  detail  information  of  the event will be a Tcl dictionary
              containing two keys, name, and data. Their values hold  all  the
              information about the lost name.

       re-connection
              This event is generated when the connection to the server is re-
              stored. The remembered data has been restored when the event  is
              posted.

              The event has no detail information.

DESIGN
       The  package  is  implemented on top of the regular nameservice client,
       i.e. package nameserv. It detects the loss of the connection by listen-
       ing for lost-connection events, on the tag nameserv.

       It reacts to such events by starting a periodic timer and trying to re-
       connect to the server whenver this timer triggers. On success the timer
       is  canceled, a re-connection event generated, and the package proceeds
       to re-enter the remembered bound names and continuous searches.

       Another loss of the connection, be it during or after  re-entering  the
       remembered  information simply restarts the timer and subsequent recon-
       nection attempts.

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)

KEYWORDS
       automatic, client, name service, reconnect, restore

CATEGORY
       Networking

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

tcllib                                0.3                 nameserv::auto(3tcl)

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