nameserv::auto(3tcl) Name service facility nameserv::auto(3tcl)______________________________________________________________________________NAME
nameserv::auto - Name service facility, Client Extension
SYNOPSIS
package require Tcl 8.4
package require nameserv::auto ?0.3?
package require nameserv
_________________________________________________________________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 for‐
mer by taking measures to ensure that longer-lived data, i.e. bound
names, continuous and unfulfilled 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 unfulfilled 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 the API of nameserv and is
therefore not described here. Please read the documentation of name‐
serv.
The differences are explained in the sections OPTIONS and EVENTS.
OPTIONS
This package supports all the option of package nameserv, and one more.
The additional option allows the user to specifies the time interval
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, and 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
restored. 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 lis‐
tening for lost-connection events, on the tag nameserv.
It reacts to such events by starting a periodic timer and trying to
reconnect 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 continous 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 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 ALSOnameserv(3tcl)KEYWORDS
automatic, client, name service, reconnect, restore
CATEGORY
Networking
COPYRIGHT
Copyright (c) 2007-2008 Andreas Kupries <andreas_kupries@users.sourceforge.net>
nns 0.3 nameserv::auto(3tcl)
