TIP #130: UNIQUE DDE SERVER NAMES. 
====================================
 Version:      $Revision: 1.4 $
 Author:       Pat Thoyts <patthoyts_at_users.sourceforge.net>
 State:        Final
 Type:         Project
 Tcl-Version:  8.5
 Vote:         Done
 Created:      Sunday, 23 March 2003
 URL:          https://tip.tcl-lang.org130.html
 Post-History: 

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 ABSTRACT 
==========

 The /dde/ package server registration code should ensure that the 
 server names are unique. The proposed changes will mean end-user 
 visible changes for some scripts. 

 RATIONALE 
===========

 This TIP is really driven by Bug 219293 
 [<URL:http://sf.net/tracker/?func=detail&aid=219293&group_id=10894&atid=110894>] 

 The DDE system actually identifies servers by combination of window ID 
 and a service and topic string identifier. There is nothing to prevent 
 multiple servers having the same string identifiers but it is then a 
 problem to determine which server you need to communicate with. 

 The /tk appname/ command handles a similar situation by making the name 
 unique during registration by appending a numerical suffix to the 
 suggested name and then returning the name registered as the result of 
 the command. 

 PROPOSED CHANGES 
==================

 This TIP proposes to use the /tk appname/ unique name algorithm within 
 the DDE server-name registration code. This TIP also proposes a 
 /-force/ option to this command to force the suggested name to be 
 registered. The /-force/ option would then provide the current 
 registration scheme. 

 REFERENCE IMPLEMENTATION 
==========================

 See the patch attached to SF patch 690354 
 [<URL:https://sourceforge.net/tracker/?func=detail&aid=690354&group_id=10894&atid=310894>] 

 CONSEQUENCES 
==============

 Firstly the /dde servername/ command may register a different name than 
 that provided to the command. Scripts will need to check the name 
 actually registered by either maintaining the result of this command, 
 or by executing the /dde servername/ command without any arguments. 
 This may impact scripts that assume the supplied argument was in fact 
 the name registered. 

 Secondly, the name registration code must obtain a list of the dde 
 server names currently registered on the system. It can do this by 
 effectively calling /dde services TclEval/. In previous versions of the 
 /dde/ package there is a potential for the /dde services/ command to 
 hang in the presence of applications that are not processing messages. 
 However, this issue has been addressed by Bug 707822's resolution. 

 COPYRIGHT 
===========

 This document is hereby placed in the public domain. 

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