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List:       kmail-devel
Subject:    Re: Architectural problems shown by the anti spam wizard
From:       Andreas Gungl <Andreas.Gungl () osp-dd ! de>
Date:       2004-01-29 7:33:13
Message-ID: 4018B739.3040707 () osp-dd ! de
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Don Sanders wrote:
> Hi Andreas,
> 
> On Thursday 29 January 2004 05:45, Andreas Gungl wrote:
> 
>>Hi,
>>
>>for those who are interested I want to describe some problems I
>>came over while I worked on some details for the anti spam wizard.
>>
> 
> 
> I'll try to answer your questions as best I can. But I'm having 
> difficulty because I don't understand the intended workflow for 
> setting up the anti-spam stuff you have been working on.
> 
> Don't get me wrong it's a critical feature in my opinion, but I'm 
> lacking clarity on how exactly it is meant to work from the end users 
> point of view. Is it intended to work like the Mozilla ant-spam 
> stuff? (I haven't used that either, but I see lots of people saying 
> good things about it).
> 
> I don't understand what value the new spam/ham statuses have for 
> instance.

I'll try to explain it in short here:
The main problem is that KMail doesn't have built in spam filtering - in 
contradiction to Mozilla. Installing Mozilla gives you all you need, so 
you can rely on your own. KMail wants to cooperate with existing anti 
spam tools. The "average user" (whoever it is) has two problems IMO. She 
would have to check what tools are installed (installation could be 
prepared by the distributors) and then (perhaps more difficult) she 
would have to define filter rules to let KMail properly cooperate with 
the tools.

The wizard tries to find installed tools. Then it allows to let create 
filters to use the tools to detect spam mails (basically by piping 
through the tools) and to handle spam messages e.g. by moving to trash 
(by identifying related headers like X-SpamFlag). Having bayesian spam 
tools, you need to learn them. So the wizard can create rules to let the 
tools learn ham and spam messages.
The creation of the tools is done based on information in a config file 
(kmail.antispamrc, see CVS), so new tools can get added without changing 
the code.
Detection and handling rules are applied on incoming messages and on 
manual filtering. Classification (learning) is done using ad-hoc 
filters. The latter do also set the ham/spam status for a message (only 
as a remider for the user).


>>Current situation:
>>
>>   The concept of ad-hoc filters allows dynamic plugging of marked
>>filters into the KMail menu with a slightly modified menu item name
>>(derived from the filter name) plus an icon (both defined in the
>>filter dialog). When the configuration has changed, all items get
>>removed from the submenu and each marked ad-hoc filter gets added
>>then into a "clean" submenu.
> 
> 
> Are we talking about KMMainWidget::initializeFilterActions() here?

Yes. It comes down to this.

> Yes in my opinion there is an implementation weakness here, rather 
> than deleting the old KActions (mFilterActions.clear()) existing 
> KActions should be reused where possible. This may be possible by 
> using the normalizedName.local8Bit() which is passed into the KAction 
> constructor and hence is the QObject::name() for that KAction.
> 
> At least I was experiencing a problem due to this clearing of existing 
> KActions, and this is the solution I was thinking of to fix it. Are 
> thinking about the same thing here?

Yes, but see below.

>>You can now use the toolbar editor to include some of the (dynamic)
>>menu items (actually actions) into the toolbar. This will work fine
>>as long as you don't remove the menu items by e.g. deleting or
>>renaming the filters. In this case the action entry in the XMLGUI
>>config file will stay but the toolbar icon is no longer shown
>>because the corresponding action can't get found.
>>Here the XMLGUI definition and the filters get out of sync which
>>can be a source for problems later on.
> 
> 
> I wonder what these 'problems later on' are. I guess they are 
> important as you mention them?

You may end up with some (many?) unused resp. invalid action entries for 
the toolbar in the XMLGUI ressource file. As soon as you have any new 
action named like such an entry, a toolbar button will show up even if 
you never intended to create one.

>>   The wizard plugs the action into the toolbar and to make the
>>change persistent it modifies the XMLGUI file. This is done by
>>manual manipulation of the XMLGUI file, currently there is no API
>>which would support automatic write back of the current config by
>>the toolbar itself. Of course the user will face the sync problems
>>described above sooner or later.
> 
> 
> Not completely sure I understand the sync problems.

The toolbar does not change it's XMLGUI config file when you plug an 
ad-hoc filter based action into it. A button would show up after you 
have plugged the action, but after a restart the button is lost if you 
don't replug it again.
The wizard tries to eliminate the restart problem by additionally adding 
the actions to the ressource file.

>>Another problem might be based on 
>>translation (i18n) issues when e.g. the user switches the language,
>>but I have no concrete scenario for this, it's just a guess.
> 
> 
> If you look at the KAction constructor in initializeFilterActions() 
> the QObject::name() is not i18n()'d so this should be invariant in 
> the case of the user switching the language.

The action names are based on the filter's name. If the wizard creates a 
filter "mark as spam" it should be "als Spam markieren" in German. When 
I change the filter's name manually, the action for the ad-hoc filter 
menu item get's a new name, but the entry in the XMLGUI ressource file 
doesn't get changed. They don't belong together anymore!!!

>>Possible solution:
>>
>>   We might add an option to the filter definition which depends on
>>the filter being marked as ad-hoc so that then it can additionally
>>marked as "include in toolbar". This would support the idea of
>>dynamic actions based on the current filter configuration. It also
>>would eliminate the sync problem between filters and XMLGUI
>>ressource.
> 
> 
> Why would if eliminate the sync problems, it seems I'm missing 
> something or not following clearly.
> 
> 
>>A drawback is that the user can't make persistent changes to the
>>position of these actions in the toolbar,
> 
> 
> Why?

To let the position change be persistent, you would have to write it 
into the XMLGUI ressource file. Then you have the problems described 
above. You might store it somewhere else, then you get problems when the 
user manipulates the toolbar manually.

>>which is really no good 
>>UI design. A special filter toolbar is bloat, IMO.
>>
>>
>>I've thought about the possibility to have some predefined default
>>actions which might be disabled or hidden as long as no action
>>provider is bound to them.
> 
> 
> What are you referring to by action provider? A KAction, based on a 
> filter in the filter dialog?

See below.

>>Let's say that we have a default action "mark as spam". The
>>appropriate filter should register to this action making the action
>>active. After that the user may configure the action regarding the
>>toolbar position. My conclusion was that this (up to now) a very
>>special case. It's more complex to implement than the solution
>>above. And I still have no clear picture about what would this
>>imply for other parts of KMail.
> 
> 
> I think default actions make sense.

The mark spam action would be by default in KMail. Then, there might be 
some code (the provider) which registers to it by saying, hey I want to 
be called when the mark spam action is triggered. It can be made inside 
the KMail code base e.g. by letting the user associate a filter with an 
action (oh, I don't really want this) or by even having a dcop interface 
for external plugins.

>>I would like to know what is your opinion about this problem? What
>>are your (the core developers') plans regarding changes to the
>>filter system in the near future? How do this ad-hoc filters fit
>>into a concept of using sieve to support filtering on the server
>>side? Does anybody has plans for a plugin system and how could it
>>deal with the problem described above?
> 
> 
> Unfortunately I don't understand the proposed anti spam wizard well to 
> understand what 'this problem' is well enough to be able to answer 
> these questions.
> 
> I should be on #kontact till about at least GMT 9:00am if you want to 
> discuss things on irc.
> 
> Don.

Sorry, I'm not at home so I've no IRC access. I hope I've explained the 
open issues detailed enough.

Andreas
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