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<div class="section" id="design-notes">
<h1>Design Notes<a class="headerlink" href="#design-notes" title="Permalink to this headline"></a></h1>
<p>This document contains design notes for plone.app.discussion.</p>
<div class="section" id="storage-and-traversal">
<h2>Storage and traversal<a class="headerlink" href="#storage-and-traversal" title="Permalink to this headline"></a></h2>
<p>For each content item, there is a Conversation object stored in annotations.
This can be traversed to via the ++conversation++ namespace, but also fetched
via an adapter lookup to IConversation.</p>
<p>The conversation stores all comments related to a content object. Each
comment has an integer id (also representable as a string, to act as an OFS
id and allow traversal). Hence, traversing to obj/++conversation++/123 retrieves
the comment with id 123.</p>
<p>Comments ids are assigned in order, so a comment with id N was posted before
a comment with id N + 1. However, it is not guaranteed that ids will be
incremental. Ids must be positive integers - 0 or negative numbers are not
allowed.</p>
<p>Threading information is stored in the conversation: we keep track of the
set of children and the parent if any comment. Top-level comments have a
parent id of 0. This information is managed by the conversation class when
comments are manipulated using a dict-like API.</p>
<p>Note that the __parent__/acquisition parent of an IComment is the
IConversation, and the __parent__/acquisition parent of an IConversation is
the content object.</p>
</div>
<div class="section" id="events">
<h2>Events<a class="headerlink" href="#events" title="Permalink to this headline"></a></h2>
<p>Manipulating the IConversation object should fire the usual IObjectAddedEvent
and IObjectRemovedEvent events. The UI may further fire IObjectCreatedEvent
and IObjectModifiedEvent for comments.</p>
</div>
<div class="section" id="factories">
<h2>Factories<a class="headerlink" href="#factories" title="Permalink to this headline"></a></h2>
<p>Comments should always be created via the &#8216;Discussion Item&#8217; IFactory utility.
Conversations should always be obtained via the IConversation adapter (even
the ++conversation++ namespace should use this). This makes it possible to
replace conversations and comments transparently.</p>
</div>
<div class="section" id="the-comment-class">
<h2>The Comment class<a class="headerlink" href="#the-comment-class" title="Permalink to this headline"></a></h2>
<p>The inheritance tree for DiscussionItem is shown below. Classes we want to
mix in and interface we want to implement in the Comment class are marked
with [x].</p>
<blockquote>
<dl class="docutils">
<dt>[ ] DiscussionItem</dt>
<dd><dl class="first last docutils">
<dt>[ ] Document</dt>
<dd><dl class="first last docutils">
<dt>[ ] PortalContent = [ ] IContentish</dt>
<dd><p class="first">[ ] DynamicType = [ ] IDynamicType
[ ] CMFCatalogAware = [ ] &lt;no interface&gt;
[ ] SimpleItem = [ ] ISimpleItem</p>
<blockquote class="last">
<dl class="docutils">
<dt>[ ] Item [ ]</dt>
<dd>[?] Base = [ ] &lt;no interface&gt;
[ ] Resource = [ ] &lt;no interface&gt;
[ ] CopySource = [ ] ICopySource
[ ] Tabs = [ ] &lt;no interface&gt;
[x] Traversable = [ ] ITraversable
[ ] Element = [ ] &lt;no interface&gt;
[x] Owned = [ ] IOwned
[ ] UndoSupport = [ ] IUndoSupport</dd>
</dl>
<p>[ ] Persistent [ ]
[ ] Implicit [ ]
[x] RoleManager = [ ] IRoleManager</p>
<blockquote>
[ ] RoleManager = [ ] IPermissionMappingSupport</blockquote>
</blockquote>
</dd>
<dt>[ ] DefaultDublinCoreImpl = [ ] IDublinCore</dt>
<dd><blockquote class="first">
[ ] ICatalogableDublinCore
[ ] IMutableDublinCore</blockquote>
<p class="last">[ ] PropertyManager = [ ] IPropertyManager</p>
</dd>
</dl>
</dd>
</dl>
</dd>
</dl>
</blockquote>
<p>Thus, we want:</p>
<blockquote>
<ul>
<li><dl class="first docutils">
<dt>Traversable, to get absolute_url() and friends</dt>
<dd><ul class="first last simple">
<li>this requires a good acquisition chain at all times</li>
</ul>
</dd>
</dl>
</li>
<li><dl class="first docutils">
<dt>Acquisition.Explicit, to support acquisition</dt>
<dd><ul class="first last simple">
<li>we do not want implicit acquisition</li>
</ul>
</dd>
</dl>
</li>
<li><p class="first">Owned, to be able to track ownership</p>
</li>
<li><p class="first">RoleManager, to support permissions and local roles</p>
</li>
</ul>
</blockquote>
<p>We also want to use a number of custom indexers for most of the standard
metadata such as creator, effective date etc.</p>
<p>Finally, we&#8217;ll need event handlers to perform the actual indexing.</p>
</div>
<div class="section" id="discussion-settings">
<h2>Discussion settings<a class="headerlink" href="#discussion-settings" title="Permalink to this headline"></a></h2>
<p>Discussion can be enabled per-type and per-instance, via values in the FTI
(allow_discussion) and on the object. These will remain unchanged. The
IConversation object&#8217;s &#8216;enabled&#8217; property should consult these.</p>
<p>Global settings should be managed using plone.registry. A control panel
can be generated from this as well, using the helper class in
plone.app.registry.</p>
<p>Note that some settings, notably those to do with permissions and workflow,
will need to be wired up as custom form fields with custom data mangers
or similar.</p>
</div>
<div class="section" id="workflow-and-permissions">
<h2>Workflow and permissions<a class="headerlink" href="#workflow-and-permissions" title="Permalink to this headline"></a></h2>
<p>Where possible, we should use existing permissions:</p>
<blockquote>
<ul class="simple">
<li>View</li>
<li>Reply to Item</li>
<li>Modify Portal Content</li>
<li>Request Review</li>
</ul>
</blockquote>
<p>In addition, we&#8217;ll need a &#8216;Moderator&#8217; role and a moderation permission,</p>
<blockquote>
<ul class="simple">
<li>Moderate comment</li>
<li>Bypass moderation</li>
</ul>
</blockquote>
<p>To control whether Anonymous can post comments, we manage the &#8216;Reply to Item&#8217;
permission. To control whether moderation is required for various roles, we
could manage the &#8216;Bypass moderation&#8217; permission.</p>
<p>These could work in a workflow like this:</p>
<blockquote>
<ul>
<li><dl class="first docutils">
<dt>&#8211;&gt; [posted] &#8211; {publish} &#8211;&gt; [published]&#8211;&gt; *</dt>
<dd><div class="first line-block">
<div class="line">^</div>
<div class="line"><a href="#id1"><span class="problematic" id="id2">|</span></a></div>
</div>
<p class="last">+&#8212;&#8211; {auto-publish} &#8212;&#8211;+
| |
+&#8212;&#8211; {auto-moderate} &#8212;-+</p>
</dd>
</dl>
</li>
</ul>
</blockquote>
<p>The &#8216;posted&#8217; state is the initial state. &#8216;published&#8217; is the state where the
comment is visible to non-reviewers.</p>
<p>The &#8216;publish&#8217; transition would be protected by the &#8216;Moderate comment&#8217;
permission. We could have states and transition for &#8216;rejected&#8217;, etc, but it
is probably just as good to delete comments that are rejected.</p>
<p>The &#8216;auto-publish&#8217; transition would be an automatic transition protected by
the &#8216;Bypass moderation&#8217; permission.</p>
<p>The &#8216;auto-moderate&#8217; transition would be another automatic transition protected
by an expression (e.g. calling a view) that returns True if the user is on
an auto-moderation &#8216;white-list&#8217;, e.g. by email address or username.</p>
</div>
<div class="section" id="forms-and-ui">
<h2>Forms and UI<a class="headerlink" href="#forms-and-ui" title="Permalink to this headline"></a></h2>
<p>The basic commenting display/reply form should be placed in a viewlet.</p>
<p>Ideally, the reply form should be inline, perhaps revealed with JavaScript
if enabled. This allows full contextualisation of replies. The current
solution, with a separate form that shows some context, is brittle and
over-complicated.</p>
<p>If we support quoting of comments in replies, we can load the text to quote
using JavaScript as well.</p>
<p>As a fall-back for non-JavaScript enabled browsers, it is probably OK not to
support quoting and/or viewing of context, e.g. the user is taken to a standalone
&#8216;comment reply&#8217; form.</p>
<p>All actual forms should be handled using z3c.form and plone.z3cform&#8217;s
ExtensibleForm support. This makes it possible to plug in additional fields
declaratively, e.g. to include spam protection.</p>
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<h3><a href="index.html">Table Of Contents</a></h3>
<ul>
<li><a class="reference external" href="#">Design Notes</a><ul>
<li><a class="reference external" href="#storage-and-traversal">Storage and traversal</a></li>
<li><a class="reference external" href="#events">Events</a></li>
<li><a class="reference external" href="#factories">Factories</a></li>
<li><a class="reference external" href="#the-comment-class">The Comment class</a></li>
<li><a class="reference external" href="#discussion-settings">Discussion settings</a></li>
<li><a class="reference external" href="#workflow-and-permissions">Workflow and permissions</a></li>
<li><a class="reference external" href="#forms-and-ui">Forms and UI</a></li>
</ul>
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