<title>Fossil Forums</title>

<h2>Introduction</h2>

Fossil includes a built-in discussion forum, designed to substitute
for a mailing list.  Email notification is available to receive posts,
but the web-based UI must be used to enter new posts.  Advantages of
the forum include:

  *  <b>Easy to Administer:</b> If you have already set up a
     [./server/|Fossil server] with [./alerts.md|email alerts]
     then turning on the forum feature
     is just a matter of flipping some permission bits.  There is
     no new software to install and configure, and the same logins
     and passwords work.

  *  <b>Consistent Display:</b>  Forum posts can be in [/md_rules|Markdown], 
     [/wiki_rules|Fossil Wiki], or plain text.  Whichever format is used, the result is
     displayed consistently across all platforms and operating systems and
     between mobile devices and desktops.

  *  <b>Editable:</b>  Forum posts can be amended after they are sent,
     to fix typos or provide updates.  The original posts are preserved
     as part of the historical record, but only the amended posts are
     displayed by default.

  *  <b>Built-in Full-Text Search:</b> Forum posts can be included in
     the index used by the built-in Fossil search logic.

  *  <b>Off-Line Access:</b> Because forum posts are synced along with
     all other artifacts, you can search the forum, or add new posts, or
     edit existing posts, all while off-line.

  *  <b>Automatically Cross-Referenced To Other Fossil Artifacts:</b> Because forum
     posts are normal Fossil artifacts, you can link from them to
     other Fossil artifacts (check-ins, wiki, tickets) and from those other 
     artifacts to forum posts.  The reverse links are recognized and
     displayed automatically on the receiver.

  *  <b>Malefactor Resistant:</b> Because Fossil accepts forum posts
     only via the web UI, it is more resistent to spam.  Passers-by
     can post to the forum anonymously (subject to moderation), without
     the hassle of a sign-up process.

  *  <b>Distributed and Tamper-Proof:</b> Posts are stored in the Fossil
     repository using the same [./fileformat.wiki | DAG/Merkle-tree design]
     that Fossil uses to store your check-ins, wiki documents, etc.
     Forum posts sync to cloned repositories.

<h2>Example Installations</h2>

Both the [forum:/forum|Fossil project itself] and the
[https://sqlite.org/forum/forum|SQLite project] use the Fossil forum in place
of mailing lists.  The forum has worked well on both projects.  The ability
to post anonymously provides a low-resistance path for people to report
problems, resulting in more problems being reported and fixed.
The ability to moderate and amend forum posts means that the 
forums contain better information.  And backups and archives
are as easy as running "clone".

Both Fossil and SQLite keep their forums as separate repositories.
But there is no requirement to do this.  A forum can be coresident in
the same repository with the source code.

<h2 id="setup">Setting up a Fossil Forum</h2>

<h3 id="caps">Capabilities</h3>

By default, no Fossil user has permission to use the forums except for
users with Setup and Admin capabilities, which get these as part of the
large package of other capabilities they get.

For public Fossil repositories that wish to accept new users without
involving a human, go into Admin &rarr; Access and enable the "Allow
users to register themselves" setting. You may also wish to give users
in [./caps/#ucat | the <tt>anonymous</tt> user category] the
<b>[./caps/ref.html#2 | RdForum]</b> and
<b>[./caps/ref.html#3 | WrForum]</b>
capabilities: this allows people to post without creating an account
simply by solving [./antibot.wiki | a simple CAPTCHA].

For a private repository, you probably won't want to give the
<tt>anonymous</tt> user any forum access, but you may wish to give the
<b>RdForum</b> capability to users in the <tt>reader</tt> category.

For either type of repository, you are likely to want to give at least
the <b>[./caps/ref.html#4 | WrTForum]</b> capability to users in the <tt>developer</tt>
category. If you did not give the <b>RdForum</b> capability to
<tt>anonymous</tt> above, you should give <tt>developer</tt> that
capability here if you choose to give it <b>WrForum</b> or
<b>WrTForum</b> capability.

If you want to use the email alert feature, by default only those
users in the Setup and Admin user categories can make use of it. Grant
the <b>[./caps/ref.html#7 | EmailAlert]</b> capability to give others access to this feature.
Alternately, you can handle alert signups outside of Fossil, with
a Setup or Admin users manually signing users up via Admin &rarr;
Notification. You'll want to grant this capability to the
<tt>nobody</tt> user category if you want anyone to sign up without any
restrictions.  Give it to <tt>anonymous</tt> instead if you want the
user to solve a simple CAPTCHA before signing up. Or, give it to
<tt>reader</tt> or <tt>developer</tt> if you want only users with Fossil
logins to have this ability. (That's assuming you give one or both of
these capabilities to every user on your Fossil repository.)

By following this advice, you should not need to tediously add
capabilities to individual accounts except in atypical cases, such as
to grant the <b>[./caps/ref.html#5 | ModForum]</b> capability to an uncommonly
highly-trusted user.


<h3 id="skin">Skin Setup</h3>

If you create a new Fossil repository with version 2.7 or newer, its
default skin is already set up correctly for typical forum
configurations.

If you have an existing repository, you have two choices if you want its
skin to be upgraded to support forums:

<ol>
  <li>Go into Admin &rarr; Skins and switch from your current skin to
  one of the stock skins.  If you were on a stock skin, just switch away
  from your current one to the actual stock skin, since they will be
  different after the upgrade.</li>

  <li>If you have local customization that you do not want to throw
  away, you can use the diff feature of Fossil's skin editor to show how
  the skins differ.</li>
</ol>

The remainder of this section summarizes the differences you're expected
to see when taking option #2.

The first thing is that you'll need to add something like the following
to the Header part of the skin to create the navbar link:

<verbatim>
  if {[anycap 23456] || [anoncap 2] || [anoncap 3]} {
    menulink /forum Forum
  }
</verbatim>

These rules say that any logged-in user with any [./caps/ref.html#2 |
forum-related capability] or an anonymous user <b>RdForum</b> or
<b>WrForum</b> capability will see the "Forum" navbar
link, which just takes you to <tt>/forum</tt>.

The exact code you need here varies depending on which skin you're
using. Follow the style you see for the other navbar links.

The new forum feature also brings many new CSS styles to the table. If
you're using the stock skin or something sufficiently close, the changes
may work with your existing skin as-is. Otherwise, you might need to
adjust some things, such as the background color used for the selected
forum post:

<verbatim>
  div.forumSel {
    background-color: rgba(0, 0, 0, 0.05);
  }
</verbatim>

That overrides the default — a hard-coded light cyan — with a 95%
transparent black overlay instead, which simply darkens your skin's
normal background color underneath the selected post. That should work
with almost any background color except for very dark background colors.
For dark skins, an inverse of the above trick will work better:

<verbatim>
  div.forumSel {
    background-color: rgba(255, 255, 255, 0.05);
  }
</verbatim>

That overlays the background with 5% white to lighten it slightly.

Another new forum-related CSS style you might want to reflect into your
existing skin is:

<verbatim>
  div.forumPosts a:visited {
    color: #6A7F94;
  }
</verbatim>

This changes the clicked-hyperlink color for the forum post links on the
main <tt>/forum</tt> page only, which allows your browser's history
mechanism to show which threads a user has read and which not. The link
color will change back to the normal link color — indicating "unread" —
when a reply is added to an existing thread because that changes where
the link from the <tt>/forum</tt> page points, taking you to the newest
post in the thread.

The color given above is suitable for the stock skin.

Beware that when changing this example, there are some
[https://hacks.mozilla.org/2010/03/privacy-related-changes-coming-to-css-vistited/
| stringent restrictions] in modern browsers to prevent snoopy web sites
from brute-forcing your browsing history. (See the link for the method,
which explains the restrictions.)


<h3 id="search">Enable Forum Search</h3>

One of the underlying assumptions of the forum feature is that you will
want to be able to search the forum archives, so the <tt>/forum</tt>
page always includes a search box. Since that depends on search being
enabled on the Fossil repository, Fossil warns that search is disabled
until you go into Admin &rarr; Search and enable the "Search Forum"
setting.

You may want to enable some of the other Fossil search features while
you're in there. All of this does come at some CPU and I/O cost, which
is why it's disabled by default.


<h3 id="sso">Single Sign-On</h3>

If you choose to host your discussion forums within the same repository
as your project's other Fossil-managed content, you inherently have a
single sign-on system. Contrast third-party mailing list and forum
software where you either end up with two separate user tables and
permission sets, or you must go to significant effort to integrate the
two login systems.

You may instead choose to host your forums in a Fossil repository
separate from your project's main Fossil repository. A good reason to do
this is that you have a public project where very few of those
participating in the forum have special capability bits for project
assets managed by Fossil, so you wish to segregate the two user sets.

Yet, what of the users who will have logins on both repositories? Some
users will be trusted with access to the project's main Fossil
repository, and these users will probably also participate in the
project's Fossil-hosted forum. Fossil has a feature to solve this
problem: [./caps/login-groups.md | login groups].


<h3 id="alerts">Email Alerts (a.k.a. Notifications)</h3>

Internet email service has become rather complicated since its initial
simple and insecure implementation decades ago. Fossil's role in all of
this is rather small at the moment, but the details of the integration
are complex enough to justify [./alerts.md | a separate document].

(The other reason that document is separate is that Fossil's email
alerts system also gets used by features of Fossil other than the
forum.)


<h2 id="access">Accessing the Forum</h2>

There are many paths to a repository's Fossil forum:

<ul>
  <li>
    If you're using the default Fossil skin as shipped with Fossil
    2.7+ or one [#skin | updated] to support it, there
    is a Forum button in the navbar which appears for users able to
    access the forum. With the default skin, that button will only
    appear if the user's browser window is at least
    1200 pixels wide.  The
    Fossil admin can adjust this limit in the skin's CSS section, down
    near the bottom in the definition of the `wideonly` style.
  </li>

  <li>The other stock skins have this button in them as of 2.7 as well,
  without the screen width restriction, since the navbar in those skins
  wraps on narrow screens more gracefully than the default skin
  does.</li>

  <li>Users who set up their Fossil repository under prior versions and
  who now have local skin changes they don't want to overwrite by
  reverting to the stock 2.7 version of the skin they chose to start
  with can easily [#skin | edit their skin] to include these links.</li>

  <li>A "Forum" link appears in the drop-down panel when you click the
  default skin's hamburger menu (&#9776;) while logged in as any user
  with one or more of the [#caps | user capabilities listed above].</li>

  <li>That same link also appears on the repository's <tt>/sitemap</tt>
  page, since it provides the content for the hamburger menu's
  panel.</li>
</ul>


<h2 id="moderation">How Moderation Works</h2>

In this section, we're going to call all of the following a "forum
update:"

  *  create a new post
  *  reply to an existing post
  *  edit a post or reply

When a person with the normal <b>WrForum</b> capability
updates the forum, Fossil saves the update in its block chain, but this
update is impermanent because of two other table updates made at the
same time:

<ol>
    <li>Fossil saves the update artifact's ID in its <tt>private</tt>
    table, preventing Fossil from sending such artifacts to any of the
    repository's clones.  (This is the same mechanism behind
    [./private.wiki | private branches].)</li>

    <li>Fossil also adds a reference to that artifact in the
    <tt>modreq</tt> table, which backs the moderation feature.  This is
    what causes Fossil to leave out the Reply button when rendering that
    post's HTML in the forum's web interface.</li>
</ol>

When a moderator approves an update, Fossil deletes these table entries,
making the update [./shunning.wiki | semi-permanent]. This changes how Fossil renders the
HTML for that update. It also means the artifact will now sync to
users with <b>[./caps/ref.html#g | Clone]</b> capability.

When a forum user edits a moderator-approved artifact, what actually
happens under the hood is that Fossil writes another artifact to the
repository which refers to the original version as its parent, causing
Fossil UI to present the new version instead of the original. The
original version remains in the repository, just as with historical
checkins. The parent must remain in the repository for referential
integrity purposes.

When you "Delete" a moderator-approved post or reply through Fossil UI,
it's actually an edit with blank replacement content. The only way to
truly delete such artifacts is through [./shunning.wiki | shunning].

When a user with <b>WrTForum</b> capability
updates the forum, it happens in the same way except that Fossil skips
the <tt>private</tt> and <tt>modreq</tt> table insertions.

When a moderator rejects an update, that artifact is unceremoniously
removed from the tip of the block chain. This is safe because Fossil
prevents replies to a reply or post awaiting moderator approval, so
referential integrity cannot be harmed.  Rejecting an edit is even
safer, since the original post remains behind, so that replies continue
to refer to that original post.


<h2 id="mod-user">Using the Moderation Feature</h2>

Having described all of the work that Fossil performs under the hood on
behalf of its users, we can now give the short list of work left for the
repository's administrators and moderators:

<ol>
    <li>Add the <b>[./caps/ref.html#5 | ModForum]</b> capability to any of
    your users who should have this ability. You don't need to do this
    for any user with <b>[./caps/ref.html#s | Setup]</b> or
    <b>[./caps/ref.html#a | Admin]</b> capability; it's
    [http://fossil-scm.org/index.html/artifact/b16221ffb736caa2?ln=1246-1257
    | already included].</li>

    <li>When someone updates the forum, an entry will appear in the
    timeline if the type filter is set to "Forum" or "Any Type". If that
    user has only the <b>WrForum</b> capability, any
    other user with the <b>ModForum</b> capability
    will see a conditional link appear at the top of the main forum
    page: "Moderation Requests".  Clicking this takes the moderator to
    the <tt>/modreq</tt> page. A moderator may wish to keep the main
    forum page open in a browser tab, reloading it occasionally to see
    when the "Moderation Requests" link reappears.</li>

    <li>A moderator viewing an update pending moderation sees two
    buttons at the bottom, "Approve" and "Reject" in place of the
    "Delete" button that the post's creator sees. Beware that both
    actions are durable and have no undo. Be careful!</li>
</ol>
