Fossil: Artifact [b2fce6c2]

Artifact b2fce6c2f88024553b61553d5eb27bdaf8c571c6abce555adfc1927824b1b713:

File www/forum.wiki — part of check-in [07943152] at 2018-09-17 09:47:37 on branch trunk — Wiki markup fixes in the recent edits to the www/forum.wiki doc (user: wyoung size: 20471) [more...]
<title>Fossil Forums</title>

<h2>Introduction</h2>

As of Fossil 2.7, Fossil includes a built-in discussion forum feature.

Any project complex enough to benefit from being managed by Fossil and
which has more than one user can probably also benefit from having a
discussion forum. Even if your project has a discussion forum already,
there are many benefits to using Fossil's built-in forum feature, some
of which you cannot get by using third-party alternatives:

  *  <b>Easy to Administer:</b> Third-party discussion forum and mailing
     list software tends to be difficult to install, set up, and
     administer. The Fossil forum feature aims to be as close to
     zero-configuration as is practical.

  *  <b>Malefactor Resistant:</b> Because Fossil accepts forum posts
     only via the web UI, it is inherently [./antibot.wiki | protected
     against bots].

  *  <b>Distributed and Tamper-Proof:</b> Posts are stored in the Fossil
     repository using the same [./fileformat.wiki | block chain technology]
     that Fossil uses to store your check-ins, wiki documents, etc.
     Posts sync to cloned repositories in a tamper-proof fashion.

  *  <b>Space Efficient:</b> Because of Fossil's [./delta_format.wiki |
     delta compression technology], discussions add little to the size
     of a cloned repository. Ten years of the SQLite project's
     discussions — averaging about 2 dozen posts per day — compress down
     to [https://fossil-scm.org/forum/forumpost/9b6f3f36bdb | just
     35&nbsp;MB of space] in a Fossil forum repository.

  *  <b>Built-in Full-Text Search:</b> Fossil forums use
     [https://sqlite.org/fts3.html | SQLite's powerful FTS4 engine] to
     handle searches. If your project currently uses a mailing list for
     discussions, this means you are no longer reliant upon third-party
     mailing list archive services to provide a useful search engine for
     your discussions. If you are running a private Fossil repository,
     you may not even have the <em>option</em> of delegating this useful
     service to a third-party; Fossil provides this service out of the
     box.

  *  <b>One Result Per Matching Post:</b> When you search the forum
     archives via the Fossil web interface, you get only one result for
     each matching post. When you search for project information via a
     standard web search engine, you might get a result from the project
     site's own mail archive plus one from Nabble, one from Gmane, one
     from The Mail Archive...

  *  <b>Search Off-Line:</b> Because Fossil is a [./concepts.wiki |
     distributed version control system], project members can search
     your forum archive while disconnected from the network where the
     central Fossil instance runs. Your past discussions are potentially
     just as valuable as a wiki document or checkin comment: there is no
     good reason why you should have to wait to get back on the Internet
     or back to the office before you can search for past posts.

  *  <b>Contribute Off-Line:</b> Fossil forum posts work like any other
     insertion into the repository, so a user can create new threads and
     reply to existing ones while off-line, then sync their
     contributions to the server they cloned from when back on-line.
     Yes, you can post to the forum from inside a tent, miles from the
     nearest wifi router or cellular data tower.

  *  <b>Interlink with Other Fossil-Managed Artifacts:</b> Because forum
     posts are normal Fossil artifacts, you can interlink them with
     other Fossil artifacts using short internal links: link to forum
     threads from a [./tickets.wiki | ticket], link to a wiki document
     from a forum post, etc.
     
  *  <b>Durable Links:</b> Once you create a valid internal artifact
     link in Fossil, it <em>remains</em> valid, durably. With
     third-party forum software and mailing list search engines, your
     links are only valid until the third-party component changes its
     URL scheme or disappears from the web.

  *  <b>Role-Based Access Control:</b> The forum uses the same
     [https://en.wikipedia.org/wiki/Role-based_access_control | RBAC
     system] that Fossil uses to control all other repository accesses.
     The Fossil forum feature simply adds several new fine-grained
     capability bits to the existing system.

  *  <b>Enduring, Open File Format:</b> Since Fossil has an
     [./fileformat.wiki | open and well-documented file format], your
     discussion archives are truly that: <em>archives</em>. You are no
     longer dependent on the lifetime and business model of a
     third-party piece of software or service. Should you choose to stop
     using Fossil, you can easily extract your discussion traffic for
     transfer to another system.

  *  <b>Lightweight Markup:</b> Posts can be marked up using Fossil's
     existing [/md_rules | Markdown] and [/wiki_rules | Wiki] markup
     processors. No longer must you choose between two bad options: to
     restrict posts to plain text only or to allow wild-west
     HTML-formatted MIME email. Fossil's lightweight markup language
     formatting features give you a middle path, providing your users
     enough formatting power to communicate complex ideas well without
     providing so much power as to risk
     [https://wonko.com/post/html-escaping | security problems].

  *  <b>Easy Email Alerts:</b> You can configure Fossil to
     [./alerts.md | send email alerts]. Forum post emails include the
     complete message content for the benefit of those that prefer to
     visit the forum only when they need to post something.  Alerts are
     optional, and each user gets the choice of immediate or daily
     digest delivery.


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

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

Fossil forums use the same role-based access control mechanism as
for normal Fossil repository logins.

There are several dedicated forum-related capability bits you can grant
a user:

  *  <b>Read Forum</b> (<tt>2</tt>): The user may read forum posts.

  *  <b>Write Forum</b> (<tt>3</tt>): The user may create new forum
     threads, reply to existing threads, and edit their own posts. New
     posts are held for moderation, and they are marked to prevent them
     from being included in clone and sync operations.

  *  <b>WriteTrusted Forum</b> (<tt>4</tt>): Same as <b>Write Forum</b>
     except that forum updates bypass the [#moderation | moderation and
     private artifact restrictions].

  *  <b>Moderate Forum</b> (<tt>5</tt>): User gets buttons on posts
     which allow them to either reject or approve posts held for
     moderation. User also gets access to a page (<tt>/modreq</tt>)
     showing the list of pending moderation tasks.

  *  <b>Supervise Forum</b> (<tt>6</tt>): User can grant or revoke
     <b>WriteTrusted</b> capability for other users. (Currently
     unimplemented.)

  *  <b>Email Alerts</b> (<tt>7</tt>): User can sign themselves up for
     email alerts, a.k.a. notifications.

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 the <tt>anonymous</tt> category the Read Forum (2) and Write Forum
(3) 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
Read Forum capability (2) to users in the <tt>reader</tt> category.

For either type of repository, you are likely to want to give at least
the WriteTrusted capability (4) to users in the <tt>developer</tt>
category. If you did not give the Read Forum capability (2) to
<tt>anonymous</tt> above, you should give <tt>developer</tt> that
capability here if you choose to give it capability 3 or 4.

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 Email Alerts capability (7) 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 Moderate Forum capability (5) 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 forum-related
capability (2-6 inclusive, as of this writing) or an anonymous user with
read or write capability on the forum (2, 3) 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 which is probably less well known than it should be, and which
has been a feature of Fossil since April of 2011: Admin &rarr;
Login-Group. This allows one Fossil repository to recognize users
authorized on a different Fossil repository.


<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>
    <p>If you're using the default Fossil skin as shipped with Fossil
    2.7 or one updated to include the changes since 2.6 or prior, there
    is a Forum button in the navbar which appears for users with any of
    the forum-related user capabilities: 2 through 6 inclusive for those
    with repository logins, or caps 2 and 3 for users without a user
    account but who have solved the Anonymous user CAPTCHA.</p>
    <p>This button will not appear in the default skin for such users if
    their browser window is not greater than 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.</p>
  </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>Write Forum</b> capability (<tt>3</tt>)
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 semi-permanent. This changes how Fossil renders the
HTML for that update. It also means the artifact will now sync to
clones, if the sync is done by a user with <b>Check-Out</b> capability
(<tt>o</tt>).

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>WriteTrusted Forum</b> capability (<tt>4</tt>)
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>Moderate Forum</b> capability (<tt>5</tt>) to any of
    your users who should have this ability. You don't need to do this
    for any user with Setup (<tt>s</tt>) or Admin (<tt>a</tt>)
    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>Write Forum</b> capability (<tt>3</tt>), any
    other user with the <b>Moderate Forum</b> capability (<tt>5</tt>)
    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>