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* Added 'Realms' to 'The Rivendell Object Paradigm' section of the Operations Guide. Signed-off-by: Fred Gleason <fredg@paravelsystems.com>
362 lines
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XML
362 lines
14 KiB
XML
<chapter xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xml:id="chapter.overview">
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<title>System Overview</title>
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<imagedata fileref="manual-outputdefault.png" scale="30"/>
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</imageobject>
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</mediaobject>
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-->
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<sect1 xml:id="sect.overview.introducting_rivendell">
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<title>Introducing Rivendell</title>
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<para>
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Rivendell is a digital audio content management and delivery system
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that is targeted for use in professional radio broadcast environments.
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It includes robust tools for the acquisition, organization, management
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and play out of audio material from and to a diverse array of sources
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and destinations. Support for a wide variety of external third party
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hardware devices and software packages commonly used in the radio
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industry is featured, including interfaces for:
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</para>
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<para>
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<itemizedlist>
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<listitem>Audio Routing Switchers</listitem>
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<listitem>Satellite Downlink Receivers</listitem>
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<listitem>Audio Mixing Consoles</listitem>
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<listitem>Commercial Traffic and Music Scheduling Systems</listitem>
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</itemizedlist>
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</para>
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<para>
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Rivendell is made available under the terms of the
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<link linkend="appendix.gplv2">GNU General Public License,
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version 2</link>.
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As such, it comes with <emphasis>absolutely no warranty</emphasis>,
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not even the implied
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warranties of merchantability or fitness for a particular purpose.
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See the full text of the GPLv2 for details.
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</para>
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<para>
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Rivendell has been designed and developed from the ground up to run
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on the popular and highly stable <trademark>GNU/Linux</trademark>
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operating system. Full source code is available online at
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<link xlink:href="https://github.com/ElvishArtisan/rivendell">https://github.com/ElvishArtisan/rivendell</link>.
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</para>
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<para>
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Rivendell has been designed to be able to operate in a wide variety
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of roles, ranging from single, self-contained workstations to large,
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multi-station clusters consisting of multiple workstations and
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centralized servers. Also included are redundancy and hot-standby
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capabilities to allow for reliable operation even in the face of
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hardware faults.
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</para>
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<para>
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Rivendell is implemented as a set of interactive tools or 'modules'
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that collectively provide the complete functionality of the system.
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Briefly, these modules and their functions are:
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</para>
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<para>
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<variablelist>
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<varlistentry>
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<term><link linkend="chapter.rdlibrary">RDLibrary</link></term>
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<listitem>
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Library content management
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><link linkend="chapter.rdcatch">RDCatch</link></term>
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<listitem>
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Automatic time-driven event scheduler
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><link linkend="chapter.rdairplay">RDAirPlay</link></term>
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<listitem>
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On-air play out application
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><link linkend="chapter.rdlogedit">RDLogEdit</link></term>
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<listitem>
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Log editing and voicetracking tool
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><link linkend="chapter.rdlogmanager">RDLogManager</link></term>
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<listitem>
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Automated log generation and interface utility
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><link linkend="chapter.rdlogin">RDLogin</link></term>
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<listitem>
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Set the current user on a Rivendell host
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><link linkend="chapter.rdcartslots">RDCartSlots</link></term>
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<listitem>
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Emulate a traditional broadcast cart machine
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>RDPanel</term>
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<listitem>
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Large "cart wall" application
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>RDCastManager</term>
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<listitem>
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Podcast feed manager
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><link linkend="chapter.rdadmin">RDAdmin</link></term>
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<listitem>
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System wide configuration
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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<para>
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The operation of each of these modules is explained in detail in the
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chapters that follow. However, we first need to cover some basic
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concepts common to all Rivendell modules.
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</para>
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<sect2 xml:id="sect.overview.the_rivendell_object_paradigm">
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<title>The Rivendell Object Paradigm</title>
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<para>
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All Rivendell modules make use of the following classes of
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system resources:
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</para>
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<para>
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<itemizedlist>
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<listitem>
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<link linkend="sect.overview.realms">Realms</link>
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</listitem>
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<listitem>
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<link linkend="sect.overview.hosts">Hosts</link>
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</listitem>
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<listitem>
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<link linkend="sect.overview.users">Users</link>
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</listitem>
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<listitem>
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<link linkend="sect.overview.groups">Groups</link>
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</listitem>
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<listitem>
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<link linkend="sect.overview.services">Services</link>
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</listitem>
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</itemizedlist>
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</para>
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<para>
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We'll cover each of these concepts in turn.
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</para>
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<sect3 xml:id="sect.overview.realms">
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<title>Realms</title>
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<para>
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A Rivendell <emphasis>realm</emphasis> is a set of one or more
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hosts that utilize a common Rivendell database. Each such
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realm has its own, independent set of objects, such as cart library,
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RDCatch event list, set of hosts, etc. Different Rivendell realms
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are effectively isolated from each other at the application level.
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</para>
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<caution>
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If more than one Rivendell realm will be residing in a single
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IP multicast domain, then each realm must be assigned a unique
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multicast notification address. See "Multicast Address for
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Notifications" in the
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<xref linkend="sect.rdadmin.manage_system_settings" />.
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</caution>
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</sect3>
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<sect3 xml:id="sect.overview.hosts">
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<title>Hosts</title>
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<para>
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Every physical or virtual computer that is running
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Rivendell software is referred to as a <emphasis>host</emphasis>.
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Any host in a
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Rivendell network can be individually configured and controlled
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from any other host within the same realm (provided the system
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administrator has enabled this capability).
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Hosts can be used for a wide variety of
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applications, including content ingestion and management,
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automatic recording (sometimes referred to as
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"netcatching"),
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on-air play out or log (sometimes also referred to as a
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<emphasis>playlist</emphasis>)
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generation. It is also possible for a single host to perform all
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of these functions.
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</para>
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<para>
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Each Rivendell host is a member of precisely one
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<link linkend="sect.overview.realms">Rivendell realm</link>.
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Each host within a given realm must be reachable from all other hosts
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in that realm and reside within the same IP multicast domain.
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In most cases, this can be ensured by connecting all hosts to the
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same network switch and configuring them to use the same IP subnet.
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If this is not feasible, then special arrangements, such as
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installation of a network bridge or multicast router between the
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host subnets may be necessary.
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</para>
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</sect3>
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<sect3 xml:id="sect.overview.users">
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<title>Users</title>
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<para>
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Every host on a Rivendell network has one or more
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<emphasis>users</emphasis> available
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to it. In this context, a 'user' is merely a set of access
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policies established by the system administrator that defines what
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tasks that user is or is not allowed to perform. The set of
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available users is global to every host in a given Rivendell system;
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with each host operating under exactly one user at a time. Each
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host also has one user designated to be the
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<emphasis>default user</emphasis>. As the name
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suggests, this is the set of user policies that are loaded by
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default when the system starts up. It is also possible to change
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the user currently in use on a given host by running the RDLogin
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module.
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</para>
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</sect3>
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<sect3 xml:id="sect.overview.groups">
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<title>Groups</title>
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<para>
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A Rivendell <emphasis>group</emphasis> is a system of categories
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that is used by the
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audio library to classify and organize the audio within the library.
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Groups are a very powerful capability, and many operations within
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Rivendell can be specified on the basis of group membership.
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The actual classification scheme, including the number of available
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groups and their names, is completely arbitrary so as to allow each
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facility to tailor a schema that best fits its own operational
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requirements. Designing and implementing the group schema is one
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of the most important tasks facing the Rivendell system
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administrator, as a well-designed schema can make long-term
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maintenance and management of the system substantially easier
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vis-a-vis a poorly thought out one. We will cover groups in
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detail in the chapters devoted to the RDLibrary and RDAdmin modules.
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</para>
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</sect3>
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<sect3 xml:id="sect.overview.services">
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<title>Services</title>
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<para>
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Every facility at which Rivendell is deployed is presumed to have
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one or more ultimate destinations for which audio is intended.
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These could be radio stations --e.g. WAVA--, satellite uplink
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channels, live Internet audio streams, or any mix of the above.
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Each of these sorts of destinations is referred to in Rivendell
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as a <emphasis>service</emphasis>, and certain parameters,
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particularly as regards
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audio play out and log (playlist) creation, can be configured on
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the basis of what particular service is being referenced.
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</para>
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</sect3>
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</sect2>
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<sect2 xml:id="sect.overview.the_rivendell_hardware_paradigm">
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<title>The Rivendell Hardware Paradigm</title>
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<para>
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In addition to the core computer hardware (CPU, motherboard, etc),
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each Rivendell host typically interacts with specialized hardware
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required to accomplish the task at hand. Three main categories of
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such 'special' hardware are of interest to us here, the three being
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audio adapters, serial ports and GPIO/switcher devices. We'll
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cover each below.
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</para>
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<sect3 xml:id="sect.overview.audio_adapters">
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<title>Audio Adapters</title>
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<para>
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An <emphasis>audio adapter</emphasis> in Rivendell is simply a
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device or facility for
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getting audio into and/or out of a host on a realtime basis.
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Often this will be a sound card, although other
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possibilities (such as AoIP or direct routing
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to other audio applications) also exist. The three main classes
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of audio adapters supported by Rivendell are:
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</para>
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<para>
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<variablelist>
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<varlistentry>
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<term>Advanced Linux Sound Architecture (ALSA)</term>
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<listitem>
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<para>
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The standard Linux sound card driver starting with the 2.6.x
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kernel series, ALSA supports a huge array of commercially
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available sound cards, ranging from entry level 'game' cards
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to high-end cards aimed at professional audio uses.
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More information, including a current list of supported
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cards, is available at the ALSA web site,
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<link xlink:href="http://www.alsa-project.org/">http://www.alsa-project.org/</link>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>HPI Adapters</term>
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<listitem>
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<para>
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These are high-performance sound cards manufactured by
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AudioScience Corporation. Designed and built specifically
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for broadcast automation applications, many feature advanced
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capabilities (such as on-board MPEG codecs and AES3 i/o)
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specially aimed for use in that setting. They are so-called
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because Rivendell uses AudioScience's special 'HPI' driver
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to access and control them. More information is available
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at AudioScience's web site at
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<link xlink:href="http://www.audioscience.com/">http://www.audioscience.com/</link>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>JACK Audio Interconnect Kit</term>
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<listitem>
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<para>
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JACK is not a class of hardware devices, but rather
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an audio 'framework' that allows compliant applications to
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share audio resources and route audio in realtime amongst
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themselves. JACK is different from similar efforts within
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the Linux realm in that it was designed from the ground up
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for professional audio work, with particular focus upon
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low-latency operation and synchronous execution of all
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clients. More information can be found at the JACK web
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site, <link xlink:href="https://jackaudio.org/">https://jackaudio.org/</link>.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</sect3>
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<sect3 xml:id="sect.overview.serial_ports">
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<title>Serial Ports</title>
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<para>
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Commonly known in the DOS/Windows world as 'COM ports',
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<emphasis>serial ports</emphasis> are often used to communicate
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with outboard gear, such as
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satellite receivers and audio switchers. Up to eight serial ports
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can be accessed simultaneously by each Rivendell host.
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</para>
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</sect3>
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<sect3 xml:id="sect.overview.gpio_switcher_devices">
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<title>GPIO/Switcher Devices</title>
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<para>
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Because these capabilities are often (although not always)
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bundled together in the same device, Rivendell lumps GPIO and
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switcher devices together within the same class.
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<emphasis>GPIO</emphasis> stands
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for 'General Purpose Input Output'. As the name implies, these
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devices can be used to interface to a huge variety of outboard
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equipment by means of control lines. <emphasis>GPI</emphasis>
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(General Purpose Input)
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lines can be used to sense changes in an outboard system's state
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(and Rivendell programmed to take various actions on the basis of
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that), while <emphasis>GPO</emphasis> (General Purpose Output)
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lines can be used to
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send commands to an outboard system. The actual physical
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interfacing of GPIO devices is complex and generally beyond
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the scope of this document. Readers are encouraged to consult
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a good handbook on radio engineering for more information.
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A current list of GPIO/Switcher devices supported by Rivendell
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can be found in <xref linkend="appendix.gpio_switcher_devices" />.
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</para>
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</sect3>
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</sect2>
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</sect1>
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</chapter>
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