repo_zf1/documentation/manual/en/module_specs/Zend_Feed_Writer.xml

<?xml version="1.0" encoding="UTF-8"?>
<!-- Reviewed: no -->
<sect1 id="zend.feed.writer">
    <title>Zend_Feed_Writer</title>

    <sect2 id="zend.feed.writer.introduction">
        <title>Introduction</title>

        <para>
            <classname>Zend_Feed_Writer</classname> is the sibling component to
            <classname>Zend_Feed_Reader</classname> responsible for generating feeds for output. It
            supports the Atom 1.0 specification (RFC 4287) and RSS 2.0 as specified by the RSS
            Advisory Board (RSS 2.0.11). It does not deviate from these standards. It does, however,
            offer a simple Extension system which allows for any extension/module for either of
            these two specifications to be implemented if they are not provided out of the box.
        </para>

        <para>
            In many ways, <classname>Zend_Feed_Writer</classname> is the inverse of
            <classname>Zend_Feed_Reader</classname>. Where <classname>Zend_Feed_Reader</classname>
            focused on providing an easy to use architecture fronted by getter methods,
            <classname>Zend_Feed_Writer</classname> is fronted by similarly named setters or
            mutators. This ensures the API won't pose a learning curve to anyone familiar with
            <classname>Zend_Feed_Reader</classname>.
        </para>

        <para>
            As a result of this design, the rest may even be obvious. Behind the scenes, data set on
            any <classname>Zend_Feed_Reader</classname> object is translated at render time onto a
            <classname>DOMDocument</classname> object using the necessary feed elements. For each
            supported feed type there is both an Atom 1.0 and RSS 2.0 renderer. Using a
            <classname>DOMDocument</classname> rather a templating solution has numerous advantages,
            the most obvious being the ability to export the <classname>DOMDocument</classname> for
            additional processing and relying on PHP DOM for correct and valid rendering.
        </para>

        <para>
            As with <classname>Zend_Feed_Reader</classname>, <classname>Zend_Feed_Writer</classname>
            is a standalone replacement for <classname>Zend_Feed</classname>'s Builder architecture
            and is not compatible with those classes.
        </para>

    </sect2>

    <sect2 id="zend.feed.writer.architecture">
        <title>Architecture</title>

        <para>
            The architecture of <classname>Zend_Feed_Writer</classname> is very simple. It has two
            core sets of classes: containers and renderers.
        </para>

        <para>
            The containers include the <classname>Zend_Feed_Writer_Feed</classname> and
            <classname>Zend_Feed_Writer_Entry</classname> classes. The Entry classes can be attached
            to any Feed class. The sole purpose of these containers is to collect data about the
            feed to generate using a simple interface of setter methods. These methods perform some
            data validity testing. For example, it will validate any passed URIs, dates, etc. These
            checks are not tied to any of the feed standards. The container objects also contain
            methods to allow for fast rendering and export of the final feed, and these can be
            reused at will.
        </para>

        <para>
            While there are two data containers, there are four renderers - two matching container
            renderers per support feed type. The renderer accept a container, and based on its
            content attempt to generate a valid feed. If the renderer is unable to generate a valid
            feed, perhaps due to the container missing an obligatory data point, it will report this
            by throwing an <classname>Exception</classname>. While it is possible to ignore
            <classname>Exception</classname>s, this removes the default safeguard of ensuring you
            have sufficient data set to render a wholly valid feed.
        </para>

        <para>
            Due to the system being divided between data containers and renderers, it can make
            Extensions somewhat interesting. A typical Extension offering namespaced feed and entry
            level elements, must itself reflect the exact same architecture, i.e. offer feed and
            entry level data containers, and matching renderers. There is, fortunately, no complex
            integration work required since all Extension classes are simply registered and
            automatically used by the core classes. We'll meet Extensions in more detail at the end
            of this section.
        </para>
    </sect2>

    <sect2 id="zend.feed.writer.getting.started">
        <title>Getting Started</title>

        <para>
            Using <classname>Zend_Feed_Reader</classname> is as simple as setting data and
            triggering the renderer. Here is an example to generate a minimal Atom 1.0 feed.
        </para>

        <programlisting language="php"><![CDATA[
/**
 * Create the parent feed
 */
$feed = new Zend_Feed_Writer_Feed;
$feed->setTitle('Paddy\'s Blog');
$feed->setLink('http://www.example.com');
$feed->setFeedLink('http://www.example.com/atom', 'atom');
$feed->addAuthor(array(
    'name'  => 'Paddy',
    'email' => 'paddy@example.com',
    'uri'   => 'http://www.example.com',
));
$feed->setDateModified(time());
$feed->addHub('http://pubsubhubbub.appspot.com/');

/**
 * Add one or more entries. Note that entries must
 * be manually added once created.
 */
$entry = $feed->createEntry();
$entry->setTitle('All Your Base Are Belong To Us');
$entry->setLink('http://www.example.com/all-your-base-are-belong-to-us');
$entry->addAuthor(array(
    'name'  => 'Paddy',
    'email' => 'paddy@example.com',
    'uri'   => 'http://www.example.com',
));
$entry->setDateModified(time());
$entry->setDateCreated(time());
$entry->setDescription('Exposing the difficultly of porting games to English.');
$entry->setContent('I am not writing the article. The example is long enough as is ;).');
$feed->addEntry($entry);

/**
 * Render the resulting feed to Atom 1.0 and assign to $out.
 * You can substitute "atom" with "rss" to generate an RSS 2.0 feed.
 */
$out = $feed->export('atom');
]]></programlisting>

        <para>
            The output rendered should be as follows:
        </para>

        <programlisting language="xml">
&#60;?xml version="1.0" encoding="utf-8"?&#62;
&#60;feed xmlns="http://www.w3.org/2005/Atom"&#62;
    &#60;title type="text"&#62;Paddy's Blog&#60;/title&#62;
    &#60;subtitle type="text"&#62;Writing about PC Games since 176 BC.&#60;/subtitle&#62;
    &#60;updated&#62;2009-12-14T20:28:18+00:00&#60;/updated&#62;
    &#60;generator uri="http://framework.zend.com" version="1.10.0alpha"&#62;
        Zend_Feed_Writer
    &#60;/generator&#62;
    &#60;link rel="alternate" type="text/html" href="http://www.example.com"/&#62;
    &#60;link rel="self" type="application/atom+xml" href="http://www.example.com/atom"/&#62;
    &#60;id&#62;http://www.example.com&#60;/id&#62;
    &#60;author&#62;
        &#60;name&#62;Paddy&#60;/name&#62;
        &#60;email&#62;paddy@example.com&#60;/email&#62;
        &#60;uri&#62;http://www.example.com&#60;/uri&#62;
    &#60;/author&#62;
    &#60;link rel="hub" href="http://pubsubhubbub.appspot.com/"/&#62;
    &#60;entry&#62;
        &#60;title type="html"&#62;&#60;![CDATA[All Your Base Are Belong To Us]]&#62;&#60;/title&#62;
        &#60;summary type="html"&#62;
            &#60;![CDATA[Exposing the difficultly of porting games to English.]]&#62;
        &#60;/summary&#62;
        &#60;published&#62;2009-12-14T20:28:18+00:00&#60;/published&#62;
        &#60;updated&#62;2009-12-14T20:28:18+00:00&#60;/updated&#62;
        &#60;link rel="alternate" type="text/html" href="http://www.example.com/all-your-base-are-belong-to-us"/&#62;
        &#60;id&#62;http://www.example.com/all-your-base-are-belong-to-us&#60;/id&#62;
        &#60;author&#62;
        &#60;name&#62;Paddy&#60;/name&#62;
        &#60;email&#62;paddy@example.com&#60;/email&#62;
        &#60;uri&#62;http://www.example.com&#60;/uri&#62;
        &#60;/author&#62;
        &#60;content type="html"&#62;
            &#60;![CDATA[I am not writing the article. The example is long enough as is ;).]]&#62;
        &#60;/content&#62;
    &#60;/entry&#62;
&#60;/feed&#62;
</programlisting>

        <para>
            This is a perfectly valid Atom 1.0 example. It should be noted that omitting an obligatory point
            of data, such as a title, will trigger an <classname>Exception</classname> when
            rendering as Atom 1.0. This will differ for RSS 2.0 since a title may be omitted so long
            as a description is present. This gives rise to Exceptions that differ between the two
            standards depending on the renderer in use. By design,
            <classname>Zend_Feed_Writer</classname> will not render an invalid feed for either
            standard unless the end-user deliberately elects to ignore all Exceptions.
        </para>
    </sect2>

    <sect2 id="zend.feed.writer.setting.feed.data.points">
        <title>Setting Feed Data Points</title>

        <para>
            Before you can render a feed, you must first setup the data necessary for
            the feed being rendered. This utilises a simple setter style API which doubles
            as an initial method for validating the data being set. By design, the API
            closely matches that for <classname>Zend_Feed_Reader</classname> to avoid
            undue confusion and uncertainty.
        </para>

        <para>
            <classname>Zend_Feed_Writer</classname> offers this API via its data container
            classes <classname>Zend_Feed_Writer_Feed</classname> and
            <classname>Zend_Feed_Writer_Entry</classname>. These classes merely store
            all feed data in type-agnostic manner, meaning you may reuse any data
            container with any renderer without requiring additional work. Both classes
            are also amenable to Extensions, meaning that an Extension may define its own
            container classes which are registered to the base container classes as extensions, and
            are checked when any method call triggers the base container's
            <methodname>__call()</methodname> method.
        </para>

        <para>
            Here's a summary of the Core <acronym>API</acronym> for Feeds. You should note it
            comprises not only the basic <acronym>RSS</acronym> and Atom standards, but also
            accounts for a number of included Extensions bundled with
            <classname>Zend_Feed_Writer</classname>. The naming of these
            Extension sourced methods remain fairly generic - all Extension
            methods operate at the same level as the Core <acronym>API</acronym> though we do allow
            you to retrieve any specific Extension object separately if required.
        </para>

        <table>
            <title>Feed Level API Methods</title>

            <tgroup cols="2">
                <tbody>
                    <row>
                        <entry><methodname>setId()</methodname></entry>

                        <entry>Set a unique ID associated with this feed. For Atom 1.0
                        this is an atom:id element, whereas for RSS 2.0 it is added
                        as a guid element. These are optional so long as a link is
                        added, i.e. the link is set as the ID.</entry>
                    </row>

                    <row>
                        <entry><methodname>setTitle()</methodname></entry>

                        <entry>Set the title of the feed.</entry>
                    </row>

                    <row>
                        <entry><methodname>setDescription()</methodname></entry>

                        <entry>Set the text description of the feed.</entry>
                    </row>

                    <row>
                        <entry><methodname>setLink()</methodname></entry>

                        <entry>
                            Set a <acronym>URI</acronym> to the <acronym>HTML</acronym> website
                            containing the same or
                            similar information as this feed (i.e. if the feed is from a blog,
                            it should provide the blog's <acronym>URI</acronym> where the
                            <acronym>HTML</acronym> version of the entries can be read).
                        </entry>
                    </row>

                    <row>
                        <entry><methodname>setFeedLinks()</methodname></entry>

                        <entry>
                            Add a link to an XML feed, whether the feed being generated or
                            an alternate URI pointing to the same feed but in a different
                            format. At a minimum, it is recommended to include a link to
                            the feed being generated so it has an identifiable final
                            URI allowing a client to track its location changes without
                            necessitating constant redirects. The parameter is an array of
                            arrays, where each sub-array contains the keys "type" and "uri".
                            The type should be one of "atom", "rss", or "rdf". If a type is
                            omitted, it defaults to the type used when rendering the feed.
                        </entry>
                    </row>

                    <row>
                        <entry><methodname>setAuthors()</methodname></entry>

                        <entry>
                            Sets the data for authors. The parameter is an array of arrays
                            where each sub-array may contain the keys "name", "email" and
                            "uri". The "uri" value is only applicable for Atom feeds since
                            RSS contains no facility to show it. For RSS 2.0, rendering will
                            create two elements - an author element containing the email
                            reference with the name in brackets, and a Dublin Core creator
                            element only containing the name.
                        </entry>
                    </row>

                    <row>
                        <entry><methodname>setAuthor()</methodname></entry>

                        <entry>
                            Sets the data for a single author following the same
                            format as described above for a single sub-array.
                        </entry>
                    </row>

                    <row>
                        <entry><methodname>setDateCreated()</methodname></entry>

                        <entry>
                            Sets the date on which this feed was created. Generally
                            only applicable to Atom where it represents the date the resource
                            described by an Atom 1.0 document was created. The expected parameter
                            may be a UNIX timestamp or a <classname>Zend_Date</classname> object.
                        </entry>
                    </row>

                    <row>
                        <entry><methodname>getDateModified()</methodname></entry>

                        <entry>
                            Sets the date on which this feed was last modified. The expected parameter
                            may be a UNIX timestamp or a <classname>Zend_Date</classname> object.
                        </entry>
                    </row>

                    <row>
                        <entry><methodname>setLanguage()</methodname></entry>

                        <entry>
                            Sets the language of the feed. This will be omitted unless set.
                        </entry>
                    </row>

                    <row>
                        <entry><methodname>getGenerator()</methodname></entry>

                        <entry>
                            Allows the setting of a generator. The parameter should be an
                            array containing the keys "name", "version" and "uri". If omitted
                            a default generator will be added referencing
                            <classname>Zend_Feed_Writer</classname>, the current Zend Framework
                            version and the Framework's URI.
                        </entry>
                    </row>

                    <row>
                        <entry><methodname>setCopyright()</methodname></entry>

                        <entry>
                            Sets a copyright notice associated with the feed.
                        </entry>
                    </row>

                    <row>
                        <entry><methodname>setHubs()</methodname></entry>

                        <entry>
                            Accepts an array of Pubsubhubbub Hub Endpoints to be rendered in
                            the feed as Atom links so that PuSH Subscribers may subscribe to
                            your feed. Note that you must implement a Pubsubhubbub Publisher in
                            order for real-time updates to be enabled. A Publisher may be implemented
                            using <classname>Zend_Feed_Pubsubhubbub_Publisher</classname>.
                        </entry>
                    </row>

                    <row>
                        <entry><methodname>setCategories()</methodname></entry>

                        <entry>
                            Accepts an array of categories for rendering, where each element is itself
                            an array whose possible keys include "term", "label" and "scheme". The "term"
                            is a typically a category name suitable for inclusion in a URI. The "label"
                            may be a human readable category name supporting special characters (it is encoded
                            during rendering) and is a required key. The "scheme" (called the domain in RSS)
                            is optional but must be a valid URI.
                        </entry>
                    </row>
                </tbody>
            </tgroup>
        </table>
    </sect2>

    <sect2 id="zend.feed.writer.setting.entry.data.points">
        <title>Setting Entry Data Points</title>

        <para>
            Here's a summary of the Core <acronym>API</acronym> for Entries/Items. You should note it
            comprises not only the basic <acronym>RSS</acronym> and Atom standards, but also
            accounts for a number of included Extensions bundled with
            <classname>Zend_Feed_Writer</classname>. The naming of these
            Extension sourced methods remain fairly generic - all Extension
            methods operate at the same level as the Core <acronym>API</acronym> though we do allow
            you to retrieve any specific Extension object separately if required.
        </para>

        <table>
            <title>Entry Level API Methods</title>

            <tgroup cols="2">
                <tbody>
                    <row>
                        <entry><methodname>setId()</methodname></entry>

                        <entry>Set a unique ID associated with this feed. For Atom 1.0
                        this is an atom:id element, whereas for RSS 2.0 it is added
                        as a guid element. These are optional so long as a link is
                        added, i.e. the link is set as the ID.</entry>
                    </row>

                    <row>
                        <entry><methodname>setTitle()</methodname></entry>

                        <entry>Set the title of the feed.</entry>
                    </row>

                    <row>
                        <entry><methodname>setDescription()</methodname></entry>

                        <entry>Set the text description of the feed.</entry>
                    </row>

                    <row>
                        <entry><methodname>setLink()</methodname></entry>

                        <entry>
                            Set a <acronym>URI</acronym> to the <acronym>HTML</acronym> website
                            containing the same or
                            similar information as this feed (i.e. if the feed is from a blog,
                            it should provide the blog's <acronym>URI</acronym> where the
                            <acronym>HTML</acronym> version of the entries can be read).
                        </entry>
                    </row>

                    <row>
                        <entry><methodname>setFeedLinks()</methodname></entry>

                        <entry>
                            Add a link to an XML feed, whether the feed being generated or
                            an alternate URI pointing to the same feed but in a different
                            format. At a minimum, it is recommended to include a link to
                            the feed being generated so it has an identifiable final
                            URI allowing a client to track its location changes without
                            necessitating constant redirects. The parameter is an array of
                            arrays, where each sub-array contains the keys "type" and "uri".
                            The type should be one of "atom", "rss", or "rdf". If a type is
                            omitted, it defaults to the type used when rendering the feed.
                        </entry>
                    </row>

                    <row>
                        <entry><methodname>setAuthors()</methodname></entry>

                        <entry>
                            Sets the data for authors. The parameter is an array of arrays
                            where each sub-array may contain the keys "name", "email" and
                            "uri". The "uri" value is only applicable for Atom feeds since
                            RSS contains no facility to show it. For RSS 2.0, rendering will
                            create two elements - an author element containing the email
                            reference with the name in brackets, and a Dublin Core creator
                            element only containing the name.
                        </entry>
                    </row>

                    <row>
                        <entry><methodname>setAuthor()</methodname></entry>

                        <entry>
                            Sets the data for a single author following the same
                            format as described above for a single sub-array.
                        </entry>
                    </row>

                    <row>
                        <entry><methodname>setDateCreated()</methodname></entry>

                        <entry>
                            Sets the date on which this feed was created. Generally
                            only applicable to Atom where it represents the date the resource
                            described by an Atom 1.0 document was created. The expected parameter
                            may be a UNIX timestamp or a <classname>Zend_Date</classname> object.
                        </entry>
                    </row>

                    <row>
                        <entry><methodname>getDateModified()</methodname></entry>

                        <entry>
                            Sets the date on which this feed was last modified. The expected parameter
                            may be a UNIX timestamp or a <classname>Zend_Date</classname> object.
                        </entry>
                    </row>

                    <row>
                        <entry><methodname>setLanguage()</methodname></entry>

                        <entry>
                            Sets the language of the feed. This will be omitted unless set.
                        </entry>
                    </row>

                    <row>
                        <entry><methodname>getGenerator()</methodname></entry>

                        <entry>
                            Allows the setting of a generator. The parameter should be an
                            array containing the keys "name", "version" and "uri". If omitted
                            a default generator will be added referencing
                            <classname>Zend_Feed_Writer</classname>, the current Zend Framework
                            version and the Framework's URI.
                        </entry>
                    </row>

                    <row>
                        <entry><methodname>setCopyright()</methodname></entry>

                        <entry>
                            Sets a copyright notice associated with the feed.
                        </entry>
                    </row>

                    <row>
                        <entry><methodname>setHubs()</methodname></entry>

                        <entry>
                            Accepts an array of Pubsubhubbub Hub Endpoints to be rendered in
                            the feed as Atom links so that PuSH Subscribers may subscribe to
                            your feed. Note that you must implement a Pubsubhubbub Publisher in
                            order for real-time updates to be enabled. A Publisher may be implemented
                            using <classname>Zend_Feed_Pubsubhubbub_Publisher</classname>.
                        </entry>
                    </row>

                    <row>
                        <entry><methodname>setCategories()</methodname></entry>

                        <entry>
                            Accepts an array of categories for rendering, where each element is itself
                            an array whose possible keys include "term", "label" and "scheme". The "term"
                            is a typically a category name suitable for inclusion in a URI. The "label"
                            may be a human readable category name supporting special characters (it is encoded
                            during rendering) and is a required key. The "scheme" (called the domain in RSS)
                            is optional but must be a valid URI.
                        </entry>
                    </row>
                </tbody>
            </tgroup>
        </table>
    </sect2>
</sect1>