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

<?xml version="1.0" encoding="UTF-8"?>
<!-- Reviewed: no -->
<sect1 id="zend.gdata.calendar">
    <title>Using Google Calendar</title>
    <para>
        You can use the
        <classname>Zend_Gdata_Calendar</classname>
        class to view, create, update, and delete events in the online Google Calendar service.
    </para>
    <para>
        See <ulink
        url="http://code.google.com/apis/calendar/overview.html">
        http://code.google.com/apis/calendar/overview.html</ulink>
        for more information about the Google Calendar <acronym>API</acronym>.
    </para>
    <sect2 id="zend.gdata.calendar.connecting">
        <title>Connecting To The Calendar Service</title>
        <para>
            The Google Calendar <acronym>API</acronym>, like all GData <acronym>API</acronym>s, is based off of the Atom Publishing
            Protocol (APP), an <acronym>XML</acronym> based format for managing web-based resources. Traffic between
            a client and the Google Calendar servers occurs over <acronym>HTTP</acronym> and allows for both
            authenticated and unauthenticated connections.
        </para>
        <para>
            Before any transactions can occur, this connection needs to be made. Creating a
            connection to the calendar servers involves two steps: creating an <acronym>HTTP</acronym> client and
            binding a <classname>Zend_Gdata_Calendar</classname> service instance to that client.
        </para>
        <sect3 id="zend.gdata.calendar.connecting.authentication">
            <title>Authentication</title>
            <para>
                The Google Calendar <acronym>API</acronym> allows access to both public and private calendar feeds.
                Public feeds do not require authentication, but are read-only and offer reduced
                functionality. Private feeds offers the most complete functionality but requires
                an authenticated connection to the calendar servers. There are three authentication
                schemes that are supported by Google Calendar:
            </para>
            <itemizedlist>
                <listitem>
                    <para>
                        <firstterm>ClientAuth</firstterm>
                        provides direct username/password authentication to the
                        calendar servers. Since this scheme requires that users
                        provide your application with their password, this
                        authentication is only recommended when other
                        authentication schemes are insufficient.
                    </para>
                </listitem>
                <listitem>
                    <para>
                        <firstterm>AuthSub</firstterm>
                        allows authentication to the calendar servers via a
                        Google proxy server. This provides the same level of
                        convenience as ClientAuth but without the security
                        risk, making this an ideal choice for web-based
                        applications.
                    </para>
                </listitem>
                <listitem>
                    <para>
                        <firstterm>MagicCookie</firstterm>
                        allows authentication based on a semi-random <acronym>URL</acronym>
                        available from within the Google Calendar interface.
                        This is the simplest authentication scheme to
                        implement, but requires that users manually retrieve
                        their secure <acronym>URL</acronym> before they can authenticate, doesn't
                        provide access to calendar lists, and is limited to
                        read-only access.
                    </para>
                </listitem>
            </itemizedlist>
            <para>
                The
                <classname>Zend_Gdata</classname>
                library provides support for all three authentication schemes.
                The rest of this chapter will assume that you are familiar the
                authentication schemes available and how to create an
                appropriate authenticated connection. For more information,
                please see section the <link
                linkend="zend.gdata.introduction.authentication">Authentication section</link>
                of this manual or the <ulink
                url="http://code.google.com/apis/gdata/auth.html">Authentication Overview in the
                Google Data <acronym>API</acronym> Developer's Guide</ulink>.
            </para>
        </sect3>
        <sect3 id="zend.gdata.calendar.connecting.service">
            <title>Creating A Service Instance</title>
            <para>
                In order to interact with Google Calendar, this library provides the
                <classname>Zend_Gdata_Calendar</classname> service class. This class provides a common
                interface to the Google Data and Atom Publishing Protocol models and assists in
                marshaling requests to and from the calendar servers.
            </para>
            <para>
                Once deciding on an authentication scheme, the next step is to create an instance
                of <classname>Zend_Gdata_Calendar</classname>. The class constructor takes an instance of
                <classname>Zend_Http_Client</classname> as a single argument. This provides an interface for
                AuthSub and ClientAuth authentication, as both of these require creation of a
                special authenticated <acronym>HTTP</acronym> client. If no arguments are provided, an unauthenticated
                instance of <classname>Zend_Http_Client</classname> will be automatically created.
            </para>
            <para>
                The example below shows how to create a Calendar service class using ClientAuth
                authentication:
            </para>
            <programlisting language="php"><![CDATA[
// Parameters for ClientAuth authentication
$service = Zend_Gdata_Calendar::AUTH_SERVICE_NAME;
$user = "sample.user@gmail.com";
$pass = "pa$$w0rd";

// Create an authenticated HTTP client
$client = Zend_Gdata_ClientLogin::getHttpClient($user, $pass, $service);

// Create an instance of the Calendar service
$service = new Zend_Gdata_Calendar($client);
]]></programlisting>
            <para>
                A Calendar service using AuthSub can be created in a similar, though slightly more
                lengthy fashion:
            </para>
            <programlisting language="php"><![CDATA[
/*
 * Retrieve the current URL so that the AuthSub server knows where to
 * redirect the user after authentication is complete.
 */
function getCurrentUrl()
{
    global $_SERVER;

    // Filter php_self to avoid a security vulnerability.
    $php_request_uri =
        htmlentities(substr($_SERVER['REQUEST_URI'],
                            0,
                            strcspn($_SERVER['REQUEST_URI'], "\n\r")),
                            ENT_QUOTES);

    if (isset($_SERVER['HTTPS']) &&
        strtolower($_SERVER['HTTPS']) == 'on') {
        $protocol = 'https://';
    } else {
        $protocol = 'http://';
    }
    $host = $_SERVER['HTTP_HOST'];
    if ($_SERVER['HTTP_PORT'] != '' &&
        (($protocol == 'http://' && $_SERVER['HTTP_PORT'] != '80') ||
        ($protocol == 'https://' && $_SERVER['HTTP_PORT'] != '443'))) {
        $port = ':' . $_SERVER['HTTP_PORT'];
    } else {
        $port = '';
    }
    return $protocol . $host . $port . $php_request_uri;
}

/**
 * Obtain an AuthSub authenticated HTTP client, redirecting the user
 * to the AuthSub server to login if necessary.
 */
function getAuthSubHttpClient()
{
    global $_SESSION, $_GET;

    // if there is no AuthSub session or one-time token waiting for us,
    // redirect the user to the AuthSub server to get one.
    if (!isset($_SESSION['sessionToken']) && !isset($_GET['token'])) {
        // Parameters to give to AuthSub server
        $next = getCurrentUrl();
        $scope = "http://www.google.com/calendar/feeds/";
        $secure = false;
        $session = true;

        // Redirect the user to the AuthSub server to sign in

        $authSubUrl = Zend_Gdata_AuthSub::getAuthSubTokenUri($next,
                                                             $scope,
                                                             $secure,
                                                             $session);
         header("HTTP/1.0 307 Temporary redirect");

         header("Location: " . $authSubUrl);

         exit();
    }

    // Convert an AuthSub one-time token into a session token if needed
    if (!isset($_SESSION['sessionToken']) && isset($_GET['token'])) {
        $_SESSION['sessionToken'] =
            Zend_Gdata_AuthSub::getAuthSubSessionToken($_GET['token']);
    }

    // At this point we are authenticated via AuthSub and can obtain an
    // authenticated HTTP client instance

    // Create an authenticated HTTP client
    $client = Zend_Gdata_AuthSub::getHttpClient($_SESSION['sessionToken']);
    return $client;
}

// -> Script execution begins here <-

// Make sure that the user has a valid session, so we can record the
// AuthSub session token once it is available.
session_start();

// Create an instance of the Calendar service, redirecting the user
// to the AuthSub server if necessary.
$service = new Zend_Gdata_Calendar(getAuthSubHttpClient());
]]></programlisting>
            <para>
                Finally, an unauthenticated server can be created for use with either public feeds
                or MagicCookie authentication:
            </para>
            <programlisting language="php"><![CDATA[
// Create an instance of the Calendar service using an unauthenticated
// HTTP client

$service = new Zend_Gdata_Calendar();
]]></programlisting>
            <para>
                Note that MagicCookie authentication is not supplied with the <acronym>HTTP</acronym> connection, but
                is instead specified along with the desired visibility when submitting queries. See
                the section on retrieving events below for an example.
            </para>
        </sect3>
    </sect2>
    <sect2 id="zend.gdata.calendar_retrieval">
        <title>Retrieving A Calendar List</title>
        <para>
            The calendar service supports retrieving a list of calendars for the authenticated
            user. This is the same list of calendars which are displayed in the Google Calendar
            UI, except those marked as "<code>hidden</code>" are also available.
        </para>
        <para>
            The calendar list is always private and must be accessed over an authenticated
            connection. It is not possible to retrieve another user's calendar list and it cannot
            be accessed using MagicCookie authentication. Attempting to access a calendar list
            without holding appropriate credentials will fail and result in a 401 (Authentication
            Required) status code.
        </para>
        <programlisting language="php"><![CDATA[
$service = Zend_Gdata_Calendar::AUTH_SERVICE_NAME;
$client = Zend_Gdata_ClientLogin::getHttpClient($user, $pass, $service);
$service = new Zend_Gdata_Calendar($client);

try {
    $listFeed= $service->getCalendarListFeed();
} catch (Zend_Gdata_App_Exception $e) {
    echo "Error: " . $e->getMessage();
}
]]></programlisting>
        <para>
            Calling <methodname>getCalendarListFeed()</methodname> creates a new instance of
            <classname>Zend_Gdata_Calendar_ListFeed</classname> containing each available calendar as an
            instance of <classname>Zend_Gdata_Calendar_ListEntry</classname>. After retrieving the feed, you
            can use the iterator and accessors contained within the feed to inspect the enclosed
            calendars.
        </para>
        <programlisting language="php"><![CDATA[
echo "<h1>Calendar List Feed</h1>";
echo "<ul>";
foreach ($listFeed as $calendar) {
    echo "<li>" . $calendar->title .
         " (Event Feed: " . $calendar->id . ")</li>";
}
echo "</ul>";
]]></programlisting>
    </sect2>
    <sect2 id="zend.gdata.event_retrieval">
        <title>Retrieving Events</title>
        <para>
            Like the list of calendars, events are also retrieved using the
            <classname>Zend_Gdata_Calendar</classname> service class. The event list returned is of type
            <classname>Zend_Gdata_Calendar_EventFeed</classname> and contains each event as an instance of
            <classname>Zend_Gdata_Calendar_EventEntry</classname>. As before, the iterator and accessors
            contained within the event feed instance allow inspection of individual events.
        </para>
        <sect3 id="zend.gdata.event_retrieval.queries">
            <title>Queries</title>
            <para>
                When retrieving events using the Calendar <acronym>API</acronym>, specially constructed query <acronym>URL</acronym>s are
                used to describe what events should be returned. The
                <classname>Zend_Gdata_Calendar_EventQuery</classname> class simplifies this task by
                automatically constructing a query <acronym>URL</acronym> based on provided parameters. A full list of
                these parameters is available at the <ulink
                url="http://code.google.com/apis/gdata/reference.html#Queries">Queries section of
                the Google Data <acronym>API</acronym>s Protocol Reference</ulink>. However, there are three
                parameters that are worth special attention:
            </para>
            <itemizedlist>
                <listitem>
                    <para>
                        <firstterm>User</firstterm>
                        is used to specify the user whose calendar is being
                        searched for, and is specified as an email address. If
                        no user is provided, "default" will be used instead to
                        indicate the currently authenticated user (if
                        authenticated).
                    </para>
                </listitem>
                <listitem>
                    <para>
                        <firstterm>Visibility</firstterm>
                        specifies whether a users public or private calendar
                        should be searched. If using an unauthenticated session
                        and no MagicCookie is available, only the public feed
                        will be available.
                    </para>
                </listitem>
                <listitem>
                    <para>
                        <firstterm>Projection</firstterm>
                        specifies how much data should be returned by the
                        server and in what format. In most cases you will want
                        to use the "full" projection. Also available is the
                        "basic" projection, which places most meta-data into
                        each event's content field as human readable text, and
                        the "composite" projection which includes complete text
                        for any comments alongside each event. The "composite"
                        view is often much larger than the "full" view.
                    </para>
                </listitem>
            </itemizedlist>
        </sect3>
        <sect3 id="zend.gdata.event_retrieval.start_time">
            <title>Retrieving Events In Order Of Start Time</title>
            <para>
                The example below illustrates the use of the <classname>Zend_Gdata_Query</classname> class
                and specifies the private visibility feed, which requires that an authenticated
                connection is available to the calendar servers. If a MagicCookie is being used for
                authentication, the visibility should be instead set to
                "<code>private-magicCookieValue</code>", where magicCookieValue is the random
                string obtained when viewing the private <acronym>XML</acronym> address in the Google Calendar UI.
                Events are requested chronologically by start time and only events occurring in the
                future are returned.
            </para>
            <programlisting language="php"><![CDATA[
$query = $service->newEventQuery();
$query->setUser('default');
// Set to $query->setVisibility('private-magicCookieValue') if using
// MagicCookie auth
$query->setVisibility('private');
$query->setProjection('full');
$query->setOrderby('starttime');
$query->setFutureevents('true');

// Retrieve the event list from the calendar server
try {
    $eventFeed = $service->getCalendarEventFeed($query);
} catch (Zend_Gdata_App_Exception $e) {
    echo "Error: " . $e->getMessage();
}

// Iterate through the list of events, outputting them as an HTML list
echo "<ul>";
foreach ($eventFeed as $event) {
    echo "<li>" . $event->title . " (Event ID: " . $event->id . ")</li>";
}
echo "</ul>";
]]></programlisting>
            <para>
                Additional properties such as ID, author, when, event status, visibility, web
                content, and content, among others are available within
                <classname>Zend_Gdata_Calendar_EventEntry</classname>. Refer to the
                <ulink url="http://framework.zend.com/apidoc/core/">Zend Framework <acronym>API</acronym>
                Documentation</ulink> and the
                <ulink url="http://code.google.com/apis/gdata/reference.html">Calendar Protocol
                Reference</ulink> for a complete list.
            </para>
        </sect3>
        <sect3 id="zend.gdata.event_retrieval.date_range">
            <title>Retrieving Events In A Specified Date Range</title>
            <para>
                To print out all events within a certain range, for example from December 1,
                2006 through December 15, 2007, add the following two lines to the previous sample.
                Take care to remove "<code>$query->setFutureevents('true')</code>", since
                <code>futureevents</code> will override <code>startMin</code> and
                <code>startMax</code>.
            </para>
            <programlisting language="php"><![CDATA[
$query->setStartMin('2006-12-01');
$query->setStartMax('2006-12-16');
]]></programlisting>
            <para>
                Note that <code>startMin</code> is inclusive whereas <code>startMax</code> is
                exclusive. As a result, only events through 2006-12-15 23:59:59 will be returned.
            </para>
        </sect3>
        <sect3 id="zend.gdata.event_retrieval.fulltext">
            <title>Retrieving Events By Fulltext Query</title>
            <para>
                To print out all events which contain a specific word, for example "dogfood", use
                the <methodname>setQuery()</methodname> method when creating the query.
            </para>
            <programlisting language="php"><![CDATA[
$query->setQuery("dogfood");
]]></programlisting>
        </sect3>
        <sect3 id="zend.gdata.event_retrieval.individual">
            <title>Retrieving Individual Events</title>
            <para>
                Individual events can be retrieved by specifying their event ID as part of the
                query. Instead of calling <methodname>getCalendarEventFeed()</methodname>,
                <methodname>getCalendarEventEntry()</methodname> should be called instead.
            </para>
            <programlisting language="php"><![CDATA[
$query = $service->newEventQuery();
$query->setUser('default');
$query->setVisibility('private');
$query->setProjection('full');
$query->setEvent($eventId);

try {
    $event = $service->getCalendarEventEntry($query);
} catch (Zend_Gdata_App_Exception $e) {
    echo "Error: " . $e->getMessage();
}
]]></programlisting>
            <para>
                In a similar fashion, if the event <acronym>URL</acronym> is known, it can be passed directly into
                <methodname>getCalendarEntry()</methodname> to retrieve a specific event. In this case, no
                query object is required since the event <acronym>URL</acronym> contains all the necessary information
                to retrieve the event.
            </para>
            <programlisting language="php"><![CDATA[
$eventURL = "http://www.google.com/calendar/feeds/default/private"
          . "/full/g829on5sq4ag12se91d10uumko";

try {
    $event = $service->getCalendarEventEntry($eventURL);
} catch (Zend_Gdata_App_Exception $e) {
    echo "Error: " . $e->getMessage();
}
]]></programlisting>
        </sect3>
    </sect2>
    <sect2 id="zend.gdata.calendar.creating_events">
        <title>Creating Events</title>
        <sect3 id="zend.gdata.calendar.creating_events.single">
            <title>Creating Single-Occurrence Events</title>
            <para>
                Events are added to a calendar by creating an instance of
                <classname>Zend_Gdata_EventEntry</classname> and populating it with the appropriate data.
                The calendar service instance (<classname>Zend_Gdata_Calendar</classname>) is then used to
                used to transparently covert the event into <acronym>XML</acronym> and POST it to the calendar server.
                Creating events requires either an AuthSub or ClientAuth authenticated connection
                to the calendar server.
            </para>
            <para>At a minimum, the following attributes should be set:</para>
            <itemizedlist>
                <listitem>
                    <para>
                        <firstterm>Title</firstterm>
                        provides the headline that will appear above the event
                        within the Google Calendar UI.
                    </para>
                </listitem>
                <listitem>
                    <para>
                        <firstterm>When</firstterm>
                        indicates the duration of the event and, optionally,
                        any reminders that are associated with it. See the next
                        section for more information on this attribute.
                    </para>
                </listitem>
            </itemizedlist>
            <para>Other useful attributes that may optionally set include:</para>
            <itemizedlist>
                <listitem>
                    <para>
                        <firstterm>Author</firstterm>
                        provides information about the user who created the
                        event.
                    </para>
                </listitem>
                <listitem>
                    <para>
                        <firstterm>Content</firstterm>
                        provides additional information about the event which
                        appears when the event details are requested from
                        within Google Calendar.
                    </para>
                </listitem>
                <listitem>
                    <para>
                        <firstterm>EventStatus</firstterm>
                        indicates whether the event is confirmed, tentative, or
                        canceled.
                    </para>
                </listitem>
                <listitem>
                    <para>
                        <firstterm>Hidden</firstterm>
                        removes the event from the Google Calendar UI.
                    </para>
                </listitem>
                <listitem>
                    <para>
                        <firstterm>Transparency</firstterm>
                        indicates whether the event should be consume time on
                        the user's free/busy list.
                    </para>
                </listitem>
                <listitem>
                    <para>
                        <firstterm>WebContent</firstterm>
                        allows links to external content to be provided within
                        an event.
                    </para>
                </listitem>
                <listitem>
                    <para>
                        <firstterm>Where</firstterm>
                        indicates the location of the event.
                    </para>
                </listitem>
                <listitem>
                    <para>
                        <firstterm>Visibility</firstterm>
                        allows the event to be hidden from the public event
                        lists.
                    </para>
                </listitem>
            </itemizedlist>
            <para>
                For a complete list of event attributes, refer to the
                <ulink url="http://framework.zend.com/apidoc/core/">Zend Framework <acronym>API</acronym>
                Documentation</ulink> and the
                <ulink url="http://code.google.com/apis/gdata/reference.html">Calendar Protocol
                Reference</ulink>. Attributes that can contain multiple values, such as where, are
                implemented as arrays and need to be created accordingly. Be aware that all of
                these attributes require objects as parameters. Trying instead to populate them
                using strings or primitives will result in errors during conversion to <acronym>XML</acronym>.
            </para>
            <para>
                Once the event has been populated, it can be uploaded to the calendar server by
                passing it as an argument to the calendar service's <methodname>insertEvent()</methodname>
                function.
            </para>
            <programlisting language="php"><![CDATA[
// Create a new entry using the calendar service's magic factory method
$event= $service->newEventEntry();

// Populate the event with the desired information
// Note that each attribute is crated as an instance of a matching class
$event->title = $service->newTitle("My Event");
$event->where = array($service->newWhere("Mountain View, California"));
$event->content =
    $service->newContent(" This is my awesome event. RSVP required.");

// Set the date using RFC 3339 format.
$startDate = "2008-01-20";
$startTime = "14:00";
$endDate = "2008-01-20";
$endTime = "16:00";
$tzOffset = "-08";

$when = $service->newWhen();
$when->startTime = "{$startDate}T{$startTime}:00.000{$tzOffset}:00";
$when->endTime = "{$endDate}T{$endTime}:00.000{$tzOffset}:00";
$event->when = array($when);

// Upload the event to the calendar server
// A copy of the event as it is recorded on the server is returned
$newEvent = $service->insertEvent($event);
]]></programlisting>
        </sect3>
        <sect3 id="zend.gdata.calendar.creating_events.schedulers_reminders">
            <title>Event Schedules and Reminders</title>
            <para>
                An event's starting time and duration are determined by the value of its
                <code>when</code> property, which contains the properties
                <code>startTime</code>, <code>endTime</code>, and <code>valueString</code>.
                <code>StartTime</code> and <code>EndTime</code> control the duration of the
                event, while the <code>valueString</code> property is currently unused.
            </para>
            <para>
                All-day events can be scheduled by specifying only the date omitting the time when
                setting <code>startTime</code> and <code>endTime</code>. Likewise, zero-duration
                events can be specified by omitting the <code>endTime</code>. In all cases,
                date/time values should be provided in
                <ulink url="http://www.ietf.org/rfc/rfc3339.txt">RFC3339</ulink> format.
            </para>
            <programlisting language="php"><![CDATA[
// Schedule the event to occur on December 05, 2007 at 2 PM PST (UTC-8)
// with a duration of one hour.
$when = $service->newWhen();
$when->startTime = "2007-12-05T14:00:00-08:00";
$when->endTime="2007-12-05T15:00:00:00-08:00";

// Apply the when property to an event
$event->when = array($when);
]]></programlisting>
            <para>
                The <code>when</code> attribute also controls when reminders are sent to a user.
                Reminders are stored in an array and each event may have up to find reminders
                associated with it.
            </para>
            <para>
                For a <code>reminder</code> to be valid, it needs to have two attributes set:
                <code>method</code> and a time. <code>Method</code> can accept one of the following
                strings: "alert", "email", or "sms". The time should be entered as an integer and
                can be set with either the property <code>minutes</code>, <code>hours</code>,
                <code>days</code>, or <code>absoluteTime</code>. However, a valid request may only
                have one of these attributes set. If a mixed time is desired, convert to the most
                precise unit available. For example, 1 hour and 30 minutes should be entered as 90
                minutes.
            </para>
            <programlisting language="php"><![CDATA[
// Create a new reminder object. It should be set to send an email
// to the user 10 minutes beforehand.
$reminder = $service->newReminder();
$reminder->method = "email";
$reminder->minutes = "10";

// Apply the reminder to an existing event's when property
$when = $event->when[0];
$when->reminders = array($reminder);
]]></programlisting>
        </sect3>
        <sect3 id="zend.gdata.calendar.creating_events.recurring">
            <title>Creating Recurring Events</title>
            <para>
                Recurring events are created the same way as single-occurrence events, except a
                recurrence attribute should be provided instead of a where attribute. The
                recurrence attribute should hold a string describing the event's recurrence pattern
                using properties defined in the iCalendar standard (<ulink
                url="http://www.ietf.org/rfc/rfc2445.txt">RFC 2445</ulink>).
            </para>
            <para>
                Exceptions to the recurrence pattern will usually be specified by a distinct
                <code>recurrenceException</code> attribute. However, the iCalendar standard
                provides a secondary format for defining recurrences, and the possibility that
                either may be used must be accounted for.
            </para>
            <para>
                Due to the complexity of parsing recurrence patterns, further information on this
                them is outside the scope of this document. However, more information can be found
                in the <ulink url="http://code.google.com/apis/gdata/elements.html#gdRecurrence">
                Common Elements section of the Google Data <acronym>API</acronym>s Developer Guide</ulink>, as well as
                in <acronym>RFC</acronym> 2445.
            </para>
            <programlisting language="php"><![CDATA[
 // Create a new entry using the calendar service's magic factory method
$event= $service->newEventEntry();

// Populate the event with the desired information
// Note that each attribute is crated as an instance of a matching class
$event->title = $service->newTitle("My Recurring Event");
$event->where = array($service->newWhere("Palo Alto, California"));
$event->content =
    $service->newContent(' This is my other awesome event, ' .
                         ' occurring all-day every Tuesday from .
                         '2007-05-01 until 207-09-04. No RSVP required.');

// Set the duration and frequency by specifying a recurrence pattern.

$recurrence = "DTSTART;VALUE=DATE:20070501\r\n" .
        "DTEND;VALUE=DATE:20070502\r\n" .
        "RRULE:FREQ=WEEKLY;BYDAY=Tu;UNTIL=20070904\r\n";

$event->recurrence = $service->newRecurrence($recurrence);

// Upload the event to the calendar server
// A copy of the event as it is recorded on the server is returned
$newEvent = $service->insertEvent($event);
]]></programlisting>
        </sect3>
        <sect3 id="zend.gdata.calendar.creating_events.quickadd">
            <title>Using QuickAdd</title>
            <para>
                QuickAdd is a feature which allows events to be created using free-form text entry.
                For example, the string "Dinner at Joe's Diner on Thursday" would create an event
                with the title "Dinner", location "Joe's Diner", and date "Thursday". To take
                advantage of QuickAdd, create a new <code>QuickAdd</code> property set to
                <constant>TRUE</constant> and store the freeform text as a <code>content</code>
                property.
            </para>
            <programlisting language="php"><![CDATA[
// Create a new entry using the calendar service's magic factory method
$event= $service->newEventEntry();

// Populate the event with the desired information
$event->content= $service->newContent("Dinner at Joe's Diner on Thursday");
$event->quickAdd = $service->newQuickAdd("true");

// Upload the event to the calendar server
// A copy of the event as it is recorded on the server is returned
$newEvent = $service->insertEvent($event);
]]></programlisting>
        </sect3>
    </sect2>
    <sect2 id="zend.gdata.calendar.modifying_events">
        <title>Modifying Events</title>
        <para>
            Once an instance of an event has been obtained, the event's attributes can be locally
            modified in the same way as when creating an event. Once all modifications are
            complete, calling the event's <methodname>save()</methodname> method will upload the changes to the
            calendar server and return a copy of the event as it was created on the server.
        </para>
        <para>
            In the event another user has modified the event since the local copy was retrieved,
            <methodname>save()</methodname> will fail and the server will return a 409 (Conflict) status code.
            To resolve this a fresh copy of the event must be retrieved from the server before
            attempting to resubmit any modifications.
        </para>
        <programlisting language="php"><![CDATA[
// Get the first event in the user's event list
$event = $eventFeed[0];

// Change the title to a new value
$event->title = $service->newTitle("Woof!");

// Upload the changes to the server
try {
    $event->save();
} catch (Zend_Gdata_App_Exception $e) {
    echo "Error: " . $e->getMessage();
}
]]></programlisting>
    </sect2>
    <sect2 id="zend.gdata.calendar.deleting_events">
        <title>Deleting Events</title>
        <para>
            Calendar events can be deleted either by calling the calendar service's
            <methodname>delete()</methodname> method and providing the edit <acronym>URL</acronym> of an event or by calling an
            existing event's own <methodname>delete()</methodname> method.
        </para>
        <para>
            In either case, the deleted event will still show up on a user's private event feed if
            an <code>updateMin</code> query parameter is provided. Deleted events can be
            distinguished from regular events because they will have their <code>eventStatus</code>
            property set to "http://schemas.google.com/g/2005#event.canceled".
        </para>
        <programlisting language="php"><![CDATA[
// Option 1: Events can be deleted directly
$event->delete();
]]></programlisting>
        <programlisting language="php"><![CDATA[
// Option 2: Events can be deleted supplying the edit URL of the event
// to the calendar service, if known
$service->delete($event->getEditLink()->href);
]]></programlisting>
    </sect2>
    <sect2 id="zend.gdata.calendar.comments">
        <title>Accessing Event Comments</title>
        <para>
            When using the full event view, comments are not directly stored within an entry.
            Instead, each event contains a <acronym>URL</acronym> to its associated comment feed which must be
            manually requested.
        </para>
        <para>
            Working with comments is fundamentally similar to working with events, with the only
            significant difference being that a different feed and event class should be used and
            that the additional meta-data for events such as where and when does not exist for
            comments. Specifically, the comment's author is stored in the <code>author</code>
            property, and the comment text is stored in the <code>content</code> property.
        </para>
        <programlisting language="php"><![CDATA[
// Extract the comment URL from the first event in a user's feed list
$event = $eventFeed[0];
$commentUrl = $event->comments->feedLink->url;

// Retrieve the comment list for the event
try {
$commentFeed = $service->getFeed($commentUrl);
} catch (Zend_Gdata_App_Exception $e) {
    echo "Error: " . $e->getMessage();
}

// Output each comment as an HTML list
echo "<ul>";
foreach ($commentFeed as $comment) {
    echo "<li><em>Comment By: " . $comment->author->name "</em><br/>" .
         $comment->content . "</li>";
}
echo "</ul>";
]]></programlisting>
    </sect2>
</sect1>