PHP response XML VAST file

Question

I'm following a low-budget project which cannot afford an expensive VAST Ads Server. Basically, what I have is a group of 5 videos to run as inline preroll. Not much important to track impressions and clicks.

I wrote a few lines of PHP to change randomly the video source and click link into a standard VAST 3.0 XML template.

What I'm missing is how to make the server respond to the video player requests with the XML file.

Here is my code.

Thanks!

    $link_1 = 'https://example.com';
    $link_2 = 'https://example.com';
    $link_3 = 'https://example.com';
    $link_4 = 'https://example.com';
    $link_5 = 'https://example.com';
    
    $srcvideo_1 = '/path-to-file/1.mp4/';
    $srcvideo_2 = '/path-to-file/2.mp4/';
    $srcvideo_3 = '/path-to-file/3.mp4/';
    $srcvideo_4 = '/path-to-file/4.mp4/';
    $srcvideo_5 = '/path-to-file/5.mp4/';
    
    $min=1;
    $max=5;
    $sessionnum = rand($min,$max);
    
    if ($sessionnum == '1') {
        $link = $link_1;
        $srcvideo = $srcvideo_1;
        }
        elseif ($sessionnum == '2') {
        $link = $link_2;
        $srcvideo = $srcvideo_2;
        }
        elseif ($sessionnum == '3') {
        $link = $link_3;
        $srcvideo = $srcvideo_3;
        }
        elseif ($sessionnum == '4') {
        $link = $link_4;
        $srcvideo = $srcvideo_4;
        }
        elseif ($sessionnum == '5') {
        $link = $link_5;
        $srcvideo = $srcvideo_15;
        }
        



    $output = '
<VAST version="3.0">
    <Ad id="1">
        <InLine>
            <AdSystem>Adserver</AdSystem>
            <AdTitle>VAST Ad</AdTitle>
        <Impression id="12345689">
            <![CDATA[ https://example.com/image.png?imp=1 ]]>
        </Impression>
        <Creatives>
            <Creative sequence="1">
                <Linear skipoffset="00:00:10">
                    <Duration>00:00:20</Duration>
                    <VideoClicks>
                        <ClickThrough>
                            <![CDATA[ ' . $link . ' ]]>
                        </ClickThrough>
                        <ClickTracking>
                            <![CDATA[ https://example.com/tracking ]]>
                        </ClickTracking>
                    </VideoClicks>
                    <MediaFiles>
                        <MediaFile width="426" height="240" delivery="progressive" type="video/mp4" bitrate="261" scalable="true" maintainAspectRatio="true">
                        <![CDATA[ ' . $srcvideo . ' ]]>
                        </MediaFile>
                    </MediaFiles>
                </Linear>
            </Creative>
        </Creatives>
        </InLine>
    </Ad>
</VAST>
';

?>

Answer 1

Do not number your variables - use arrays. That is what they are for.

$ads = [
    [
        'url' => 'https://example.com/',
        'video-url' => '/path-to-file/1.mp4/'
    ],
    [
        'url' => 'https://example.com/',
        'video-url' => '/path-to-file/2.mp4/'
    ],
    [
        'url' => 'https://example.com/',
        'video-url' => '/path-to-file/3.mp4/'
    ],
    [
        'url' => 'https://example.com/',
        'video-url' => '/path-to-file/4.mp4/'
    ],
    [
        'url' => 'https://example.com/',
        'video-url' => '/path-to-file/5.mp4/'
    ],
];

$ad = $ads[array_rand($ads, 1)];
var_dump($ad);

Example output:

array(2) {
  ["url"]=>
  string(20) "https://example.com/"
  ["video-url"]=>
  string(20) "/path-to-file/2.mp4/"
}

To create XML use a library like DOM. You could use methods to create the whole structure or load a file and manipulate it. In this case I would use a template file because the bootstrap is larger then the actual content.

vast-template.xml:

<VAST version="3.0">
    <Ad id="1">
        <InLine>
            <AdSystem>Adserver</AdSystem>
            <AdTitle>VAST Ad</AdTitle>
            <Impression id="12345689">https://example.com/image.png?imp=1</Impression>
            <Creatives>
                <Creative sequence="1">
                    <Linear skipoffset="00:00:10">
                        <Duration>00:00:20</Duration>
                        <VideoClicks>
                            <ClickThrough/>
                            <ClickTracking>https://example.com/tracking</ClickTracking>
                        </VideoClicks>
                        <MediaFiles>
                            <MediaFile 
                                width="426" height="240" 
                                delivery="progressive" 
                                type="video/mp4" bitrate="261" 
                                scalable="true" 
                                maintainAspectRatio="true"/>
                        </MediaFiles>
                    </Linear>
                </Creative>
            </Creatives>
        </InLine>
    </Ad>
</VAST>

Note the the ClickThrough and MediaFile elements are empty. Next load the template and fill the elements.

$document = new DOMDocument();
$document->load(__DIR__.'/vast-template.xml');
$xpath = new DOMXpath($document);

$link = $xpath->evaluate('//ClickThrough')->item(0);
$link->textContent = $ad['url'];
$file = $xpath->evaluate('//MediaFile')->item(0);
$file->textContent = $ad['video-url'];

echo $document->saveXML();

Example output:

<?xml version="1.0"?>
<VAST version="3.0">
    <Ad id="1">
        <InLine>
            <AdSystem>Adserver</AdSystem>
            <AdTitle>VAST Ad</AdTitle>
            <Impression id="12345689">https://example.com/image.png?imp=1</Impression>
            <Creatives>
                <Creative sequence="1">
                    <Linear skipoffset="00:00:10">
                        <Duration>00:00:20</Duration>
                        <VideoClicks>
                            <ClickThrough>https://example.com/</ClickThrough>
                            <ClickTracking>https://example.com/tracking</ClickTracking>
                        </VideoClicks>
                        <MediaFiles>
                            <MediaFile width="426" height="240" delivery="progressive" type="video/mp4" bitrate="261" scalable="true" maintainAspectRatio="true">/path-to-file/2.mp4/</MediaFile>
                        </MediaFiles>
                    </Linear>
                </Creative>
            </Creatives>
        </InLine>
    </Ad>
</VAST>