What does it do? 

This extension detects and extracts metadata (EXIF / IPTC / XMP / ...) from potentially thousand different file types (such as MS Word/Powerpoint/Excel documents, PDF and images) and bring them automatically and natively to TYPO3 when uploading assets.

It works with built-in PHP functions but takes advantage of Apache Tika and other external tools for enhanced metadata extraction.

Requirements 

• PHP methods: exif_read_data, iptcparse

Following tools are optional but recommended for best extraction results:

Apache Tika

The Apache Tika|TM| toolkit detects and extracts metadata and text from over a thousand different file types (such as PPT, XLS, and PDF). All of these file types can be parsed through a single interface, making Tika useful for search engine indexing, content analysis, translation, and much more.

Use of PHP method fsockopen is required when using Tika Server.

ExifTool

ExifTool is a plateform-independant Perl library plus a command-line application for reading, writing and editing meta information in a wide variety of files. ExifTool supports many different metadata formats including EXIF, GPS, IPTC, XMP, JFIF, GeoTIFF, ICC Profile, Photoshop IRB, FlashPix, AFCP and ID3, as well as the maker notes of many digital cameras.

ExifTool is also available as a standalone Windows executable (which does not require Perl) and a Macintosh OS X package.

Pdfinfo

Pdfinfo prints the content of the "Info" dictionary (plus some other useful information) from a Portable Document Format (PDF) file.

Available fields 

Apache Tika 

Using Apache Tika is highly recommended for best extraction results. You may use either the standalone application jar or connect to an Apache Tika server. The latter should probably be quicker to answer since it runs as a daemon.

Apache Tika may be downloaded from https://tika.apache.org/download.html.

Connection to an Apache Tika Server

When connecting to a server and not to the standalone Jar application, handy animations, in Extension Manager, will let you easily double check that provided parameters are correct:

Successful connection

Broken connection

External Tools 

This extension is capable of using external tools to extract metadata:

• exiftool for files containing EXIF, IPTC / XMP

  metadata;

• pdfinfo for PDF.

Dedicated log file for the extraction of metadata 

If you want to redirect every logging information from this extension to typo3temp/logs/metadata.log and send log entries with level "WARNING" or above to the system log, you may add following configuration to typo3conf/AdditionalConfiguration.php:

$GLOBALS['TYPO3_CONF_VARS']['LOG']['Causal']['Extractor']['writerConfiguration'] = [
    \TYPO3\CMS\Core\Log\LogLevel::DEBUG => [
        'TYPO3\\CMS\\Core\\Log\\Writer\\FileWriter' => [
            'logFile' => 'typo3temp/logs/metadata.log'
        ],
    ],

    // Configuration for WARNING severity, including all
    // levels with higher severity (ERROR, CRITICAL, EMERGENCY)
    \TYPO3\CMS\Core\Log\LogLevel::WARNING => [
        'TYPO3\\CMS\\Core\\Log\\Writer\\SyslogWriter' => [],
    ],
];

JSON mapping configuration file 

A mapping configuration file is of the form:

[
  {
    "FAL": "caption",
    "DATA": "CaptionAbstract"
  },
  {
    "FAL": "color_space",
    "DATA": [
      "ColorSpaceData",
      "ColorSpace->Causal\\Extractor\\Utility\\ColorSpace::normalize"
    ]
  }
]

FAL

This is the name (column) of the metadata in FAL.

DATA

This is either a unique key or an array of ordered keys to be checked for content in the extracted metadata. In addition, an arbitrary post-processor may be specified using the -> array notation.

Hook 

The method \Causal\Extractor\Service\Extraction\AbstractExtractionService::getDataMapping() is the central method invoked to map extracted metadata to FAL properties. Developers may dynamically alter the mapping by hooking into the process using $GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['extractor']['dataMappingHook'].

Signal after extraction 

Once the meta data has been extracted, a signal is emitted, which allows other extensions to process the file further. The Signal can be connected to a Slot as follows (e.g., in file file:ext_localconf.php of your extension).

Registration in TYPO3 v8 and v9

// Initiate SignalSlotDispatcher
$signalSlotDispatcher = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance(
    \TYPO3\CMS\Extbase\SignalSlot\Dispatcher::class
);

// Connect the Signal "postMetaDataExtraction" to a Slot
$signalSlotDispatcher->connect(
    \Causal\Extractor\Service\AbstractService::class,
    'postMetaDataExtraction',
    \VENDOR\MyExtension\Service\Extractor::class,
    'enhanceMetadata'
);

This requires a PHP class \VENDOR\MyExtension\Service\Extractor and a method enhanceMetadata() in this class:

<?php
namespace VENDOR\MyExtension\Service;

use TYPO3\CMS\Core\Resource\FileInterface;

class Extractor
{
    public function enhanceMetadata(FileInterface $file, array &$metadata): void
    {
        // your code
    }
}

Registration since TYPO3 v10

The signal slot dispatcher is deprecated since TYPO3 v10 and you should instead register a middleware by creating file Configuration/Services.yaml within your extension:

services:
  _defaults:
    autowire: true
    autoconfigure: true
    public: false

  VENDOR\MyExtension\EventListener\ExtractorEventListener:
    tags:
      - name: event.listener
        identifier: 'causal/extractor'
        method: 'postMetaDataExtraction'
        event: Causal\Extractor\Resource\Event\AfterMetadataExtractedEvent

This requires a PHP class \VENDOR\MyExtension\EventListener\ExtractorEventListener and a method enhanceMetadata() in this class:

<?php
namespace VENDOR\MyExtension\EventListener;

use Causal\Extractor\Resource\Event\AfterMetadataExtractedEvent;

class Extractor
{
    public function postMetaDataExtraction(AfterMetadataExtractedEvent $event): void
    {
        // your code
    }
}

How to contribute 

This extension is using the same contribution workflow as for TYPO3 Core, but with GitHub PRs for the review process. Please read more about the workflow in the TYPO3 Contribution Guide.