The file abstraction layer (FAL) brings a number of changes relevant to the administrator of a TYPO3 site. This chapter is trying to shed light on these points.
No copies - but references!
The most fundamental change the File Abstraction Layer brings is that files are not copied any more for each usage but referenced instead each time you use it.
For the editors, this means that:
- Less disk space is used. If the same image is displayed in four different locations on the site, only one fourth of disk space is needed for this.
- Assets can be replaced centrally: It’s possible to centrally replace a file with an updated version without having to change each individual place where it’s used.
- Tracking of usage is possible. It’s possible to identify for any asset where it is used throughout the page and display or count the references to it. This makes it technically possible to display warnings when deleting an asset to warn the user of existing references to it.
One more central concept of FAL is “storages”. A storage can be seen as a
“mounted directory” either local or from remote systems. Not only
additional mounts are handled as storages, but also the main
fileadmin/ directory. The ‘fileadmin’ storage will be created
automatically when you upgrade an installation to TYPO3 6.0 or later. From
then on it behaves just like any other storage.
To create a new storage, just create a new “Storage” record in the
List module (Web->List) on the root page (uid=0). That way you can create
any number of storages besides the
fileadmin directory or
even remove the initial “fileadmin” storage altogether or change its
location easily by editing its storage record.
Beware that simply changing the storage path can break relations to the files if you don’t move the files in the filesystem as well.
Technically a storage is a record in table sys_file_storage.
Images as IRRE-Child records¶
IRRE stands for “Inline Relational Record Editing”.
When attaching images to a content record, TYPO3 CMS uses an IRRE-based inline child record for each image where settings such as the ALT or TITLE HTML tag can be configured along with the image link and the description. This makes the interface for an editor much cleaner. It removes the disadvantage of older versions where for example such meta data like caption text, image link, and description had to be entered newline-separated in different fields.
The IRRE child records are records from the sys_file_reference table with each child record represents a single reference from a content element to a file. This is the same from other tables as well.
The file itself is represented by a sys_file record.