Basic concepts

This chapter presents the general concepts underlying the TYPO3 file abstraction layer (FAL). The whole point of FAL - as its name implies - is to provide information about files abstracted with regards to their actual nature and storage.

Information about files is stored inside database tables and using a given file is mostly about creating a database relation to the record representing that file.

Storages and drivers

Every file belongs to a storage, which is a very general concept encompassing any kind of place where a file can be stored: a local file system, a remote server or a cloud-based resource. Accessing these different places requires an appropriate driver.

Each storage relies on a driver to provide the user with the ability to use and manipulate the files that exist in the storage. By default, TYPO3 provides only a local file system driver.

A new TYPO3 installation comes with a predefined storage, using the local file system driver and pointing to the fileadmin/ directory, located in your public folder. If it is missing or offline after installation, you can create it yourself.

Files and metadata

For each available file in all present storages, there exists a corresponding database record in the table sys_file, which contains basic information about the file (name, path, size, etc.), and an additional record in the table sys_file_metadata, designed to hold a large variety of additional information about the file (metadata such as title, description, width, height, etc.).

File references

Whenever a file is used - for example, an image attached to a content element - a reference is created in the database between the file and the content element. This reference can hold additional information like an alternative title to use for this file just for this reference.

This central reference table (sys_file_reference) makes it easy to track every place where a file is used inside a TYPO3 installation.

All these elements are explored in greater depth in the chapter about FAL components.