4.8.10.3. Standard File Storage Implementation

The standard implementation stores files in a dedicated folder structure within one or several file locations.

The roots of the structure can be defined in the cuba.fileStorageDir application property in the format of comma-separated paths list. For example:

cuba.fileStorageDir=/work/sales/filestorage,/mnt/backup/filestorage

If the property is not defined, the storage will be located in the filestorage sub-folder of the Middleware’s work directory. This folder is tomcat/work/app-core/filestorage in standard Tomcat deployment.

With several locations defined, the storage behaves as follows:

  • First folder in the list is considered as primary, others – as backup.

  • Stored files are first placed in the primary folder, and then copied to all of the backup directories.

    The system checks that each folder is accessible before storing a file. If the primary directory is not accessible, the system throws an exception without storing the file. If any of the backup directories are not accessible, the file gets stored in available ones and the corresponding error is logged.

  • The files are read from the primary directory.

    If the primary directory is not accessible, the system reads files from the first available backup directory containing the required files. A corresponding error is logged.

The storage folder structure is organized in the following way:

  • There are three levels of subdirectories representing the files upload date – year, month, and day.

  • The actual files are saved in the day directory. The file names match the identifiers of the corresponding FileDescriptor objects. The file extension matches that of the source file.

  • The root folder of the structure contains a storage.log file with the information on each stored file, including the user and upload time. This log is not required for operation of the storage mechanism, but it could be useful for troubleshooting.

The app-core.cuba:type=FileStorage JMX bean displays the current set of storage roots and offers the following methods for troubleshooting:

  • findOrphanDescriptors() – finds all instances of FileDescriptor in the database that do not have a matching file in the storage.

  • findOrphanFiles() – finds all files in the storage that do not have a corresponding FileDescriptor instance in the database.