The design principles of FLAM:
An online data storage media files compressed with FLAM4 can be used in connection with both sequential and index sequential access methods without additional intermediate conversions. The same transparency applies for data exchange (file transfer) in a heterogeneous network between computers with different hardware and different operating systems.
Formatting of the compressed files can be controlled in a way that all requirements are met for maximum memory usage and for portability on any type of transmission lines with any file transfer product. This is especially true for punched card formats (80 columns) and for FTAM formats. Compressed records can be created in both fixed and variable format.
FLAM4 is even able to generate compressed files in a printable format. This allows to convert the compressed file from EBCDIC to ASCII and vice versa at any time. At the other hand, code conversions can be performed in combination with compression or decompression.
Optionally FLAM4 can convert file and record formats. This allows FLAM to solve compatibility problems between heterogeneous systems or version dependent file management systems. Restrictions regarding record format (fix), duplicate key, etc. are neutralized using FLAM as an access method.
A FLAMFILE can be used on all computer systems where FLAM is available. The FLAMFILE is the base for the access method FLAM without sacrificing the different system specific access methods of the particular file management system.
A FLAMFILE can be converted during decompression into any file or record format as specified by the user. This guarantees continuity. An archived FLAMFILE can always be processed (especially decompressed) on any system.
This insures independency from a particular operating system. However, it must be made sure, that the storage medium can be read by the hardware (e.g. tape unit). Also the FLAMFILE should not be converted into a system dependent format of any given archiving product.
FLAM4 encrypts data and seals the compressed files using checksums for better protection. The FLAMFILE has internal synchronisation points, which allow to restart decompression after an erroneous data block caused by physical defects. Requirements for revision and controlling are fully supported.
FLAM4 provides a variety of interfaces derived from a real file management system with index sequential access. FLAM can be executed as a subprogram under control of an application. User exits within FLAM4 allow pre- and postprocessing of uncompressed records as well as FLAMFILE records.
FLAM4 is an optional compression standard for different applications used in German banking, within the framework of Banking Communication Standard (BCS), TARGET2, SEPA, and others.