TITLE
    Desktop Manager and Desktop Databases: What are they? (10/95)
Article ID:
Created:
Modified: 		18727
10/11/95
10/11/95
TOPIC


    This article describes the history of the Desktop Manager and Desktop DB files. It also discusses the use and support of the Desktop Manager extension.

DISCUSSION


    In the early days of the Macintosh operating system, new objects like icons and windows had to be stored and managed somewhere by the operating system. Information such as the bit mapped representation of the icon picture to display and the association of documents to the application that created them was saved in a database. This file was called "Desktop" and was an invisible file at the top level of every diskette. Information was placed in this file by the action of the Finder making calls to the Desktop Manager. The Desktop Manager, in turn, made calls to the Resource Manager, creating resource items within the Desktop file.

    When hard drives came into use on the Macintosh and the file system was enhanced with real folders and a hierarchical organization. This became known as the Hierarchical File System (HFS). The Desktop file maintained the same information as before, but became much larger in size since hard drives held many more files and documents.

    AppleShare File Servers added the ability for the Macintosh to share larger and larger hard drives. The fast access needs of the file servers began to strain the capabilities of the Resource Manager to maintain the Desktop database. A new database organization was designed for use by the Desktop Manager for use on AppleShare 2.0.x servers. This new Desktop database consisted of two invisible files called "Desktop DB" and "Desktop DF".

    These files are of a more modern database design with an index and data file and provide much faster access to information than the original resource based file, especially when the number of files being managed becomes very large. These files are also created at the top level of every volume over 2 Megabytes in size. Floppy disks kept the original resource based Desktop file, since it is an adequate method for small volumes.

    The support of the internal interface for the new Desktop Manager database routines under System 6 was implemented as an extension on AppleShare Servers called Desktop Manager. Many users who owned the AppleShare 2.0.x product ran with this extension on their client computer with System 6 to help manage their growing file systems on large hard drives. This use of the Desktop Manager extension was never a supported or approved configuration by Apple outside of the AppleShare Server environment.

    This new desktop database design was integrated into System 7 and is still in current use. In the early transition days from System 6 to System 7, many users were using the Desktop Manager extension from AppleShare with non-server computers because they found that╩when switching back and forth between System 6 and System 7, it would prevent a Desktop rebuild from occurring. This extension was enabling the same desktop files to be shared between the two different versions of the Mac OS. This was an untested and unsupported configuration that seemed to work for those who tried it.


    Support Information Services

Document Information
Product Area: Mac OS System Software
Category: General OS
Sub Category: General Topics
Keywords: ksts,kcompat

Copyright © 2000 Apple Computer, Inc. All rights reserved.