Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
1998-08-14
2001-11-20
Choules, Jack (Department: 2177)
Data processing: database and file management or data structures
Database design
Data structure types
Reexamination Certificate
active
06321219
ABSTRACT:
BACKGROUND
The present invention relates to electronic data processing, and more specifically concerns the creation and use of symbolic links for organizing file structures in a computer.
Most computer operating systems provide facilities for storing individual files in a structured arrangement from which they can be accessed by user application programs. Hierarchical file systems, the most common type, posit a root directory for each logical or physical storage device such as a disk drive. The root directory can contain individual files, and can also contain subdirectories which in turn contain files and subdirectories to any desired level. Directories and subdirectories are identical in function, and are sometimes called folders or other names. Some file systems, the best known of which is UNIX, attach file systems from different devices into a single file hierarchy. This is referred to as “mounting” a file system.
Users employ directory structures to organize their data and programs. For example, a storage device designated “C:” may contain legal documents in a directory “C:\LegalDocs”. A user wishes to organize the documents by docket number, and accordingly sets up a subdirectory for each one: “C:\LegalDocs\111803”, “C:\LegalDocs\98007”, and so on. Each directory at the lowest level then contains files dealing with that particular docket. However, another user may desire to organize the same files on the same storage device by author, using directories such as “C:\LegalDocs\Norm_D_Plume”, “C:\LegalDocs\Sue_Donym”, etc. A third user may desire all files created within the current month to be in a single directory “C:\LegalDocs\Recent”. But, if the operating system can only store each file in a single folder, then the files can be organized in only one way. Application programs such as document-control utilities sidestep this problem by allowing users to create profiles for each file, and then accessing the files in response to users' queries for files having certain characteristics in the profiles. Although these programs function well, they function with only one application program, or with applications that adhere to certain protocols or standards. Placing a number of existing files within a document-control system requires manually generating profiles for each file. These programs tend to be large, expensive, and difficult to configure or modify. In addition, switching from one document-control system to a different one usually requires redoing the profiles of all the files. Also, commercial document-control systems are overkill in many small tasks or ad-hoc situations.
Another approach introduces the concept of symbolic links. Many operating systems include a facility that allows a user or an administrator to create a link between an existing file or directory and a new name. Thereafter, both the new name and the old name refer to the same file or directory. Changes made during an access under either name appear under a later access under the other name as well. These links provide aliases for files, different ways to access the same physical entity.
Conventional links, however, are “static” symbolic links. They require explicit create and delete actions on behalf of a computer user. The links must be manually removed when no longer needed, even after the physical files or directories to which they refer have been removed from the system. The administration of static symbolic links quickly becomes unwieldy as the number of links increases. Because of oversights or interruptions, some files that should be linked will not be linked, and broken links will remain after their underlying files have been removed or renamed. Although system scripts or programs can be written by systems administrators to automate portions of link-management tasks, they are error-prone and have limited function. Such software must be run periodically, and links are likely to become obsolete between runs. Pushed beyond relatively simple file structures, static links obscure the relationships between file-system objects. Further, the creation and maintenance of static links are difficult enough to deter naive or casual users from even attempting to learn how they work.
Therefore, the file structures of many operating systems lack an effective facility for handling multiple organizations of files, folders, directories, and other objects in a manner that is error-free, transparent to all application programs, and simple to learn.
SUMMARY OF THE INVENTION
The present invention provides facilities in the file system of an operating system or other program for creating and maintaining dynamic links among file-system objects. These links differ from conventional static links in that they come into being only when needed to access an object, and they cease to exist whenever a user's access ceases. At the same time, however, dynamic links are more than mere ad hoc relationships that need to be defined anew for every file access. Although the links themselves go away between successive accesses, a persistent rule or definition recreates the links automatically for every access. Therefore, changes to files or directories between accesses are automatically reflected whenever a new access occurs, without any user action in changing or recreating the links.
A utility program accessible to users receives definitions of rules or associations for creating symbolic links among particular file-system objects such as files and directories. Rule creation is simple and direct, and the rules can be general and powerful. A file-system component called a dynamic link driver detects operations occurring at points in the file-system name space where rules have been defined, creates symbolic links among objects as specified by the rules. This link driver can be inserted in the file-management or other modules of conventional operating systems without extensive modifications, perhaps even as a third-party device driver. Because the link driver creates and handles the links within the file system itself, the symbolic links are transparent to all application programs that access files and directories, and even to other levels of the file system itself. That is, an application accesses a linked file or directory with exactly the same mechanisms with which it accesses any file or directory; with no change whatsoever to the application code, and without complying with any additional standard or protocol. A rules component or query processor, either within the file-system link driver or located separately, stores and accesses the data required to carry out the rules. The rules defining a given set of dynamic symbolic links can be satisfied directly by the link driver; that is, the link driver can directly execute and satisfy the rule. Alternatively, the rule can be forwarded to any supported query processor. For example, Microsoft® WindowsNT® 5 supports full content indexing on all files, and its Windows content-indexing component can be the target of the dynamic symbolic link rule. The content-indexing component can receive the query, execute it, and return the result to the link driver, which can use the result to execute the file or directory operation.
The utility program receives from a user a request to associate certain file-system objects. The utility requests the user to specify a location in the file system name space for the association, and to specify a rule, association, relation, or query (these terms are interchangeable) for the insertion point. The utility then installs that rule at the insertion point. A subsequent request from a user application program—or, equivalently, from the system browser—for a file-system object such as a file or a directory at the insertion point invokes the file-system component to call the rules component to determine which objects at what actual locations fit the rule for that insertion point. The file system creates the appropriate links for objects that satisfy the rule, effectively plugging their names or other ident
Gainer Patrick J.
Hamilton James R.
Verma Surendra
Choules Jack
Merchant & Gould P.C.
Microsoft Corporation
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