Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
1998-12-17
2001-06-19
Black, Thomas (Department: 2171)
Data processing: database and file management or data structures
Database design
Data structure types
C707S793000
Reexamination Certificate
active
06249782
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to reducing lengths of computer file names and for retrieving files with reduced length names. More particularly, the invention relates to using a unique file identifier for reducing file names and for retrieving files with reduced length names.
2. Discussion of Background Art
Many existing Application Programming Interfaces (APIs) only support file names that contain thirty-one (31) or fewer characters. Other APIs, however, permit file names as long as 255 characters or longer. Hence, a problem arises when a file name longer than 31 characters needs to be accessed via an API which only permits a maximum file length of 31 characters. Additionally, many APIs have a limited set of representable or allowable characters and, thus, cannot effectively support file names that include characters not within a given API's set of allowable characters.
One manner in which the prior art has accommodated overlength file names is by merely truncating the portion of the file name that exceeds the maximum permitted file name length. For example, if a file name is 145 characters long, the final 114 characters (the number of characters in excess of 31) are truncated from the end of the file name to create a file name of acceptable length. This approach presents a number of problems.
For example, one significant limitation with merely truncating the portion of the file name in excess of the maximum allowable length is that a given data volume may contain a number of distinct, but lengthy, names which, when truncated, become identical. That is, the distinguishing features of a file name may be located toward the end of the file name and would thus be removed by the truncation, potentially rendering several truncated file names identical. Having identical file names associated with different files is highly undesirable and problematic in that the different files having identical truncated file names cannot be distinguished by file name.
An additional problem associated with this approach is that by truncating the end of the file name, valuable information that may be present in a file name extension is lost. In general, file names frequently have extensions appended to the end of the file name to indicate the type of content in the associated file. For example, the file name extension of the file name “example.txt” is the character string “.txt” which indicates to the system and to the user that the file associated with this file name is a text file and should be opened with an application appropriate for such a file type. By merely truncating the end of a file name, the extension is deleted and valuable information concerning the type of the file contents is lost. Consequently, this approach is highly unsatisfactory for many applications.
Another approach has been to truncate a lengthy file name and to then modify the truncated name until the name becomes unique. This approach, however, requires that copies of the lengthy file names and the associated truncated file names be continuously maintained and monitored to verify that all the lengthy file names and all the truncated file names are always unique. The requirement of maintaining and searching through both sets of file names, on a continual basis, to confirm that both sets of file names are unique, may create system performance problems and, therefore, makes this approach undesirable.
Other attempts to address the problem of reducing the lengths of file names have employed a probabilistic approach in which the shortened file names are likely, but not guaranteed, to be unique. One of these attempts addresses the problem by truncating the file name and then appending a number, based on a check sum of the entire name, to the truncated file name. A check sum is a formula through which the characters of a file name may be passed to arrive at a number. Unfortunately, however, like some of the other approaches, this probabilistic approach is limited in that the shortened file names are not guaranteed to be unique.
Consequently, a need exists for a system and method for reliably reducing the length of a file name that guarantees a unique reduced file name. Such a method should not be so burdensome that the creation and use of reduced file names significantly reduces the performance of the system. Moreover, such a system and method should preserve the valuable information regarding file type found in the file name extension. Lastly, an additional need exists to provide a system and method for reliably reducing a file name including unrepresentable characters into a unique representable file name.
SUMMARY OF THE INVENTION
The present invention is directed to reducing unsupportable file names. Indeed, the present invention provides a system and method for reducing file names to be supportable by a given Applications Programming Interface (API) while, at the same time, guaranteeing that all file names are unique by embedding a unique file identifier within each reduced file name. A system and method are also provided by which a file may be located using a reduced file name.
In general, a file name longer than those supportable by a given API is truncated. After the name has been truncated, a unique file identifier is appended to the truncated file name to guarantee the uniqueness of the file name after truncation. Advantageously, the file identifier is a unique number created and associated with a file upon creation of the file. In this manner, the uniqueness of the reduced file name is guaranteed.
Some file names contain characters that are not representable by a given-API because such characters may not be within the API's set of representable or allowable characters. Where the original file name contains unrepresentable characters, each unrepresentable character is replaced with a representable character. Alternatively, each contiguous sequence of unrepresentable characters could be replaced with a single representable character to further conserve file name length. A unique file name identifier is then appended to the file name to create a reduced file name that is supportable by the API and is guaranteed to be unique.
In particular, one embodiment of the present invention reduces a file name by first receiving an original file name associated with a given file in a particular volume. A unique file identifier associated with the file is also received. Next, if the file name is too long, a portion of the original file name is truncated. If the file name contains unrepresentable characters, the system replaces each unrepresentable character with a representable character. The file identifier is then combined with the remaining characters of the file name, together with a reduced file name marker and the file name extension, to create a reduced file name.
More specifically, the present invention includes a system and method for reducing file name length and for retrieving the reduced file name entitled files. In response to a request to call up a file name that has a length longer than that supported by a given API, a file manager program first retrieves an original file name having an original file name length and an original file identifier. Next, the file manager divides the original file name into a set of original file name primary characters and a set of extension characters. By encoding the original file identifier, a shortened, or encoded, identifier having a set of shortened identifier characters is created. In a preferred embodiment, the original file identifier is a binary number that may be encoded by conversion to an equivalent, but shorter, hexadecimal number. Alternately, the original file identifier could be otherwise encoded by conversion to a number system more compact than hexadecimal to further conserve file name length.
The reduced file name length should be no longer than a maximum file name length supportable by the API so that the reduced file name can pass through the API. To this end, the number of shortened identifier characters and
Brady Donald J.
Day Mark S.
Horn Deric S.
Apple Computer Inc.
Black Thomas
Carr & Ferrell LLP
Loomis John C.
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