Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
1998-02-13
2002-09-03
Jung, David (Department: 2175)
Data processing: database and file management or data structures
Database design
Data structure types
C707S793000, C709S226000
Reexamination Certificate
active
06446093
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a distributed system comprising a document server and a plurality of clients which are connected to the document server via a network and, more particularly, to a method of managing a document shared in the distributed system.
In prior art, various proposals are already made as regards technique for permitting the plurality of clients carrying out an editing operation for the same document. By way example, a document managing method (which will be herein called a first prior art) is disclosed in Japanese Unexamined Patent Publication of Tokkai (JP-A) No. 7-85020 (which will be herein called a first reference) on Mar. 31, 1995. In the first prior art according to the first reference, a plurality of clients share the same document in a document data base on a server. On simultaneously carrying out the editing operation on the same document by the plurality of clients, the document as an editing object is copied to a document work file for each client. As a result, each client simultaneously carries out the editing operation on the document without affecting other clients. However, in the first prior art according to the first reference, it is difficult for each client to confirm edited contents in other clients. This is because the same document is copied to the document work file for each client and the editing operation is independently carried out by each client. As a result, it is difficult for a plurality of clients to work in cooperation with the edited contents mutually confirmed for the same document.
In addition, a computer conference device (which will be herein called a second prior art) is disclosed in Japanese Examined Patent Publication of Tokkou (JP-B) No. 7-50884 (which will be herein called a second reference) on May 31, 1995. In the second prior art according to the second reference, each client is provided with a document file for storing the same contents. When a plurality of clients simultaneously refer and renew a document in the document file, an editing command, etc. generated by each client are transmitted to a server and the server unanimously transmits the editing command, etc. to all of the clients to make all of the clients process the editing command, etc. With this structure, it is possible to carry out the editing operation for the same document with edited results confirmed by all of the clients.
In the second prior art according to the above-mentioned second reference, it is possible to proceed with group work with edited contents for each client confirmed by all of the clients. This is because, when the editing operation is carried out by any client, the editing operation is delivered to all of clients via the server so that the document of each client is edited in the similar manner in other clients. However, the second prior art according to the second reference is disadvantageous in that it is impossible to carry out access control for each portion composing the document so as to make a particular client see a portion in the document. Such access control is required on carrying out the group work by a plurality of clients. In this sense, the second prior art according to the second reference is still insufficient for applying to a distributed cooperation system.
Furthermore, a document database-based system (which will be herein called a third prior art) is known. Such a document database-based system is, for example, Notes which is developed by Lotus Development Corporation in U. S. A. In the third prior art, the same document is referred to a document structure defined by predetermined document components via an application program on the basis of the document structure. In addition, writing is simultaneously carried out for different document components (portions of the document) in the same document. Furthermore, in order to prevent data destruction by simultaneous access to the same portion in the same document, an access limitation is made on the basis of a lock used by a conventional database technique.
In the third prior art, if structure of the document is defined as a unit each of the predetermined document components, it is possible to carry out the access control so as to refer or modify the portion (the document component) in the document. From this point of view, the third prior art is most adapted for a group work system among the above-mentioned three prior arts. However, performing of such an access control is restricted to each unit or each of the predetermined document components. As a result, it is impossible for the third prior art to carry out the access control as regards, as a unit, a document component which will be prepared from now. Specifically, the third prior art can carry out, for the document having a structure which is designed the document so as to share by all of the clients, the access control on the portion defined as the document component but the third prior art cannot dynamically generate, in the document, a memorandum for private use or another memorandum which should like to make particular clients see that satisfy a particular condition. This is because, for that purpose, an area playing a role in the memorandum must be preliminarily prepared on definition of the document structure. In general, the required area for the memorandum depends on progress of the group work. As a result, it is difficult to preliminarily prepare the required area on definition of the document structure.
Various other distributed systems are already known. By way of example, a system and method for document database retrieval (which will be herein called a fourth prior art) is disclosed in Japanese Unexamined Patent Publication of Tokkai (JP-A) No. 8-77201 (which will be herein called a third reference) on Mar. 22, 1996. The fourth prior art according to the third reference improves the productivity, maintainability, etc., of an application program by enabling standardized access to a document database consisting of a main text file and bibliographical information by a standard database language.
A ciphered file sharing method (which will be herein called a fifth prior art) is disclosed in Japanese Unexamined Patent Publication of Tokkai (JP-A) No. 6-17505 (which will be herein called a fourth reference) on Jun. 24, 1994. The fifth prior art according to the fourth reference reduces management information even at the time of enciphering plural files by different keys by giving a hierarchical reference premission to a user, in the sharing method of a ciphered file.
A file sharing system between system (which will be herein called a sixth prior art) is disclosed in Japanese Unexamined Patent Publication of Tokkai (JP-A) No. 6-83691 (which will be herein called a fifth reference) on Mar. 25, 1994. The sixth prior art according to the fifth reference shares files between plural systems by accessing the files present in the respective system on a network at an application software level by a server for accessing the files based on requests from the users of the respective systems.
A method for sharing file by utilizing network of distributed system (which will be herein called a seventh prior art) is disclosed in Japanese Unexamined Patent Publication of Tokkai (JP-A) No. 6-68044 (which will be herein called a sixth reference) on Mar. 11, 1994. The seventh prior art according to the sixth reference reduces the communication processing overhead for file access request and file information transfer in each processing node and a file management node and to shorten the time required for access from each processing node to a shared file.
A system operation method for shared disk device (which will be herein called an eighth prior art) is disclosed in Japanese Unexamined Patent Publication of Tokkai (JP-A) No. 7-319828 (which will be herein called a seventh reference) on Dec. 8, 1995. The eighth prior art according to the seventh reference improves a restoration ratio in transaction unit at the time of generating a fault by excluding the restriction of access to a shared file to b
Jung David
NEC Corporation
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