International Business Machines Corporation

Thomas G Burket

Tawei Hu

Gerald Edward Kozina

Thomas S Lee

Krishnamurthi Kannan

Seifu Ali

Seraphin Bernard Calo

Gordon Wesley Braudaway

Suk Suet Soo

Clifford B Meltzer

Deborah J Kruesi

John W Wiley, Jr

The present invention is directed to a method and system for storing and managing objects, such as binary large objects (blobs) in a digital library system which includes a plurality of clients, an object server for storing an object, a cache server for storing an copy of the object, and a centralized server for storing information identifying the object as being stored in the object server and associating one or more of the clients with the cache server, in which one of the clients, as a requesting client, requests retrieval of an object, a copy of the requested object is sent from the cache server to the requesting client if the object is stored in said cache server, and a copy of said object is sent from the object server to said requesting client if the object is not stored in the cache server; and a copy of the requested object is sent from the object server to the cache server after the object server sends the object to the client, in which the object sent to the client is made available to the client regardless of whether sending of the copy of the object to the cache server is completed.

Distributed storage management system having a cache server and method

The present invention is directed to a method and system for storing and managing objects, such as binary large objects (blobs) in a digital library system which includes a plurality of clients, an object server for storing an object, a cache server for storing a copy of the object, and a centralized server for storing information identifying the object as being stored in the object server and associating one or more of the clients with the cache server, in which one of the clients, as a requesting client, requests retrieval of an object, a copy of the requested object is sent from the cache server to the requesting client if the object is stored in said cache server, and a copy of said object is sent from the object server to said requesting client if the object is not stored in the cache server; and a copy of the requested object is sent from the object server to the cache server after the object server sends the object to the client, in which the object sent to the client is made available to the client regardless of whether sending of the copy of the object to the cache server is completed.

An architecture for the implementation of an information utility for accessing information and executing transactions on an interactive basis between Videotex databases and individual end user terminals, some or all of which may be remotely located with respect to each other. The utility may be associated with a Videotex Application Network (VAN) and includes a combination of distributed, semiautonomous Operations Nodes (ONs), each characterized by (1) one or more affiliated users, (2) the inclusion of some form of database, and (3) one or more customized application programs, and each is also capable of 'standalone' operation. Each database comprises pages of control information and displayable data. Each node comprises a directory of databases at other nodes.

Electronic system for accessing graphical and textual information

A system or scheme for automatic detection of and recovery from transmission errors in the asynchronous communication mode at the data link level with complete transparency at the higher levels is disclosed wherein the transmissions are in the form of a sequence of data packets, and an improved combination of end-of-text (ETX) bytes along with checksums is used in each data packet to detect errors. The ETX character is dynamically selected for each packet after the data comprising the packet has been assembled. This character is coded differently from the remaining character codes in its respective packet and is made the second byte thereof following the start-of-text byte (STX). The third byte in each packet is made the complement of the preceding ETX byte, the latter of which is also made the last byte in the packet. Thus, the second and last bytes in each packet are identical, and different from all the other bytes, and the third byte is their complement. Other bytes in each packet include: one byte indicating the location of the packet in a set in a given transmission sequence; a byte distinguishing the packet's set from other transmission sequences; two bytes indicative of the number of data bytes in the packet; one byte operating as a control character indicating the functional nature of the packet; data bytes; and, two checksum bytes which precede the last ETX byte. Among the advantages of transmissions using packets containing the foregoing improved combination of bytes, is the fact that all transmission errors will be detected and upon detection of an error in a packet, the transmitter is immediately notified and retransmission is carried out only from the erroneous packet rather than from the beginning of the entire sequence as in the prior art.

Protocol for handling transmission errors over asynchronous

Growing community of inventors

Potomac, MD, United States of America

Thomas G Burket