At+t Corp.

Lucent Technologies Inc.

Other

At&t Intellectual Property I, LP

Glenn Stephen Fowler

Balachander Krishnamurthy

Jia Wang

Adam Louis Buchsbaum

Kenneth Ward Church

Yennun Huang

Kiem-Phong Vo

David G Korn

Elefterios Koutsofios

Yi-Min Wang

Yih-Farn Robin Chen

Stephen Charles North

Pi-Yu Chung

Donald Caldwell

Chung-Hwa Herman Rao

Ryan S Wallach

Donald F Caldwell

An improved data compression method and apparatus is provided, particularly with regard to the compression of data in tabular form such as database records. The present invention achieves improved compression ratios by utilizing metadata to transform the data in a manner that optimizes known compression techniques. In one embodiment of the invention, a schema is generated which is utilized to reorder and partition the data into low entropy and high entropy portions which are separately compressed by conventional compression methods. The high entropy portion is further reordered and partitioned to take advantage of row and column dependencies in the data. The present invention enables not only much greater compression ratios but increased speed than is achieved by compressing the untransformed data.

Data compression method and apparatus

A method for clustering together network IP addresses is disclosed. A number of IP addresses are received and processed to determine which IP addresses share a longest prefix matching. The longest prefix matching process is performed according to radix encoded trie which facilitates on-line clustering of the IP addresses. Client and/or server IP addresses may be clustered in accordance with the teachings herein.

Method for fast network-aware clustering

The present invention increases the efficiency of performing longest prefix matching operations by selecting a radix-encoded trie structure optimized with respect to memory cost. The structure is optimized by determining memory costs for retrie structures indexed on different numbers of high-order characters, and then selecting the structure corresponding to the lowest memory cost. The optimization improves performance in IP look-up operations as well as longest-prefix matching operations performed on general alphabets.

Fast prefix matching of bounded strings

The present invention relates to systems for sharing idle workstation computers that are connected together through a network and shared file system. More particularly, a user of a local host workstation may submit jobs for execution on remote workstations. The systems of the present invention select a remote host that is idle in accordance with a decentralized scheduling scheme and then continuously monitor the activity of the remote host on which the job is executing. If the system detects certain activity on the remote host by one of the remote host's primary users, the execution of the job is immediately suspended to prevent inconvenience to the primary users. The system also suspends job execution if the remote host's load average gets too high. Either way, the suspended job is migrated by selecting another idle remote workstation to resume execution of the suspended job (from the point in time at which the last checkpoint occurred).

Apparatus and methods for sharing idle workstations

A data processing apparatus and method for creating data analysis applications using reusable software operators . An initial operator is provided for converting source information into a virtual database format. Query operators are provided for receiving data in a virtual database format, processing the data in the virtual database, and outputting the results of the processing in another virtual database which has the same schema as the received virtual database. A plurality of query operators may be combined in order to customize the processing of the virtual database data. A terminal operator is provided for converting data in a virtual database into an external format which may then be further processed by an external operator. By combining initial, query, terminal, and external operators, users may create customizable data processing applications. In accordance with one embodiment of the invention, operators are provided for analyzing the difference between a first document and a second document. An initial operator converts the documents into a virtual database format containing information about the structure of the documents. A differencing operator compares the virtual databases and creates a virtual database containing difference information. Terminal and external operators are provided for converting the difference information into a directed graph layout which graphically represents the difference information and which is displayed through a graphical interface. In accordance with a further aspect of the invention, additional difference analysis processing may be initiated through the graphical interface.

Data analysis system using virtual databases

A backup file system which can be used without modification of application programs, the operating system, or the hardware. The backup file system is implemented by means of a dynamically-linkable replacement library and user-level processes on a primary computer system and a backup computer system. The dynamically-linkable replacement library has the same interfaces as a standard dynamically-linkable library of file operations. The functions in the replacement library perform the same file operations as their counterparts in the standard library; in addition, they send messages specifying the just-performed operation to a user-level process on the backup computer system. The user-level process executes the operation specified in the message on a backup file in the backup computer system. The files to be backed up are specified by identifying subtrees in the namespace of the primary file system; the subtrees make up a user-defined namespace. The backup file system is made fault tolerant by the use of monitor processes which monitor the backup computer system and the processes of the backup file system and deal with failures as required to keep the backup file system operating.

Using dynamically-linked libraries to add side effects to operations

Techniques for analyzing and controlling operation of a system of cooperating processes. A library of system calls used by the processes is replaced by a dynamically-linked library which performs the system calls and also sends messages indicating that the system calls have been performed. The messages are received by a display system which responds to the messages by making a graphical display showing the current state of the system of processes. The graphical display displays the system of processes as a tree. Nodes in the tree represent the processes in the system and resources such as files used by the processes; edges in the tree represent relationships between processes and other processes or resources. Users may control which system calls result in messages, may control the rate at which the display system responds to the messages, and may also control execution of the processes.

Apparatus and methods for visualizing operation of a system of processes

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Scotch Plains, NJ, United States of America

Glenn Stephen Fowler