Xerox Corporation

Oracle International Corporation

Alan J Demers

James William Stamos

Marvin Michael Theimer

Douglas Brian Terry

Karin Petersen

Brent B Welch

Michael J Spreitzer

Roy Want

Daniel H Greene

Lik Wong

Mark D Weiser

Sandeep Jain

Bridget A Spitznagel

Alan Robert Downing

Curtis Elsbernd

Daniel Gureasko Bobrow

Roger J Bamford

Robert Thomas Krivacic

Lawrence W Jacobs

Nimar Singh Arora

Christopher Angel Kantarjiev

Ronald A Frederick

Benny Souder

Brian M Oki

A Lawrence Spitz

Mahesh Subramaniam

Harry Sun

Wayne Smith

John C Graham

Steven B Putz

J Craig Mudge

Lewis S Kaplan

Christian Peter Jacobi

Barry Hayes

Ivan V Krsul

Norman C Woo

Norman Woo

Techniques for making a replica of a particular group of database objects of a database on a particular node that does not initially have the particular group of database objects include determining whether conditions for copying a full database from a first node are satisfied. If conditions for copying the full database from the first node are not satisfied, then a database-object-copy routine is employed for each database object in the particular group of database objects. If conditions for copying the full database from the first node are satisfied, then a full-database-copy routine for performing a copy of an entire database is employed.

Techniques for replicating groups of database objects

Schema evolution involves defining flavored object groups. Specifically, related collections of replicated tables and other database objects, which are defined as belonging to an object group, are given different 'flavors.' A flavor describes different subsets of the objects and even different subsets of the columns in the master tables. In one embodiment, when one site in a distributed database system propagates changes to a replicated database object, the current flavor for the site is also transmitted, so that the destination site can make the necessary adjustments in the uploaded changes by dropping the values for obsolete columns and using default values for new columns.

Schema evolution in replication

Techniques for making a replica of a particular group of database objects of a database on a particular node that does not initially have the particular group of database objects include transferring description data from a first node to the particular node during a first time period. The description data describes the particular group of database objects at a first time. The first time period begins at the first time and ends at a second time. During the first time period, a request from a user of the database to perform an operation involving particular data in the particular group of database objects is processed.

Techniques for adding a master in a distributed database without suspending database operations at extant master sites

A method for applying changes to a standby system is described in which multiple apply tasks or 'slaves' are scheduled to changes from redo logs, especially those changes in large transactions, in parallel and as soon as they are encountered in the logs. To foster data convergence, a partial ordering may be imposed on the transactions so that those transactions that actually depend on others are forced to wait on the transactions they are dependent upon commit. To foster read consistency, synchronization points may be periodically established, at which points a read consistent state of the standby database system can be obtained-all without adversely impact the throughput of the system.

Method of applying changes to a standby database system

A multi-tier caching system is provided for a computing device. The system comprises a first cache implemented in operating system or kernel space (e.g., in memory managed by or allocated to an operating system). The system also comprises a second cache implemented in application or user space (e.g., in memory managed by or allocated to an application program). Also provided is a method of operating the multi-tier caching system to serve one type of data from the first cache and a second type of data from the second cache. The first cache may store frequently requested data items and/or those that require little processing of a data request in order to identify a responsive data item. The first cache may also store data items that can be served in response to data requests having different forms, types, parameters, qualifiers or other indicia. Data that may vary according to the form or content of a data request, and data items that are responsive to data requests that must be fully parsed, examined or processed may be stored in the second cache. A content analysis engine may be configured to determine which of said first cache and said second cache a data item should be stored in. Such determinations may be made by analyzing data requests and/or data items served in response to the requests, guidelines set by a system administrator, and other criteria.

Multi-tier caching system

Replication for front office automation involves the use of snapshots that are instantiated on laptops, in which refreshing the snapshots is driven from a master site with a high-performance protocol. All of the necessary snapshot metadata for performing the snapshot refreshes is stored at the master site, so that the laptop only needs to send a single refresh request. In response to the refresh request, the master site reconciles the differences between the master tables and the laptop's snapshots and transmits the differences to the laptop, reducing the necessary network traffic for updating a snapshot to a single round trip.

Data replication for front office automation

An efficient set of indexes to cover a plurality of anticipated query types is determined by building a directed acyclic graph whose nodes correspond to anticipated query types. A minimum leaf spanning tree for the equivalent graph is determined by repeatedly finding an augmenting path for a current spanning tree and producing a reduced leaf spanning tree based on the current spanning tree and the augmenting path until an augmenting path can no longer be found. The leaves of the minimum leaf spanning tree indicate which indexes should be built.

Minimum leaf spanning tree

A method of verifying electronic payments generated using a key unknown to the verifier. In anticipation of accepting electronic payments, a seller requests and receives from a bank a conversation key and a first set of electronic verifiers for a first set of electronic payments from a customer. Each verifier allows authentication of an associated electronic payment without revealing the private key used by the customer to generate the electronic payments. Prior to initiating a transaction or series of transactions, the customer requests payment information from the seller for use, along with the master key, in generating electronic payments Afterward, when the customer pays with an electronic payment, the seller authenticates the electronic payment using one of the verifiers. The seller responds to the buyer's request if the electronic payment is authenticated.

Space efficient method of verifying electronic payments

A method of space efficient electronic payments. A customer initiates an electronic transaction by transmitting a request for payment information to a seller. In response, the customer receives from the seller the payment information needed to generate an electronic payment. The customer determines the reliability of the payment information by authenticating it. If the payment information is authenticated, then the customer generates an electronic payment using the payment information and a master key unknown to the seller. Finally, the customer transmits the electronic payment to the seller along with a request for desired goods and/or services.

Space efficient method of electronic payments

As an electronic pen (16) moves across a display screen (12), a position resolver (14) generates a series of x,y-coordinate positions which are sent to a remote computer system (20) having a relatively high latency or time delay before the positions are processed and intended display information is returned to the memory cells of a memory array (24) which controls the display on the display screen (12). During the time delay, a temporary display of the trajectory is created, preferably in light gray or another distinguishable color. Each x,y-coordinate position is compared (32) with an immediately preceding coordinate position to determine whether the pen has moved. If so, the new coordinate is stored in a memory (36) which stores a preselected number of the most recent coordinate positions and to a toggle circuit (38) which toggles a preselected bit of the display information stored in the corresponding memory cell of the memory array. After a preselected time, determined by clocking the recent coordinate position memory (36), the oldest stored coordinate position is clocked out and display information in the memory cell corresponding to the clocked out coordinate position is retrieved (42) and analyzed (44). If the toggled bit is still in the toggled position, the toggle circuit (38) toggles it back to the initial state. If the preselected bit has been reset by the intended drawing in the interim, it is not altered.

Local inking with gray pixels

A method and system are provided for processing records from a set of records, where records are repeatedly being added to the set of records, and where each record in the set of records has to be processed once for each of a plurality of entities. According to the method, each record that is added to the set of records is marked with a default batch value. For each entity of the plurality of entities, a batch of the records is processed by performing the steps of: reading a last batch value associated with the entity, processing the records in the set of records that are marked with batch values that are more recent than the last batch value associated with the entity, and updating the last batch value associated with the entity to a most recent batch value of the records processed for the entity. Between processing consecutive batches for an entity of the plurality of entities, the set of records are marked by performing the steps of: updating a batch counter value to reflect a more recent batch number; and marking all records in the set of records that have the default batch value with the batch counter value.

Dequeuing using queue batch numbers

A method and system are provided for duplicating at a destination site changes made to data at a source site. According to the method a plurality of streams are established between the source site and the destination site. The plurality of streams are used in parallel to propagate changes made at the source site to the destination site. A record of transactions that made changes that need to be propagated from the source site to the destination site is maintained at the source site. Before propagating changes made by a transaction to the destination site on a stream of the plurality of streams, the record of transactions is inspected to identify a set of transactions whose changes are not known to have been made permanent at the destination site. It is then determined whether the transaction could possibly depend on any transaction in the set of transactions. If the transaction could not possibly depend on any transaction in the set of transactions, then the changes made by the transaction are propagated to the destination site using one of the plurality of streams.

Parallel queue propagation

A method of redeeming for a seller electronic payments generated by and received from a customer using a master key unknown to the seller. In anticipation of making electronic payments, a customer sends a bank the master key that he will use to generate electronic payments. The bank stores the master key. Later, the bank receives from the seller a redemption request including a seller identifier, a first value of a payment index, and an electronic payment associated with the first value of the payment index. The bank authenticates the electronic payment by comparing the electronic payment to a hash of a string including the master key, the seller identifier, and the first value of the payment index. If the electronic payment is authenticated, the bank determines an amount due to the seller and credits that amount to the seller.

Space efficient method of redeeming electronic payments

A method of generating electronic monetary tokens that supports off-line transactions while preventing double-spending. Generation of electronic token halves by a financial services provider begins in response to a request from a buyer to generate electronic monetary tokens to be used with an identified seller. First, the financial services provider generates a multiplicity of electronic monetary tokens. Second, the provider splits each electronic monetary token into two electronic token halves and associates with each the same serial number. These electronic token halves when combined recreate the electronic monetary token from which they were generated, but by themselves neither electronic token half has any value. Nor can either electronic half by itself be used to create the electronic monetary token without the token half's mate. After splitting all of the electronic monetary tokens, the services provider assigns a half of each electronic token the seller and the other half of each electronic token to the buyer. The buyer and seller can now engage in multiple transactions off-line of the financial services provider.

Method of electronic payments that prevents double-spending

A method and system are provided for recovering after a failure in a data replication environment. According to the method, a transaction is executed at a source site that makes changes that must be replicated at a destination site. The changes are made permanent at the source site. The changes are made permanent at the source site without the source site being informed as to whether the changes were successfully applied at the destination site. The changes are sent to the destination site. The changes are applied at the destination site. If the changes are successfully applied before the failure, then the changes are made permanent at the destination site and a record is added to a set of records at the destination site. The record indicates that the changes where made permanent at the destination site. After a failure, the set of records at the destination site are used to determine which changes must be sent from the source site to the destination site after the failure.

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Boulder Creek, CA, United States of America

Alan J Demers