Abstract: This invention defines a method and mechanisms for maintaining a consistent group membership, based on the leader-follower strategy of Semi-Active or Passive replication. Each member of the group is assigned a rank, and a precedence, determined by the order in which it is added to the group. The Primary maintains the membership of the group, while each Backup monitors the behavior of the Primary. When a Backup detects that the Primary is faulty, the Backup announces that it is the new Primary and removes the faulty Primary from the membership of the group. The group membership algorithm disclosed here does not require a consensus decision to reconfigure the membership and effects a membership change more quickly in the common case where the Backup of lowest rank takes control as the new Primary when it determines that the existing Primary failed.
Type:
Grant
Filed:
August 30, 2003
Date of Patent:
February 27, 2007
Assignee:
Eternal Systems, Inc.
Inventors:
Louise E. Moser, Peter M. Melliar-Smith
Abstract: Mechanisms for achieving consistent message ordering within a fault-tolerant distributed computer system based on semi-active or passive replication are described. The mechanisms communicate message ordering information from the primary replica to its backup replicas in such a way as to minimize the end-to-end request/response time, to minimize the number of additional messages that are multicast, and to ensure that, in the event of a fault, a backup replica has, or can obtain, the messages and the message ordering information that it needs to reproduce the actions of the primary replica.
Type:
Grant
Filed:
July 29, 2003
Date of Patent:
August 9, 2005
Assignee:
Eternal Systems, Inc.
Inventors:
Louise E. Moser, Peter M. Melliar-Smith
Abstract: Mechanisms for a Networked Enterprise Server that provide fault tolerance for computer programs that interact with computer programs within and between enterprises over a communication network, such as the Internet or a virtual private network. Fault tolerance is provided by unifying transaction processing and object or process replication. Transaction processing is used in this invention to protect the local data and processing against faults, while replication is used to protect the processing and communication that span multiple enterprises.
Type:
Grant
Filed:
October 26, 2001
Date of Patent:
July 26, 2005
Assignee:
Eternal Systems, Inc.
Inventors:
Louise E. Moser, Peter M. Melliar-Smith
Abstract: A process that assists a computer programmer to perform an upgrade to a computer program while that program continues to operate and provide service. The upgrade process includes three phases: (1) the preparation by a computer programmer of a new computer program P″ that is to replace an existing computer program P, (2) an offline preparation of the upgrade from P to P″ with the assistance of the computer programmer, and (3) an online, fully automatic, live upgrade from P to P″.
Type:
Grant
Filed:
December 30, 1998
Date of Patent:
March 19, 2002
Assignee:
Eternal Systems, Inc.
Inventors:
Louise E. Moser, Peter M. Melliar-Smith