Method and apparatus for providing failure detection and recovery with predetermined degree of replication for distributed applications in a network

A fault-managing computer apparatus on a host computer in a computer system, said apparatus comprising:

• a manager daemon process for receiving an indication of a failure of a copy of an application module running on at least one of a plurality of host computers in the computer system and for initiating failure recovery with at least one idle backup copy of the application module;
• and
• means for receiving a registration message specifying the application module and a degree of replication for the application module, said degree of replication indicating the number of running copies of the application module to be maintained in the system;
• wherein the number of running copies of the application module in the system is maintained at the registered degree of replication by executing one of the idle backup copies upon detecting a failure of one of the running copies of the application module.

A fault-tolerant computing apparatus for use in a computer system, said apparatus comprising:

• a failure-detection daemon process running on said apparatus, said failure-detection daemon process monitoring the ability of a running copy of an application module to continue to run on said apparatus;
• and
• means for sending a registration message to a manager daemon process specifying the application module and a degree of replication to be maintained by the manager daemon process for the application module with respect to the number of running copies of the application module to be maintained in the system;
• wherein the number of running copies of the application module in the system is maintained at the registered degree of replication by executing an idle backup copy of the application module on a different computing apparatus upon detecting a failure of the running copy of the application module.

A method for operating a fault-tolerant computer system, said system comprising a plurality of host computers interconnected on a network, one or more copies of an application module each one running on a different one of said plurality of host computers, and one or more idle backup copies of the application module each stored on a different one of said host computers;

• said method comprising the steps of:
• receiving a registration message specifying the application module and a degree of replication to be maintained for the application module, said degree of replication indicating the number of running copies of the application module to be maintained in the system;
• and
• executing at least one of the idle backup copies upon detecting a failure of one of the running copies of the application module to maintain the total number of running copies of the application module in the system at the registered degree of replication.