Weak leader election

• US 7,139,790 B1
• Filed: 08/17/2000
• Issued: 11/21/2006
• Est. Priority Date: 08/17/1999
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Wang, Yi-Min, Arora, Anish K., Russell, Wilf G.
• Primary Examiner(s): Barot, Bharat
• Application Number:
  US09/641,553
• Time in Patent Office: 2,287 Days
• Field of Search: 709201-202, 709/205, 709/206, 709220-224, 709/226, 709237-238, 714/2, 714/4, 714 11- 12, 714/31, 714/41, 714/736, 370/216, 370242-245
• US Class Current: 709/201
• CPC Class Codes: H04B 2203/5458 Monitor sensor; Alarm systems
• CPC Class Codes: H04B 3/542 the information being in digital form
• CPC Class Codes: H04L 63/1408 by monitoring network traffic monitoring network traffic per se H04L43/00

Abstract

A weak leader election approach to determine which of a number of redundant nodes is the leader node is disclosed. The redundant nodes exchange information particular to them, such as age information. Based on the information received from the other nodes, each node determines whether it is the leader. Where the information is age information, a criteria that can be used to make this determination is that the oldest node is the leader. Each redundant node knows only whether it is the leader node. Redundant nodes that are not the leader do not know which node is the leader node.

Claims

1. In a distributed system including a plurality of redundant components, a method for leader election by a first redundant component, comprising:

multicasting age information, wherein the age information includes a duration of time on-line, particular to the first redundant component to all other components in the plurality of redundant components, the age information relating to one or more criteria according to which a currently-active leader component is to be determined;

receiving age information from each other component in the plurality of redundant components particular to each component and relating to the one or more criteria according to which the currently-active leader component is to be determined; and

determining whether the first redundant component is the currently-active leader component by comparing the age information particular to the first redundant component with the age information received from each of the redundant components,

wherein if the first redundant component determines that it is not the currently-active leader component, the first component knows one of the components in the plurality of redundant components is the currently-active leader component.

2. The method of claim 1, further comprising periodically repeating the method.

3. The method of claim 1, wherein the determining whether the first component is the currently-active leader component comprises determining whether the first component is an oldest component.

4. In a computer system including a plurality of redundant components, a method for electing a currently-active leader component, comprising:

multicasting currently-active leader election criteria information among all the plurality of redundant components; and

at each component in the plurality of redundant components;

a) determining whether the component is the currently-active leader component, based on a currently-active leader election criteria information received from all the other components in the plurality of redundant components, wherein the currently-active leader election criteria information includes age information, wherein the age information includes a duration of time on-line; and

b) repeating the determining whenever the component detects an occurrence of a failure that has a potential to affect the currently-active leader component.

5. The method of claim 4, further comprising:

periodically repeating the method.

6. The method of claim 4, wherein the determining whether the component is the currently-active leader component comprises:

determining whether the component is an oldest component; and

if the component determines that it is the oldest component, concluding that the component is the currently-active leader component.

7. The method of claim 4, wherein the multicasting age information includes multicasting information regarding how long each component in the plurality of redundant components has been online.

8. The method of claim 4, wherein the redundant components are redundant instances of a daemon.

9. The method of claim 8, wherein the daemon is a system management daemon.

10. The method of claim 8, wherein the daemon is a power line monitoring daemon.

11. The method of claim 4, wherein the redundant components are redundant executing processes.

12. The method of claim 4, wherein the redundant components are redundant class objects.

13. The method of claim 4, wherein the redundant components are redundant devices in an automation system.

14. The method of claim 4, wherein the redundant components are redundant nodes in a network.