Cluster architecture having a star topology with centralized services

• US 20050188021A1
• Filed: 12/30/2003
• Published: 08/25/2005
• Est. Priority Date: 12/30/2003
• Status: Active Grant

• Current Assignee: SAP SE
• Original Assignee: SAP AG (SAP SE)
• Inventors: Rohland, Hans-Christoph, Kilian, Frank
• Granted Patent: US 8,190,780 B2
• Time in Patent Office: Days
• US Class Current: 709/206
• CPC Class Codes: H04L 51/23 Reliability checks, e.g. acknowledgments or fault reporting
• CPC Class Codes: H04L 67/10 in which an application is distributed across nodes in the network software deployment G06F8/60; multiprogramming arrangements G06F9/46
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1034 Reaction to server failures by a load balancer
• CPC Class Codes: H04L 67/566 Grouping or aggregating service requests, e.g. for unified processing
• CPC Class Codes: H04L 67/567 Integrating service provisioning from a plurality of service providers

Abstract

A cluster of architecture having a star topology with the central services node at its center. Application server instances are organized in a star topology with the central services node at its center. The central services node may include services such as a messaging server for interinstance cluster communications. A locking server may also be provided to provide cluster wide locking to facilitate changes and updates within the cluster. A database may also be shared by all instances in the cluster, thereby reducing the need for data replication. In one embodiment, the message server has no persistent state. In such an embodiment, if the message server fails, it can merely be restarted without any state recovery requirement.

Claims

1. A system comprising:

a database;

a message server having no persistent state; and

a plurality of instances of an application server implementing a Java application model coupled in a star topology with the message server at a center of the star topology, the plurality of instances sharing the database.

2. The system of claim 1 wherein each instance comprises:

a dispatcher node; and

a plurality of server nodes.

3. The system of claim 2 wherein each server node comprises:

a java 2 enterprise edition (J2EE) engine.

4. The system of claim 1 further comprising:

a central lock server to provide cluster wide locks to the plurality of instances.

5. The system of claim 1 wherein the message server comprises:

a first data structure to store a list of connected clients; and

a second data structure and a list of services provided in the system.

6. A computer readable storage media containing executable computer program instructions which when executed cause a digital processing system to perform a method comprising:

starting a central services node to provide at least one of a locking service and a messaging service;

starting a plurality of application server instances; and

organizing the application server instances into a cluster having star topology with the central services node at a center of the star topology.

7. The computer readable storage media of claim 6 containing executable computer program instructions which when executed cause a digital processing system to perform the method further comprising:

sharing a database among the plurality of application server instances.

9. The computer readable storage media of claim 6 containing executable computer program instructions which when executed cause a digital processing system to perform the method further comprising:

starting a message server having no persistent state.

10. The computer readable storage media of claim 6 containing executable computer program instructions which when executed cause a digital processing system to perform the method further comprising:

registering each application server with the messaging server.

11. The computer readable storage media of claim 6 containing executable computer program instructions which when executed cause a digital processing system to perform the method further comprising:

conducting inter instance communication through the messaging service.

12. The computer readable storage media of claim 9 containing executable computer program instructions which when executed cause a digital processing system to perform the method further comprising:

restarting the message server without state recovery responsive to a system failure.

13. The computer readable storage media of claim 10 containing executable computer program instructions which when executed cause a digital processing system to perform the method further comprising:

notifying all registered instances from the message server when an additional instance joins the cluster.

8. The computer readable storage media of 6 containing executable computer program instructions which when executed cause a digital processing system to perform the method wherein starting a plurality of application server instances comprises:

starting, for each application server instance of the plurality, a dispatcher node and a plurality of server nodes.

14. A system comprising:

means for organizing a plurality of application servers instances into a cluster having a star topology with a central services node at a center of the star topology;

means for sharing a storage resource across the cluster; and

means for performing centralized inter instances communication.

15. The system of claim 14 further comprising:

means for centralized locking of a resource within the cluster.

16. The system of claim 14 wherein the means for performing comprises:

a message server having no persistent state.

17. The system of claim 14 wherein the means for performing comprises:

means for registering instances; and

means for recording services provided in the cluster.

18. A method comprising:

starting a central services node to provide at least one of a locking service and a messaging service;

starting a plurality of application server instances; and

organizing the application server instances into a cluster having star topology with the central services node at a center of the star topology.

19. The method of claim 18 further comprising:

sharing a database among the plurality of application server instances.

20. The method of claim 18 wherein starting a plurality of application server instances comprises:

starting, for each instance of the plurality, a dispatcher node and a plurality of server nodes.

21. The method of claim 18 wherein starting a central service node comprises:

starting a message server having no persistent state.

22. The method of claim 18 wherein organizing comprises:

registering each application server with the messaging server.

23. The method of claim 18 further comprising:

conducting inter instance communication through the messaging service.

24. The method of claim 21 further comprising:

restarting the message server without state recovery responsive to a system failure.

25. The method of claim 22 wherein organizing further comprises:

notifying all registered instances from the message server when an additional instance joins the cluster.