Exactly once data framework method

• US 7,487,244 B2
• Filed: 07/09/2004
• Issued: 02/03/2009
• Est. Priority Date: 09/06/2001
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: BEA Systems Incorporated (Oracle Corporation)
• Inventors: Jacobs, Dean Bernard, Halpern, Eric M.
• Primary Examiner(s): Meky; Moustafa M
• Assistant Examiner(s): El Chanti; Hussein A
• Application Number:
  US10/887,740
• Publication Number:
  US 20040249946A1
• Time in Patent Office: 1,670 Days
• Field of Search: 709/223, 709/224, 709/226, 709/217
• US Class Current: 709/226
• CPC Class Codes: H04L 67/1095 Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes
• CPC Class Codes: H04L 67/288 Distributed intermediate devices, i.e. intermediate devices for interaction with other intermediate devices on the same level
• CPC Class Codes: H04L 67/56 Provisioning of proxy services store-and-forward switching systems in data switching networks H04L12/54
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04L 69/40 for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection management of faults, events, alarms or notifications in data switching networks H04L41/06
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A method for managing objects in a clustered network includes a file system containing at least one copy of a data object. The method can involve several clustered servers in communication with the file system. A distributed consensus algorithm is used to select a host server. The selected host server can contain a copy of the data object, such as in local cache, providing access to the local copy to any other server in the cluster. Any change made to an item hosted by the host server can also be updated in the file system. If the host server becomes unable to host the object, a new host can be chosen using the distributed consensus algorithm. The other servers are then notified of the new host by multicast messaging.

Claims

1. A method for managing objects on a network, comprising:

providing a plurality of network servers, the plurality of network servers adapted to communicate with a network data source and including a lead server, wherein the lead server leads one or more consensus rounds;

selecting a host server from the plurality of network servers, wherein selecting the host server includes;

informing the plurality of network servers that a new consensus round is starting;

proposing a host server to the plurality of network servers;

waiting for a period of time to receive from the plurality of network servers messages accepting the host server;

if the lead server does not receive message accepting the host server from a majority of the plurality of network servers within the period of time, starting a new consensus round;

after receiving messages accepting the host server from a majority of the plurality of network servers within the period of time, multi-casting a notification to the plurality of network servers to commit selection of the host server;

assigning a data object to the host server, the data object related to a data item in the network data source, wherein the data object is configured to be accessed solely through the host server; and

accessing the data item on the host server by one of the plurality of network servers other than the host server.

2. The method of claim 1 wherein the host server is selected by the lead server.

3. The method of claim 1 wherein the data item is an access point to an application.

4. The method of claim 1 further comprising:

providing a second server, the second server assigned the data object and configured to provide data object access if said host server encounters a problem, the second server being one of the plurality of network servers.

5. The method of claim 1 wherein the data object is located in a local cache of the host server.

6. The method of claim 1 wherein the data item is located in a file system, the host, server having access to the file system.

7. The method of claim 1 wherein the data object is located in a cache which is distributed among the plurality of network servers.

8. The method of claim 1, further comprising:

retrieving the data object from one of the plurality of network servers if the host server fails.

9. The method of claim 1, further comprising:

writing to the network data source when the data object is updated.

10. The method of claim 1, further comprising:

selecting anew host server after a period of time, the new host server configured to own the data object and being one of the plurality of network servers.

11. The method of claim 1, further comprising:

confirming the existence of the data object on the host server.

12. The method of claim 11 wherein confirming the existence of the data object includes:

confirming the existence of the data object on the host server periodically.

13. The method of claim 1 further comprising:

relinquishing ownership of the data object by the host server when the lead server is unable to reach the host server within a period of time.

14. The method of claim 1, wherein the data object is stored in a cache on any server in the plurality of network servers and all access to the cache goes through the host server.

15. The method of claim 1, wherein the data object is a transaction log.

16. The method of claim 1, wherein the data object exists in exactly one place in the plurality of network servers.

17. The method of claim 1, further comprising receiving messages from a majority of the plurality of network servers regarding a previously conducted round in which the majority of the plurality of network servers participated.

18. A method for managing objects on a network, comprising:

providing a plurality of network servers, the plurality of network servers adapted to communicate with a network data source and including a lead server, wherein the lead server leads one or more consensus rounds;

informing the plurality of network servers that a new consensus round is starting;

proposing a host server to the plurality of network servers;

sending responses from several of the plurality of network servers to the lead server indicating that the several network servers of the plurality of network servers accept the host server;

waiting a period of time for the responses accepting the host server from the plurality of network servers;

if the lead server does not receive the responses accepting the host server from a majority of the plurality of network servers within the period of time, starting a new consensus round;

after receiving the responses accepting the host server from a majority of the plurality of network servers within the period of time, multi-casting a notification to the plurality of network servers to commit selection of the host server;

committing the selection of the host server at each of the plurality of network servers;

sending acknowledgements from the plurality of network servers to the lead server acknowledging that the plurality of network servers committed the selection of the host server,

assigning a data object to the host server, the data object related to a data item in the network data source, wherein the data object is configured to be accessed solely through the host server; and

accessing the data item on the host server by one of the plurality of network servers other than the host server.

19. A system, comprising:

a plurality of network servers, the plurality of network servers adapted to communicate with a network data source and including a lead server,

the lead server of the plurality of network servers, wherein the lead server leads one or more consensus rounds;

a host server of the plurality of network servers,

wherein the host server is selected after the lead server informs the plurality of network servers that a new consensus round is starting,

wherein the lead server proposes a new host server to the plurality of network servers,

wherein the lead server waits a period of time for messages accepting the host server from the plurality of network servers,

wherein if the lead server does not receive messages accepting the host server from a majority of the plurality of network servers within the period of time, the lead server starting a new consensus round,

wherein after receiving messages accepting the host server from a majority of the plurality of network servers within the period of time,

wherein the lead server multi-casts a notification to the plurality of network servers to commit selection of the host server;

a transaction log stored in a file system; and

a copy of the transaction log hosted by the host server in a cache, wherein the host server makes the copy available to other servers in the plurality of network servers, wherein all access to the copy is through the host server.

20. The system of claim 19, wherein after an update is written to the cache, the update to the cache is written to a persistent storage.