Protocol for providing replicated servers in a client-server system

• US 6,247,141 B1
• Filed: 09/24/1998
• Issued: 06/12/2001
• Est. Priority Date: 09/24/1998
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Holmberg, Per Anders
• Primary Examiner(s): Ray, Gopal C.
• Application Number:
  US09/159,771
• Time in Patent Office: 992 Days
• Field of Search: 714/2, 714/4, 714/43, 714/56, 714/15, 714/20, 714/3, 714/48, 714/758, 714/807, 707/1, 707/10, 707/204, 709/203, 709/217, 709/212, 709/227, 709/101, 709/228, 709/219, 709/216, 711/162, 370/216
• US Class Current: 714/2
• CPC Class Codes: G06F 11/1451 by selection of backup contents
• CPC Class Codes: Y10S 707/99931 Database or file accessing

Abstract

A fault-tolerant client-server system has a primary server, a backup server; and a client. The client sends a request to the primary server, which receives and processes the request, including sending the response to the client, independent of any backup processing. The response includes the primary server state information. The primary server also performs backup processing that includes periodically sending the primary server state information to the backup server. The client receives the response from the primary server, and sends the primary server state information to the backup server. The primary server state information includes all request-reply pairs that the primary server has handled since a most recent transmission of primary server state information from the primary server to the backup server. The primary server'"'"'s backup processing may be activated periodically based on a predetermined time interval. Alternatively, it may be activated when the primary server'"'"'s memory for storing the primary server state information is filled to a predetermined amount.

Claims

1. A fault-tolerant client-server system, comprising:

a primary server;

a backup server; and

a client,

wherein;

the client comprises;

means for sending a request to the primary server;

means for receiving a response from the primary server,

wherein the response includes primary server state information;

means for sending the primary server state information to the backup server;

the primary server comprises;

means for receiving and processing the request;

means, responsive to the request, for sending the response to the client, independent of any backup processing, wherein the response includes the primary server state information;

means for performing backup processing that includes periodically sending the primary server state information to the backup server; and

the backup server comprises;

means for receiving the primary server state information from the primary server;

means for receiving the primary server state information from the client.

2. The fault-tolerant client-server system of claim 1, wherein the primary server state information includes all request-reply pairs that the primary server has handled since a most recent transmission of primary server state information from the primary server to the backup server.

3. The fault-tolerant client-server system of claim 1, wherein the primary server state information includes a checksum derived from a reply.

4. The fault-tolerant client-server system of claim 1, wherein the primary server'"'"'s means for performing backup processing is activated periodically based on a predetermined time interval.

5. The fault-tolerant client-server system of claim 1, wherein:

the primary server further includes means for storing the primary server state information; and

the primary server'"'"'s means for performing backup processing is activated in response to the means for storing the primary server state information being filled to a predetermined amount.

6. A method of operating a fault-tolerant client-server system that comprises a primary server, a backup server and a client, the method comprising the steps of:

sending a request from the client to the primary server;

in the primary server, receiving and processing the request, including sending a response to the client, independent of any backup processing being performed by the primary server, wherein the response includes primary server state information;

performing backup processing in the primary server, including periodically sending the primary server state information to the backup server;

in the client, receiving the response from the primary server; and

sending the primary server state information from the client to the backup processor.

7. The method of claim 6, wherein the primary server state information includes all request-reply pairs that the primary server has handled since a most recent transmission of primary server state information from the primary server to the backup server.

8. The method of claim 6, wherein the primary server state information includes a checksum derived from a reply.

9. The method of claim 6, wherein the step of performing backup processing in the primary server is performed periodically based on a predetermined time interval.

10. The method of claim 6, wherein:

the primary server further performs the step of storing the primary server state information in storage means; and

the step of performing backup processing in the primary server is performed in response to the storage means being filled to a predetermined amount.