Name service for a redundant array of internet servers

• US 6,360,256 B1
• Filed: 07/01/1996
• Issued: 03/19/2002
• Est. Priority Date: 07/01/1996
• Status: Expired due to Term

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Lim, Swee B.
• Primary Examiner(s): Harrison, Jessica J.
• Assistant Examiner(s): CHERUBIN, YVESTE GILBERTE
• Application Number:
  US08/673,951
• Time in Patent Office: 2,087 Days
• Field of Search: 364/200, 395/200.11, 395/200.59, 395/200.53, 395/200.31, 709/200, 709/203, 709/229, 709/217, 709/219-223, 709/227, 709/238, 709/242, 709/224, 709/200.11, 709/200.59, 709/200.53, 709/200.31, 709/105, 709/100, 709/102, 709/103, 709/104, 709/107, 709/108, 709/207, 709/218
• US Class Current: 709/223
• CPC Class Codes: G06F 11/3495 for systems
• CPC Class Codes: G06F 2201/875 Monitoring of systems including the internet
• CPC Class Codes: G06F 9/505 considering the load
• CPC Class Codes: G06F 9/5083 Techniques for rebalancing the load in a distributed system
• CPC Class Codes: H04L 67/1017 based on a round robin mechanism
• CPC Class Codes: H04L 67/1029 using data related to the state of servers by a load balancer
• CPC Class Codes: H04L 67/1038 Load balancing arrangements to avoid a single path through a load balancer

Abstract

A self-reconfiguring name service that distributes workload among the available servers in a system. A Service Monitor for each host system of a site periodically broadcasts information about available servers. The broadcast message also indicates the workload of the host. Each name service (DNS) has an associated process called a Name Binder Modifier that receives the broadcast messages from the Service Monitors. Periodically, each Name Binder Modifier reviews the information it has received from various Service Monitors and updates zones that are used by the DNS to perform load balancing. The Service Monitor and the Name Binding Modifier have associated configuration files.

Claims

1. In a computer system adapted to offer a plurality of services to a plurality of client devices, the computer system including at least one name server and a plurality of hosts, each host adapted to offer at least one of the plurality of services, a method for automatically reconfiguring a workload among the plurality of hosts comprising the steps of:

for each host, periodically determining by a Service Monitor executing on the host which, if any, of the offered services are available from the host;

for each service determined to be available, sending by the Service Monitor executing on the host from which the service is available a broadcast message including a workload of the host and a list of host addresses for accessing the available service from the host;

receiving, by a Name Binding Modifier, each broadcast message;

for each service offered by the computer system, periodically compiling by the Name Binding Modifier a list of currently available host addresses received through the broadcast messages, and truncating said list of host addresses by the Name Binding Modifier in accordance with a set of predetermined criteria, wherein, in the step of truncating, entries having a workload value greater than a predetermined workload index are removed from the list of currently available host addresses;

for each service offered by the computer system, updating a corresponding zone file in accordance with the information from the list of currently available host addresses associated with the service; and

in response to a service request from one of the client devices, performing, by the name server, a load balancing operation in accordance with the updated zone file corresponding to the requested service.

2. In a computer system adapted to offer a plurality of services to a plurality of client devices, the computer system including at least one name server and a plurality of hosts, each host adapted to offer at least one of the plurality of services, a method for automatically reconfiguring a workload among the plurality of hosts comprising the steps of:

for each host, periodically determining by a Service Monitor executing on the host which, if any, of the offered services are available from the host;

for each service determined to be available, sending by the Service Monitor executing on the host from which the service is available a broadcast message including a workload of the host and a list of host addresses for accessing the available service from the host;

receiving, by a Name Binding Modifier, each broadcast message;

for each service offered by the computer system, periodically compiling by the Name Binding Modifier a list of currently available host addresses received through the broadcast messages, and truncating said list of host addresses by the Name Binding Modifier in accordance with a set of predetermined criteria, wherein the step of truncating is only performed if the number of entries in the list of currently available host addresses is greater than a predetermined minimum number of entries;

for each service offered by the computer system, updating a corresponding zone file in accordance with the information from the list of currently available host addresses associated with the service; and

in response to a service request from one of the client devices, performing, by the name server, a load balancing operation in accordance with the updated zone file corresponding to the requested service.

3. In a computer system adapted to offer a plurality of services to a plurality of client devices, the computer system including at least one name server and a plurality of hosts, each host adapted to offer at least one of the plurality of services, a method for automatically reconfiguring a workload among the plurality of hosts comprising the steps of:

for each host, periodically determining by a Service Monitor executing on the host which, if any, of the offered services are available from the host;

for each service determined to be available, sending by the Service Monitor executing on the host from which the service is available a broadcast message including a workload of the host and a list of host addresses for accessing the available service from the host;

receiving, by a Name Binding Modifier, each broadcast message;

for each service offered by the computer system, periodically compiling by the Name Binding Modifier a list of currently available host addresses received through the broadcast messages, and truncating said list of host addresses by the Name Binding Modifier in accordance with a set of predetermined criteria;

for each service offered by the computer system, updating a corresponding zone file in accordance with the information from the list of currently available host addresses associated with the service, wherein the step of updating comprises the steps of comparing the truncated list of currently available host addresses to a truncated list of previously available host addresses, and modifying the corresponding zone file for the service only if the truncated list of currently available host addresses differs from the truncated list of previously available host addresses; and

in response to a service request from one of the client devices, performing, by the name server, a load balancing operation in accordance with the updated zone file corresponding to the requested service.

4. The method of claim 3 wherein the truncated list of previously available host addresses for the current period is the truncated list of currently available host addresses from the preceding period.

5. A computer system adapted to offer a plurality of services to a plurality of client devices, the computer system comprising:

a plurality of hosts, each host adapted to offer at least one of the plurality of services and including a Service Monitor configured to periodically send, for each available service on the host, a broadcast message including a workload of the host on which the available service is located and a list of host addresses for accessing the available service on the host;

a Name Binding Modifier adapted to receive each broadcast message and, for each of the plurality of services offered by the computer system, periodically compile a list of currently available host addresses received through the broadcast messages, remove certain entries from the list of currently available host addresses if a corresponding set of predetermined criteria is satisfied, and update a corresponding zone file in accordance with the compiled list, wherein the Name Binding Modifier is further adapted to compare the list of currently available host addresses to a previous list of host addresses, and the corresponding zone file is not updated unless the list of currently available host addresses differs from the previous list of host addresses; and

a name server adapted to receive a plurality of service requests from a plurality of client devices, and for each service request received, perform a load balancing operation in accordance with the updated zone file corresponding to the requested service, thereby assigning the service request to a next available host offering the requested service.

6. The computer system of claim 5 wherein the previous list of host addresses for the current period is the list of currently available host addresses from the preceding period.

7. A computer program product for reconfiguring a load balancing system, the computer program product embodying computer program instructions for execution by a computer system offering a plurality of services, the instructions comprising:

determining, at predetermined time intervals, the availability of each service offered by the computer system;

sending, for each service determined to be available, a broadcast message including a workload of a host on which the service is available and a list of host addresses for accessing the available service from the host;

receiving each broadcast message;

compiling, at predetermined time intervals for each service offered by the computer system, a list of currently available host addresses received through the broadcast messages, adding each received host address and corresponding workload to the list of currently available host addresses, and removing entries from the list of currently available host addresses in accordance with a set of predetermined criteria; and

updating, for each list of currently available host addresses, a zone file associated with the corresponding service offered by the computer system, whereby the zone file is available to the computer system for use in load balancing operations in response to a request for the corresponding service, wherein the instruction of updating further comprises the instructions of comparing the list of currently available host addresses to a previous list of host addresses, and updating the corresponding zone file for the service only if the list of currently available host addresses differs from the previous list of host addresses.

8. The computer program product of claim 7 wherein the previous list of host addresses for the current time interval is the list of currently available host addresses from the preceding time interval.