Non-delegable client requests to servers storing local information only

• US 6,970,932 B1
• Filed: 12/14/1999
• Issued: 11/29/2005
• Est. Priority Date: 12/14/1999
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Juster, Doron
• Primary Examiner(s): Sheikh, Ayaz
• Assistant Examiner(s): LAFORGIA, CHRISTIAN A
• Application Number:
  US09/461,487
• Time in Patent Office: 2,177 Days
• Field of Search: 709/231, 709/312, 709/235, 709/237, 709/238, 709/105, 709/229, 709/203, 709/206, 709/217, 705/1, 707/3, 718/105, 713/201, 713/150
• US Class Current: 709/229
• CPC Class Codes: H04L 61/4541 Directories for service discovery
• CPC Class Codes: H04L 67/02 based on web technology, e.g. hypertext transfer protocol [HTTP]
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1038 Load balancing arrangements to avoid a single path through a load balancer

Abstract

Non-delegable client requests to servers storing local information only are disclosed. In one embodiment, a request is sent from a client to a server of a list of servers. The server determines whether it is inappropriate to fulfill the request. If so, it sends an error message to the client that it is off-line. When the client receives the message that the server is off-line, it sends the request to another server on the list, which is continued until a server is found that is able to fulfill the request. Embodiments of the invention thus leverage existing client-known error messages to redirect client requests to other servers.

Claims

1. A computer-implemented method for an on-line server responsive to a client, the method comprising

receiving a request from the client, the server being chosen from a list of servers, the list being maintained by the client;

determining whether the server is inappropriate to fulfill the request based on the client being a non-delegable client that does not understand a delegation of the request to another server; and

if the server determines that the server is inappropriate to fulfill the request, sending an error message to the client, the error message identifying the server as being off-line, even though the server is on-line, such that the error message is a false error message, to enable the client to send the request to a next server on the list of servers.

2. The method of claim 1, wherein receiving the request from the client comprises generating the request at a query manager of the client.

3. The method of claim 2, wherein the client receives the request from the query manager at an application programming interface (API) of the client.

4. The method of claim 3, wherein the request from the client is received from the API at a component of the client that maintains the list of servers.

5. The method of claim 1, wherein sending the request from the client further comprises sending the request using a remote procedure call of the client.

6. A machine-readable medium having instructions stored thereon for execution by a processor of a client to perform a method comprising:

sending a request to a server, the server being chosen from a list of servers, the list being maintained by the client;

receiving a response to the request from the server; and

upon determining that the response comprises an error message that the server is off-line, automatically repeating the sending of the request to a next server of the list until the error message is not received, wherein the error message that the server is off-line is received even though the server is on-line, such that the error message is a false error message, which the server sends to the client upon determining that the server is inappropriate to fulfill the request;

wherein the client is a non-delegable client that does not understand a delegation of the request to another server.

7. The medium of claim 6, wherein sending a request to a server comprises generating the request at a query manager of the client.

8. The method of claim 7, wherein sending a request to a server further comprises receiving the request from the query manager at an application programming interface (API) of the client.

9. The method of claim 8, wherein sending a request to a server further comprises receiving the request from the API at a component of the client that maintains the list of servers.

10. The method of claim 9, wherein sending a request to a server further comprises sending the request using a remote procedure cell of the client.

11. A client computer comprising:

a communications device; and

,

a computer program designed to automatically send a request to a different server of a list of servers, the list being maintained by the client, via the communications device, wherein the automatic sending is responsive to an off-line error message indicating that a server is off-line, wherein the off-line error message labeling received from on-line servers that determine that the client computer is incapable of receiving delegated responses to requests, such that the off-line error message is a false error message;

wherein the client is a non-delegable client that does not understand a delegation of the request to another server.

12. A machine-readable medium having instructions stored thereof for execution by a processor of a server to perform a method comprising:

receiving a request from a client;

determining whether the server is inappropriate to fulfill the request;

determining whether the client is a non-delegable client that does not understand a delegation of the request to another server; and

upon determining that the server is inappropriate to fulfill the request due to the client being non-delegable, sending an off-line error message to the client, even though the server is on-line, such that the off-line error message is a false error message, wherein said off-line error message causes the client to forward the request to an alternative server based on a list of servers maintained by the client.

13. The medium of claim 12, the method further comprising:

determining whether the client is of a type capable of understanding a delegation of the request;

upon determining that the server is inappropriate to fulfill the request and that the client is of the type capable of understanding a delegation, delegating the request to another server.

14. The method of claim 12, the method further comprising upon determining that the server is appropriate to fulfill the request, fulfilling the request.

15. A method for a server comprising:

receiving a request from a non-delegable client that does not understand a delegation of the request to another server;

determining whether the request can be fulfilled locally; and

if the request cannot be fulfilled locally, sending an error message indicating that the server is off-line, even though the server is on-line, such that the error message is a false error message, to enable the non-delegable client to send the request to a next server.

16. A method for enabling non-delegable clients to exist in a client-server architecture having servers that do not maintain enterprise-wide directory service-related information, the method comprising:

providing each of the servers in the client-server architecture with computer-implemented instructions enabling the server to determine a client from which the server receives a request is a non-delegable client that does not understand a delegation of the request to another server;

responding to the client by determining whether the request can be fulfilled; and

if the request cannot be fulfilled, sending an error message, indicating that the server is off-line, even though the server is on-line, such that the error message is a false error message, wherein said off-line error message results in the non-delegable client determining that the server is unavailable to receive the request.

17. A server computer comprising:

a computer device; and

,

a computer program with computer-implemented instructions enabling the server computer to perform;

determining whether a client from which the server receives a request is a non-delegable client that does not understand a delegation of the request to another server;

if the request cannot be fulfilled, responding by providing that the communications device send a false error message to the non-delegable client, the false error message indicating that the server is off-line, even though the server is on-line, wherein the false error message causes the client to send the request to an alternative server computer.

18. The computer of claim 17, wherein the computer program is further designed to delegate the request to another server computer via the communications device in response to a request from a delegable client that understands a delegation of the request to another server when the server computer is inappropriate to fulfill the request.

19. The computer of claim 17, wherein the computer program is further designed to fulfill the request when the server computer is appropriate to fulfill the request.