Efficient message routing when using server pools

• US 20060031536A1
• Filed: 05/21/2004
• Published: 02/09/2006
• Est. Priority Date: 05/21/2004
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Eydelman, Vadim, Shoroff, Srikanth
• Granted Patent: US 8,024,476 B2
• Time in Patent Office: Days
• US Class Current: 709/228
• CPC Class Codes: H04L 61/45 Network directories; Name-to-address mapping
• CPC Class Codes: H04L 63/166 at the transport layer
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/1104 Session initiation protocol [SIP]
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1008 based on parameters of servers, e.g. available memory or workload monitoring of computer activity G06F11/30
• CPC Class Codes: H04L 67/101 based on network conditions
• CPC Class Codes: H04L 69/22 Parsing or analysis of headers

Abstract

Approaches for efficiently routing messages using a server pool are provided. In an embodiment, the system attempts to ensure high availability of servers by enabling clients to specify a domain name for the server pool even though the server pool comprises multiple servers, each having a distinct name. When a client initiates a session by using the server pool'"'"'s domain name, the system may select an available server with a different name, and will route the request and subsequent messages during the session to the selected server. The system may select a server from the pool having the lowest load. The system may also indicate servers that subsequent messages in the session are to transit. Subsequent messages may then be routed to indicated servers to enable application services on the indicated servers to take actions based on the messages and the direction of the messages.

Claims

1. A method performed by a computer system for efficiently routing messages to a front end server of a server pool, the server pool comprising multiple front end servers, the method comprising:

receiving a message from a client computing device indicating to open a dialog, the message sent to a domain name identifying the server pool;

selecting a front end server of the server pool, the front end server having a server domain name;

modifying a header field of the message to add an indication of the server domain name of the selected front end server so that subsequent messages of the dialog can be sent to the selected front end server based on the indication; and

forwarding the modified message to the selected front end server to open the dialog between the client computing device and the selected front end server.

2. The method of claim 1 including:

receiving subsequent messages of the dialog from the client computing device;

detecting the selected front end server from the indication of the server domain name contained in a header field of the subsequent messages; and

forwarding the subsequent messages to the selected front end server based on the indication of the server domain name contained in the subsequent messages.

3. The method of claim 2 wherein the computer system is a proxy server.

4. The method of claim 1 wherein subsequent messages of the dialog are exchanged between the client computing device and the selected front end server without forwarding by another computing device of the server pool.

5. The method of claim 4 wherein the computer system is another computing device of the server pool.

6. The method of claim 1 wherein the modifying includes adding a parameter to a header field.

7. The method of claim 6 wherein the header field is a Session Initiation Protocol Record-Route header field.

8. The method of claim 6 wherein the parameter indicates the server domain name.

9. The method of claim 8 wherein the server domain name is a fully qualified domain name.

10. The method of claim 1 including adding a header field value indicating a role for the front end server.

11. The method of claim 10 wherein the role is From.

12. The method of claim 10 wherein the role is To.

13. The method of claim 10 wherein an application program performs processing based on the indicated role.

14. The method of claim 1 including selecting an alternate front end server of the server pool when the selected front end server of the server pool becomes unavailable.

15. The method of claim 1 wherein the selecting includes determining a server load.

16. The method of claim 1 wherein the subsequent messages traverse an identical set of network devices.

17. The method of claim 1 wherein the message is a Session Initiation Protocol message.

18. A system for efficiently routing messages to a front end server of a server pool, the server pool comprising multiple front end servers, comprising:

a component that receives a message from a client computing device indicating to open a dialog, the message sent to a domain name identifying the server pool;

a component that selects a front end server of the server pool, the front end server having an identifier; and

a component that modifies the message by adding an indication of the identifier of the selected front end server to a header field of the message.

19. The system of claim 18 wherein the message is a Session Initiation Protocol message.

20. The system of claim 18 wherein the identifier is a server name of the selected front end server.

21. The system of claim 20 wherein the server name is a fully qualified domain name.

22. The system of claim 18 including a component that forwards the modified message to the selected front end server to open the dialog between the client computing device and the selected front end server.

23. The system of claim 18 including a component that receives subsequent messages from the client computing device and forwards each subsequent message to the front end server indicated in a header field of the subsequent message.

24. A computer-readable medium whose contents cause a computing system to perform a method comprising:

receiving a message from a client computing device indicating to open a dialog, the message indicating a domain name identifying a server pool;

selecting a front end server of the pool, the front end server having an identifier;

modifying a header field of the message to add an indication of the identifier of the selected front end server so that subsequent messages of the dialog can be sent to the selected front end server based on the identifier; and

forwarding the modified message to the selected front end server to open the dialog between the client computing device and the selected front end server.

25. The computer-readable medium of claim 24 including:

receiving subsequent messages of the dialog from the client computing device;

detecting the selected front end server from the indicator of the selected front end server contained in a header field of the subsequent messages; and

forwarding the subsequent messages to the selected front end server based on the indicator of the front end server contained in the header field of subsequent messages.

26. The computer-readable medium of claim 24 wherein subsequent messages of the dialog are exchanged between the client computing device and selected front end server without forwarding by another computing device of the server pool.

27. The computer-readable medium of claim 24 wherein the message is a Session Initiation Protocol message.

28. The computer-readable medium of claim 24 wherein the identifier of the front end server is a fully qualified domain name.

29. The computer-readable medium of claim 28 wherein the domain name is a fully qualified domain name.

30. The computer-readable medium of claim 24 wherein the identifier of the front end server is a server name.

31. The computer-readable medium of claim 24 wherein the identifier of the front end server is unique to the server pool.

32. A computer-readable medium for indicating a front end server of a server pool, comprising:

a message containing a header field, wherein the header field identifies the server pool; and

a parameter for the header field indicating the front end server.

33. The computer-readable medium of claim 32 wherein the identification of the server pool is a fully qualified domain name.

34. The computer-readable medium of claim 33 wherein the domain name is a fully qualified domain name.

35. The computer-readable medium of claim 32 wherein the parameter is a domain name of the front end server.

36. The computer-readable medium of claim 35 wherein the domain name is a fully qualified domain name.

37. The computer-readable medium of claim 32 wherein the parameter uniquely identifies the front end server in the server pool.

38. The computer-readable medium of claim 32 including an indication of a role for the front end server.

39. The computer-readable medium of claim 38 wherein the role is From.

40. The computer-readable medium of claim 38 wherein the role is To.