Routing client requests to back-end servers

• US 6,823,391 B1
• Filed: 10/04/2000
• Issued: 11/23/2004
• Est. Priority Date: 10/04/2000
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Hopmann, Alex, Deen, Brian, Soderberg, Joel
• Primary Examiner(s): Thompson, Marc D.
• Assistant Examiner(s): DELGADO, MICHAEL A
• Application Number:
  US09/679,720
• Time in Patent Office: 1,511 Days
• Field of Search: 707/10, 707/4, 709/218, 709/219, 709/224, 709/331, 709/229, 718/105
• US Class Current: 709/229
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: H04L 61/30 Managing network names, e.g. use of aliases or nicknames name-to-address mapping H04L61/45
• CPC Class Codes: H04L 61/301 Name conversion
• CPC Class Codes: H04L 63/08 for authentication of entities cryptographic mechanisms or cryptographic arrangements for entity authentication H04L9/32
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1014 based on the content of a request
• CPC Class Codes: H04L 67/1023 based on a hash applied to IP addresses or costs
• 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 67/567 Integrating service provisioning from a plurality of service providers
• CPC Class Codes: H04L 67/63 Routing a service request depending on the request content or context

Abstract

Methods and computer program products for using a front-end server to access content stored on one or more back-end servers. The front-end server receives requests for content from client systems. Back-end servers store the content, but to the client system, it appears as if the front-end server is the content'"'"'s source. Upon receiving the request, the front-end server checks the validity of the request and examines a global catalog that dynamically maps client system requests to the back-end server or servers that store the requested content. In some circumstances, the content will be stored at a single back-end server and the front-end server directs the request to that server. Alternatively, a list of back-end servers storing the requested content may be generated. If so, the front-end then uses an authentication token as a key to a hash operation that is performed on the list and a single server that is capable of satisfying the request for content is identified. A given request and authentication token always identify the same server if the list of servers available for providing the requested content remains the same. The front-end server provides a single source for content requests so that client systems are not required to alter requests or invalidate local caches when content is moved from one back-end server to another. The front-end server also provides an additional level of security for back-end servers.

Claims

1. In a computerized system that includes a client system, a front-end server, and one or more back-end servers, all interconnected with a communication link, a method of accessing content stored at a particular back-end server such that the client system does not know which of the one or more back-end servers store the content, the method comprising the front-end server performing the acts of:

receiving a request for the content from the client system, the request including a resource identifier that references the front-end server and the content being requested by the client system;

examining a global catalog that dynamically maps the resource identifier to a plurality of back-end servers storing the requested content;

identifying a particular back-end server storing the requested content, from the plurality of back-end servers mapped to the resource identifier in the global catalog, wherein the same particular back-end server is identified for a given request over time, as long as the same particular back-end server is available and stores the content being requested; and

directing the request to the particular back-end server.

2. A method as recited in claim 1 further comprising the acts of:

receiving the requested content from the particular back-end server; and

sending the requested content to the client system.

3. A method as recited in claim 1 further comprising the act of rejecting the request if the request is invalid.

4. A method as recited in claim 1 wherein the content is specific to a user at the client system and is stored only at the particular back-end server.

5. A method as recited in claim 4 further comprising the acts of:

requesting authentication credentials from a user at the client system;

receiving proper authentication credentials from the user at the client system; and

adding at least a portion of the authentication credentials to the resource identifier so that the resource identifier is limited to a user associated with the authentication credentials.

6. A method as recited in claim 5 wherein the content is email content.

7. A method as recited in claim 1 further comprising the acts of:

requesting authentication credentials from a user at the client system who initiated the request for content; and

receiving proper authentication credentials from the user at the client system.

8. A method as recited in claim 7 wherein the particular back-end server requires user authentication, the method further comprising the act of including the user authentication credentials with the request for content directed to the particular back-end server.

9. A method as recited in claim 7 further comprising the acts of:

receiving from the global catalog an authentication token associated with the authentication credentials; and

using the authentication token as a key for a hash operation to identify the particular back-end server.

10. A method as recited in claim 7 further comprising the acts of:

receiving a subsequent request for the content from the client system, the request including the same resource identifier as the prior request;

examining the global catalog; and

identifying the same particular back-end server that was identified for the prior request.

11. A method as recited in claim 7 further comprising the acts of:

receiving a subsequent request for the content from the client system, the request including the same resource identifier as the prior request;

examining the global catalog; and

identifying a different back-end server from the particular back-end server identified for the prior request because the particular back-end server is either unavailable or no longer stores the requested content.

12. A method as recited in claim 1 wherein the front-end server is part of a hosting system and is identified by a plurality of server names, and wherein the global catalog dynamically maps resource identifiers referencing the front-end server based at least in part on a server name portion of the resource identifier.

13. A method as recited in claim 1 wherein the client system communicates with the front-end server using at least one of hypertext transfer protocol, post office protocol, and internet message access protocol.

14. In a computerized system that includes a client system, a front-end server, and one or more back-end servers, all interconnected with a communication link, a method of accessing content stored at a particular back-end server such that the client system does not know which of the one or more servers store the content, the method comprising the front-end server performing the acts of:

receiving a request for the content from the client system, the request including a resource identifier that references the front-end server and the content being requested by the client system;

checking the request to insure that the request is a valid request;

examining a global catalog that dynamically maps resource identifiers to the one or more back-end servers storing the content;

identifying a particular back-end server storing the requested content based on the mappings in the global catalog, wherein the same particular back-end server is identified for a given request over time, as long as the same particular back-end server is available and stores the content being requested; and

directing the request to the particular back-end server.

15. A method as recited in claim 14 further comprising the acts of:

requesting authentication credentials from the client system; and

receiving proper authentication credentials from the client system.

16. A method as recited in claim 15 wherein the one or more back-end servers require user authentication, the method further comprising the act of including the user authentication credentials with the request for content directed to the particular back-end server.

17. A method as recited in claim 15 further comprising the acts of:

receiving from the global catalog an authentication token associated with the authentication credentials; and

using the authentication token as a key for a hash operation to identify the particular back-end server.

18. A method as recited in claim 14 wherein the content is Web content.

19. A method as recited in claim 18 further comprising the acts of:

receiving a subsequent request for the content from the client system, the request including the same resource identifier as the prior request;

examining the global catalog; and

identifying the same particular back-end server that was identified for the prior request.

20. In a computerized system that includes a client system, a front-end server, and one or more back-end servers, all interconnected with a communication link, a method of accessing content stored at a particular back-end server such that the client system does not know which of the one or more back-end servers store the content, the method comprising the front-end server performing:

an act of receiving a request for the content from the client system, the request including a resource identifier that references the front-end server and the content being requested by the client system;

a step for mapping a request received from the client system to a particular one of a plurality of back-end servers that store the requested content, wherein a given request maps to the same particular back-end server over time, as long as the same particular back-end server is available and stores the content being requested;

a step for retrieving the requested content from the particular back-end server; and

an act of sending the requested content to the client system.

21. A method as recited in claim 20 further comprising a step for validating the request.

22. A method as recited in claim 20 further comprising a step for authenticating the client system.

23. A method as recited in claim 22 further comprising a step for altering the resource identifier based on the step for authenticating the client system.

24. A method as recited in claim 22 further comprising a step for distributing the request to the particular back-end server based on the client system authentication.

25. A method as recited in claim 20 further comprising a step for authenticating the client system to the particular back-end server.

26. A method as recited in claim 20 wherein the content comprises at least one of Web or email content.

27. A method as recited in claim 20 further comprising a step for hosting a plurality of back-end servers.

28. For a computerized system that includes a client system, a front-end server, and one or more back-end servers, all interconnected with a communication link, a computer program product for implementing a method of accessing content stored at a particular back-end server such that the client system does not know which of the one or more back-end servers store the content, comprising:

a computer readable medium for carrying machine-executable instructions for implementing the method; and

wherein said method is comprised of machine-executable instructions for performing the acts of;

receiving a request for the content from the client system, the request including a resource identifier that references the front-end server and the content being requested by the client system;

examining a global catalog that dynamically maps the resource identifier to a plurality of back-end servers storing the content;

identifying a particular back-end server storing the requested content, from the plurality of back-end servers mapped to the resource identifier in the global catalog, wherein the same particular back-end server is identified for a given request over time, as long as the same particular back-end server is available and stores the content being requested; and

directing the request to the particular back-end server.

29. A computer program product as recited in claim 28 wherein the method is comprised further of machine-executable instructions for performing the acts of:

receiving the requested content from the particular back-end server; and

sending the requested content to the client system.

30. A computer program product as recited in claim 28 wherein the method is comprised further of machine-executable instructions for performing the act of rejecting the request if the request is invalid.

31. A computer program product as recited in claim 28 wherein the method is comprised further of machine-executable instructions for performing the acts of:

requesting authentication credentials from the client system; and

receiving proper authentication credentials from the client system.

32. A computer program product as recited in claim 31 wherein the method is comprised further of machine-executable instructions for performing the act of adding at least a portion of the authentication credentials to the resource identifier so that the resource identifier is limited to a user associated with the authentication credentials.

33. A computer program product as recited in claim 31 wherein the one or more back-end servers require client system authentication, and wherein the method is comprised further of machine-executable instructions for performing the act of including the client authentication credentials with the request for content directed to the particular back-end server.

34. A computer program product as recited in claim 31 wherein the method is comprised further of machine-executable instructions for performing the acts of:

receiving from the global catalog, an authentication token associated with the authentication credentials; and

using the authentication token as a key for a hash operation to identify the particular back-end server.

35. A computer program product as recited in claim 28 wherein the front-end server is part of a hosting system and is identified by a plurality of server names, and wherein the global catalog dynamically maps resource identifiers referencing the front-end server based at least in part on a server name portion of the resource identifier.

36. For a computerized system that includes a client system, a front-end server, and one or more back-end servers, all interconnected with a communication link, a computer program product comprising one or more computer readable media carrying computer executable instructions that implement a method of accessing content stored at a particular back-end server such that the client system does not know which of the one or more servers store the content, the method comprising the front-end server performing the acts of:

receiving a request for the content from the client system, the request including a resource identifier that references the front-end server and the content being requested by the client system;

checking the request to insure that the request is a valid request;

examining a global catalog that dynamically maps resource identifiers to the one or more back-end servers storing the content;

identifying a particular back-end server storing the requested content based on the mappings in the global catalog, wherein the same particular back-end server is identified for a given request over time, as long as the same particular back-end server is available and stores the content being requested; and

directing the request to the particular back-end server.

37. A computer program product as recited in claim 36, the method further comprising acts of:

requesting authentication credentials from the client system; and

receiving proper authentication credentials from the client system.

38. A computer program product as recited in claim 37 wherein the one or more back-end servers require user authentication, the method further comprising the act of including the user authentication credentials with the request for content directed to the particular back-end server.

39. A computer program product as recited in claim 37, the method further comprising the acts of:

receiving from the global catalog an authentication token associated with the authentication credentials; and

using the authentication token as a key for a hash operation to identify the particular back-end server.

40. A computer program product as recited in claim 36 further comprising the acts of:

receiving a subsequent request for the content from the client system, the request including the same resource identifier as the prior request;

examining the global catalog; and

identifying the same particular back-end server that was identified for the prior request.