System and method for the distribution and synchronization of data and state information between clients in a distributed processing system

• US 5,987,376 A
• Filed: 07/16/1997
• Issued: 11/16/1999
• Est. Priority Date: 07/16/1997
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Olson, Kipley J., Cohen, Andrew R.
• Primary Examiner(s): Maung, Zarni
• Assistant Examiner(s): Najjar, Saleh
• Application Number:
  US08/893,960
• Time in Patent Office: 853 Days
• Field of Search: 395/200.31, 395/200.35, 395/200.78, 709/201, 709/205, 709/248
• US Class Current: 701/201
• CPC Class Codes: A63F 2300/402 Communication between platforms, i.e. physical link to protocol
• CPC Class Codes: H04L 67/00 Network arrangements or protocols for supporting network services or applications user-to-user messaging H04L51/00; network arrangements, protocols or services for supporting real-time applications in data packet communications networks H04L65/00
• CPC Class Codes: H04L 67/10 in which an application is distributed across nodes in the network software deployment G06F8/60; multiprogramming arrangements G06F9/46
• CPC Class Codes: H04L 67/1095 Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes
• CPC Class Codes: H04L 67/131 Protocols for games, networked simulations or virtual reality
• CPC Class Codes: H04L 67/14 Session management for real-time applications in data packet communications networks H04L65/1066
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

The present invention is directed to a novel system and method for sharing common data and state information between network connected application clients participating in an application session. The application session is invoked by a host client. The host client is responsible for selectively admitting other network connected clients into the application session, and is also the application client that is responsible for distributing a common set of application data for storage at each admitted application client. The application data includes a unique identifier, assigned by the host client, for each application client in the application session. In the event that an application client effects a change to the application data, that change is communicated to each of the other application clients in the session. In this way, each client is always operating on a common set of application data. When a new client is admitted into an application session, application data is forwarded to it in a manner so that the new client receives data that is synchronized with the data possessed by every other application client in the session. A method for migrating host client duties to another application client is also disclosed.

Claims

1. In a distributed processing system that includes a plurality of network connected application clients, a method for sharing application data between at least two of the application clients, the method comprising the following steps:

(a) in a host client, initiating an application session and selectively admitting a new client into the application session, such that the application clients include the host client, the new client, and any other client participating in the application session;

(b) transferring the application data from the host client to the new client, the application data comprising;

(i) a data structure including a unique identifier for each of at least the host client and said any other client participating in the application session; and

(ii) state data; and

(c) in the event that any application client changes application data stored therein;

(i) forwarding a state update packet from the application client changing the application data directly to all other application clients in the application session; and

(ii) at each of the other application clients, receiving the state update packet and altering the application data stored at the receiving application client in accordance with the contents of the state update packet.

2. A method for sharing application data as defined in claim 1, further comprising the step of assigning host duties from the host client to another of the application clients, the step of assigning being conducted during the application session.

3. A method for sharing application data as defined in claim 2, further comprising the step of selecting said other of the application clients to which the host duties are assigned based on the unique identifiers contained in the application data at each application client.

4. A method for sharing application data as defined in claim 1, wherein the step of selectively admitting a new client into the application session comprises the following steps:

(a) receiving, by the host client, an admission request from the new client; and

(b) transmitting, by the host client, a unique identifier for the new client to each of said other clients participating in the application session.

5. A method for sharing application data as defined in claim 4, further comprising the step of selectively admitting the new client into the application session by the host client based on predetermined admission criteria.

6. A method for sharing application data as defined in claim 2, wherein the host duties include selectively admitting other new clients to the application session.

7. A method for sharing application data as defined in claim 4, further comprising the steps of:

during the step of transferring the application data from the host client to the new client, compiling pending queue data at the new client, the pending queue data including data derived from at least one state update packet received by the new client from any other application client as the application data is transferred to the new application client; and

updating the application data at the new client in accordance with the contents of the pending queue data.

8. A method for sharing application data as defined in claim 1, wherein the data structure further includes a unique identifier for the new client.

9. A method for sharing application data as defined in claim 1, wherein the application session enables a computer game to be executed at the application clients.

10. A method for sharing application data as defined in claim 9, wherein at least one of the application clients supports multiple clients.

11. In a network based distributed processing system that includes a single host client and at least one existing application client that are participating in a single application session and that are each operating on common application data, a method for admitting a new client into the application session such that the application clients of the application session include the host client, each of the at least one existing application client, and the new client, the method comprising the following steps:

(a) receiving, by the host client, an admission request from the new client;

(b) transmitting, by the host client, a unique identifier for the new client to each of the at least one existing application client;

(c) transmitting, by the host client, application data to the new client, the application data comprising;

(i) a data structure including a unique identifier for each of at least the host client and the at least one existing application client; and

(ii) state data;

(d) while the host client is transmitting the application data to the new client, compiling at the new client pending queue data, the pending queue data including data derived from at least one state update packet forwarded directly to the new client by any other application client in the application session; and

(e) updating the application data received at the new client in accordance with the contents of the pending queue data.

12. A method as defined in claim 11, further comprising the following steps:

in the event that any application client changes application data stored therein;

(a) forwarding a state update packet from the application client changing the application data to all other application clients in the application session; and

(b) at each of the other application clients, receiving the state update packet and altering the application data stored at the receiving application client in accordance with the contents of the state update packet.

13. A method as defined in claim 11, further comprising the step of assigning host duties from the host client to another of the application clients, the step of assigning being conducted during the application session, and said other of the application clients to which the host duties are assigned being selected from among the application clients based on predetermined characteristics of the unique identifiers contained in the application data at each application client.

14. A computer-readable medium for implementing, in a client computer, a method of enabling the client computer to become a new client admitted to an application session conducted in a distributed processing system, wherein application clients participating in the application session include a host client, at least one existing application client, and the new client, the computer-readable medium having computer-executable instructions comprising:

means for forwarding an admission request message to the host client that requests admission to the application session;

means for receiving from the host client a unique identifier assigned to the new client;

means for receiving from the host client application data used in the application session, the application data comprising;

(i) a data structure including a unique identifier for each of at least the host client and the at least one existing application client; and

(ii) state data;

means for compiling pending queue data, the pending queue data including data derived from at least one state update packet forwarded directly to the new client by any other application client in the application session while the new client is receiving the application data from the host client; and

means for updating the application data received at the new client in accordance with the contents of the pending queue data.

15. A computer-readable medium as defined in claim 14, further comprising computer-executable instructions comprising means for uncompressing application data received from the host client.

16. In a distributed processing system that includes a plurality of network connected clients, a method for hosting an application session between at least two of the network connected clients, the method comprising the following steps:

(a) in a host client selected from among the plurality of network connected clients, receiving a request from another of the plurality of network connected clients to be admitted into the application session;

(b) in the host client, selectively admitting the requesting client into the application session based upon predetermined admission criteria, such that application clients participating in the application session include the host client, the requesting client, and any other of the plurality of network connected clients participating in the application session;

(c) transferring application data from the host client to the requesting client, the application data comprising;

(i) a data structure including a unique identifier for each of at least the host client and said any other of the plurality of network connected clients participating in the application session; and

(ii) state data;

(d) in the event that any application client changes its application data;

(i) forwarding a state update packet from the application client changing its application data directly to any other application client in the application session; and

(ii) at each of the other application clients in the application session, receiving the state update packet and altering the application data stored at the receiving application client in accordance with the contents of the state update packet; and

(e) exiting the application by the host client and, as the application session continues, causing host duties to migrate from the host client to another one of the application clients based on predetermined selection criteria.

17. A method as defined in claim 16, wherein the step of selectively admitting the requesting client into the application session comprises the following steps:

(a) while the application data is being transferred to the requesting client, compiling at the requesting client pending queue data, the pending queue data including data derived from at least one state update packet forwarded to the requesting client by any other application client in the application session; and

(b) when the step of transferring application data is complete, updating the application data transferred to the requesting client from the host client in accordance with the contents of the pending queue data.