Method and system for sharing applications between computer systems

• US 6,271,839 B1
• Filed: 07/02/1998
• Issued: 08/07/2001
• Est. Priority Date: 07/05/1995
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: MacFarquhar, Roderick F., Pollitt, Alex J., Batty, John P., Downes, Anthony M., Hughes, Kenneth P., Mairs, Christopher J.
• Primary Examiner(s): SAX, STEVEN PAUL
• Application Number:
  US09/109,958
• Time in Patent Office: 1,132 Days
• Field of Search: 345/340, 345/342, 345/343, 345/346, 345/344, 345/345, 345/347, 345/341, 345/332, 345/329, 345/330-331, 707/10
• US Class Current: 715/807
• CPC Class Codes: G06F 3/1462 with means for detecting differences between the image stored in the host and the images displayed on the remote displays
• CPC Class Codes: G09G 5/14 Display of multiple viewports

Abstract

Methods and systems for coordinating the z-order of windows shared among computers are disclosed. A shared application runs on a host computer and its output is displayed in windows both on the host computer and on shadow computers. The “z-order” on each computer tells which window is logically the “topmost” one displayed (that is, the window not obscured by other windows), which window is logically just below that one, etc., down to the window logically at the “bottom” of the stack. When the z-order of the windows on the host or on a shadow computer is changed, notification of that change is sent to the other computers so that they can adjust their own z-order accordingly.

Claims

1. A method in a computer system of coordinating z-ordering of shared windows on a host computer system with shadow windows on a shadow computer system, the shared windows and the shadow windows having a one-to-one correspondence, the method comprising the steps of:

displaying the shared windows on the host computer system, the shared windows having a z-ordering;

displaying the shadow windows on the shadow computer system, the shadow windows having a z-ordering;

when the z-ordering of the shared windows is modified at the host computer system, sending a notification to the shadow computer system, and upon receiving the sent notification at the shadow computer system, modifying the z-ordering of the shadow windows in accordance with the z-ordering of the shared windows;

sending a notification to the host computer system when the z-ordering of the shadow windows is modified at the shadow computer system; and

modifying the z-ordering of the shared windows in accordance with the z-ordering of the shadow windows upon receiving the sent notification at the host computer system.

2. The method of claim 1 wherein the shadow computer system has a plurality of local windows, wherein the local windows and the shadow windows have a combined z-ordering, and wherein when modifying the z-ordering of the shadow windows in accordance with the z-ordering of the shared windows, the combined z-ordering of the local windows is not modified.

3. The method of claim 1 wherein the host computer system has a plurality of local windows, wherein the local windows and the shared windows have a combined z-ordering, and wherein when modifying the z-ordering of the shared windows in accordance with the z-ordering of the shadow windows, the combined z-ordering of the local windows is not modified.

4. A method in a computer system for coordinating z-ordering of windows on a first computer system and a second computer system, the method comprising:

displaying the windows on the first computer system, the windows having a z-ordering;

displaying the windows on the second computer system, the windows having a z-ordering;

when the z-ordering of the displayed windows is modified at the first computer system, sending a notification to the second computer system so that the second computer system can modify the z-ordering of its windows in accordance with the z-ordering of the windows at the first computer system;

sending a notification to the first computer system when the z-ordering of the displayed windows is modified at the second computer system; and

modifying the z-ordering of the first computer system'"'"'s windows in accordance with the z-ordering of the second computer system'"'"'s windows upon receiving the sent notification at the first computer system.

5. The method of claim 4 including when the second computer system cannot modify its z-ordering in accordance with the z-ordering of the windows at the first computer system, sending a notification to the first computer system so that the first computer system can modify the z-ordering of its windows in accordance with the z-ordering of the windows of the second computer system, the notification indicating the z-ordering of the windows of the second computer system.

6. The method of claim 5 wherein the second computer system cannot modify the z-ordering of its windows because of a top-most attribute of a window.

7. The method of claim 4 wherein the first computer system is a host computer system and the displayed windows are shared windows and wherein the second computer system is a shadow computer system.

8. The method of claim 7 wherein the notification includes a list of the z-ordering of the windows.

9. The method of claim 8 wherein when the second computer system detects a window in the list that was not in a previous list, it displays a shadow window for that detected window.

10. The method of claim 4 wherein the second computer system is a host computer system and the displayed windows are shared windows and wherein the first computer system is a shadow computer system.

11. The method of claim 10 wherein the notification includes a list of the z-ordering of the windows.

12. A computer-readable medium containing instructions for causing a computer system to coordinate z-ordering of windows on a first computer system and a second computer system, by:

displaying the windows on the first computer system, the windows having a z-ordering;

displaying the windows on the second computer system, the windows having a z-ordering;

when the z-ordering of the displayed windows is modified at the first computer system, sending a notification to the second computer system so that the second computer system can modify the z-ordering of its windows in accordance with the z-ordering of the windows at the first computer system;

sending a notification to the first computer system when the z-ordering of the displayed windows is modified at the second computer system; and

modifying the z-ordering of the first computer system'"'"'s windows in accordance with the z-ordering of the second computer system'"'"'s windows upon receiving the sent notification at the first computer system.

13. The computer-readable medium of claim 12 including instructions so that when the second computer system cannot modify its z-ordering in accordance with the z-ordering of the windows at the first computer system, sending a notification to the first computer system so that the first computer system can modify the z-ordering of its windows in accordance with the z-ordering of the windows of the second computer system, the notification indicating the z-ordering of the windows of the second computer system.

14. The computer-readable medium of claim 13 wherein the second computer system cannot modify its z-ordering of the windows because of a top-most attribute of a window.

15. The computer-readable medium of claim 12 wherein the first computer system is a host computer system and the displayed windows are shared windows and wherein the second computer system is a shadow computer system.

16. The computer-readable medium of claim 15 wherein the notification includes a list of the z-ordering of the windows.

17. The computer-readable medium of claim 16 wherein when the second computer system detects a window in the list that was not in a previous list, displaying a shadow window for that detected window.

18. The computer-readable medium of claim 12 wherein the second computer system is a host computer system and the displayed windows are shared windows and wherein the first computer system is a shadow computer system.

19. The computer-readable medium of claim 18 wherein the notification includes a list of the z-ordering of the windows.

20. A method for coordinating a z-ordering of windows shared among a group of computers, where each of the computers has a base number for tracking a state of the z-ordering of the windows, the method comprising the steps of:

initially setting the base numbers to equal values for all of the computers in the group;

changing the z-ordering of the windows at one of the computers;

increasing the value of the base number of the one computer to a new value in response to the changing of the z-ordering;

notifying other computers in the group of the change in the z-ordering at the one computer and the new value of the base number; and

applying the change at each of the other computers in the group and setting the base number to the new value of the base number if the new value of the base number is greater than the base number at the other computer.

21. The method of claim 20 wherein notifying of the change in the z-ordering includes listing the shared windows.

22. A computer-readable medium containing instructions that when executed perform the method of claim 20.

23. A method on a first computer for coordinating a z-ordering of windows shared between the first computer and a second computer, where each of the computers has a base number for tracking a state of the z-ordering of the windows, the method comprising:

initially setting the first computer'"'"'s base number to a value equal to the value of the second computer'"'"'s base number;

changing the z-ordering of the windows at the first computer;

increasing the value of the first computer'"'"'s base number to a new value in response to the changing of the z-ordering;

sending a notification to the second computer of the change in the z-ordering at the first computer and the new value of the first computer'"'"'s base number;

receiving a notification from the second computer of a change in the z-ordering at the second computer and a new value of the second computer'"'"'s base number; and

applying the change at the first computer and setting the first computer'"'"'s base number to the received value of the base number if the received value of the base number is greater than the first computer'"'"'s base number.

24. The method of claim 23 wherein sending a notification of the change in the z-ordering includes sending a list of the shared windows.

25. A computer-readable medium containing instructions that when executed perform the method of claim 23.