Controlling the transfer of terminal server data

• US 20070237077A1
• Filed: 03/31/2006
• Published: 10/11/2007
• Est. Priority Date: 03/31/2006
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Hagiu, Costin, Lotlikar, Mahesh, Abdo, Nadim, Patwardhan, Makarand, Butt, Hammad
• Granted Patent: US 7,548,547 B2
• Time in Patent Office: Days
• US Class Current: 370/230
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/19 at layers above the network layer network arrangements for networked applications for scheduling or organising the servicing of application requests H04L67/60
• CPC Class Codes: H04L 47/2433 Allocation of priorities to traffic types
• CPC Class Codes: H04L 47/30 in combination with information about buffer occupancy at either end or at transit nodes

Abstract

The present invention extends to methods, systems, and computer program products for controlling the transfer of terminal server data. In some embodiments, contending request to send terminal server data are resolved by a flow control module situated between a terminal server protocol and a transport/network protocol. The flow control module utilizes channel priorities along with amounts of previously sent data per channel to determine how to distribute bandwidth in a relatively controlled manner between contending channels. The flow control module can be configured to intercept communication between terminal server protocol and a transport/network protocol to facilitate bandwidth distribution. In other embodiments, data is simultaneously sent over multiple channels of terminal server connection. A first write operation obtains a lock on a corresponding channel but the channel lock does not prevent write operations on other channels.

Claims

1. At a computer system, a method for determining how to allocate bandwidth for transferring terminal server data, the method comprising:

an act of receiving a first request to transfer terminal server data for a first application layer module, the first application layer module associated with a first priority;

an act of determining that current bandwidth pressure has caused any buffers configured for transferring terminal server data to be in use;

an act of receiving a second request to transfer terminal server data for a second application layer module, the second application layer module associated with a second priority;

an act of determining that the first request and the second request are in contention for the next buffer that is freed up;

an act of calculating the number of bytes charged for application layer modules having the first priority during at least the current bandwidth pressure;

an act of calculating the number of bytes charged for application layer modules having the second priority during at least the current bandwidth pressure;

an act of detecting that a buffer has been freed up;

an act of comparing the number of bytes charged for application layer modules having the first priority to the number of bytes charged for application layer modules having the second priority; and

an act of appropriately allocating the buffer to transfer terminal server data based on the results of the comparison.

2. The method as recited in claim 1, wherein the act of receiving a first request to transfer terminal server data for a first application layer module comprises an act of receiving a request to send display data for presentation at a client.

3. The method as recited in claim 1, wherein the act of receiving a first request to transfer terminal server data for a first application layer module comprises an act of intercepting a buffer request sent from a terminal server protocol to a transport/network protocol.

4. The method as recited in claim 3, wherein the act of intercepting a buffer request sent from a terminal server protocol to a transport/network protocol comprises an act of intercepting a buffer request sent from remote desktop protocol to TCP/IP.

5. The method as recited in claim 1, wherein the act of receiving a second request to transfer terminal server data for a second application layer module comprises an act of receiving a request to send virtual channel data to a client.

6. The method as recited in claim 1, wherein an act of determining that the first request and the second request are in contention for the next buffer that is freed up comprises an act of receiving the first request and the second request when no buffers are available.

7. The method as recited in claim 1, wherein the act of calculating the number of bytes charged for application layer modules having the first priority during at least the current bandwidth pressure comprises an act of calculating number of bytes charged for application layer modules having the first priority during a specified period of time.

8. The method as recited in claim 1, wherein the act of calculating the number of bytes charged for application layer modules having the first priority during at least the current bandwidth pressure comprises an act of calculating number of bytes charged for application layer modules having the first priority in accordance with a specified allocation factor of the priority such that bytes changed can be directly compared to bytes charged for other priorities.

9. The method as recited in claim 1, wherein the act of detecting that a buffer has been freed up comprises an act of intercepting a buffer that was sent from a transport/network protocol to terminal server protocol.

10. The method as recited in claim 1, wherein the act of comparing the number of bytes charged for application layer modules having the first priority to the number of bytes charged for application layer modules having the second priority comprises an act of comparing bytes charge for display data to bytes charged for virtual channel data.

11. The method as recited in claim 1, wherein an act of appropriately allocating the buffer to transfer terminal server data based on the results of the comparison comprises an act of allocating the buffer to the first request.

12. The method as recited in claim 11, further comprising:

an act of filling the buffer with terminal server data for the first application layer module; and

an act of sending the buffer to transport/network protocol for delivery to a client.

13. The method as recited in claim 1, further comprising:

an act of including the first request in a buffer queue list corresponding to the first priority; and

an act of including the second request in a buffer queue list corresponding to the second priority.

14. A computer system, comprising:

one or more processors;

system memory; and

one or more computer-readable media having stored thereon a terminal server flow control module, the terminal server flow control module being including in a communication stack situated between a terminal server protocol and a transport/network protocol, the terminal server flow control module configured to intercept communication between the terminal server protocol and a transport/network protocol to perform the following;

receive a first request to transfer terminal server data for a first application layer module, the first application layer module associated with a first priority;

determine that current bandwidth pressure has caused any buffers configured for transferring terminal server data to be in use;

receive a second request to transfer terminal server data for a second application layer module, the second application layer module associated with a second priority;

determine that the first request and the second request are in contention for the next buffer that is freed up;

calculate the number of bytes charged for application layer modules having the first priority during at least the current bandwidth pressure;

calculate the number of bytes charged for application layer modules having the second priority during at least the current bandwidth pressure;

detect that a buffer has been freed up;

compare the number of bytes charged for application layer modules having the first priority to the number of bytes charged for application layer modules having the second priority; and

appropriately allocating the buffer to transfer terminal server data based on the results of the comparison.

15. The method as recited in claim 14, wherein the terminal server flow control module being configured to intercept communication between the terminal server protocol and a transport/network protocol comprises the terminal server flow control module being configured to intercept communication between the remote desktop protocol and TCP/IP.

16. At a computer system, a method for simultaneously performing a plurality of channel writes on a terminal server connection, the method comprising:

an act of receiving first terminal server data corresponding to a write operation on a first channel of a terminal server connection that includes a plurality of channels;

an act of locking a write resource associated with the first channel to prevent other write operations on the first channel without locking write operations on other channels of the terminal server connection;

an act of receiving second terminal server data corresponding to a write operation on a second channel of the terminal server connection;

an act of determining that a write resource associated with the second channel is not locked; and

an act of simultaneously writing at least a portion of the first terminal server data on the first channel of the terminal server connection and at least a portion of the second terminal server data on the second channel of the terminal server connection while the write resource associated with the first channel is locked.

17. The method as recited in claim 16, wherein the act of receiving first terminal server data corresponding to a write operation on a first channel of a terminal server connection that includes a plurality of channels comprises an act of receiving a write operation on a channel of a remote desktop protocol connection.

18. The method as recite din claim 16, wherein the act of locking a write resource associated with the first channel comprises an act of modifying a value in a channel data structure used to represent the first channel.

19. The method as recited in claim 18, wherein the act of determining that a write resource associated with the second channel is not locked comprises an act checking a value in a second different channel data structure used to represent the second channel.

20. The method as recited in claim 16, wherein an act of simultaneously writing at least a portion of the first terminal server data on the first channel and at least a portion of the second terminal server data on the second channel comprises an act of simultaneously writing data over two virtual channels of a remote desktop protocol connection.