Session multiplex protocol

• US 7,966,405 B2
• Filed: 06/29/2004
• Issued: 06/21/2011
• Est. Priority Date: 06/29/2004
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Sundaresan, Sharad, Erdogan, Tahsin
• Primary Examiner(s): Follansbee; John
• Assistant Examiner(s): Anwari; Maceeh
• Application Number:
  US10/879,428
• Publication Number:
  US 20050286516A1
• Time in Patent Office: 2,548 Days
• Field of Search: 709/227
• US Class Current: 709/227
• CPC Class Codes: H04L 67/14 Session management for real-time applications in data packet communications networks H04L65/1066
• CPC Class Codes: H04L 69/14 Multichannel or multilink protocols
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

Session multiplex protocol (“SMUX”) is a protocol layered above existing reliable transport mechanisms that can be used to create multiple sessions over a single connection. Data from several different SMUX sessions can be interleaved and message boundaries preserved. Because it sits on top of reliable transport mechanisms, it takes advantage of the underlying protocols to ensure byte-alignment, loss detection/recovery, and reliable delivery. It provides a window based flow control mechanism to ensure suitable fairness among streams of different sessions and prevent deadlocks.

Claims

1. A method implemented in a computing system of communicating between a first network application and a second network application, comprising:

receiving at a first multiplexer application a plurality of SQL transactions from a first network application directed to a second network application, the second network application being a SQL server application, each of the plurality of SQL transactions associated with a separate logical session between the first network application and the second network application;

for each of the plurality of SQL transactions, generating a packet comprising the SQL transaction and a session identifier identifying a logical session between the first network application and the second network application;

sending the generated packet through a physical connection to a second multiplexer application, using a supported network protocol;

receiving the generated packet through the physical connection using the supported protocol at the second multiplexer application;

retrieving the generated packet from the supported protocol;

processing the generated packet to retrieve the SQL transaction; and

for the SQL transaction;

identifying from the session identifier the logical session associated with the SQL transaction between the first network application and the second network application; and

when the packet is a data packet, forwarding the SQL transaction to the second network application at the logical session, the forwarding the SQL transaction comprising checking if there is sufficient buffer space available for the session, and forwarding the transaction to the second network application if there is sufficient buffer space available.

2. The method of claim 1, wherein checking if there is sufficient buffer space available comprises checking a list of available buffer space for each session and if the available buffer space is greater than or equal to the amount required for the transaction, determining that there is sufficient buffer space.

3. The method of claim 1, wherein generating a packet containing the received transaction and routing information comprises:

generating a header for the packet, wherein the header comprises a session identification field, a control flag field, a window field, a sequence number field, and a length field; and

appending transaction data from the transaction, if any, to the packet header.

4. The method of claim 3, further comprising setting the window field to the available buffer space for the session, if the transaction is a data transaction, else setting the window field to zero.

5. The method of claim 3, further comprising increasing the sequence number by one more than a stored sequence number for the session only if the transaction is a data transaction, else setting the sequence number to zero.

6. The method of claim 3, further comprising setting the control flag to indicate the type of packet generated.

7. The method of claim 6, wherein setting the control flag to indicate the type of packet generated further comprises:

setting the control flag to indicate that the packet is a FIN packet, if the received transaction is a request to close a session, wherein the FIN packet carries instructions to close a session;

setting the control flag to indicate that the packet is a SYN packet, if the received transaction request is a request to open a session, wherein the SYN packet carries instructions to open a session; and

setting the control flag to indicate that the packet is a DATA packet, if the received transaction request is a data transaction, wherein the DATA packet carries data for a particular session.

8. The method of claim 3, further comprising setting the length field to the length of the header plus the appended data if any.

9. The method of claim 1, wherein processing the generated packet comprises:

determining the type of the packet;

if the packet is an ACK packet, wherein the ACK packet carries instructions to update a session buffer, updating the available buffer space for the session by the amount specified in the window field;

if the packet is a FIN packet, wherein the FIN packet carries instructions to close a session, adding the session identification number to a list of available session identification numbers, removing the session identification number from a list of active sessions, and generating a response packet and sending it to the first network application; and

if the packet is a SYN packet, wherein the SYN packet carries instructions to open a session, opening a new session by adding the session identification number to the list of active sessions.

10. The method of claim 1, further comprising receiving the transaction by the second network application at the logical session, and adding the transaction to a buffer.

11. The method of claim 10, further comprising updating the available buffer space for the logical session to indicate that the transaction has been added to the buffer.

12. The method of claim 10, further comprising processing a received transaction from the buffer for the logical session by the second network application.

13. The method of claim 12, further comprising generating and sending an ACK packet, wherein the ACK packet carries instructions to update a session buffer, to the first network application by the second multiplexer application, indicating that buffer space is available for the logical session.

27. A computer-readable storage medium containing computer-executable instructions for performing the method of claim 1.

14. A system that multiplexes logical sessions over a physical connection comprising:

means for receiving at a first multiplexer application a plurality of SQL transactions from a first network application directed to a second network application, the second network application being a SQL server application, each of the plurality of SQL transactions associated with a separate logical session between the first network application and the second network application;

means for generating, for each of the plurality of SQL transactions, a packet based on the contents of the SQL transaction and comprising a session identifier identifying a logical session between the first network application and the second network application at the first multiplexer;

means for sending the generated packet to a second multiplexer, along with other generated packets if any, using a protocol supported by the physical connection; and

means for extracting the generated packet at the second multiplexer, along with other generated packets if any, from the protocol supported by the physical connection;

means for processing the generated packet at the second multiplexer to retrieve the SQL transaction; and

means for the SQL transaction;

identifying from the session identifier the logical session associated with the SQL transaction between the first network application and the second network application; and

when the packet is a data packet, forwarding the SQL transaction to the second network application, the forwarding the SQL transaction comprising checking if there is sufficient buffer space available for the session, and forwarding the transaction to the second network a lication if there is sufficient buffer space available.

15. The system of claim 14, further comprising:

means for routing the generated packet to the session, if the generated packet is a data packet; and

means for managing an available buffer for the session.

16. The system of claim 14, wherein the means for generating a packet further comprises means for assigning values to a packet header.

17. A method implemented in a computing system of communicating between a first network application and a second network application, comprising:

sending using an API a plurality of SQL transactions from the first network application directed to the second network application through one of a plurality of logical sessions, the SQL transactions comprising transaction data, the second network application being a SQL server application, each of the plurality of SQL transactions associated with a separate logical session between the first network application and the second network application;

receiving the plurality of SQL transactions at a first multiplexer, and formatting each of the plurality of SQL transactions to form a packet, wherein the packet comprises a logical session identifier field indicating the session used to send the transaction between the first network application and the second network application, and a data field containing the transaction data;

sending the packet from the first multiplexer to a second multiplexer across a network using a supported network protocol;

receiving the packet by the second multiplexer;

processing the packet by the second multiplexer, comprising removing the SQL transaction from the packet; and

for the SQL transaction;

identifying from the session identifier the logical session associated with the SQL transaction between the first network application and the second network application; and

forwarding the SQL transaction data to the second network application through the one of the logical session identified by the session identifier field, the forwarding the SQL transaction comprising checking if there is sufficient buffer space available for the session, and forwarding the transaction to the second network application if there is sufficient buffer space available.

18. The method of claim 17, wherein determining if there is buffer space available comprises checking a list of available buffer space for each session and if the available buffer space for the one of the plurality of communication sessions is greater than or equal to the amount required for the transaction, concluding that there is buffer space available.

19. The method of claim 17, further comprising updating the available buffer space for the one of the plurality of communication sessions to indicate that the transaction has been added to the buffer.

20. The method of claim 17, further comprising processing a received transaction from the buffer for the one of the plurality of communication sessions by the second network application.

21. The method of claim 20, further comprising generating and sending a packet to the first network application by the second multiplexer, indicating that buffer space is available for the one of the plurality of communication sessions.

22. The method of claim 17, wherein the packet further comprises:

a control flag field indicating the type of the packet;

a window identifier field indicating the available buffer space for the communication session;

a sequence number field indicating the order of the packet; and

a length field indicating the total length of the packet.

23. The method of claim 17, further comprising receiving the transaction by the second network application at the one of the plurality of communication sessions, and adding the transaction to a buffer.

28. A computer-readable storage medium containing computer-executable instructions for performing the method of claim 17.

24. A system, comprising:

a computing processor;

computing memory communicatively coupled with the computing processor, the computing memory having instructions for providing;

a first network application that sends a plurality of SQL transactions directed to a second network application, the second network application being a SQL server application, each of the plurality of SQL transactions associated with a separate logical session between the first network application and the second network application;

a first multiplexer that receives the plurality of SQL transactions from the first network application, generates for each of the plurality of SQL transactions a packet comprising the SQL transaction and a session identifier identifying a logical session between the first network application and the second network application, and sends the generated packet over a physical connection using a supported protocol, and

a second multiplexer that receives the generated packet over the physical connection using the supported protocol;

removes the generated packet from the supported protocol;

processes the generated packet;

identifies a logical session associated with the SQL transactions; and

forwards the SQL transactions to the second network application through the logical session, the forwarding the SQL transactions comprising checking if there is sufficient buffer space available for the session, and forwarding the transactions if there is sufficient buffer space available.

25. A system for communicating between a first network and a second network, comprising:

one or more computing processors;

computing memory communicatively coupled with the one or more computing processors, the computing memory having instructions for providing;

an application at a first network that sends a plurality of SQL transactions directed to a second application, the second application being a database application, each of the plurality of SQL transactions associated with a separate logical session between the first network application and the second network application;

a multiplexer at the first network that receives the plurality of SQL transactions from the application at the first network, generates, for each of the plurality of SQL transactions, a packet comprising the SQL transaction and a session identifier identifying a logical session between the first network application and the second network application, and sends the generated packet over a physical connection using a supported protocol to a second multiplexer at the second network;

a multiplexer at the second network that receives the generated packet over the physical connection using the supported protocol, removes the generated packet from the supported protocol, processes the generated packet, identifies a logical session associated with the SQL transactions; and

forwards the SQL transactions to the second network application through the logical session, the forwarding the SQL transactions comprising checking if there is sufficient buffer space available for the session, and forwarding the transactions if there is sufficient buffer space available.

26. A computer readable storage device having stored thereon computer readable instructions that, if executed by a computing system, cause the computing system to perform operations comprising:

receiving at a first multiplexer application a plurality of SQL transactions from a first network application directed to a second network application, the second network application being a SQL server application, each of the plurality of SQL transactions associated with a separate logical session between the first network application and the second network application;

for each of the plurality of SQL transactions, generating a packet comprising the SQL transaction and a session identifier identifying a logical session between the first network application and the second network application;

sending the generated packet through a physical connection to a second multiplexer application, using a supported network protocol;

receiving the generated packet through the physical connection using the supported protocol at the second multiplexer application;

retrieving the generated packet from the supported protocol;

processing the generated packet to retrieve the SQL transaction; and

for the SQL transaction;

identifying from the session identifier the logical session associated with the SQL transaction between the first network application and the second network application; and

when the packet is a data packet, forwarding the SQL transaction to the second network application at the logical session, the forwarding the SQL transaction comprising checking if there is sufficient buffer space available for the session, and forwarding the transaction to the second network application if there is sufficient buffer space available.