Concurrency management component for use by a computer program during the transfer of a message

• US 5,675,796 A
• Filed: 08/16/1996
• Issued: 10/07/1997
• Est. Priority Date: 04/08/1994
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Hodges, Clark Douglas, Williams, Antony S., Posch, Johann
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): VU, VIET DUY
• Application Number:
  US08/699,137
• Time in Patent Office: 417 Days
• Field of Search: 395/701, 395/670, 395/671, 395/672, 395/601, 395/608, 395/615
• US Class Current: 718/100
• CPC Class Codes: G06F 9/547 Remote procedure calls [RPC]; Web services

Abstract

An improved mechanism for communicating between computer programs is provided. In a preferred embodiment of the present invention, a computer system has a source computer program, a destination computer program and a communication mechanism for sending a communication from the source computer program to the destination computer program. The communication mechanism contains a concurrency management mechanism for handling events when a communication is pending. The source computer program sends a communication to the destination computer program using the communication mechanism. While the remote communication is pending, the concurrency management mechanism of the preferred embodiment provides concurrency management. The source computer program then receives a reply to the communication from the destination computer program.

Claims

1. In a computer system having a source application program that receives events, a destination application program, and a communication mechanism for sending a message between the source application program and the destination application program, a method comprising the steps of:

providing a concurrency management mechanism to the source application program that processes events, wherein the source application program provides instructions to the concurrency management mechanism that indicate how to process the events;

sending a message from the source application program to the destination application program using the communication mechanism, wherein the concurrency management mechanism is invoked, the message requesting a reply from the destination application program to the source application program;

while the source application program is waiting for the reply to the message, receiving events by the source application program and processing the received events by the concurrency management mechanism in accordance with the instructions provided by the source application program to ensure that the source application program and the destination application program concurrently operate in a desirable manner; and

receiving the reply to the message from the destination application program after processing the received events.

2. The method of claim 1 wherein said step of processing the received events includes the step of processing the received events to allow the source application program to concurrently execute a plurality of paths of execution.

3. The method of claim 1 wherein the destination application program is waiting on the source application program to perform an action and wherein said step of processing the received events includes the step of processing the received events to prevent the source application program and the destination application program from becoming deadlocked.

4. A computer system comprising:

a source component for generating a first message and for outputting instructions;

a destination component for receiving the first message from the source component; and

a communication mechanism for sending the first message from said source component to said destination component and for receiving the instructions from said source component, said communication mechanism comprising;

a concurrency management component for executing the instructions received from said source component when a second message is received by said source component from a message source while said communication mechanism is sending the first message to said destination component and before the sending of the first message has completed, the instructions to manage concurrency on behalf of said source component to ensure that said source component and said destination component concurrently operate in a desirable manner.

5. In a data processing system having a memory for storing computer programs and a communication mechanism for sending a message between the computer programs in the memory, said computer programs including a source computer program and a destination computer program, a method comprising the steps of

providing instructions for processing messages to the communication mechanism;

sending a first message from the source computer program to the destination computer program via the communication mechanism, the first message including a request for a response to the first message from the destination computer program; and

receiving a second message from a message source at the source computer program;

determining whether the second message is a response from the destination computer program indicating that the first message was successful; and

when the second message is not a response from the destination computer program indicating that the first communication was successful, executing the instructions provided to the communication mechanism by the source computer program to determine how to process the second message.

6. The method of claim 5 wherein the data processing system has a plurality of computer systems and wherein said step of sending a first message includes the step of sending a first message from the source computer program on a first of the computer systems to the destination computer program on a second of the computer systems.

7. The method of claim 5 wherein the source computer program is a process and the destination computer program is a process separate from the source computer program and wherein said step of sending a first message includes the step of sending the first message from the source computer program to the destination computer program.

8. The method of claim 5 wherein the destination computer program has functions and wherein said step of sending a first message includes the step of invoking a function in the destination computer program by the source computer program.

9. The method of claim 5 wherein the data processing system has a plurality of computer systems connected to a local area network and wherein said step of sending a first message includes the step of sending the first message over the local area network from the source computer program on a first of the computer systems to the destination computer program on a second of the computer systems.

10. The method of claim 5 wherein the data processing system has a plurality of computer systems connected to a wide area network and wherein said step of sending a first message includes the step of sending the first message over the wide area network from the source computer program on a first of the computer systems to the destination computer program on a second of the computer systems.

11. The method of claim 5 wherein the communication mechanism communicates by placing the first message in a shared area in the memory of the computer system and wherein said step of sending a first message includes the step of sending the first message from the source computer program through the shared area of memory to the destination computer program.

12. The method of claim 5 wherein the destination computer program is waiting on the source computer program to perform an action and wherein said step of executing the instructions includes the step of executing the instructions to perform the action to prevent deadlock.

13. The method of claim 5 wherein said step of executing the instructions includes the step of executing the instructions to allow the source computer program to perform a plurality of lines of execution concurrently without crossing the lines of execution.

14. In a computer system containing a calling process, a plurality of remote processes and a communication mechanism, wherein the remote processes are in separate address space from the calling process, each process comprises procedures and each procedure is a plurality of instructions and the calling process can invoke the procedures of a first remote process, said invocation of one procedure of the first remote process being a remote procedure call, and a plurality of procedures being contingency procedures for processing messages received while the calling process is waiting for the remote procedure call to complete, a method for the calling process to invoke the remote procedure call comprising the steps of:

providing the contingency procedures to the communication mechanism so that the communication mechanism can process messages received while the calling process is waiting for the remote procedure call to complete;

while the calling process is waiting for the remote procedure call to complete,

receiving a first message from a second remote process and invoking a first of the contingency procedures in response to receiving the first message;

receiving a second message from a computer user and invoking a second of the contingency procedures in response to receiving the second message; and

receiving a reply to the remote procedure call, said reply indicating that the remote procedure call was unsuccessful but may be retried and invoking a third of the contingency procedures in response to receiving the reply.

15. The method of claim 14 wherein the calling process executes multiple threads of execution, wherein said step of providing the contingency procedures includes the step of providing the contingency procedures to allow the calling process to execute multiple threads of execution simultaneously.

16. The method of claim 14 wherein the calling process can wait on the remote process to perform a first action and wherein the remote process can wait on the calling process to perform a second action and wherein the calling process defines deadlock contingency procedures that allow the calling process to perform the second action to prevent deadlock, wherein said step of providing the contingency procedures includes the step of providing deadlock contingency procedures.

17. The method of claim 14 wherein said step of invoking the first of the contingency procedures includes the steps of:

maintaining states for the calling process, said states comprising an acceptable state for receiving messages and unacceptable states for receiving messages, said unacceptable states for receiving messages comprising permanent unacceptable states and temporary unacceptable states;

determining whether the calling process is in one of the acceptable states for receiving the first message by examining contents of the first message;

when the calling process is in one of the acceptable states for receiving the first message, sending the first message to the calling process;

when the calling process is in one of the unacceptable states for receiving the first message, determining whether the unacceptable state is a permanent unacceptable state or a temporary unacceptable state;

when the calling process is in a permanent unacceptable state, sending a third message to the remote process indicating that the calling process is unable to accept the first message; and

when the calling process is in a temporary unacceptable state, sending a fourth message to the remote process indicating that the remote process may resend the first message.

18. The method of claim 14 wherein said step of invoking the second of the contingency procedures includes the steps of:

determining an amount of time elapsed since the remote procedure call was invoked by the calling process;

determining to wait for the remote procedure call to finish when the amount of time elapsed is less than a predetermined amount of time;

querying the computer user whether to continue waiting for the remote procedure call when the amount of time elapsed is greater than a predetermined amount of time;

canceling the remote procedure call when the computer user indicates;

determining to wait for the remote procedure call when the computer user indicates; and

determining to perform actions indicated by the second message when the second message indicates manipulation of information displayed by a computer display.

19. The method of claim 14 wherein said step of invoking a third of the contingency procedures includes the steps of:

determining whether a fifth message has been received from a message source and is waiting to be processed;

when it is determined that the fifth message is waiting to be processed,

invoking the first of the contingency procedures to process the fifth message waiting to be processed; and

reinvoking the remote procedure call on the remote process;

when it is determined that the fifth message is not waiting to be processed,

querying the computer user whether to retry the remote procedure call, whether to cancel the remote procedure call or whether to switch execution of the computer system to the first remote process;

retrying the remote procedure call when the computer user indicates;

canceling the remote procedure call when the computer user indicates; and

switching execution of the computer system to the first remote process when the computer user indicates.

20. A computer-readable memory device that contains an interface data structure comprising a plurality of entries, the interface data structure for use in sending reply-based messages from a source application program to a destination application program using a communication mechanism in a computer system, the reply-based messages requesting replies from the destination application program to the source application program, the computer system having a concurrency management component that is provided to the source application program and that processes incoming messages by invoking functions contained in the interface data structure, wherein incoming messages are messages received by the source application program while the source application program is waiting to receive a reply from the destination application program to a reply-based message, the interface data structure being registered with the concurrency management component by the source application program, each entry comprising:

a function containing instructions provided by the source application program for use by the concurrency management component to process incoming messages received by the source application program while the source application program is waiting to receive a reply to a reply-based message from the destination application program.

21. In a computer system having a source application program, a destination application program, and a communication mechanism for sending a message between the source application program and the destination application program, a method comprising the steps of:

providing a concurrency management mechanism to the source application program to prevent the source application program and the destination application program from becoming deadlocked, wherein the source application program provides instructions to the concurrency management mechanism that indicate how to prevent becoming deadlocked;

invoking the concurrency management mechanism to send a message from the source application program to the destination application program, wherein the concurrency management mechanism invokes the communication mechanism to send the message to the destination application program, the message requesting a reply from the destination application program to the source application program;

while the source application program is waiting for the reply to the message,

receiving events by the concurrency management mechanism that are destined for the source application program; and

processing the received events by the concurrency management mechanism in accordance with the instructions provided by the source application program to prevent the source application program and the destination application program from becoming deadlocked; and

receiving the reply to the message from the destination application program after processing the received events.

22. In a computer system having a source computer program, a destination computer program, and a communication mechanism for sending messages in the computer system, the messages having types, a first type of the messages requesting replies from the destination computer program to the source computer program, a method comprising the steps of:

providing a concurrency management mechanism to the source computer program that processes incoming messages while the reply to a message of the first type is pending and not yet received by the source computer program, wherein incoming messages are a second type of the messages that are received by the source computer program while the reply to a message of the first type is pending;

configuring the concurrency management mechanism by the source computer program with functionality to process the incoming messages;

invoking the concurrency management mechanism to send one of the messages of the first type from the source computer program to the destination computer program, wherein the concurrency management mechanism invokes the communication mechanism to send the one message to the destination computer program;

while the reply to the one message is pending,

receiving incoming messages from the communication mechanism by the concurrency management mechanism, wherein the incoming messages are destined for the source computer program; and

processing the received incoming messages by the concurrency management mechanism .in accordance with the functionality configured by the source computer program to ensure that the source computer program and the destination computer program concurrently operate in a desirable manner; and

receiving the reply to the one message from the destination computer program after processing the received incoming messages.

23. The method of claim 22 wherein said step of configuring the concurrency management mechanism includes the step of providing the concurrency management mechanism with instructions for processing the incoming messages.

24. A computer-readable medium containing instructions for controlling a computer system to transfer messages, the computer system having a source application program that receives events, a destination application program, and a communication mechanism for sending messages between the source application program and the destination application program, by performing the steps of:

providing a concurrency management mechanism to the source application program that processes events, wherein the source application program provides instructions to the concurrency management mechanism that indicate how to process the events;

sending a message from the source application program to the destination application program using the communication mechanism, wherein the concurrency management mechanism is invoked, the message requesting a reply from the destination application program to the source application program;

while the source application program is waiting for the reply to the message, receiving events by the source application program and processing the received events by the concurrency management mechanism in accordance with the instructions provided by the source application program to ensure that the source application program and the destination application program concurrently operate in a desirable manner; and

receiving the reply to the message from the destination application program after processing the received events.

25. A computer-readable medium containing instructions for controlling a computer system to transfer messages, the computer system having a source application program, a destination application program, and a communication mechanism for sending messages between the source application program and the destination application program, by performing the steps of:

providing a concurrency management mechanism to the source application program to prevent the source application program and the destination application program from becoming deadlocked, wherein the source application program provides instructions to the concurrency management mechanism that indicate how to avoid becoming deadlocked;

invoking the concurrency management mechanism to send a message from the source application program to the destination application program, wherein the concurrency management mechanism invokes the communication mechanism to send the message to the destination application program, the message requesting a reply from the destination application program to the source application program;

while the source application program is waiting for the reply to the message,

receiving events by the concurrency management mechanism that are destined for the source application program; and

processing the received events by the concurrency management mechanism in accordance with the instructions provided by the source application program to prevent the source application program and the destination application program from becoming deadlocked; and

receiving the reply to the message from the destination application program after processing the received events.

26. A computer-readable medium containing instructions for controlling a computer system to transfer messages, the computer system having a source computer program, a destination computer program, and a communication mechanism for transferring the messages in the computer system, the messages having types, a first type of the messages requesting replies from the destination computer program to the source computer program, by performing the steps of:

providing a concurrency management mechanism to the source computer program that processes incoming messages while the reply to a message of the first type is pending and not yet received by the source computer program, wherein incoming messages are a second type of the messages that are received by the source application program while the reply to a message of the first type is pending;

configuring the concurrency management mechanism by the source computer program with functionality to process the incoming messages;

invoking the concurrency management mechanism to send one of the messages of the first type from the source computer program to the destination computer program, wherein the concurrency management mechanism invokes the communication mechanism to send the one message to the destination computer program;

while the reply to the one message is pending,

receiving incoming messages from the communication mechanism by the concurrency management mechanism, wherein the incoming messages are destined for the source application program; and

processing the received incoming messages by the concurrency management mechanism in accordance with the functionality configured by the source computer program to ensure that the source computer program and the destination computer program concurrently operate in a desirable manner; and

receiving the reply to the one message from the destination computer program after processing the received events.

27. The instance of computer-readable media of claim 26, wherein said step of configuring the concurrency management mechanism includes the step of providing the concurrency management mechanism with instructions for processing the incoming messages.