MESSAGE STATE MAINTENANCE AT A MESSAGE LOG

• US 20090132868A1
• Filed: 11/03/2008
• Published: 05/21/2009
• Est. Priority Date: 11/16/2007
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Gurunath, Pramond, Hill, Richard D., Srinivasan, Krishnan, Chkodrov, Gueorgui, Critchley, Craig A., Tarnavski, Tihomir, Morris, Mitchell G.
• Granted Patent: US 7,945,819 B2
• Time in Patent Office: Days
• US Class Current: 714/54
• CPC Class Codes: H04L 51/00 User-to-user messaging in packet-switching networks, transmitted according to store-and-forward or real-time protocols, e.g. e-mail
• CPC Class Codes: H04L 51/02 using automatic reactions or user delegation, e.g. automatic replies or chatbot-generated messages
• CPC Class Codes: H04L 51/42 Mailbox-related aspects, e.g. synchronisation of mailboxes

Abstract

The present invention extends to methods, systems, and computer program products for maintaining message state at a message log. Messages are accumulated at a message log in accordance with a message retention policy. Any of a variety of message capture assurances can be used when capturing a message from a message producer within a message log. A message becomes visible to message consumers after the outcome of writing the message is known (either failure or success). Messages are requested using (e.g., monotonically increasing) sequence numbers. Messages are also dropped from the message log in accordance with the message retention policy.

Claims

1. In a componentized messaging system including a sending computer system with a message log, a second different receiving computer system with a cursor, and a computer network, wherein the sending computer system and the receiving computer system are connected to the network, the componentized message system for delivering messages from a message producer to a message consumer, the message log for capturing messages for delivery to the message consumer, the cursor maintaining message state for the message consumer such that message consumer state is maintained separate from the sending computer system, a method for maintaining message log state, the method comprising:

an act of receiving a first message from the message producer that is to be stored in the message log;

an act of assigning a sequence number for the first message;

an act of indicating in the message log that the status of the first message is in doubt without making the portion of the message log corresponding to assigned sequence number visible to the cursor;

an act of attempting to write the first message to the message log;

an act of indicating the success or failure of writing the first message to the message log, success resulting in the assigned sequence number corresponding to the first message within the message log, failure resulting in the assigned sequence number not corresponding to any message within the message log;

an act of updating the status of the message to successful or failed based on the indicated success or failure of writing the message to the message log respectively; and

an act making the portion of message log corresponding to the assigned sequence number visible to the cursor subsequent to updating the status of the message.

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

an act of configuring the message log to retain messages in accordance with a drop oldest policy, the drop oldest policy indicating a threshold for an amount of storage space used to store messages in the message log such that when the threshold is reached, an older message is removed from the message log when it is requested that a new message be stored in the message log.

3. The method as recited in claim 2, further comprising:

an act of determining that the threshold would be exceeded by storing the first message in the message log; and

an act of dropping a previously received message from the message log in response to the determination so as to free up storage space for the first message.

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

act of configuring the message log to retain messages in accordance with a drop on acknowledgement policy, the drop on acknowledgement policy indicating that a message can be deleted when the cursor acknowledges receipt of the message.

5. The method as recited in claim 4, further comprising:

an act of receiving an acknowledgement range from the cursor subsequent to making the portion of message log corresponding to the assigned sequence number visible to the cursor, the acknowledgment range acknowledging receipt of a range of sequence numbers within the message log, the range of sequence numbers including the assigned sequence number; and

an act of freeing up space within the message log corresponding to the range of sequence numbers in response to receiving the acknowledgement range.

6. The method as recited in claim 1, further comprising prior to receiving the first message:

an act of providing an exactly once assurance for writing the first message to the message log, including;

an act of receiving a transaction ID for participating in a transaction to capture the first message within the message store; and

an act of enlisting in the transaction based on the transaction ID.

7. The method as recited in claim 6, wherein the act of indicating the success or failure of writing the first message to the message log comprises an act of indicating if the transaction committed or aborted, committing the transaction resulting in the assigned sequence number corresponding to the first message within the message log, aborting the transaction resulting in the assigned sequence number not corresponding to any message within the message log.

8. The method as recited in claim 7, further comprising:

an act of aborting the transaction;

an act of expressly indicating in the message log that the assigned sequence number does not correspond to any message;

an act of receiving a second transaction ID for participating in a second transaction to capture the first message within the message store subsequent to aborting the first transaction;

an act of enlisting in the second transaction based on the second transaction ID;

an act of assigning a second sequence number for the first message;

an act of committing the second transaction resulting in the second sequence number corresponding to the first message within the message log; and

an act of making a portion of message log corresponding to the second sequence number visible to the cursor.

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

an act of successfully writing the message to a durable data store prior to indicating the success or failure of writing the first message to the message log.

10. In a componentized messaging system including a sending computer system with a message log, a second different receiving computer system with a cursor, and a computer network, wherein the sending computer system and the receiving computer system are connected to the network, the componentized message system for delivering messages from a message producer to a message consumer, the message log for capturing messages for delivery to the message consumer, the cursor maintaining message state for the message consumer such that message consumer state is maintained separate from the sending computer system, a method for maintaining message log state, the method comprising:

an act of accumulating a plurality of messages from the message producer in the message log in accordance with a message retention policy;

an act of receiving a read request for a message from the cursor, the read request including a specified sequence number within the message log, the read request being for the next message subsequent to a specified sequence number within the message log;

an act of identifying the next sequence number after the specified sequence number that corresponds to a message; and

an act of returning the next sequence number and the corresponding message to the cursor.

11. The method as recited in claim 10, wherein the act of accumulating a plurality of messages in accordance with a message retention policy comprises an act of accumulating messages in accordance with a drop oldest message retention policy.

12. The method as recited in claim 10, wherein the act of accumulating a plurality of messages in accordance with a message retention policy comprises an act of accumulating messages in the message log in accordance with a drop on acknowledgment policy, the drop on acknowledgement policy providing an assurance that the cursor receives messages stored in the message log at least once.

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

an act of receiving an acknowledgement range from the cursor subsequent to returning the next sequence number and the corresponding message to the cursor, the acknowledgment range acknowledging receipt of a range of sequence numbers within the message log, the range of sequence numbers including the next sequence number; and

an act of freeing up space within the message log corresponding to the range of sequence numbers in response to receiving the acknowledgement range.

14. The method as recited in claim 10, wherein the act of identifying the next sequence number after the specified sequence number that corresponds to a message comprises an act of identifying a sequence number that is visible to the cursor.

15. The method as recited in claim 10, wherein the act of identifying the next sequence number after the specified sequence number that corresponds to a message comprises an act of passing over one or more other sequence numbers that do not correspond to messages, the one or more other sequence numbers being between the specified sequence number and the next sequence number in the message log.

16. A componentized messaging system for delivering messages from a message producer to a message consumer, the componentized message system comprising:

a sending computer system, the sending computer system comprising;

one or more processors;

system memory; and

a message log

a receiving computer system, the receiving computer system comprising;

one or more processors;

system memory; and

a cursor, the cursor configured to maintain message state for the message consumer such that message consumer state is maintained separate from the sending computer system;

a computer network, wherein the sending computer system and receiving computer are connected to the network; and

wherein the sending computer system further comprises one or more computer storage media having stored thereon computer-executable instructions for implementing a method for maintaining message log state, the computer-executed instructions, that when executed at one of the processors of the sending computer system, cause the sending computer system to perform the method, including performing the following;

accumulate a plurality of messages from the message producer in the message log in accordance with a message retention policy, including;

receiving a first message from the message producer that is to be stored in the message log;

assigning a sequence number for the first message;

indicating in the message log that the status of the first message is in doubt without making the portion of the message log corresponding to assigned sequence number visible to the cursor;

attempting to write the first message to the message log; and

indicating the success or failure of writing the first message to the message log, success resulting in the assigned sequence number corresponding to the first message within the message log, failure resulting in the assigned sequence number not corresponding to any message within the message log;

update the status of the message to successful or failed based on the indicated success or failure of writing the message to the message log respectively; and

make the portion of message log corresponding to the assigned sequence number visible to the cursor subsequent to updating the status of the message; and

provide messages to the cursor in response to message requests, including;

receiving a request for a message from the cursor, the request including a specified sequence number within the message log, the request being for the next message subsequent to a specified sequence number within the message log;

identifying the next sequence number after the specified sequence number that corresponds to a message; and

returning the next sequence number and the corresponding message to the cursor.

17. The componentized messaging system of claim 16, wherein the computer-executable instructions further comprise computer-executable instructions that when executed at one of the processors of the sending computer system, cause the sending computer system to:

receive an acknowledgement range from the cursor subsequent to making the portion of message log corresponding to the assigned sequence number visible to the cursor, the acknowledgment range acknowledging receipt of a range of sequence numbers within the message log, the range of sequence numbers including the assigned sequence number; and

free up space within the message log corresponding to the range of sequence numbers in response to receiving the acknowledgement range.

18. The componentized messaging system of claim 16, wherein the computer-executable instructions further comprise computer-executable instructions that when executed at one of the processors of the sending computer system, cause the sending computer system to:

provide an exactly once assurance for writing the first message to the message log, including;

receiving a transaction ID for participating in a transaction to capture the first message within the message store; and

enlisting in the transaction based on the transaction ID.

19. The componentized messaging system of claim 18, wherein the computer-executable instructions, that when executed at one of the processors of the sending computer system, cause the sending computer system to indicate the success or failure of writing the first message to the message log comprise computer-executable instructions, that when executed at one of the processors of the sending computer system, cause the sending computer system to indicate if the transaction committed or aborted, committing the transaction resulting in the assigned sequence number corresponding to the first message within the message log, aborting the transaction resulting in the assigned sequence number not corresponding to any message within the message log.

20. The componentized messaging system of claim 16, further comprising:

a durable store at the sending computer system, the durable store for storing messages that are successfully written to the message log.