Consider how to address the impractical assumptions we made in order to meet the validity and agreement properties for the reliable multicast protocol based on IP multicast. Hint: add a rule for deleting retained messages when they have been delivered everywhere, and consider adding a dummy ‘heartbeat’ message, which is never delivered to the application, but which the protocol sends if the application has no message to send.
What will be an ideal response?
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A process can delete a retained message when it is known to have been received by all group members. The latter condition can be determined from the acknowledgements that group members piggy back onto the messages they send. (This is one of the main purposes of those acknowledgments; the other is that a process may learn sooner that it has missed a message than if it had to wait for the sender of that message to send another one.)
A group member can send periodic heartbeat messages if it has no application-level messages to send. A heartbeat message records the last sequence number sent and sequence numbers received from each sender, enabling receivers to delete message they might otherwise retain, and detect missing messages.
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What will be an ideal response?
The item marked 9 in the accompanying figure is the ____ Tool.
A. Oval Primitive B. Deco C. Rectangle Primitive D. PolyStar
Which of the following will allow the user to input the values 15 and 20 and have them stored in variables named base and height, respectively?
a. cin << base << height; b. cin base, height; c. cin >> base >> height; d. cin base >> cin height; e. None of these
A(n) ____ is a set of structures in which each structure contains at least one member whose value is the address of the next logically ordered structure in the list.
A. array B. stack C. queue D. linked list