Avalanche control for video on demand session setup

1 . A method for managing session setup requests for video on demand sessions, comprising:

a) operating in a normal mode when a session setup request arrival rate is below a normal transition boundary; and

b) transitioning from the normal mode to a coalescing mode when the session setup request arrival rate rises above a coalescing transition boundary.

2 . The method of claim 1 , wherein:

the normal mode comprises processing each session setup request individually; and

the coalescing mode comprises coalescing a plurality of session setup requests into a batch of session setup requests.

3 . The method of claim 2 , wherein the coalescing mode further comprises:

j) processing the batch of session setup requests collectively.

4 . The method of claim 3 , wherein the coalescing mode further comprises:

k) forming a first batch of session setup requests; and

l) forming at least a second batch of session setup requests before initiating the processing of the first batch of session setup requests.

5 . The method of claim 1 , further comprising:

c) after step b), transitioning from the coalescing mode to the normal mode when the session setup request arrival rate falls below the normal transition boundary.

6 . The method of claim 1 , wherein the coalescing transition boundary and the normal transition boundary have the same value.

7 . The method of claim 1 , wherein the coalescing transition boundary is greater than the normal transition boundary, and the method further comprises:

d) prior to step b) continuing operation in the normal mode when the session setup request arrival rate:

i) rises above the normal transition boundary, and

ii) lies below the coalescing transition boundary.

8 . The method of claim 5 , wherein the coalescing transition boundary is greater than the normal transition boundary, and the method further comprises:

e) prior to step c), continuing operation in the coalescing mode when the session setup request arrival rate:

i) falls below the coalescing transition boundary, and

ii) lies above the normal transition boundary.

9 . The method of claim 1 , wherein the session setup request arrival rate comprises a rate at which session setup requests are received by a session manager, and the method further comprises:

f) monitoring arrival of the session setup requests at the session manager; and

g) controlling transition between the normal mode and the coalescing mode based on the monitoring.

10 . The method of claim 1 , wherein the session setup request arrival rate comprises a rate at which session setup requests are received by a session manager, and the method further comprises:

i) during operation of the session manager in the normal mode or the coalescing mode, dynamically varying at least one of the normal transition boundary and the coalescing transition boundary.

11 . The method of claim 10 , wherein dynamically varying at least one of the normal transition boundary and the coalescing transition boundary controls a frequency of transitions between the normal mode and the coalescing mode.

12 . The method of claim 1 , wherein at least one of the coalescing transition boundary and the normal transition boundary is dynamically varied according to a subscriber volume to a real-time transmission of digital video content.

13 . The method of claim 1 , wherein at least one of the coalescing transition boundary and the normal transition boundary is dynamically varied according to an availability of network resources.

14 . Processor-accessible storage media comprising processor-executable instructions, that when executed, direct a computer system to perform the method as recited in claim 1 .

15 . A method for processing requests for video on demand sessions, comprising:

a) monitoring session setup requests received by a session manager;

b) determining a session setup request arrival rate, wherein the session setup request arrival rate comprises a rate of arrival of the session setup requests at the session manager;

c) operating the session manager in a normal mode when the session setup request arrival rate is below a coalescing transition boundary;

d) transitioning operation of the session manager from the normal mode to a coalescing mode when the session setup request arrival rate rises above the coalescing transition boundary;

e) continuing operation of the session manager in the coalescing mode when:

i) the session setup request arrival rate falls below the coalescing transition boundary, and

ii) the session setup request arrival rate lies above a normal transition boundary, wherein the normal transition boundary is less than the coalescing transition boundary; and

f) transitioning operation of the session manager from the coalescing mode to the normal mode when the session setup request arrival rate falls below the normal transition boundary.

16 . The method of claim 15 , wherein step c) comprises continuing operation in the normal mode when the session setup request arrival rate:

i) rises above the normal transition boundary, and

ii) lies below the coalescing transition boundary.

17 . The method of claim 15 , wherein:

the normal mode comprises processing each session setup request individually,

the coalescing mode comprises coalescing a plurality of session setup requests into a batch of session setup requests and processing the batch of session setup requests collectively.

18 . A session manager for managing session setup requests for video on demand sessions, comprising:

a state machine configured to transition the session manager from a normal mode of operation to a coalescing mode of operation when a session setup request arrival rate rises above a coalescing transition boundary.

19 . The method of claim 18 , wherein:

the normal mode comprises processing each session setup request individually,

the coalescing mode comprises coalescing a plurality of session setup requests into a batch of session setup requests and processing the batch of session setup requests collectively.

20 . The session manager of 19 , wherein the state machine is further configured to transition the session manager from the coalescing mode to the normal mode when the session setup request arrival rate falls from at least the coalescing transition boundary to below a normal transition boundary.

21 . The session manager of claim 20 , wherein:

the coalescing transition boundary is greater than the normal transition boundary, and

the state machine is further configured to operate the session manager in the normal mode when the session setup request arrival rate:

i) rises above the normal transition boundary, and

ii) lies below the coalescing transition boundary.

22 . The session manager of claim 21 , wherein:

the coalescing transition boundary is greater than the normal transition boundary, and

the state machine is further configured to operate the session manager in the coalescing mode when the session setup request arrival rate:

i) falls below the coalescing transition boundary, and

ii) lies above the normal transition boundary.

23 . The session manager of claim 22 , wherein:

each of the session setup requests includes a channel number associated with a video on demand session; and further comprising setting up a session, wherein setting up a session comprises at least one of:

i) translating the channel number to a content identifier, wherein the content identifier identifies content related to the video on demand session,

ii) authorizing a client's entitlement to access the content identified by the content identifier, and

iii) retaining network resources for the video on demand session.