Performance Modeling and Benchmarking of Event-Based ... - DVS

4.2. PERFORMANCE MODELING PATTERN 57
Pattern 5: Time Controlled Pull II
Timer
1‘Disconnected!
T3
1‘Trigger!
Trigger
Store
1‘Event 1‘Event 1‘Event 1‘Event
Producer
T1
Broker
T2
Consumer
T2-I: Pull Event
Broker
Event
1 1
Consumer
Event
T2-II: Disconnect
Trigger Store
Trigger
1
1
Timer
Disconnected
Trigger Store
Trigger
1
1
Trigger Store
Trigger
T3: Connect
Timer
Disconnected
1
1
Trigger Store
Trigger
Figure 4.13: Time-controlled Pull Pattern
Characteristics
• Dynamic pull-based communication
• Time controlled behavior: the consumer connects frequently to the broker to pull all
waiting events after a certain time interval.
Example
An event consumer connects frequently to a broker to check whether notifications are waiting.
If yes, the consumer downloads all of them, closes the connection afterwards and waits for a
specified period of time before reconnecting.
Description
In this scenario we face again a time controlled pull-based communication behavior. In contrast
to Pattern 4, the consumer does not only pull one event per connection, but all event notifications
available at the broker. To reflect this, we introduce this pattern.
Similar to Pattern 4, the scenario can be described as a loop composed of four phases:
Phase I:
Phase II:
Phase III:
Phase IV:
Consumer is disconnected
Establish connection
Pull all available events
Consumer disconnects
Phase I, II and IV are comparable to the one of the previous pattern. However, Phase
III differs from Pattern 4, where the consumer tries to pull a fixed number (1) of Events. In the