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

Broker
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1
48 Event 1
CHAPTER 4. State PERFORMANCE A
ENGINEERING OF EVENT-BASED SYSTEMS Not.
T2-II
Pattern 3: Standard Pub/Sub - Configurable No. of Subscribers
1‘Sub.
1‘Sub.A
Init T0 Controller
Configure Controlller
T2
Creates the configured no. of
notifications for each incoming Event.
1‘Event 1‘Event 1‘Notification 1‘Notification
Producer
T1
Publish Event
Broker
T3
Forward Event
Consumers
The Modi of Transition 2
T2 has four modi (T2-I to T2-IV), which
a) implement states in the Controller place
and
b) create a configured number of notification
tokens for each incoming event.
T2-III: State A
Controller
State A
Sub. B
1
1
1
1
1
Controller
State A
Sub. A
Broker
Not.
Controller
State A
State B
Broker
Event
1
1
1
1
T2-I
Switch to
State B
1
1
Switch to
State A
T2-II
Controller
State A
State B
T2-IV: State B
Controller
State B 1
Sub. A
1
1
1
1
Controller
State B
Sub. B
Broker
Not.
Figure 4.9: Standard Pub/Sub Pattern - Configurable No. of Subscribers
1‘Sub.
1‘Sub.A
Characteristics
Creates the configured no. of
• Init 1 : n communication T0 Controller (one event is consumed T2
notifications
by a configurable
for each
number
incoming
of consumers)
Event.
Configure Controlller
• Dynamic number of notifications
1‘Event 1‘Event 1‘Notification 1‘Notification
Example
A
Producer
dynamic number of T1 event consumers
Broker
subscribe to a topic. T3
Publish Event
Forward Event
Description
Consumers
In complex and flexible models we need the possibility to scale the number of notifications easily.
In these cases Pattern 2 is not applicable. As a consequence, we define Pattern 3 where the
number of notifications per event can be configured by the token count.
Pattern 3 is based on the underlying idea of Pattern 2 regarding the service demand. In
contrast to Pattern 2, the user can configure the number of notifications for each event simply
by adjusting the number of tokens named Subscriber in the system without modifying the