The document proposes an event actors based approach to support analysis and verification of event-driven architectures. It introduces event actors as computational units that interact through well-defined event-based interfaces. The approach aims to reduce non-determinism while preserving loose coupling. Event actors and their relationships are mapped to Petri nets for formal analysis and verification of properties like dead execution paths and deadlocks. The approach provides intuitive abstractions grounded in formal methods to enhance understanding and analysis of event-driven systems.

1. Event Actors Based Approach for
Supporting Analysis and Verification of
Event-Driven Architectures
Huy Tran and Uwe Zdun
Software Architecture Group
Faculty of Computer Science
University of Vienna, Austria.
http://cs.univie.ac.at/swa

2. 2
About Us
Software Architecture Group @ University of Vienna, Austria
 Founded in 2010
 1 University Professor
 1 Post-doctoral Researcher
 7 Pre-doc Research Assistants
 Research areas
 software architecture, distributed systems, event-driven
architecture, model-driven software development, service-
oriented computing

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Content
Problem
Verification supports for event-driven software
systems
1
Proposed Solution
Event actors, event-based interfaces, Petri Nets
Summary
Achievements, lessons learned, future directions
2
3

4. 4
Problem
Context: Event-driven architectures
Event Publishers Event Consumers
Event
Channel/Bus

5. 5
Problem
Context: Event-driven architectures
SmartFlow Project

6. 6
Problem
Context: Event-driven architectures
EBBITS Project

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Problem
Summary
 Event-driven architectures
+ Loose coupling
+ Independent execution
+ Potential for flexibility, scalability and
concurrency
- Inherently non-deterministic
- Challenging for understanding and analyzing
(esp. large architecture designs)
- Limited supports for verifications (mostly low-
level abstractions, i.e., pub/sub)
A
B
event
event
event

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Proposed Solution
 Reducing non-determinism while preserving loose
coupling, flexibility
 Well-defined event-based interfaces
 Easy-to-understand abstractions
 Close to traditional constructs: sequence, branching, etc.
 Textual vs. graphical
 Supports for analysis by grounding on formal
specifications
 Process algebras, Petri Nets, etc.

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Proposed Solution
Reducing non-determinism
event(s) event(s)
Event-based interface
input output

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Proposed Solution
Easy-to-understand abstractions

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Proposed Solution
Grounding on formal specifications

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Dynamic Event-Driven Actors (DERA)
Overview
Developer
develops
Snapshot
analyzes &
verifies
Execution Domain
Execution Domain
Execution Domain
event
bridge
DERA Engine
deploys
Petri nets
description
(e.g., PNML)
DeraLang
captures
translates
translates

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Dynamic Event-Driven Actors (DERA)
Meta-model of DERA primitives

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Dynamic Event-Driven Actors (DERA)
DERA Primitives: Computational Unit
Event Actor
• computational unit or data
processing
eTruck
Arrived
eFreeDock
Requested
TruckMonitor

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Dynamic Event-Driven Actors (DERA)
DERA Primitives: Branching Unit
Condition
• branching unit (i.e.,
if-then-else)
eStoring
Finished
isStoring
Finished
eUnit
Stored
eStoring
NotFinished

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Dynamic Event-Driven Actors (DERA)
DERA Primitives: Synchronization Unit
Barrier
• synchronization unit
eTruck
Moved
eUnloading
Started
Synchronizer
eCamera
Received

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Dynamic Event-Driven Actors (DERA)
DERA Primitives: Domain Bridging Unit
Event Bridge
• connect two domains
Yard Management Domain
Warehouse Management Domain
YMS-to-WMS

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Grounding DERA constructs on Petri Nets
General Petri Nets representation of DERA constructs
General Petri Nets representation of a “connection”

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Grounding DERA constructs on Petri Nets

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Dynamic Event-Driven Actors (DERA)
An example of mapping a DERA-based system to Petri Nets

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DERA-based system verifications
Dead execution paths

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DERA-based system verifications
Deadlocks (jamming before reaching the end)

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DERA-based system verifications
Livelocks (trapping in endless cycles)

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Summary
Achievements, lessons learned, and future directions
 Reducing non-determinism is important to
enhance supports for understanding and analyzing
event-based systems
 Intuitive notational abstractions, which are
 close to traditional constructs: important for lessening
the learning-curve
 grounded on formal specifications: enabling formal
verifications
 Potential future directions
 additional constructs
 other aspects: data, fault handling, temporal, etc.
 inter-domain specifications and verifications

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Many thanks for your attention!
Huy Tran
huy.tran@univie.ac.at
Research Group Software Architecture
Faculty of Computer Science
University of Vienna, Austria.
http://cs.univie.ac.at/swa