Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Workflows and Agents
Markus Michael Geipel
Department of Computer Science
Technische Universitaet Muenchen
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Outline
1
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3
4
Workflows
Basics
Challenges
Multi Agent Systems
MAS Design
Challenges
Combining WF and MAS
Incentive
Related Work
My Ideas
More Standards
More Flexibility
More Fault Tolerance
Workflows for AOSE
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Basics
Challenges
Outline
1
2
3
4
Workflows
Basics
Challenges
Multi Agent Systems
MAS Design
Challenges
Combining WF and MAS
Incentive
Related Work
My Ideas
More Standards
More Flexibility
More Fault Tolerance
Workflows for AOSE
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Basics
Challenges
BPM
The acronym without proper definition
First of all: there is no definition!
However there are plenty of acronyms and buzz words:
Business Process: a recipe for achieving a commercial
result.
Business Process Reengineering and Redesign (BPR)
Workflows and Workflow Management Systems (WMS)
Enterprise Application Integration (EAI)
Supply Chain Management, Lean Management, Total
Quality Management, Six Sigma,
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Basics
Challenges
BPM Activities
What BPM gurus normally do
Activities in BPM:
Designing processes
Analyzing processes
Enacting processes
The first two are supplementary to a business process. The
third will necessarily be entangles with the business process
and is thus critical.
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Basics
Challenges
Ingredients
What a workflow consists of
Workflows are a description of the implementation of a
business process. A workflow describes the . . .
participants
process steps (a.k.a. tasks or activities)
dependencies
decisions
deadline conditions
relevant data
applications
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Basics
Challenges
Representation
What a workflow looks like
Rules
Petrinets
Flowcharts
UML
EPK, ICN, OMT, RAD, SOM . . .
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Basics
Challenges
Example
Creating a new login at TIKI
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Basics
Challenges
Workflow Enactment
The workflow coming to life
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Basics
Challenges
Standardization
What a workflow management has to look like
The Workflow Management Coalition tries to impose standards
upon the industry (1999, 1995, 2002).
Among them:
Terms and Glossary
An abstract Architecture
Interfaces to the Workflow Engine:
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2
3
4
5
A Workflow Description Language, XPDL
Workflow Client Applications
Invoked Applications
Other Workflow Enactment Services
Administration and Monitoring Tools
However, big companies like IBM have their own ones.
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Basics
Challenges
Actual Problems
Causes and Symptoms
rigidity
loss of productivity
bad user acceptance
loss of flexibility
central control
bad user acceptance
single point of failure
unsuited for transnational corporations
bad exception handling
(Ellis, 1999;
Swenson and Irwin, 1995;
Georgakopoulos et al., 1995;
Nutt, 1996;
Alonso and Mohan, 1997)
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
MAS Design
Challenges
Outline
1
2
3
4
Workflows
Basics
Challenges
Multi Agent Systems
MAS Design
Challenges
Combining WF and MAS
Incentive
Related Work
My Ideas
More Standards
More Flexibility
More Fault Tolerance
Workflows for AOSE
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
MAS Design
Challenges
Properties of MAS
Literature ((Wooldridge, 2002) e.g.) refers to MAS as . . .
Distributed
Proactive
”Intelligent”
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
MAS Design
Challenges
MAS Design
what most AOSE methodologies advise
Models in Gaia:
Role Model
Models in ROAD-MAP:
Interaction Model
Goal Model
Agent Model
Plan Model
Service Model
Belief Model
Dependency Model
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
MAS Design
Challenges
Challenges
The complexity of MAS Design
MAS should make life easier in complex and distributed
domains. However . . .
Interactions in MAS are hard to specify (see also (Yan et
al., 2001))
concurrency makes it hard to keep track of all side effects
current BDI architectures are byzantine
AOSE methodologies stop right before it gets tricky
They don’t scale: e.g. even for toy-problems, Tropos
produces rather cryptic diagrams
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
MAS Design
Challenges
Challenges
A Tropos Example
(Bresciani et al., 2004)
And now try to implement all the interactions and debug!
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
MAS Design
Challenges
Challenges
Some personal impressions
Objective: Implement a simple communication scheme with
three agents.
use Jade:
With Jade alone it is hard to keep track of all possible agent
interactions.
Inconsistencies are unavoidable.
use Jadex
Jadex introduces a BDI Architecture.
A mixture of XML and Java makes jadex a debugging
nightmare.
Conjecture: Behind all of Jadex’s syntactic sugar lurks a
mere reflex agent.
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
MAS Design
Challenges
Challenges
The gap between Design and Implementation
Proposition 1: There is a wide gap between design and
implementation!
Proposition 2: All the models used in AOSE are secondary,
what we really want the agents to do is correctly
execute processes.
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Incentive
Related Work
Outline
1
2
3
4
Workflows
Basics
Challenges
Multi Agent Systems
MAS Design
Challenges
Combining WF and MAS
Incentive
Related Work
My Ideas
More Standards
More Flexibility
More Fault Tolerance
Workflows for AOSE
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Incentive
Related Work
Combining Workflows and MAS
Idea: Let’s combine Workflows and MAS in the hope
that all their disadvantages will cancel out.
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Incentive
Related Work
Related Work
Huhns and Singh (1998) hold the opinion that multi agent
technology has the potential to naturally address.
Gang et al. (2000) present workflow agents for e-business.
However they only describe a mobile agent
architecture.
M. et al. (1997) show how the theory of reflective agents can
be used to tackle dynamic change in workflows.
Kaldoudi et al. (1997) use workflow enacting agents to address
the challenges of distribution and heterogeneity in
workflow scenario in the health care domain.
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Incentive
Related Work
Related Work
Kaldoudi et al. first to propose an actual multi agent
architecture including a workflow agent, a
manager agent and a resource agent. refer to the
WfMC standards (Workflow Management
Coalition, 1995).
Kaiser et al. (1999) concentrate on remote execution of
workflow tasks by mobile agents, they call
worklets. Worklets are written in JPython.
Stormer and Knorr (2001) introduce an elaborated architecture
for workflow execution that includes even PDAs.
Agent role scheme includes workflow agents,
process agents, task agents, work-list agents as
well as personal agents. However no standard is
addressed.
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Incentive
Related Work
Current Situation
There are no recent breakthroughs.
Current workflow literature doesn’t even mention
Workflow-Agents: (Mueller, 2005) e. g.
java source.net, a well known source for open-source
workflow engines written in Java doesn’t list even a single
agent based engine.
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
More Standards
More Flexibility
More Fault Tolerance
Workflows for AOSE
My Ideas
1
2
3
4
Workflows
Basics
Challenges
Multi Agent Systems
MAS Design
Challenges
Combining WF and MAS
Incentive
Related Work
My Ideas
More Standards
More Flexibility
More Fault Tolerance
Workflows for AOSE
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
More Standards
More Flexibility
More Fault Tolerance
Workflows for AOSE
More Standards
Bringing standards together:
FIPA
WfMC
Bringing technologies together:
Workflow Management (XPDL)
Multi Agent Systems (Jade)
Ontologies (OWL)
Business Rules (Jena, Proova e.g.)
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
More Standards
More Flexibility
More Fault Tolerance
Workflows for AOSE
More Flexibility
Decouple the enactment from the strict workflow definition:
Interpret change of control locus as an interface
Give an Agent the right to change its tasks, with the
restriction to stay interface compliant
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
More Standards
More Flexibility
More Fault Tolerance
Workflows for AOSE
More Reasoning
Ingredients of a Workflow-agent Knowledge-base:
Ontologies
Workflow Ontology
Domain Ontology
Data
Workflow Data
Domain Data
Rules
OWL Rules
Workflow Rules
Domain Rules
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
More Standards
More Flexibility
More Fault Tolerance
Workflows for AOSE
More Reasoning
Some ideas to map the XPDL model to the BDI framework:
Successfully terminating a process could be a root goal
Activities could be plan steps
Applications or tools could be actions
Postconditions of activities could be subgoals.
Process information could be beliefs
Workflows could be plans (note the similarity to the
STRIPS notation for plans)
We can also describe the BDI framework with an ontology . . .
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
More Standards
More Flexibility
More Fault Tolerance
Workflows for AOSE
More Reasoning
Change the way to think about Workflows:
Don’t define what to do
Define what to achieve
Define the ways to achieve it
Proposition: The ways to achieve a goal are always flexible.
However the goal itself is not.
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
More Standards
More Flexibility
More Fault Tolerance
Workflows for AOSE
More Fault Tolerance
We can gain fault tolerance by . . .
the before mentioned reasoning
defining rollback actions for each action, such that rollback
workflows can be generated on the fly.
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
More Standards
More Flexibility
More Fault Tolerance
Workflows for AOSE
Workflows for AOSE
Use workflows during the . . .
Design
The processes in a MAS can be defined with
workflows.
This implies all the interactions, so most of the
common AOSE diagrams can be created
automatically.
Implementation may bridge the gap between design and
implementation, by allowing direct execution.
Note that unlike the common AOSE methodologies, workflows
scale to problem domains as big a the value chains of ’Fortune
500’ corporations!
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Summary
What you should remember . . .
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5
Workflows are the implementation of a business process
Workflow engines have several severe drawbacks
MAS may hold the promise to take on these drawbacks
So far, nobody presented an architecture that stands the
trial
I presented Ideas how to make workflow enactment
more standardized
more flexible
more ”intelligent”
more fault tolerant
6
I put forth the proposition that workflows are a valuable tool
for designing MAS
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Summary
Thanks for your patience.
Please ask critical questions.
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Alonso G, Mohan C (1997)
Workflow management systems: The next generation of
distributed procesing tools.
Bresciani P, Giorgini P, Giunchiglia F, Mylopoulos J, Perini A
(2004)
Tropos: An agent-oriented software development
methodology.
Ellis CA (1999)
CSCW, chapter Chapter 2
John Wiley and Sons, New York.
Gang W, Quanyuan W, Huaimin W (2000)
A novel workflow management model based on mobile
agents for internet electronic commerce
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
In 36th International Conference on Technology of
Object-Oriented Languages and Systems. TOOLS Asia.
Georgakopoulos D, Hornick MF, Sheth AP (1995)
An overview of workflow management: From process
modeling to workflow automation infrastructure.
Distributed and Parallel Databases 3:119–153.
Huhns MN, Singh MP (1998)
Workflow agents.
IEEE Internet Computing 2:94–96.
java source.net (2005)
Open source workflow engines in java
http://java-source.net/open-source/workflow-engines.
Kaiser G, Stone A, Dossick S (1999)
A mobile agent approach to lightweight process workflow
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Technical report, Columbia University, Department of
Computer Science, 1214 Amsterdam Avenue, MC
0401,New York, NY 10027, United States.
Kaldoudi E, Zikos M, Leisch E, Orphanoudakis S (1997)
Agent-based workflow processing for functional integration
and process re-engineering in the health care domain.
M. BU, P. B, P. M, Pareschi R (1997)
Reflective agents for adaptive workflows
In Proc. 2nd Int’l. Conf. on the Practical Application of
Intelligent Agents and Multi-Agent Technology (PAAM ’97),
pp. 405–420, London, U. K. Blackpool, U. K.: The Practical
Application Company Ltd.
Mueller J (2005)
Workflow-based Integration
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
Springer-Verlag Berlin Heidelberg.
Nutt GJ (1996)
The evolution toward flexible workflow systems
In Distributed Systems Engineering.
Stormer H, Knorr K (2001)
Pda- and agent-based execution of workflow tasks
In Bauknecht K, Brauer W, M?ck T, editors, Proceedings of
the Informatik 2001 Conference, pp. pp. 968–973, Vienna,
Austria.
Swenson KD, Irwin K (1995)
Workflow technology: trade-offs for business process
re-engineering
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
In COCS ’95: Proceedings of conference on Organizational
computing systems, pp. 22–29, New York, NY, USA. ACM
Press.
Wooldridge MJ (2002)
An Introduction to MultiAgent Systems
John Wiley and Sons Ltd.
Workflow Management Coalition (1995)
The workflow reference model
http://www.wfmc.org/standards/model.htm.
Workflow Management Coalition (1999)
Terminology and glossary
http://www.wfmc.org/standards/model.htm.
Workflow Management Coalition (2002)
Xml process definition language
Markus Michael Geipel
Workflows and Agents
Workflows
Multi Agent Systems
Combining WF and MAS
Ideas
Summary
http://www.wfmc.org/standards/XPDL.htm.
Yan Y, Maamar Z, Shen W (2001)
Integration of workflow and agent technology for business
process management
In The Sixth International Conference on CSCW in Design,
London, Ontario, Canada.
Markus Michael Geipel
Workflows and Agents