Integrating Humans in Scientific Workflows

Support for Human Users
in Scientific Workflows

Diploma Thesis

Dimitrios Dentsas
Institute of Architecture of Application Systems

d.dentsas@googlemail.com

Contents
 Motivation
 Properties of Scientific Workflows
 Automation boundaries
 Roles of WS-HT and BPEL4People
 Integration of Humans
 Basics
 Message Structures & Communication Flows
 Outline Solutions
 Research Design
 SW4H – Scientific Workflows for Humans
 Abstract Architecture
 Using transactions
 Message-based Routing
 Demo – Editing a task
© Dimitrios Dentsas 2

Motivation

© Dimitrios Dentsas

Motivation

 Numerical simulations have become the third pillar of
science

 Analyzing and visualizing data-centric simulation results
is a highly repetitive process but nevertheless necessary

 Automation and orchestration of work units in scientific
simulations are needed

 Workflow-Management-Systems (WfMS) are an
established tool in the business domain for such
challenges
 Scientific Workflow Management Systems (SWfMS)

Motivation – Automation boundaries
 Simulation steps cannot be fully automated if:
 The requirements for automation are too difficult to meet
 The „decision making process“ can only be executed by
„cognitive entities“
 e.g. Quality assurance of simulation results
 Smart allocation of resources
 Controlling and manipulating critical parameters
 Scenario: Simulation executions over the weekend


Motivation – Current needs
 There is demand for a smooth integration of human users
in SWfMS
 Network-based communication channels are hardly ever
used

 Efficient management of simulation-related tasks
 Web service standards like WS-HumanTask and
BPEL4People are used in the business domain.
 As specifications they are part of the WS-*
 They determine how to integrate human users into business
processes
 The WS-BPEL language has to be extended


Motivation

[2]


Integration of Humans


Basics
 Cloud-based integration of applications
 Special requirements for integrating human users have to
be considered and managed
 Human Communication Flows are introduced in order to
reach these objectives
 In this paradigm all participants hold one of the following
roles:
 Communication Initiator
 Human Communication Manager
 Communication Services
 Communication Devices


Communication participants

© Dimitrios Dentsas [3] 10

Message structure
 We distinguish between two types of communication
parameters:
 Communication Parameters:
 Communication type (Notification, Response required/optional)
 List of all message receivers
 Communication channels (Skype, Chat, etc.)
 Further options (response schema, attachments, default responses)
 Communication Message Properties:
 subject
 body
 Importance level
 etc.


Message structure
 Messages consist of:
 Communication Request Message
 Communication Message
 Channel-Specific Message

[3]

Communication Flows – User Notification

[3]

Communication Flows – Response Required

[3]

Communication Flows – Response Optional

[3]

SW4H - Message structure
 Structure of all input and output XML messages of the
WSDL operations


SW4H - Message structure
 Structure of all input and output XML messages of the WSDL
operations


Outline
Solutions


Approach – The communication flow
 A multitude of different technical realization possibilities.
Two very popular ones are:
1. BPEL-Process
2. Message-oriented Middleware (MOM)
 EAI through Enterprise Integration Patterns
BPEL MOM
Pros • uniform modeling • Large open source
environment community
• Easier integration with
process fragments
Cons • Tight coupling with • Introduction of new
workflows dependencies by
using EAI-
Frameworks


Approach – The communication flow

 Requirements for EAI-Frameworks:
 Fault tolerance

 Guaranteed deliveries

 Scalability

 Support for popular protocols of the ISO/OSI application layer

Apache Camel
[4]
Apache ActiveMQ
[5]


Approach– Data model
 Don‘t reinvent the wheel!

 What similar solutions are there for the data model?
 Project Bangkok (Uni Stuttgart ) 
 Tempo (Intalio)
 Apache HISE (Incubator Project)

 Project Bangkok and Apache HISE are open source
implementations of the WS-Human Task specification.
 Tempo implements BPEL4People (REST APIs).


Project Bangkok

 An embedded Human Task Manager for Java

 APIs for client applications

 Support for:
 HumanTaskModel vs HumanTaskInstance

 People queries (logical people groups, literals)

 Task presentation

 User management


SW4H
 Scientific-Workflows-for-Humans (SW4H)
 Human Communication Manager
 What it is based on:
 Project Bangkok
 Apache Camel (Routing Engine)
 Apache ActiveMQ (Embedded Message Broker)

 What it offers:
 Web-frontend with a task worklist
 Easily integratable into the Eclipse platform
 A multitude of integrated Messaging Endpoints

 Exchangable Back-End systems for persistency (currently
MySQL)

SW4H – Abstract Architecture


Integration of new services
 Using a uniform Service Endpoint Interface (SEI)
 Service Integration API


Human Interaction Activity

 Implemented as a process
fragment

 Asynchronous communication
 One <invoke> activity

 One <pick> activity

 Conditional constructs with a
<if> activity

 Invoking the Communication
Inititation API
(sendMessage, onMessage)

SW4H – Communication Manager


Task-loop – A command interpreter

 The message body of coupled
devices is analyzed:
 #<command>( [-h] -p1 foo –p2 bar)
 forward
 resend
 useChannel
 stop
 fail
 claim
 start
 getUsers
 help
 release
 …

Task-loop – Parsing of XSD documents

 XML-Schema for describing tasks is analyzed with a XSD-Parser
 A proper subset of the XML-Schema spezification
 Simple types :
 Explicit and anonymous type definitions
 Primitive data types:
 string, decimal, integer, boolean, date, time
 Restrictions and facets:
 enumeration, maxinclusive, mininclusive, maxexclusive, length, maxlength, minl
ength, pattern, totaldigits
 Complex types:
 Explicit and anonymous type definitions
 Recursive complex types
 Child elements:
 sequence, choice, all
 Attributes:
 maxoccurs, minoccurs, required, optional


SW4H – Messaging


Implementation of the Communication Flows
 EIP-Diagram – The constituents are:


Implementation of the Communication Flows

 User Notification: The constituents are :
 Message: Header and body
 Recipient List: Content-based Routing
 Persistent Queues
 Endpoints: User-Devices


Transactional behavior
 Local transactions of the messaging layer
 Cooperation of the Spring JmsTransaction Manager with
the JMS Broker (ActiveMQ)

[6]


Transactional behavior
 Persistent Queues act as „Safe Havens“
 Reaching atomic behavior between queues

[7]

SW4H – Presentation Layer


SW4H Frontend – Use cases


SW4H Frontend – Login window


SW4H Frontend – Task window


SW4H Frontend – Invitation dialog


SW4H Frontend – Registration invitation


SW4H Frontend – My Devices


SW4H Frontend – My Services


SW4H Frontend – Registration form


SW4H Frontend – Eclipse integration


Editing a task


Communication Request Message

Communication
Parameters

XML-Schema of
the task

static user list


Demo Run – Contacting the HCM

 Using XMPP (Google GTALK)


Demo Run – The resulting response message

 The XSD-Parser processes all inputs and produces a
valid XML document

 Callback – The task is finished successfully and sends a
response message back to the workflow


Thank you for your attention
Questions?…
http://code.google.com/p/sw4h-2012/


List of references
(1) M.Sonntag,D.Karastoyanova: (2010) Next Generation Interactive Scientific
Experimenting Based On The Workflow Technology. 21st IASTED
International Conference on Modelling and Simulation.
(2) Schumm, David; Karastoyanova, Dimka: Integrating Humans in Scientific
Workflows: Integrate, Register & Communicate. In: The 4th SimTech Status
Seminar, 2011
(3) Schumm, David; Fehling, Christoph; Karastoyanova, Dimka;
Leymann, Frank; Rütschlin, Jochen: Processes for Human Integration in
Automated Cloud Application Management, Universität
Stuttgart, Technischer Bericht Nr. 2012/02, 2012.
(4) http://camel.apache.org/
(5) http://activemq.apache.org/
(6) Ian J. Taylor, Ewa Deelman, Dennis B. Gannon, and Matthew Shields.
2006. Workflows for E-Science: Scientific Workflows for Grids. Springer-
Verlag New York, Inc., Secaucus, NJ, USA.


End Of Document


Integrating Humans in Scientific Workflows

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