BondFlow: A Platform for Distributed Workflows over Web Services

1
BondFlow A Platform for Distributed Workflows
over Web Services

• Janaka Balasooriya
• Department of Computer Science
• University of Missouri Rolla
• The BondFlow System was Developed
• in the Department of Computer Science
• Georgia State University

2
Agenda

• Web Services Infrastructure and Research Issues.
• Distributed Workflows Over Web Services.
• Web Coordination Bonds
• Web Service Coordination Management Middleware
• BondFlow System
• Future Directions.
• The BondFlow system as a web based tool kit
• Incorporate WS-Security protocol in Web
  Coordination Bonds
• Minimum set of coordination primitives for web
  service coordination
• QA.

3
Web Services Hide Network and System
Heterogeneity

• Conventional Distributed Systems
• Conventional middleware and Enterprise
  Application Integration (EAI) technologies have
  limited success.
• Lacks interoperability.

RMI
B
Inter-Operability Protocols
C
A
CORBA
COM

• Web Services
• Uniform interface (WSDL Web Service Description
  Language)
• Common communication platform (SOAP Simple
  Object Access Protocol)
• Hide the network and system heterogeneity.

4
Web Services Infrastructure Current State of the
Art
Directory
Web Services Can be
Look up

• Identified by a Uniform Resource Identifier
  (URI)
• Described and discovered
• Composed to create complex applications
• Loosely coupled

Publish
Service Requestor
WSDL
WS
Invoke/Response (SOAP)
Web Service Infrastructure Current State of the
Art
5
Proliferation of The Web Service Technology

• Applicable In Many Application Domains
• E-Commerce (Supply Chain, Banking, Travel
  Application)
• Scientific applications (bio-medical, space
  exploration )
• Open Grid Service Architecture (Open Grid
  Services Architecture).

Statistics

• Web services based projects will reach 11
  billion by 2008, compared to 1.1 billion in 2003
  International Data Coorporation,
  http//www.idc.com.
• A Gartner (http//www.gartner.com) survey of 110
  companies also indicates that 54 are already
  working on or planning to work on Web services
  projects.

6
Web Service Applications Purchase Order Workflow
Receive Purchase Order
(RPO)
Initiate Product Scheduling
Decide on Shipper
Initiate Price Calculation
PS
PC
DS
Complete Price Calculation
Complete Product Scheduling
Arrange Logistics
Invoice Processing
(IP)
7
Web Service Application Development Current
Practice and Research Issues

• Web Service Based Workflow Applications
• Web services are distributed across the network.

IPS

• Web service composition.

Composite Web Process

• Issues
• Detailed level Programming Confined only to
  expert users.
• Centralized Coordination Web services are not
  live participants.

Developing Purchase Order Workflow Current
Practice
8
Current State of the Art

• Centralized Coordination

• Web services are not active participants
• Composite applications require
• Centralized coordination
• Significant application development effort
• Performance and Security issues

• Many Workflow Composition Languages

• Currently, too many standards for Web service
  composition and coordination
• No fundamental Web service composition
  framework
• Solutions are not elegant
• Fundamental issues have not been filtered out

9
Workflow Languages (http//www.ebpml.org/status.ht
m)
10
Our Vision
BondFlow System

• Core set of primitives for web service
  coordination - Web Coordination Bonds

WSCMM
WS

• Extend the Web service infrastructure beyond the
  basic service architecture (invoke and respond)
  Web Coordination Management Middleware (WSCMM)

Bonding Artifacts
WSCMM
WS
WSCMM
WS
WSCMM
WS

• Workflow configuration and execution platform

11
Web Coordination Bonds Analogy Between Web Bonds
and Chemical Bonds
Chemical Bonding
H

• Chemical Bonds Simple but powerful enough to
  produce complex compounds.

C
C
H
H
H
CH4
Four H atoms and One C atom
12
Web Coordination Bonds

• Web Bonds enables an application to create and
  enforce interdependencies, constraints and
  automatic updates among groups of Web entities
  HICSS, 04.
• Two types Negotiation bonds and Subscription
  bonds
• Subscription Bonds

Semantics
Hotel (B)
Subscription Bond Change A then Try Change B,
Change C.
Flight (A)
Pickup (C)

• Automatic flow of information.

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Negotiation Bond

• Negotiation bonds enforce
• Dependencies and constraints across entities
• Trigger changes based on constraint
  satisfaction.

B
Verify product availability
A
C
Online purchase
Verify payment Information
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Modeling Dependencies Using Web Bonds
Consumer web process
Produce web process
Negotiation bond
PlaceOrder()
AcceptOrder()
Subscription bond
Negotiation bond
Accept Delivery ( )
Dispatch Goods ( )
Producer-Consumer Relationship

• How capable web bonds are?

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Capabilities of Web Coordination Bonds
Modeling Power

• Web bonds have the modeling power of extended
  Petri nets (Petri net with inhibitor arcs) HICSS
  05.
• Web bonds can express all the benchmark
  patterns for workflows and for inter-process
  communication HICSS 05.

Expressiveness
-
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Expressiveness Modeling Benchmark Workflow
Control Flow Patterns
Sequence Using Web Bonds
Sequence
A
B
C
A
B
C
AND split followed by AND join using web bonds
AND split followed by AND join
B
B
A
C
E
E
A
C
D
D
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Our Vision and Contributions
BondFlow System

• Core set of primitives for web service
  coordination - Web Coordination Bonds

WSCMM
WS

• Extend the Web service infrastructure beyond the
  basic service architecture (invoke and respond)
  Web Coordination Management Middleware (WSCMM)

Bonding Artifacts

• Workflow configuration and execution platform

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Analogy Evolution of Database Applications vs
Web Service Applications
Proposed development for Web service
infrastructure
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Web Service Coordination Management Middleware
Requirements ICWS 06
High-level Description of the workflow
Composite Web process Code
Enforce Workflow Dependencies
WSCMS
Enorce Workflow Dependencies (Coodrination
Context)
IPS
Preserve State Information, WS Method
invocation
Process Messages
WSMS
Communication handling (Message Correlation,
State)
Composite Web Process
Stateless Web Service
Stateless Web Service
Functional decomposition of composite web
process ICWS 06
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Web Service Coordination Management Middleware
An Overview
WF j
WF k
WF i

• WSMS
• Preserve state
• Process messages
• Coordinator proxy object
• WSCMS
• Maintain coordination Information
• Enforce workflow dependencies

SOAP/Messaging System
Message Handler
WSMS
WSCMS
i
k
j
i
j
k
Coordination context
Coordinator object handler
Web Service
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Coordinator Proxy Object

• The coordinator object provides the same
  interface as the web service provides to the
  outer world.
• Web service method invocations of the workflow
  take place through the coordinator object.
• The web bond coordination layer ensures that pre
  and post method invocation dependencies are
  satisfied.

The Coordinator Proxy Object
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Flow Within a Coordinator Object

• Each web service method call is encapsulated by
  pre and post dependency check.

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Our Vision and Contributions
BondFlow System

• Core set of primitives for web service
  coordination - Web Coordination Bonds

WSCMM
WS

• Extend the Web service infrastructure beyond the
  basic service architecture (invoke and respond)
  Web Coordination Management Middleware (WSCMM)

Bonding Artifacts

• Workflow configuration and execution platform

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BondFlow System Architecture HCW 05

• Web service interface module
• Proxy object generator module
• Workflow configuration module
• Execution module.
• Handheld based Execution MW 04

Web Service Interface Module
Lookup for Web services
Web Services Registry (UDDI)
S O A P
WS Locator
WSDL
WSDL Parser
Parsed WSDL
Workflow Execution Module
Proxy Object Generator Module
Web Bond Runtime
SOAP/ SyD
Workflow Configuration Module
JVM
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BondFlow System Developers Perspective
Search web service (WS)-UDDI directory
WSDL parser
Select suitable WSs for the workflow
Coordinator objects
Configure workflow
Select WS pairs for bonding
Create bonds between methods of selected WS
pairs.
Execute workflow
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Distributed Workflow Execution of the BondFlow
System
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Book Price Workflow
BN
CE
eB
AM
Barnes and Noble Price Quote (http//www.xmethod
s.net/sd/2001/BNQuoteService.wsdl )
eBay Price Watcher (http//www.xmethods.net/sd/
2001/EBayWatcherService.wsdl  )
Amazon Query Service (http//majordojo.com/amazo
n_query/amazon_query.wsdl )
Currency Exchange (http//www.atlaz.net/webserv
ices/GetCurrencyExchange.wsdl  )
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Purchase Order Workflow Using Web Bonds
Receive Purchase Order
Initiate Product Scheduling
Decide on Shipper
Initiate Price Calculation
Complete Price Calculation
Complete Product Scheduling
Arrange Logistics
Invoice Processing
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Performance Measurements

• Size of WSDL (number of methods) vs. Coordinator
  Proxy Object Generation Time

• Proxy object generation time is very small and
  wrapper size is less than 10 KB even for a Web
  service with 17 methods.

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Workflow Execution Timings
SB Subscription bond, NB Negotiation bond

• Bond related execution time is only a small
  fraction the total workflow execution time .

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Footprint of Workflows
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Broader View
Negotiation Bonds
Subscription Bond

• Limitations of Web service composition
  (orchestration) and coordination (choreography)
• For experts only
• Web Services not live participants
• Centralized

Coordination among self-coordinating Web services
using Web bonds
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Future Directions

• Web based toolkit for workflow configuration and
  deployment
• Develop the BondFlow system as a web based
  tool.
• Handheld based execution of such workflows.
• Application of the BondFlow system in different
  domains (Biological workflows, E-Commerce
  applications)

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Future Directions

• Incorporation WS-Security protocol
• Specify how to preserve the confidentiality of
  SOAP messages by attaching signatures and
  encryption headers.
• Specify how to attach security tokens (binary
  format) to messages.
• Goal
• Use WS-Security specifications to incorporate
  security policies to Web Coordination Bond
  related communication.

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Future Directions

• Extend the web coordination bond concept towards
  distributed coordination theory.
• Minimum set of coordination primitives that is
  sufficient to model workflow dependencies.
• Idea
• Group workflow dependencies into equivalent
  classes.
• Identify coordination primitives required that
  covers all the equivalent classes.

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• QA?

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Related Publications

• ICWS 06 Janaka Balasooriya, Jaimini Joshi,
  Sushil K. Prasad, and Shamkant Navathe,
  Distributed Coordination of Workflows over Web
  Services and Their Handheld-based
  Execution, Accepted in the 4th Intl. Conf. on
  Web Services (ICWS06), Chicago, September, 2006.
• ICWS 05 Janaka Balasooriya and Sushil K.
  Prasad, Toward Fundamental Primitives
  and Infrastructure Enhancements for Distributed
  Web Object Coordination and Workflows, In Proc.
  of IEEE, 3rd Intl. Conf. on Web Services
  (ICWS05), Orlando, July, 2005.
• ICWS 05 Sushil K.Prasad, Anu G. Bourgeois,
  Praveen Madiraju, Srilaxmi Malladi, and Janaka
  Balasooriya, A Methodology for Engineering
  Collaborative Applications over Mobile Web
  Objects using SyD Middleware, In Proc. of IEEE,
  3rd Intl. Conf. on Web Services (ICWS05),
  Orlando, July, 2005 (acceptance rate 20)

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Related Publications

• HCW 05 Janaka Balasooriya, Mohini Padye, 
  Sushil Prasad, and Shamkanth B. Navathe,
  BondFlow A System for Distributed Coordination
  of Workflows over Web Services, In Proc. of
  IEEE, 14th Heterogeneous Computing Workshop in
  Conjunction with IPDPS 2005. Denver, Colorado,
  USA, April.
• HICSS05 Sushil K. Prasad and Janaka
  Balasooriya, Fundamental Capabilities of Web
  Coordination Bonds Modeling Petri Nets and
  Expressing Workflow and Communication Patterns
  over Web Services, In Proc. of IEEE, 38th Hawaii
  Intl, Conf. on System Sciences (HICSS-38), Big
  Island, Hawaii, January, 2005.
• HICSS04 Sushil K. Prasad and Janaka
  Balasoorya, Web Coordination Bonds A Simple
  Enhancement to Web Services Infrastructure for
  Effective Collaboration, In Proc. of IEEE, 37th
  Hawaii Intl. Conf. on System Sciences
  (HICSS-37), Big Island, Hawaii, January, 2004.

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Related Publications
MW 04 S. K Prasad ... et al. 2004.  System on
Mobile Devices (SyD) A Middleware Testbed for
Collaborative Applications over Small
Heterogeneous Devices and Data Stores, Procs.
ACM/IFIP/USENIX 5th International Middleware
Conference, Toronto, Ontario, Canada, October
18th - 22nd
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Thank you !