IBM Research
Dr. Biplav Srivastava http://www.research.ibm.com/people/b/biplav/
IBM T. J. Watson Research Center, USA and India Research Lab, India
Major Collaborators:
IBM Research Labs: India, Watson, Zurich; Arizona State University; DAGSTHL Seminar 07061;
University of Georgia, Athens
ASU: April 2008
© 2008 IBM Corporation

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IBM Research
 IT Issues Faced by Businesses Today
 Web Services Composition – What is it and Why is it Important
–
Basics
–
Typical scenarios
 A model for understanding different approaches
– Suitability of approaches for different scenarios
– Examples
 An Update on Progress in Automated WSC
–
Myth: Resolve scale-up and search issues for WSC composition
–
Reality: Resolve composition set-up issues (at problem set-up or solving phases)
 Emerging Trends
– Plan reuse and modification in the context of richer, but unstructured, domain models
– Planning in the presence of impoverished domain models: model-lite planning
 Conclusion
The Myth and Reality of Web Services Composition © 2008 IBM Corporation

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 Business-IT alignment
– Are my investments in IT supporting my business?
– Can my investment in IT give competitive edge?
 Enterprise Application Integration
– Integrating across divisions in the same company
– Integrating with suppliers, partners
 Collaboration
– Perennial, new global dimension
 Asset Reuse
– Software reuse is perennial
– Documents, methods, even presentations
The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
Service
Broker
WSDL
Search with UDDI and get WSDL of match
Execute BPEL
Service
Provider
Invoke using SOAP
Return Solution
Service
Requester
4
What is the service representation?
 (Advertised) Instances : A service that can be invoked at a physical URL. It is represented by WSDL. Some semantic representations can compete in this space (OWL-S).
 Deployed and Running Instances: Not all advertised services may be running at a given execution time.

Type : Collection of services sharing common capabilities (what they do) but differing in how to access them.
Semantic representations should capture this.
The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
Requester
Search with Requirement
Composition
Module
S1 -> S3
S1
S2
S3
…
Service Registry
5
S1
Execute based on Composition
S3
Centralized v/s Decentralize Orchestration
(S1 could have sent output to S3 directly)
The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
Service As Business Benefit CS Areas
(in addition to AI!)
Online, Deployed
Applications
IT Systems
Software Components
Business Processes
Mashups, Collaboration,
New Revenue Streams,
Data Integration
EAI
Software Reuse
User Interfaces,
Visualization, Databases/
Streaming
Metadata Management,
Distributed Systems,
Messaging/ Networking
Software Engineering,
Databases
Business-IT alignment Business Process,
Management Metrics
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7 The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
User
3 rd Party
Providers
Telco Enterprise User
User
 Service/content providers are often 3 rd parties
 Telco is the intermediary for delivery of services to enterprises/consumers
– Must improve ease-of-use of its software infrastructure
– Must optimize the utilization of its IT infrastructure
 Need to adopt standards-based framework
– Use Web services to build end-user services
– Use semantic annotations allowing service functionality to be programmatically composed
The Myth and Reality of Web Services Composition © 2008 IBM Corporation 8

IBM Research
Customer Interaction
Problem
Reporting
Top-down or bottom-up
Problem Ticket
Problem Ticket,
Desk-based Expert ID
Problem
Classification
Agent Assignment
Location-based
Agent Selection
Expert Lookup
Call
Setup
Help Desk
Problem Ticket,
Resolution Status
Registry
Update
Source: A Service Creation Tool Based on End-to-End Composition of Web Services. V. Agarwal et al, WWW 2005
9 The Myth and Reality of Web Services Composition
Problem Ticket,
Field Expert ID
Message
Delivery
On Site
Problem Ticket,
Resolution Status
© 2008 IBM Corporation

IBM Research
New service capabilities
New service providers
Network / environment changes
Specify end-user service capability
Select service providers
Design the flow
Deploy the service
• Manual business process integration
• Use tools like WSAD-IE to create flows and business logic
• Deploy using a flow engine (such as
MQWF / WBI SF)

Main Issues

Scalability of composition solution

Level of automation

Modeling domain information

Leverage industry practices
10
Source: A Service Creation Tool Based on End-to-End Composition of Web Services. V. Agarwal et al, WWW 2005
The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
Service
Specification
Service Creation
Environment
Logical
Composer
Abstract
Workflow
(Plan)
Physical
Composer
Deployable
Workflow
Domain
Ontology
Service
Registry
 Key Components
–
Service Capabilities Database
• Information about services available in-house as well as with 3 rd party providers
–
Telecom Ontology
• Domain-specific terminology
– Logical Composer including Planner
• automated aggregation of services via generative planning -based reasoning techniques
– Physical composer
• Instance selection based on end to end QoS specification
 Input
–
Requirements document for the new service that needs to be composed
Execution Environment  Output
Synthy: http://domino.research.ibm.com/comm/research_people.nsf/pages/biplav.Synthy.html
– Deployable workflow representing a composite service
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IBM Research
Service Requester Service Developer
OWL-S,
WSDL
BPEL
Deployment Engineer
BPEL
OWL-S
Web
Service
Rqmt.
Service
Discovery
Service
Selection
Service
Aggregation
Service
Deploy-
-ment
Composite
Service
12
Administrator

An IDE needs to support several views each applicable to a different kind of role
– Service Requester
– Service Developer
– Deployment Engineer
– Administrator
 Different technological and Interface Requirements
The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
 Lack of Service Composition tools
– tooling available for creation of web services
– existing prototypes handle only part of the problem
– Need for an Integrated Development Environment (IDE) to ease the process of composition, thereby reducing development time and integration efforts
 Tooling Challenges
– web services are actively running entities that need to be composed together
– new web services may come up or old ones may go down dynamically, leading to much more frequent changes than in traditional software libraries or components
– the tool should be able to work with components in the runtime environment in addition to offline development modules
– has implications on functionality, interface, performance and runtime behavior of the IDE
© 2008 IBM Corporation 13 The Myth and Reality of Web Services Composition

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
Online information services
– Services are data sources; can be modeled as databases which can be queried with no, or controlled , side-effects
– Composite service should be responsive but accuracy can be negotiated
– Services are heterogeneously owned, hence relatively autonomous in choosing specifications
Source: Getting from Here to There:. Interactive Planning and Agent. Execution for Optimizing Travel. José Luis Ambite et al, IAAI 2002
The Myth and Reality of Web Services Composition © 2008 IBM Corporation

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Source: Getting from Here to There:. Interactive Planning and Agent. Execution for Optimizing Travel. José Luis Ambite et al, IAAI 2002
The Myth and Reality of Web Services Composition © 2008 IBM Corporation

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IBM Research
 MashupAdvisor exploits a repository of mashups to provide design-time assistance to the user through relevant suggestions as to what outputs can be generated along with the best plans to generate those outputs. The system has two components: an output ranker, which ranks the outputs based on their popularity scores, and a planner, which uses metric planning algorithms and a configurable utility function. The system takes into account popularity and semantic similarity when recommending services and sources.
 Main Contributions:
– Recommends new outputs to enrich the mashup
–
Generates better plans by reusing knowledge built by other users
–
Saves development time by automatically recommending and linking services
 Link to demo
18
Team: Hazem Elmeleegy Anca Ivan, Rama Akkiraju, Richard Goodwin
Extended Team: Biplav Srivastava
The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
Mashup
Editor
Client
(Fusion
Client)
Internet
Partial
Mashup
Ranked
Output List
Mashup
Editor
Server
(Fusion
Server)
Partial
Mashup
Desired
Output
Minimum
Cost Plan
Output
Ranker
Planner
MashupAdvisor
Repository Manager
Catalogue
Manager
Statistics
Manager
MashupA
Semantic
Matcher
Mashup
Repository
Thesaurus
Domain
Ontology
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21
 An Overall Web Service Composition and Execution view is important in practice
Specification of Requirement
Available
Capabilities
Events
Web Service
Composition and
Execution
Execution
Trace
[ Templates,
Policies ]
 Today, it is not clear what are fundamentally different possible types of WSCE approaches and which type to use in a given scenario?
*Services are assumed to be stateless
The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
 Are composition and execution separable?
– No, Yes
 When does composition happen?
–
Offline, Online
 How does composition happen?
– Search-based, Template-based
 What information is used for composition?
– Service types, Service instances published, Services deployed, Templates/
Policies
 How are external events handled at runtime (adaptation)?
–
On-the-fly, gradual
© 2008 IBM Corporation 22 The Myth and Reality of Web Services Composition

IBM Research
Specifications
Search-based
Composition
X={x
1
,x
2
,…x

} Events
Execution
T=
{t
1
,t
2
,…t

}
23
On-line
Example:
ConGolog, Heracles+Theseus
The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
Specifications
24
I={i
1
, i
2
,… i

}
Monolithic
Composition
 ≥ 
F
RE
X={x
1
,x
2
,…x

} Events
Runtime
T=
{t
1
,t
2
,…t

} R
IW
W={W
1
,W
2
,…W
L
}
R
EW
Off-line
On-line
Example:
SWORD, SHOP-2 based, Petrinet-based, Astro, METEOR-S
The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
Specifications
C={c
1
,c
2
,…c

}
 
F
PC

I={i
1
, i
2
,… i

}
 ≥ 
F
RE
X={x
1
,x
2
,…x

} Events
Logical
Composition
R
AW
S={S
1
,S
2
,…S
K
}
Physical
Composition
Runtime
R
IW
W={W
1
,W
2
,…W
L
}
R
EW
T=
{t
1
,t
2
,…t

}
Off-line
Off-line On-line
25
Example:
Synthy, Self-Serv with web communities (but informal modeling)
The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
Interleaved
T= {t
1
,t
2
,…t

}
Traces
Monolithic
W={W
1
,W
2
,…W
L
}
Executable Workflow
Staged
S={S
1
,S
2
,…S
K
}
Abstract Workflow
Generalize
: remove commitments to get templates
© 2008 IBM Corporation 26 The Myth and Reality of Web Services Composition

IBM Research
Interleaved
T= {t
1
,t
2
,…t

}
Traces
Monolithic
W={W
1
,W
2
,…W
L
}
WSCE
Executable Workflow
Staged
S={S
1
,S
2
,…S
K
}
Abstract Workflow
Add commitments to generate workflow or trace
( Assign values to template parameters)
27
Example: Heracles+Theseus, METEOR-S (Semantic templates, other templates), template-based planning
The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
 Are composition and execution separable?
– No, Yes
 When does composition happen?
–
Offline, Online
 How does composition happen?
–
Search-based, Template-based
 What information is used for composition?
– Service types, Service instances published, Services deployed, Templates/ Policies
 How are external events handled at runtime (adaptation)?
– On-the-fly, gradual
Separable?
No
Yes
Yes
Yes
When
Online
Offline
Offline
Offline,
Online
How
Search
Search
Search
Template
What
Services deployed
How
On-the-fly
Services instances published Gradual
Service types, Service instances published
Templates/ policies, Services instances published, deployed
Gradual
On-the-fly, Gradual
The Myth and Reality of Web Services Composition © 2008 IBM Corporation 28
Interleaved
Monolithic
Staged
Template

IBM Research
Interleaved Monolithic Staged Template
Composition
Effort
O(
 λ )
O(
β λ
)
Min: O(
 λ )
O( α λ + M λ ) O(M λ )
Composition
Control
None
Low:
< R
IW
; F
E
>
High:
< R
AW
;R
IW
; F
C
; F
E
>
High:
<template, underlying composition method>
Ability to Handle
Composition
Failure
Adaptation during
Execution
None
High
Low
Medium
High
Medium
Low
Low to Medium
Information
Modeling
Simple
(Instances)
Simple (Instances)
Elaborate (Types and Instances)
Elaborate (Templates and Instances)
Limitation
Search should be dead-end free
Always a time-lag between service information offline v/s online
Always a time-lag between service information offline v/s online
Search restricted by template
– can cause
INCOMPLETENESS ;
Any restriction of the underlying composition method
Details in: Understanding approaches for web service composition and execution,
Vikas Agarwal, Girish Chafle, Sumit Mittal, Biplav Srivastava, ACM COMPUTE 2008
The Myth and Reality of Web Services Composition © 2008 IBM Corporation 29

IBM Research

Online information services
– Services are data sources; can be modeled as databases which can be queried with no, or controlled , side-effects
– Composite service should be responsive but accuracy can be negotiated
– Services are heterogeneously owned, hence relatively autonomous in choosing specifications
– Sub-scenarios:
• Comparison product review/ shopping sites, Online travel booking
• Mash-ups: ad-hoc data services created by users

Enterprise Application Integration
– Services are applications; can be modeled as programs with or without side-effects
– Composite service should accurate but responsiveness can be negotiated
– Services are more homogeneously owned (e.g., intranet); hence some control in choosing specifications can be exercised
– Sub-scenarios:
• Service creation to connect internal or partner organizations
• Scientific workflows: bioinformatics, Geological sciences
© 2008 IBM Corporation 30 The Myth and Reality of Web Services Composition

IBM Research
 Online information services
– Services are data sources; can be modeled as databases which can be queried with controlled side-effects at the time of purchase
– Composite service should be responsive but accuracy can be negotiated
– Services are heterogeneously owned, hence relatively autonomous in choosing specifications
Composition Effort
Composition Control
Composition Failure
Resolution
Adaptation
Information Modeling
Limitation
Interleaved
O(
 λ )
None
None
High
Simple (Instances)
Monolithic
O( β λ )
Min: O(
 λ )
Low:
< R
IW
; F
E
>
Low
Medium
Simple (Instances)
Search should be deadend free
Always a time-lag between service information offline v/s online
Staged
O( α λ + M λ )
High:
< R
AW
;R
IW
; F
C
; F
E
>
High
Medium
Elaborate (Types and
Instances)
Always a time-lag between service information offline v/s online
Template
O(M λ )
High:
<template, underlying composition method>
Low
Low to Medium
Elaborate (Templates and
Instances)
Search restricted by template – can cause
INCOMPLETENESS ; Any restriction of the underlying composition method
The Myth and Reality of Web Services Composition © 2008 IBM Corporation 31

IBM Research

Scalability – with number of services
 Adaptability – to changes
 Failure Resolution
 User Interaction – control and supervision important
32
Composition Effort
Composition Control
Composition Failure
Resolution
Adaptation
Information Modeling
Limitation
Interleaved
O(
 λ
)
None
None
High
Simple (Instances)
Monolithic
O(
β λ
)
Min: O(
 λ
)
Low:
< R
IW
; F
E
>
Low
Medium
Simple (Instances)
Search should be deadend free
Always a time-lag between service information offline v/s online
Staged
O(
α λ
+ M
λ
)
High:
< R
AW
;R
IW
; F
C
; F
E
>
High
Medium
Elaborate (Types and
Instances)
Always a time-lag between service information offline v/s online
Template
O(M
λ
)
High:
<template, underlying composition method>
Low
Low to Medium
Elaborate (Templates and
Instances)
Search restricted by template
– can cause
INCOMPLETENESS ; Any restriction of the underlying composition method
The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
33 The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
 Logic/ Constraints/ Planning
– Semantic Web Services , McIlraith, S., Son, T.C. and Zeng, H. IEEE Intelligent Systems. Special Issue on the Semantic Web.
16(2):46--53, March/April, 2001. Copyright IEEE, 2001.
– SWORD: A Developer Toolkit for Web Service Composition, Shankar R. Ponnekanti and Armando Fox, WWW 2002
– Getting from Here to There:. Interactive Planning and Agent. Execution for Optimizing Travel, José Luis Ambite et al, 2002.
 Web Service Composition - Current Solutions and Open Problems, B. Srivastava and J. Koehler, 2003
 Semantics, Planning, Model Checking
– Semi-automatic Composition of Web Services using Semantic Descriptions, E. Sirin, James Hendler and Bijan Parsia,2003
– Planning and Monitoring Web Service Composition, Pistore et al, 2004
– Automated Composition of Semantic Web Services into Executable Processes, P. Traverso and M. Pistore, 2004

Semantics, Planning, Non Functional requirements
– A Service Creation Tool Based on End-to-End Composition of Web Services, V. Agarwal et al, 2005
– Planning with Templates, IEEE Intelligent Systems special issue, 2005

Web Service Composition as Planning, Revisited: In Between Background Theories and Initial State
Uncertainty, J. Hoffmann, P. Bertoli, M. Pistore, AAAI 2007.
 Understanding approaches for web service composition and execution, Vikas Agarwal, Girish Chafle, Sumit
Mittal, Biplav Srivastava, ACM COMPUTE 2008
 Domain Specific, Adaptation
– SewNet - A Framework for Creating Services utilizing Telecom Functionality, WWW 2008
– Dagstuhl Seminar on Autonomous and Adaptive Web Processes, http://www.dagstuhl.de/programm/kalender/semhp/?semnr=07061
© 2008 IBM Corporation 34 The Myth and Reality of Web Services Composition

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35
 Resolve scale-up and search issues, and WSC will be solved with existing, or incrementally enhanced, planners
 WSC has much commonality with Planning
–
Services are Actions
–
Side-affects and inputs/ outputs can be modeled as preconditions/ effects
–
Use existing or favorite new methods
 Many research papers but not many wide-scale systems
– Success in generating compositions
– But generation is one thing, execution another
• How to prove composition is correct at runtime?
• Are middleware available to execute?
• Can domain models be built by typical IT professionals?
 Anecdote –
– Planner4J family of Java planners: Classical, Metric and Contingent planners in three different composition systems
– Never encountered a composition situation where the scalability of the planner was an issue!
– More work on making planner integratable with external systems
• Automatic Parameter Turning (AAAI 05)
• Analyzing plans (IAAI05)
• Validating input domain and problem models (ISWC 2005)
• Generating diverse plans (IJCAI 07)
• Reachability analysis to identify potentially relevant services from a large repository
• See AAAI06 Nectar paper for details
Planner4J: http://domino.research.ibm.com/comm/research_people.nsf/pages/biplav.Planner4J.html
The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research

– Which expert to believe? Companies in monopolistic situations
(e.g. Windows, SAP) have easier time.
– Can domain models be built by typical IT professionals?
– What is the right level of abstractions?

– How to prove composition is correct at runtime?
– Are middleware available to execute?

© 2008 IBM Corporation 36 The Myth and Reality of Web Services Composition

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37 The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
 Packaged Middleware: SAP,
Oracle, PeopleSoft
 Custom-assembly (IBM)
Figure Source: Model-driven Business Process Platforms, David Frankel, SAP
38 The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
Business Process
39 The Myth and Reality of Web Services Composition
SOA Implementation
(Multiple vendors)
© 2008 IBM Corporation

IBM Research
Content Sources
SAP
BPR
IBM
ReAL
Tagged Content
Specialize
 Reuse business processes
 Reuse services implementing business processes
– Reuse plans representing composite services
© 2008 IBM Corporation The Myth and Reality of Web Services Composition

IBM Research



 Knowing no more than I/O types?
 Missing a couple of preconditions/effects?
41 The Myth and Reality of Web Services Composition
Source: Model-Lite Planning for the Web Age Masses, S. Kambhampati, AAAI07
© 2008 IBM Corporation

IBM Research
1.
(Helping human planners)
2.
(Planners deal with incompleteness)
3.
(Help complete the model)
42 The Myth and Reality of Web Services Composition
Source: Model-Lite Planning for the Web Age Masses, S. Kambhampati, AAAI07
© 2008 IBM Corporation

IBM Research
 IT Issues Faced by Businesses Today
 Web Services Composition is very important
–
Model for looking at WSC
– Case Studies
 Looked at progress in automated WSC
– Myth: Resolve scale-up and search issues for WSC composition
–
Reality: Resolve composition set-up issues (at problem set-up or solving phases)
 Emerging Trends
– Plan reuse and modification in the context of richer, but unstructured, domain models
– Planning in the presence of impoverished domain models: model-lite planning
 Future Issue : Adaptation
© 2008 IBM Corporation 43 The Myth and Reality of Web Services Composition

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44 The Myth and Reality of Web Services Composition © 2008 IBM Corporation

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45 The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
What Causes the Change (inputs/ events)
 Structural
– Component specific events (reconfiguration) e.g. failures
– Temporal specific events e.g. timeouts, unexpected (w.r.t. protocol) messages
 Contractual: contract as list of attributes and possible values
– Contract violations or cancellation
–
Request for re-negotiation from providers
 Non-functional (QoS) parameter changes
– Maintain efficiency or optimality
–
Avoid contract violations
 Changes in the business environment
–
E.g. New laws, business models, personnel changes, technology changes
46 The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
What Could the Techniques Change in the Process (outputs/reactions)
47
 Structural
– Spatial/ component: activity/ topology – addition and deletion
– Temporal: change in ordering constraints
 Contractual
– Contract as list of attributes and possible values
•
Agreement sections: attributes and tolerable values
•
Separation clauses; re-negotiation clauses
– Differences
• Adaptation: governed by agreement section
• Re-negotiation: governed by re-renegotiation section
•
Separation followed by negotiation: there are be no constraints
– Approach: choose the change provided by the contract and perform
•
To what extent can be done automatically?
The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
A Narrow Mapping from Event Types to Possible Reactions Does Not Exist !!
 Default for any event
– Ignore
 Marginal QoS Changes
– Ignore
– Re-configuration (using policies)
– Contract cancellation, re-negotiate violating contract, re-adjust other contracts
 Contractual cancellation
–
Ignore
– Re-configuration (using policies)
– Re-negotiate/ re-adjust violating contract, re-adjust/ cancel other contracts
48 The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
Adaptation Techniques
 Ignore
 Hard-wired ad-hoc changes
– Procedural hacks
– Using policies/ rule-based systems/ Event-Condition-Action
 Mediation
– Ontology-based (semantics)
• Type mapping in Meteor-S
– Behavioral
• Controller synthesis (Karsten Wolf’s work)
 Re-configuration
– Using policies
– Using LP (Benatallah)
– Using Logic (Berardi, ConGolog)
– Graph transformation (Hyperedge replacement - Ugo Montanari)
 Negotiation and Re-negotiation
– Game theory
 Ooops … ask the human!
49 The Myth and Reality of Web Services Composition © 2008 IBM Corporation

IBM Research
Speculation on Complexity of Handling of Events
Protocol violations
E.g. controller synthesis
Marginal
QoS differences
(A-WSCE)
Semantic mediation
Template-based negotiation
Ignore events Contract cancellation
New clauses in contract;
Renegotiation
Negotiate
Unknown events
Trivial
[0] low hanging fruit [1]
Ideas exist
[2]
Structure
Challenging
[3]
Many years away
[4]
Impossible
[5]
Contract
QoS
Business
50 The Myth and Reality of Web Services Composition © 2008 IBM Corporation