Rapid Prototyping for Service-Oriented Architectures

Rapid Prototyping for ServiceOriented Architectures
2nd Workshop on Web Services
Interoperability (WSI 2006)
Bordeaux, France, March 21, 2006

Julien Vayssière1, Gorka Benguria2, Brian Elvesæter3,
Klaus Fischer4, Ingo Zinnikus4
1 SAP

Research, Brisbane, Australia, julien.vayssiere@sap.com

2 European
3 SINTEF
4 DFKI

Software Institute (ESI), Bizkaia, Spain, gorka.benguria@esi.es

ICT, Oslo, Norway, brian.elvesater@sintef.no

GmbH, Saarbrücken, Germany, {klaus.fischer, ingo.zinnikus}@dfki.de

Outline
• Background and motivation
• Framework overview
– Model-driven development framework
– Web services enactment framework
– Agent-based execution platform

• Prototyping case study
• Conclusion


2

Background
• Service-Oriented
Architecture
– architectural style
– gaining momentum
– mainstream in enterprise
computing

• Four tenets of serviceorientation (Box 2004)

• Web services architecture
– technology most often used
for implementing SOAs
– standards-based stack of
specifications
– enable interoperable
interactions between Webbased applications

– explicit boundaries
– autonomy of services
– declarative interfaces and
data formats
– policy-based service
description

3

Motivation
• Prototyping SOAs
– working implementation of an SOA that can be used for validating
the initial design choices

• Different compared to traditional application development
– need to take into account existing services
– developed by organisations over which we have no control
– introduces constraints into the prototyping exercise

• Current state of the art tools
– assumes that we are starting with a blank page
– merely extends the approach of regular software prototyping to
the scale of SOAs
– they make the implicit assumption that services will behave as
expected

• This is why we designed an approach that
– from the start, takes into account the fact that parts of the SOA
needs to be considered as a given; and
– should be treated with a healthy dose of caution.

4

Framework overview
• The ATHENA baseline methodology for SOA
provides guidelines for developing platform
independent models for SOA (PIM4SOA).
• Provides a set of modelling tools and services for
mapping between PIM4SOA and platform specific
models (Web services and BDI agents)

Modelling

• Johnson and Lyndon providemethodology all the
• The ATHENA baseline enactment of
• The Web service extensions PIM4SOA JACK
to the
roles External WSDLin an SOA (consumer, provider,
found Documents
for SOA provides guidelines for
autonomous agents platform allow SOAs to
intermediary) andWSDL Documents communication between
developing flexible independent BDI Teams
platform
MDD Framework
use agents for brokering, mediation and
Web services through an intuitive user interface
models for SOA (PIM4SOA).
negotiation between Web services
WSDL Analyzer
Lyndon
• The WSDL Analyzer toolmodellingsyntactical
• Provides a set of detected tools and
• BDI teams provide a flexible and composable
mismatches between service descriptions and
services for mapping between
Jack
alternative to «invoke»
traditional Johnson
approaches to Web
«invoke»
provides a basis andruntime mediationmodels
PIM4SOA for platform specific of Web
service composition
service messages
(Web services and BDI agents)
Agents
Services
• Johnson and Lyndon provide enactment of all the roles found
in an SOA (consumer, provider, intermediary) and flexible
communication between Web services through an intuitive user
interface
• The WSDL Analyzer tool detected syntactical mismatches
between service descriptions and provides a basis for runtime
mediation of Web service messages

• The Web service extensions to the JACK
autonomous agents platform allow SOAs to use
agents for brokering, mediation and negotiation
between Web services
alternative to traditional approaches to Web service
composition
5

UML Profile for POP*
• Process
• Organisation
• Product
•…

annotated with
Enterprise
Model
Reference Ontology

Business
Requirements
Analysis

Model to Model
Transformation

Architecture Specification
UML Profile for SOA
• Information
• Service
• Process
• QoS

annotated with
Service-Oriented
Architecture Model
Model to Model Transformation

Model Transformation
UML Profile for Web Services

annotated
with
Web Service
Specification Model

UML Profile for Agents
Agent Specification
Model

BPEL Specification
Model

Model to Text
Transformation

P2P Specification
Model

UML Profile for BPEL
UML Profile for P2P

Model Transformation

annotated
with
OWL
Ontology

Web Service
Execution Artefacts

Agent
Execution Artefacts

BPEL
Execution Artefacts

P2P
Execution Artefacts
Deployment

Service Wrappers
(Enterprise X)

Registry
Repository

Semantic
Space

ATHENA Integrated
Execution Infrastructure


Service Wrappers
(Enterprise Y)

Public
Infrastructure Services

Evaluation & Negotiation of Available Functionality

Internal
Infrastructure Services

Process
Execution
Platform
(BPEL)

Goal-oriented
Adaptive
Execution
Platform
(Agents)

Adaptive Distributed
Resource Mgt Platform

Active
Model
Platform
(AKMii)

Composed
WebService
Platform

(WebServices)

Enhanced Service Interconnection Bus

(P2P)

Legend
Business Process/Agent
Active (Business) Model
Web/Server Component
Middleware Process/Agent
Middleware Component

Crossorg.

Service Wrappers (Enterprise A)

Server-side
Component
Platform
(.NET, J2EE)

MessageOriented
Platform
(MQSeries)

Existing Enterprise Applications

Intraorg.

ATHENA
baseline
methodology
for SOA
(overview)

6

PIM4SOA
Model

Model-driven development framework
Information
View

Service
View

1

Process
View

QoS
View

Model to Model Transformation

UML Profile for PIM4SOA
• Information
• Service
• Process
• QoS

1..*
Platform
Specific
Model

UML Profile for XSD
UML Profile for WSDL
XML
Schema

WSDL
Description

1
Execution
Artefacts

•

BPEL
Process

UML Profile for BDI Agents
UML Profile for BPEL

Model to Text Transformation

1

•

BDI
Teams

XSD
Document

WSDL
Document

JACK
BDI Teams

BPEL
Document

Integrated Execution
Infrastructure for
Web Services
and BDI Agents

Follows the OMG Model Driven Architecture (MDA)
– Defines a Platform Independent Model (PIM) for SOA (PIM4SOA)
– Platform Specific Models (PSMs) for describing Web services (XML Schemas and WSDL),
Jack BDI agents and BPEL (Business Process Execution Language)
PIM4SOA is a visual PIM which specifies services in a technology independent manner
– Integrated view of the SOA in which different components can be deployed on different
execution platforms.
– The PIM4SOA model helps us to align relevant aspects of enterprise and technical IT models
– Allows us to raise the abstraction level at which we can talk about and reason on the
architecture we design.


7

PIM4SOA → platform specific models

PIM4SOA
Metamodel

Symbols

PIM

Metamodel
Concept
Relationship

PSMs

Correspondence

Web Services
Metamodel


Agent Metamodel
(AgentMM)

P2P
Metamodel

Grid
Metamodel

8

PIM4SOA addresses four system aspects
Metamodel for (software) services
Services are an abstraction and an
encapsulation of the functionality provided by
an autonomous entity. Service architectures
are composed of functions provided by a
system or a set of systems to achieve a
shared goal.
Web Services Architecture as proposed by
W3C (W3C 2004)
UML Profile for Enterprise Distributed Object
Computing (OMG 2002)

Metamodel for information
Information is related to the messages or
structures exchanged, processed and stored
by software systems or software components.
Structural constructs for class modelling in
UML 2.0 (OMG 2003)


Metamodel for (automated software) processes
Processes describe sequencing of work in
terms of actions, control flows, information
flows, interactions, protocols, etc.
Business Process Definition Metamodel
(BPDM) (IBM et al. 2004)

Metamodel for quality of service (QoS)

Extra-functional qualities that can be applied
to services, information and processes.
UML Profile for Modeling Quality of Service and
Fault Tolerance Characteristics and
Mechanisms (OMG 2004)

9

Web services architecture metamodel

<<Metamodel>>
Coordination
+ WS-Coordination.

<<Metamodel>>
Registry
+ UDDI.

+ WS-MetadataExchange.
+ WS-Policy.
+ WS-PolicyAttachement.

<<Metamodel>>
Composition
+ ACE-GIS Composition Extensions.
+ WS-BPEL.
+ WS-CDL.

<<Metamodel>>
Reliability
+ WS-ReliableMessaging.

<<Metamodel>>
Endpoint Description

<<Metamodel>>
Service Interface
Description
+ WSDL 1.1.
+ WSDL 2.0.

<<Metamodel>>
Eventing
+ WS-BaseNotification.
+ WS-BrokeredNotification.
+ WS-Eventing.
+ WS-Topics.

<<Metamodel>>
Messaging
+ SOAP.
+ WS-Addressing.

<<Metamodel>>
Security
+ WS-Security.

<<Metamodel>>
Resource Access and
Management
+ WS-Enumeration.
+ WS-Resource.
+ WS-ResourceLifetime.
+ WS-ResourceProperty.
+ WS-Transfer.

<<Metamodel>>
Transport
+ HTTP.

<<Metamodel>>
XML
+ XML Core / XSD.
+ XML Encryption.
+ XML Signature.
+ XPATH.

<<Metamodel>>
eContract
+ ATHENA eContract Extensions.

10

PIM4SOA → platform specific models
PIM4SOA
source
metamodel

Mapping
model

Web services
target
metamodels


11

Model transformations
EMF

eProc
Model
(.ecore)

PIM4SOA
Metamodel
(.ecore)

BPEL
Metamodel
(.ecore)

eProc
Model
(.emx)

PIM4SOA
Plugin

<<applied>>

EMF

BPEL
Document
(.bpel)

a)

UML 2.0
Metamodel
(.ecore)

RSM

WID

EMF

MTF

b)
eProc Model
(.ecore)

EMF: Eclipse Modeling Framework
RSM: Rational Software Modeler UML modelling tool
PIM4SOA Plugin: RSM plugin – UML Profile for PIM4SOA

UML Profile for
PIM4SOA (.epx)

WSDL
Metamodel
(.ecore)

c)

WSDL
Document
(.wsdl)

Eclipse
WST
MTF: Model Transformation Framework
Eclipse WST: WSDL graphical editor
WID: WebSphere Integration Developer

12

Rapid prototyping framework for SOA

Modelling

PIM4SOA

External WSDL Documents
WSDL Documents

WSDL Analyzer

MDD Framework

Lyndon

Johnson

«invoke»

Services
interface

BDI Teams

«invoke»

Jack

Agents
composition
13

WSDL Analyzer

•

The WSDL Analyzer is a tool for detecting similarities between Web service
descriptions.
– The tool can be used to find a list of similar services and produces a mapping
between messages, thereby enabling brokering and mediation of services.
– The idea of the tree-edit distance is that a similarity between two XML structures
can be measured by stepwise transforming a tree representation of the first
structure into the other.

•

A possible scenario for using the WSDL Analyzer is that the user already
knows a service which provides the correct format.
– The WSDL of this service can be used as requirement for a similarity search.
– The WSDL Analyzer allows browsing the original WSDL and the candidate files.


14

Web services enactment framework (1)

•

Inbound processing
chains

Folders for
storing messages

Outbound
processing chains

Outbound
Endpoints

Outgoing messages

Inbound
Endpoints

OUTBOX

INBOX

Incoming messages

User Interface

Johnson is a runtime enactment tool
– It enables users to enact most of the roles typically found in an SOA.
– It allows sending real SOAP messages between Web services without having to
write a single line of code.
– It features a Web-based user interface designed to closely resemble Web-based
email applications
– SOAP messages and Web Services endpoints are used in place of email
messages and email addresses
– The user can see incoming SOAP messages in the Inbox and create outgoing
SOAP messages in the Outbox that will be sent to external Web services.
– A powerful user-interface generator relieves the user from having to deal with XML
documents by generating forms for displaying and editing any XML-based data
type.


15

Web services enactment framework (2)

•

Inbound processing
chains

Folders for
storing messages

Outbound
processing chains

Outbound
Endpoints

Outgoing messages

Inbound
Endpoints

OUTBOX

INBOX

Incoming messages

User Interface

Lyndon is the design-time counterpart of the Johnson tool
– It analyses WSDL files and automatically configures Johnson for playing either the
role of consumer or provider of the service described.
– Lyndon parses a WSDL file and determines which endpoints need to be created,
and which processing chains need to be assigned to them.
– Determining which processing modules to include in the processing chain takes
into account information extracted from the WSDL file as well as options set by the
user.
– The user may, for example, specify whether Johnson should be configured as a
service consumer or a service provider, or whether messages sent to or from the
service should be logged
– Some configuration information can be extracted from the WSDL file, such as the
need for implementing the WS-Addressing specification, which is specified as part
of the description of the bindings of a Web service.


16

Rapid prototyping framework for SOA

Modelling

PIM4SOA

WSDL Documents

WSDL Analyzer

MDD Framework

Lyndon

Johnson

«invoke»

Services
interface

BDI Teams

«invoke»

Jack

Agents
composition
17

Agent-based execution platform
Teams/Agents
Web Service
send

Incoming
request

use

Events

Plans

trigger
handle

Supplier 1
WS calls

User
Supplier 2
Web Service
Interface

•
•
•
•

Beliefs

modify
Web Service

At its core the JACK agent framework with plan library and knowledge base.
Following the MDA approach, a modeller specifies at design time a set of
plans (PSM level) that constitute the workflow library of the agents.
Web service calls are integrated as steps into plans.
Workflows are modelled graphically and most of the common workflow
patterns are supported.


18

Prototyping case study
e-procurement PIM4SOA

WSDL Documents

Services
Enactment

WSDL Analyzer

2

MDD Framework

Lyndon

1

3
4

«invoke»
•

Johnson

BDI Teams

5
«invoke»

Jack

The following approach was followed for the validation of the rapid prototyping framework
– Used the MDD framework (1) to derive the WSDL files and BDI models from the eprocurement PIM4SOA model.
– Enact the services identified for the e-procurement scenario using the WSDL Analyser (2) and
the Lyndon (3) tools.
• Used the WSDL Analyser to locate existing services similar to those required in the eprocurement scenario.
• Used the Lyndon tool to configure the Johnson platform to simulate required, new
services.
– Configure Johnson (4) to act as a service proxy
• This allowed us to change the final service endpoints without affecting the process
execution.
– Finally the PSM model for Jack (5) was implemented and tested with the enacted services.


19

M1. Request for Quotation
M2. Quotation

R1. Request for Quotation
R2. Quotation

M3. Order

M4. Order
Confirmation

R4. Order
Confirmation

R3. Order

MANUFACTURER
●

●

PROVIDER

●

Retailer-Manufacturer
●
1. RFQ
●
2. Quote
●
3. Order
Manufacturer-Supplier
●
1. RFQ
●
2. Quote
●
3. Order
●
4. Order Confirmation
Retailer-Manufacturer
●
4. Order Confirmation

Interior
Decoration
Project

RETAILER

PIM4SOA: Order process


21

PIM4SOA: Furniture procurement collaboration
• Three roles
– “Retailer”,
– ”Manufacturer”
– “Supplier”

• Two usage of
collaboration
– “Goods Supply”
– “Materials Supply”

• Relationships
between role and
collaboration use
– “RoleBinding”


22

PIM4SOA: Goods supply collaboration


23

PIM4SOA: Services interfaces


24

PIM4SOA: Order document


25

Conclusion
•

This paper presented a rapid prototyping framework for SOAs built
around a model-driven development (MDD) methodology which is
used for
– transforming high-level specifications of an SOA into executable artefacts
– Web Services
– autonomous agents

•

The framework can handle
– a mix of new and existing services; and
– provides facilities for simulating, logging, analysing and debugging

•

The framework was validated in an industrial electronic procurement
scenario from the furniture manufacturing industry
– input from business expert had been collected
– creating the high-level PIM4SOA model
– deriving the Web service description and incorporating existing Web
services took less than a day for a person already familiar with all the
tools involved

•

The model-based approach helps us in
– keeping all the pieces of the SOA aligned with high-level business
objectives throughout rounds of prototyping


26

Rapid Prototyping for Service-Oriented Architectures

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