Towards StyleOriented SOA Design

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Towards Style-Oriented SOA Design
First International Workshop on Design of
Service-Oriented Applications
Chen Wu, Elizabeth Chang, Vidyasagar Potdar
School of Information Systems Curtin University
of Technology Perth, AUSTRALIA
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Agenda

• Motivation
• Software Architectural Styles
• Framework of WS-Architecture Styles
• Catalog of WS-Architecture Styles
• Related Work
• Conclusion and Future work

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Motivation

• Quality requirement really matters
• Second most significant criteria to choose
  WS-Solutions (Ciganek et al. 2005)
• Architecture heavily affects QR (Lundberg et al.
  1999)
• An essential artifacts for architectural design
  Style
• We need
• a catalog of well-identified web services
  architecture styles (patterns) with their
  corresponding rationales and business contexts
• This paper provides
• An investigation of existing web services
  architectural styles

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Software Architectural Styles

• Originally borrowed from the classical field of
  architecture
• Major characteristic prescriptive nature
  constraint
• Definition of Style an architectural style is a
  coordinated set of architectural constraints that
  restricts the roles/features of architectural
  elements and the allowed relationships among
  those elements within any architecture that
  conforms to that style (Fielding 2000)
• Purposes of Style
• Categorizing architectures,
• Defining common characteristics of architecture,
  and
• Composing new architecture

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Classification of WS-Architecture Styles

• Traditional Architectural Styles
• e.g. layered, broker, distributed, blackboard,
  event-driven, etc.
• Agent Classification
• Middle-agent
• Matchmaker
• Facilitator
• Multi-agent
• Web Services Lifecycle
• Discovery
• Execution
• Composition

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Framework of WS-Architecture Styles
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Basic Styles within WS-Lifecycle
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Matchmaker

• Matchmaker Architectural Style

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Matchmaker

• Basic Matchmaker (BM)
• Layered Matchmaker (LM) (Wang et al 2004, Yu and
  Lin 2004, and Degwekar et al 2004)

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Primary Problems for Centralized Matchmaker

• UDDI is not scale well, lead to serious
  performance bottlenecks (Papazoglou et al. 2003,
  Paolucci et al 2004)
• Load-balancing strategies does not constitute a
  practical solution (Pilioura et al. 2004)
• Replication between UDDI registries does not
  occur in practice (Thaden et al. 2003, Wang et al
  2003)
• Creating a scalable model for distribution of
  data is difficult (Sivashanmugam et al 2004)

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Matchmaker (cont.)

• Hierarchical matchmaker
• Papazoglou et al 2003

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Matchmaker (cont.)

• Federated Matchmaker (FM)
• (Thaden et al. 2003, Sivashanmugam et al. 2004,
  Verma et al. 2004)

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Peer-to-Peer

• Peer-to-Peer Architectural Style

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P2P Discovery Style(Ayyasamy et al 2003, Wang et
al 2003, Prasad and Lee 2003, Emekci et al 2004,
Paolucci et al 2003, Schmidt and Parashar 2004,
Banaei-Kashani et al 2004)

• Common application of leveraging P2P in DWS
  environments
• Major problems
• Existing UDDI model is not utilized at all
• Trust and Security is not guaranteed

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P2P Service Composition Approaches

• P2P Composition
• Static Composition Style (P2PC-S)
• Partition and assignment of process specification
  at design-time (Muth et al 1998, Nanda et al
  2004)
• each local engine at run-time only obtains the
  partial process (Benatallah et al 2002, Chafle et
  al 2004)
• Mobil Composition Style (P2PC-M)
• whole process specification and its related
  instances to the hosts during the run-time
  (Lakhal et al 2004)
• Hybrid Composition Style (P2PC-H)
• Mixed SC-P2PE and MC-P2PE (Schuler et al 2004)

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Static Composition Style (P2PC-S)
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Mobil Composition Style (P2PC-M)
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Broker

• Broker Architectural Style

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Broker Style

• Classical broker (Buschmann et al., 1996)

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Broker (cont.)

• Basic broker
• Layered broker
• (Pires et al., 2003, Paolucci et al., 2004,
  Fuchs, 2004).

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Broker (cont.)

• Enterprise Service Bus from Industry vendors
  (Balani, 2005)

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Asynchronous Broker

• Callback
• WSIF JMS (opensource http//ws.apache.org/wsif)
  
• WS-Callback (Goland et al., BEA Systems, 2003)
• WS-Addressing (Gudgin and Hadley, 2005)
• Client-Side Framework (Ruth et al. 2005)
• Publish-Subscribe
• WS-Notification (Graham and Niblett, 2004)
• WS-BaseNotification
• WS-Brokered Notification
• WS-Topics
• WS-Eventing (Geller, 2004)
• Matching is a major issue
• semantics and ontology

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Broker (cont.)

• Async-Federated broker (Wu et al., 2005)

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RESTful WS Style (Fielding 2000, Mitchell 2002,
Prescod 2002, He 2004)

• REpresentational State Transfer Web part of
  Web Services
• An architectural style for Web
• No need to reinvent the wheel ! existing Web
  architecture is a proven scalable distributed
  systems
• Web Services ? Web RPC (Traditional
  WS-Architecture)
• Architectural Constraints
• Stateless _at_ Server, Stateful _at_ Client
• Small set of consistent interface (GET, POST,
  PUT, DELTE)
• Message Centric rather than Interface API
  Centric (SOAP 1.2)
• Explicit resource identifier URI
• Real Case Amazon.com (80 vs. 20)

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Tuplespace Service

• Fensel 2004, Bussler et al., 2005

Tuple-Space
read
write
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Related Work

• Buschmann et al., 1996 presented architecture
  patterns, but not related to web services
  applications
• A series of architectural styles for network
  application are surveyed in (Fielding, 2000)
• Web services architectural patterns are defined
  and identified in (Endrei et al., 2004) from
  Industry perspective for e-Business applications
• Research in (Maximilien and Singh, 2005) is the
  closest work to our efforts. It catalogs SOA
  architectural styles and conceptually evaluates
  these identified six styles based on their
  proposed multi-agent model rather than from
  related literature research and industry
  practices

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Conclusion

• In this paper, we surveyed web services
  architectural styles in current literature
• Our next research goal is to offer an analysis of
  these architecture styles based on a well-defined
  quality framework
• The aim of such analysis is to help architect
  select the most appropriate architecture styles
  given specified requirements captured from the
  stakeholders

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Questions SuggestionsThank you for your
attention!
First International Workshop on Design of
Service-Oriented Applications