International Conference on Architecture of Computing Systems (ARCS 2008) Feb. 2008, Dresden Germany
A Reference Architecture for Self-organizing Service-oriented Computing Lei Liu, Stefan Thanheiser, Hartmut Schmeck Institute for Applied Informatics und Formal Description Methods (AIFB) Karlsruhe Institute of Technology (KIT)
Agenda
Motivation
Key Design Challenges for self-organising SOA
Reference Architecture
Rationale
Summary & Outlook
2 | A Reference Architecture for Self-organising Service-oriented Computing Lei Liu | ARCS‘08 | 3/5/2008
Today – Service-orientation as design paradigm
Challenge – managing Service-oriented Architecture (SOA) as large scale distributed application
Encapsulating business capabilities with reusable Web service interfaces Increasing adoption in enterprise
Complexity in SOA Existing centralized management solutions insufficient Service Provider
Service Consumer
Motivation
Idea – hybrid management approach by embedding controlled selfDocument organisation in SOA
SQL-DB
Management System
httpd 1
httpd 2
Application Server
Decentralized Self-organisation via multi-level Observer/Controller Architecture of Organic Computing Centralized external control via high-level policies Mainframe
Database
UNIXServer
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Windows -Server
LinuxServer
Java
.NET
Key Design Challenges for Self-organising SOA
SOA reduces IT complexity
→
Abstraction of technical details Consistent representation of business logic and data Better structured IT infrastructure
SOA complicates decentralized management
Service autonomy
Transparency
Dependency
Serviceoriented Architecture Scalability
Increasing integration Distributed application across organisations Design challenges
4 | A Reference Architecture for Self-organising Service-oriented Computing Lei Liu | ARCS‘08 | 3/5/2008
Heterogeneity and Interoperability
Dynamism
Decentralization and Distribution
Related Work
Reference architectures for Service-oriented computing
Service-oriented Solution Stack (S3) (Arsanjani et al., 2007)
Similar approaches: Integrated Service-oriented Architecture (iSOA) (KIM, 2005) or Extended Service-oriented Architecture (eSOA) (Papazoglou, 2005)
Addressing abstractly the management/governance aspect
Reference architectures for Self-organisation
Viable System Model (VSM) (Beer, 1959)
Recursive generic model for self-organisation 3 interacting aspects: operation, control, and environment 5 interacting subsystems with predefined capabilities
MAPE control loop of Autonomic Computing (IBM, 2005) Generic Observer/Controller (O/C) Architecture of Organic Computing (Branke et al., 2006)
5 | A Reference Architecture for Self-organising Service-oriented Computing Lei Liu | ARCS‘08 | 3/5/2008
Reference Architecture
Goal – an architectural blueprint for designing SOA with:
Decentralized self-organisation within SOA component Collaboration between self-organising SOA components Control over SOA components with high-level policies Hiding system complexity
Our Approach
Local - Managing Element
Establishing self-organisation in SOA component
Global - Management Overlay
Organising managing elements into overlay Separation between management-centric and service-centric communication Enabling collaboration between managing elements
6 | A Reference Architecture for Self-organising Service-oriented Computing Lei Liu | ARCS‘08 | 3/5/2008
Reference Architecture – Managing Element (I)
Service Component: e.g. a Web service or a Web server
Environment: the set of (related) managing elements
Self-organisation
Local Coordinator
Local Control
Global Coordinator
Global Control
Control
Global Control
External high-level policies
Managing Element Global Control
Global Coordinator
Local Control Local Operative Unit(s) Monitor
Local Coordinator Control
Service Component 7 | A Reference Architecture for Self-organising Service-oriented Computing Lei Liu | ARCS‘08 | 3/5/2008
Concrete
External Policies
Abstract
Abstract architectural pattern for Managing Element with controlled selforganisation
Environment
Reference Architecture – Managing Element (II) The architecture pattern for Managing Element covers
Aspect-separation allows
Operational aspect of local service component Control aspect, in particular by external policies Environment aspect Managing Element
Clear and modular design of self-organizing component Increased reusability
Address the design challenges
Service autonomy Transparency
External Policies
Global Control
Environment
Global Coordinator
Local Control Local Operative Unit(s) Monitor
Local Coordinator Control
Service Component 8 | A Reference Architecture for Self-organising Service-oriented Computing Lei Liu | ARCS‘08 | 3/5/2008
Reference Architecture – Management Overlay (I)
Management Overlay
1-1 Management
Structure Mapping
Relationship Mapping
9 | A Reference Architecture for Self-organising Service-oriented Computing Lei Liu | ARCS‘08 | 3/5/2008
Reference Architecture – Management Overlay (II)
Separation between management-centric and service-centric communication
Service-oriented management overlay
Organising managing elements with service-orientation
Flexible management overlay
Managing elements expose management capabilities via Web services interface Managing elements communicate via Web services Internal changes of managing elements do not effect the management overlay Including additional component(s) into overlay, e.g. services providing decision support in case of conflicts Dynamic overlay wrt. changes in the underlying SOA layer
Address several design challenges
10 | A Reference Architecture for Self-organising Service-oriented Computing Lei Liu | ARCS‘08 | 3/5/2008
Rationale – Our Approach for Decentralized Management Advantages
Combining local and global context
Enabling flexible design of management overlay
Robust management approach vs. centralized management
Remaining controllable via external policies
Disadvantages
More communication and coordination efforts
(Possibly) suboptimal decision due to limited view
Trade-off between centralized but restricted control and decentralized but robust control 11 | A Reference Architecture for Self-organising Service-oriented Computing Lei Liu | ARCS‘08 | 3/5/2008
Summary & Outlook
Analysed existing reference architectures for SOC and Self-organisation
Proposed a reference architecture for self-organising SOA
Characteristics of our reference architecture
Management Overlay for global context Managing Element for local management
Generic and technology independent approach Flexible and agile architecture wrt. underlying SOA layer
Outlook
Refinement of the reference architecture Proof-of-concept implementation in an SOA simulation environment Implementation of self-healing scenarios in the simulation environment
12 | A Reference Architecture for Self-organising Service-oriented Computing Lei Liu | ARCS‘08 | 3/5/2008
Thank you for your attention! Questions? For any question please feel free to contact Lei Liu Karlsruhe Institute of Technology (KIT) University of Karlsruhe Institute of Applied Informatics and Formal Description Methods (AIFB) Email:
[email protected]
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Backup Slides
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Viable System Model (VSM)
Environment
System 5 System 4 System 3
A
System 1 (A)
B
System 1 (B)
System 2
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Reference Architecture – Managing Element (III) Global Control
Global Coordinator Environment Local Control
Local Opertional Unit
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Local Coordinatior
Reference Architecture – Managing Element (IV) Global Control
Global Coordinator Environment Local Control
Local Opertional Unit
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Local Coordinatior
Reference Architecture – Managing Element (V) Global Control
Global Coordinator Environment Local Control
Local Opertional Unit
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Local Coordinatior
