A Reference Architecture for Self-organizing Service-oriented Computing

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) International Conference on Architecture of Computing Systems (ARCS 2008) Feb. 2008, Dresden Germany

Agenda Motivation Key Design Challenges for self-organising SOA Reference Architecture Rationale Summary & Outlook 2 A Reference Architecture for Self-organising Service-oriented Computing

Service Provider Service Consumer Motivation Today Service-orientation as design paradigm Encapsulating business capabilities with reusable Web service interfaces Increasing adoption in enterprise Challenge managing Service-oriented Architecture (SOA) as large scale distributed application Complexity in SOA Existing centralized management solutions insufficient Idea hybrid management approach by embedding controlled selforganisation in SOA Document SQL-DB Management httpd httpd Application Decentralized Self-organisationSystem via multi-level 1 Observer/Controller 2 Server Architecture of Organic Computing Centralized external control via high-level policies Mainframe Database UNIX- Server Windows -Server Linux- Server Java.NET 3 A Reference Architecture for Self-organising Service-oriented Computing

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 Increasing integration Distributed application across organisations Design challenges Transparency Scalability Heterogeneity and Interoperability Service autonomy Serviceoriented Architecture Dynamism Dependency Decentralization and Distribution 4 A Reference Architecture for Self-organising Service-oriented Computing

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

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

Concrete Environment Abstract Reference Architecture Managing Element (I) Abstract architectural pattern for Managing Element with controlled selforganisation Service Component: e.g. a Web service or a Web server Environment: the set of (related) managing elements Self-organisation Managing Element Global Control External Policies Local Coordinator Local Control Global Coordinator Global Control Global Coordinator Local Control Control Global Control Local Operative Unit(s) Local Coordinator External high-level policies Monitor Control Service Component 7 A Reference Architecture for Self-organising Service-oriented Computing

Environment Reference Architecture Managing Element (II) The architecture pattern for Managing Element covers Operational aspect of local service component Control aspect, in particular by external policies Environment aspect Aspect-separation allows Clear and modular design of self-organizing component Increased reusability Address the design challenges Service autonomy Transparency Managing Element Global Control Global Coordinator Local Operative Unit(s) Local Control External Policies Local Coordinator Monitor Control Service Component 8 A Reference Architecture for Self-organising Service-oriented Computing

Reference Architecture Management Overlay (I) Management Overlay Structure Mapping 1-1 Management Relationship Mapping 9 A Reference Architecture for Self-organising Service-oriented Computing

Reference Architecture Management Overlay (II) Separation between management-centric and service-centric communication Service-oriented management overlay Organising managing elements with service-orientation Managing elements expose management capabilities via Web services interface Managing elements communicate via Web services Flexible management overlay 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

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

Summary & Outlook Analysed existing reference architectures for SOC and Self-organisation Proposed a reference architecture for self-organising SOA Management Overlay for global context Managing Element for local management Characteristics of our reference architecture 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

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: lei.liu@kit.edu 13 A Reference Architecture for Self-organising Service-oriented Computing

Backup Slides 14 A Reference Architecture for Self-organising Service-oriented Computing

Viable System Model (VSM) Environment System 5 System 4 System 3 A System 1 (A) B System 1 (B) System 2 15 A Reference Architecture for Self-organising Service-oriented Computing

Reference Architecture Managing Element (III) Global Control Environment Global Coordinator Local Control Local Opertional Unit Local Coordinatior 16 A Reference Architecture for Self-organising Service-oriented Computing

Reference Architecture Managing Element (IV) Global Control Environment Global Coordinator Local Control Local Opertional Unit Local Coordinatior 17 A Reference Architecture for Self-organising Service-oriented Computing

Reference Architecture Managing Element (V) Global Control Environment Global Coordinator Local Control Local Opertional Unit Local Coordinatior 18 A Reference Architecture for Self-organising Service-oriented Computing