Risk Management for Service-Oriented Systems Natallia Kokash Advisor: Vincenzo D’Andrea

20/07/2007ICWE Doctoral Consortium Como, Italy 2/20 Introduction What is Risk Management (RM)? Why do we need RM for SOA? Design of Service-Oriented Systems (SOSs) Risk-aware SOS design Risk Assessment Conclusions and Future Work

20/07/2007ICWE Doctoral Consortium Como, Italy 3/20 What is Risk Management? Risk –potential negative impact to an asset that may arise from some present process or future event –Risk = probability of an accident x losses per accident Risk Management –Process of identifying, assessing, and reducing the risk to an acceptable level –implementing the right mechanisms to maintain that level of risk.

20/07/2007ICWE Doctoral Consortium Como, Italy 4/20 Risk Management in IT Is indispensable! A lot of research has been done –Project management [Freimut et al. 2001, Verdon and McGraw 2003] –Outsourcing [O'Keeffe et al. 2004] –Business processes [Neiger et al. 2006] –Security-critical systems Model-based RM (CORAS [Jurjens and Houmb, 2004])

20/07/2007ICWE Doctoral Consortium Como, Italy 5/20 Risk analysis methodologies Analysis = identification + assessment [ Qualitative techniques: –Preliminary Risk Analysis (PHA) –HAZard and OPerability study (HAZOP) –Failure Mode and Effect Criticality Analysis (FMECA). Tree-based techniques –Fault-Tree Analysis (FTA), –Event-Tree Analysis (ETA) –Cause- Consequence Analysis (CCA) –Management Oversight Risk Tree (MORT) –Safety Management Organization Review Technique (SMORT) Techniques for dynamic systems –Go Method –Digraph/Fault Graph –Markov Modeling –Dynamic Event Logic Analytical Methodology –Dynamic Event Tree Analysis Method

20/07/2007ICWE Doctoral Consortium Como, Italy 6/20 Why do we need RM for SOA? No control over involved services –Correct behavior is not ensured –Services are difficult to test –May become unavailable or malfunctioning –Can be easily modified –Can misuse the data –Performance may vary Conflicting interests of involved partners –Conditions (payment, etc.) may vary –New services appear –Will the system be profitable in new settings?

20/07/2007ICWE Doctoral Consortium Como, Italy 7/20 Why RM for SOA is a challenge? Classification of SOAs [Tsai et al. 2007] –Static SOA Collaboration protocols are known Services are pre-selected –Dynamic SOA Collaboration protocols are known Services are selected at runtime –Dynamic collaboration Collaboration established at runtime, Services are selected at runtime Run-time RM! No party exists with full knowledge about the system

20/07/2007ICWE Doctoral Consortium Como, Italy 8/20 Service-Oriented Systems (SOSs) s2s2 s1s1 + + s3s3 s5s5 + s4s4 + Client Provide r Partners s0s0 Invoke XY Service composition Z XY Service oriented system

20/07/2007ICWE Doctoral Consortium Como, Italy 9/20 QoS Issues Domain-independent parameters –Throughput, capacity, execution cost, response time, availability, reliability, etc. Domain-dependent parameters Evaluate QoS at design time to create a dependable system Manage QoS at execution time to dynamically re-configure the application to maintain a certain QoS level

20/07/2007ICWE Doctoral Consortium Como, Italy 10/20 Design of SOSs 1.Design abstract business processes 2.Identify abstract web services 3.Define collaborative patterns 4.Formalize functional and non-functional requirements 5.Find and evaluate existing web services, model alternative solutions 6.Evaluate risks 7.Adapt design models to reduce risks 8.Negotiate conditions and stipulate contracts with involved web services [Bochicchio et al. 2007]

20/07/2007ICWE Doctoral Consortium Como, Italy 11/20 SOA Risks Threats –Loss of service, data, clients –Unexpected service behavior or modifications –Performance problems –Violations of contracts Assessment –Likelihood and implication of threats –Analysis of user expectations –Service testing –User feedback, reputation systems Mitigation –Service selection, redundancy, redesign –Runtime monitoring –Service Level Agreements and policies

20/07/2007ICWE Doctoral Consortium Como, Italy 12/20 Risk–aware SOS design

20/07/2007ICWE Doctoral Consortium Como, Italy 13/20 Risk assessment Quantitative techniques Two dimensions: –how likely the uncertainty is to occur (probability) –what the effect would be if it happened (impact) How to combine risks? –All threats are independent - sum –Otherwise? There is one dominating threat – consider only it There are mutually exclusive threats …

20/07/2007ICWE Doctoral Consortium Como, Italy 14/20 History of risk assessments

20/07/2007ICWE Doctoral Consortium Como, Italy 15/20 Risk-driven service selection Assumption: threats are independent! [Kokash and D'Andrea, 2007] Cost-benefit analysis –Choose the composition that maximized the expected profit

20/07/2007ICWE Doctoral Consortium Como, Italy 16/20 A composite web service must accomplish multiple user requests Strategy: –increase the probability that all requests will be accomplished by the service Redundant compositions –reduce resources per request (time, money, etc.) Failed services increase losses (e.g., time) If request is not accomplished (before deadline), penalty to the client must be paid. Mitigating risk of a composite service failure [Kokash and D'Andrea, 2007]

20/07/2007ICWE Doctoral Consortium Como, Italy 17/20 Where to take data for Risk Assessment? Advertised service descriptions –Full information is rarely available –Must we trust it? Testing agencies –Rarely available –How often is it updated? Testing by the client –Requires time Shared sources of clients’ experience

20/07/2007ICWE Doctoral Consortium Como, Italy 18/20 What we would like to have Design time –Case studies Execution time –A model for representing and tracking risks –Risk assessment strategies and quantitative metrics –A supporting tool Risk mitigation via SOA redesign/reconfiguration –Transition from risks to QoS requirements, SLAs and policy assertions –Run-time selection of services and coordination patterns

20/07/2007ICWE Doctoral Consortium Como, Italy 19/20 Related work 1.Verdon, D., McGraw, G.: Risk analysis in software design. IEEE Security and Privacy (2004) Roy, G.G.: A risk management framework for software engineering practice. ASWEC, (2004) Freimut, B., Hartkopf, S., Kaiser, P., Kontio, J., Kobitzsch, W.: An industrial case study of implementing software risk management. ESEC/FSE, (2001) Neiger, D., Churilov, L., zur Muehlen, M., Rosemann, M.: Integrating risks in business process models with value focused process engineering. ECIS, (2006) 5.O'Keeffe, F., Vanlandingham, S.: Managing the risks of outsourcing: a survey of current practices and their effectiveness. White paper, Protivity, sheets/business risk/Protiviti ORM WhitePaper.pdf (2004) 6.Kokash, N., D'Andrea, V.: Evaluating quality of web services: A risk- driven approach. BIS. Volume 4439 of LNCS, Springer (2007) Bochicchio, M.A., D'Andrea, V., Kokash, N., Longo, F. Conceptual Modelling of Service-Oriented Systems, AWSOR, 2007

20/07/2007ICWE Doctoral Consortium Como, Italy 20/20 The end! Questions?