Policy Support for Business-oriented Web Service Management Stephen Gorton and Stephan Reiff-Marganiec Department of Computer Science, University of Leicester University Road, Leicester LE1 7RH United Kingdom Latin-American Web Congress, Cholua, Mexico, 25-27 October 2006
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Policy Support for Business-oriented Web Service Management Stephen Gorton and Stephan Reiff-Marganiec Department of Computer Science, University of Leicester.
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Policy Support for Business-oriented Web Service Management
Stephen Gorton and Stephan Reiff-Marganiec
Department of Computer Science, University of LeicesterUniversity Road, Leicester LE1 7RH United Kingdom
Latin-American Web Congress, Cholua, Mexico, 25-27 October 2006
SENSORIA
• Software Engineering for Service-oriented Overlay Computers• IST project funded by the EU• http://sensoria.fast.de
“The aim of SENSORIA is to develop a novel comprehensive approach to the engineering of software systems for service-oriented overlay computers where foundational theories, techniques and methods are fully integrated in a pragmatic software engineering approach.”
• Work Package 1: Service Description• Task 1.3: Service-oriented business modelling
• Service oriented computing and web services• Service management• Introduction to policies• The Appel PDL• Appel in telecommunications• How we use policies• The process execution engine• Specifying requirements• Example usage• Further and related work• Summary and conclusions
SOC and web services
• Services are:– Loosely coupled units of software available over a network, exposed by well-
defined interfaces;– Based on open standards;– Composable, i.e. you can orchestrate two or more together to make a composite
service.
• Web services:– A popular implementation of SOA, incorporating open standards such as XML;– Are also optionally self-describing and discoverable;– Communicate via standard HTTP.
Service-oriented computing (SOC) is an architectural approach to building loosely coupled applications.
• The link with telecommunications:– Internet telecommunications based on components or features;– Features include call forwarding, call waiting, etc.;– SOC is similar in the sense of component composition;– Can we use telecoms technology for SOC?
Feature FA
Feature FB
Feature FC
Service SA
Service SB
Service SC
Service management
• Present:– Not huge uptake in WS;– Lots of “large” implementations;– Relatively few open access services;– Amazon, Ebay and Google provide public WS interfaces.
• Future:– Lots of WS?– “Smaller” WS capable of doing more atomic activities?– Composition of WS provides required functionality.
• Business needs:– Align IT objectives with business objectives;– Adaptability and flexibility of systems;– Business-oriented management?
“As a substantial number of Web Services become available, so the attention shift will be from service infrastructure to service management”.
Casati et al. Business-oriented management of Web Services. Comm. ACM, 46(10):55-60, 2003.
Policies and web services
• Policies are:– “…information that can be used to modify the behaviour of a system.”
(Lupu and Sloman. Conflicts in Policy-based Distributed Systems Management. IEEE Transactions on Software Engineering, Nov 1999.
– Automatic negotiations Lamparter and Agarwal. Specification of policies for automatic negotiations of web services. In L. Kagal, T. Finin and J. Hendlerm editors, SWPW, 2005.
• Our policies are:“a high level statement as to how business requirements
should be processed in the management system.”
Appel policy framework
• The Accent Project Policy Environment/Language;• A Policy Description Language (PDL), allowing users to write their own
policies;• Designed by Reiff-Marganiec et al at the University of Stirling;
S. Reiff-Marganiec, K. Turner and L. Blair. Appel: The Accent policy environment/language. Technical report CSM-164, University of Stirling, Jun 2005.
• Developed for the Accent project (telecommunications control).
• PDL allows for the definition of ECA policies or goals;• Appel defines an XML Schema based around:
– Triggers– Conditions– Actions
• Extended by functions:– Prompt
• to get information from the user
– Display • to output data in some visual format
Abstract Web Service Protocol Stack
APPEL
Composition (BPEL, etc.)
UDDI, USML, etc.
WSDL, WSCM, etc.
Messaging (HTTP, HTTPS, SOAP, etc.)
Wizards, Display Managers, etc.Presentation
Policy
Enterprise
Description
Transport
Discovery
Where policies fit in
Corporate Space
Project Space
Service Space
TaskTaskTask
WSWSWS
Business Domain
Web Service Domain
WSWSWSWSWSWS
WSWSWS
TaskTaskRuleTaskTaskRule
Tasks map to (composite) services
Composition / Orchestration Mechanisms
Composition / Orchestration Mechanisms
The proposed architecture
User Interface Layer
Policy ServerLayer
ServiceLayer
Policy Server Policy Server Policy Server
Service Service Service Service Service Service Service
services located and composed using UDDI, WSDL, etc. or equivalent
WS
Policies
Task Map Workflow
Skeleton Composition
Stubless Composition
Appel policies
• Triggers (adapted from the SENSORIA ontology):– Message events– Time events– Change events– Service events– Interaction events
• Conditions:– Checks on local or remote data values
• Includes standard mathematical operators
• Actions– Core information in the policy– Defines what service to invoke via different tags– Can specify more than one action with tags <and>, <andthen>, <else>, <or>, or
• Express preferences– “I will only fly with British Airways on flights lasting over 8 hours”– “Given a choice, I prefer to use a supplier in my phone book”
– Options:• Modalities include must, should, prefer, and their negations.
• Express requirements– “Purchase a rail ticket from X to Y, with times T and S…”– “Quote for a holiday”
– Options:• Unbounded on what we can express• Restrictions are on classifications of requirements (tags).
• Express restrictions– “Services not allowed from originating country X”– Capping the maximum expense claim amount
• Not a web service policy but a management policy
• Quality:– Any identified qualitative value can be addressed, provided it is published in the
directory entry (UDDI or similar), or it is “testable”;– Qualitative checks based on similar condition checks;– Named parameters compared against values;– Operators include:
• Equal to• Less than• Less than or equal to• Greater than• Greater than or equal to
• Interaction of policies with task maps;• Refinement of policy functions and definition of further functions;
• Mediation of user-defined and service requested data types;• Integration of this technology with service coordination technology;• Mapping of task maps to workflow languages (e.g. YAWL)
• Related work:– Task maps– SRML– YAWL
Summary and Conclusions
• With increasing numbers of web services, management will shift further into the business domain;
– Management of software will shift closer to the business analyst rather than the software engineer;
– Align IT objectives with business objectives.
• Similarities between telecoms and SOC:– Feature composition;– Management issues.
• Appel extended as a PDL for SOC:– Users define their own policies to express goals, requirements and preferences;– Extension functions allow us to address the SOC domain.