Graphical Modelling of Workflows: Foundation for Handling Uncertainty in the Model Web 76th OGC Technical Committee Bonn, Germany Benjamin Proß, IfGI/52°North March 01, 2011
Dec 25, 2015
Graphical Modelling of Workflows: Foundation for Handling Uncertainty in
the Model Web
76th OGC Technical CommitteeBonn, Germany
Benjamin Proß, IfGI/52°NorthMarch 01, 2011
UncertWeb Facts
• Uncertainty-enabled Model Web, FP7 Project (http://www.uncertweb.org/)
• Feb 2010 – Jan 2013• 8 Partners
• Aston University• Italian National Research Council • Food and Environment Research Agency • Joint Research Centre• Norwegian Institute for Air Research• Eindhoven University of Technology• University of Muenster• Wageningen University
Definitions
• Uncertainty– Model inputs
• E.g. through measurement errors of sensors • Taking outputs of other models as inputs
– Models itself• By aproximating reality, models introduce errors, and
should inform the user about (annotate its output with) the degree this happens
Definitions
• Model Web“The goal of the Model Web is to enable the development of a modelling infrastructure. To achieve this, the Model Web focuses on enhancing interoperability of existing models and making their outputs more accessible” (GEOSS AIP-2 Summary Engineering Report GEOSS Architecture Implementation Pilot).
• Vision, NOT implementation• Infrastructure is not yet existing
The UncertWeb concept
When chaining services of limited or unknown quality, uncertainty must be accounted for if rational decisions are to be made.
ECMWFensembles
GEMSensembles
Emissions data
Air quality forecastmodel
Modelparameters
Uncertaintyenabled air quality
forecast
Air qualitysensor network
Short range airquality forecasts
Meteorologicalsensor network
ECMWF model
GEMS models
Near real-time airquality nowcasts
Land use data
Albatross individualactivity simulator
Historical activitydata
Traffic model
Individualexposure
assessment
Emissions model
GISinfrastructure
data
Demographicdata
“UncertWeb develops mechanisms, standards, tools and test-beds for accountable uncertainty propagation in web service chains.”
Uncertainty quantification
• Even more important when considering service chains.
• Quantification achieved by:– Standards for representing and communicating
uncertainty.– Adding uncertainty-enabled inputs and outputs to
existing services.– Developing tools to assist users with uncertainty
management.• Computational issues will be non-trivial too!
UncertWeb and UncertML
• Standards for coupling models under uncertainty.– Develop UncertML to provide a complete
probabilistic model for uncertainty, and consider other (e.g. Fuzzy, Bayes Linear) representations.
– Provide an API for using UncertML.– Take UncertML through the standardisation
process (where? OGC?, W3C?, IETF?).
Chaining UncertWeb services
• Chaining and discovery of services under uncertainty.– Extend existing interoperable services to permit
their use in the uncertainty-enabled model web.– Implement a framework for uncertainty-enabled
model web services.– Develop uncertainty-enabled OGC Web Services.– Also support standard W3C WS.
• Uncertainty enabled WPS (UWPS)– Encapsulates models– Understands UncertML– Executes Monte Carlo simulations
• Uncertainty Transformation Service (UTS)– Transforms Uncertainties– E.g. distributions to realisations
• Spatio Temporal Aggregation Service (STAS)
Use of WPS
WP2: Chaining and discovery services under
uncertainty• Develop the methods and the Web-based
technology framework needed to discover and chain uncertainty-enabled or deterministic models in the presence of uncertainty– Composition as a Service (CaaS) approach– SOAP/WSDL + WPS service profiles– Metadata extensions
The CaaS
• Definition of a Composition-as-a-Service– From the literature
• A service “…for avoiding the need to install a client-side composition infrastructure”
– From a Cloud Computing point-of-view• Something between the customized Software-as-a-
Service (SaaS) and the flexible but complex Platform-as-a-Service (PaaS)
The UncertWeb CaaS
• Features– The CaaS supports business process modelling
through composition ( = re-use of existing) of (software) services
– BPMN -> BPEL– Preprocessing– The composition result is still exposed as a
service through a Workflow Engine
The UncertWeb CaaS
• Three functional Layers:– User Interface (editor, library, pre-processor for
domain-specific notations,…)– Mediation (orchestration logic, abstract
processes selector,…)– Adaption (adapters for external processes)
52°North Web Based Workflow Modeller
• http://52north.org/maven/project-sites/wps/52n-wps-orchestration-site/index.html
• Developed during a research project with the Sejong University, Seoul through the funding from the Seoul R&BD program(10540)
• Further use and development in the context of UncertWeb
52°North Web Based Workflow Modeller
• Lightweight browser application, that allows the:– Graphical composition and execution of
workflows consisting of different OGC services like WPS, WFS and WMS
– Execution of single WPS-processes– Visualisation of results– Creation of a new BPEL-process out of a workflow
and uploading it to a WPS-T
52°North Web Based Workflow Modeller
OpenLayers-map.
Easy adding and connecting of WPS-processes and data.
Graphical workflow-modelling.
Drag & Drop of Workflow-elements, like e.g. WFS-Layer.
52°North Web Based Workflow Modeller
• Features– GWT web application– OpenLayers map– Orchestration of workflows either through
• 52°North WPS Orchestration API• Workflow Engine (e.g. Apache ODE)
52°North Web Based Workflow Modeller
• A more complex scenario
Estimation of air pollution
from local emissions at point locations
• Special thanks to:• Lydia Gerharz• Christoph Stasch• Richard Jones• Dan Cornford• Lucy Bastin• Matthew Williams• Stefano Nativi• Paolo Mazzetti