Proceedings of the
iEMSs Fourth Biennial Meeting
Main Editors:
Miquel Sànchez-Marrè. Javier Béjar, Joaquim Comas,
Andrea E. Rizzoli, Giorgio Guariso
International Congress on
Environmental Modelling and Software
iEMSs 2008
Integrating Sciences and Information Technology for Environmental
Assessment and Decision Making

Volume 2

Universitat Politècnica de Catalunya, Barcelona, Catalonia
7-10 July 2008

iEMSs 2008: International Congress on Environmental Modelling and Software
Integrating Sciences and Information Technology for Environmental Assessment and Decision Making
4th Biennial Meeting of iEMSs, http://www.iemss.org/iemss2008/index.php?n=Main.Proceedings
M. Sànchez-Marrè, J. Béjar, J. Comas, A. Rizzoli and G. Guariso (Eds.)
International Environmental Modelling and Software Society (iEMSs), 2008
A Design for Framework-Independent Model
Components of Biophysical Systems
M. Donatellia,**,
, A.E. Rizzolib
a Agriculture Research Council, 40128 Bologna, Italy;
** currently seconded to European Commission Joint Research Centre, Institute for the
Protection and Security of the Citizen, Agriculture Unit, Agri4cast Action, Ispra, Italy
b Dalle Molle Institute for Artificial Intelligence, Manno-Lugano, Switzerland;

Corresponding author, marcello.donatelli@jrc.it
Abstract: Most efforts in the design of software frameworks for biophysical systems
simulation have focused on the compromise between domain specificity and use flexibility.
Models in such frameworks fall in two main categories: either framework-specific, or
“legacy” code. In the former case, models implemented as software components can take
full advantage of the framework services, but they depend on the framework. In the latter
case, components are seen as discrete units of software, in general of coarse granularity in
modelling terms, and the dependency on the framework is minimal, but the potential for
composition and reuse is limited. Thus, modellers who want to use a modelling framework
are faced with two choices: if the framework is extensible, implement a framework specific
component (i.e. not reusable outside the specific framework); else, the alternative is to
provide a component as a black-box, taking little or no advantage of the framework itself.
We argue that component design choices, rather than being driven by the specific
framework architecture, should rather promote re-usability by including design traits that
represent a compromise between generality and specificity in order to maximize the
adaptability of components. This paper present: 1) a software design of non-framework
specific components, and 2) real-world applications of the design presented.
Keywords: Modelling; Component-oriented programming; Software components.
1. INTRODUCTION
In the past decade there has been an increasing demand for modularity and replaceability in
biophysical models (e.g. [Jones et al., 2001]; [David et al., 2002]; [Donatelli et al., 2003,
2004, 2006]), both aimed at improving the efficiency of use of resources and at fostering a
higher quality of modelling units. Rather than having generalist modellers working on all
details of complex integrated models, it is more efficient and effective to assemble sub-
models developed by specialists in the specific sectors.
The modular approach developed in the software industry is based on the concept of
encapsulating the solution of a modelling problem in a discrete, replaceable, and
interchangeable software unit. Such discrete units are called components. A software
component can be defined as “a unit of composition with contractually specified interfaces
and explicit context dependencies only. A software component can be deployed
independently and is subject by composition by third parties” [Szypersky et al., 2002].
Component-oriented designs actually represent a natural choice for building scalable,
robust, large-scale applications, and to maximize the ease of maintenance in a variety of
domains, including agro-ecological modelling [Argent, 2004]. This concept has been
applied to biophysical simulation and has led to the development of several modelling
frameworks (e.g. Simile, MODCOM, IMA, TIME, OpenMI, SME, OMS, as listed in
Argent and Rizzoli [2004], and in Rizzoli, Leavesley et al. [in press]), which allow the use
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