Interactive Cooperative Objects

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Informal Presentation

The Interactive Cooperative Objects (ICOs) formalism is a formal notation dedicated to the specification of interactive systems.

ICOs use concepts borrowed from the object-oriented approach (dynamic instantiation, classification, encapsulation, inheritance, client/server relationship) to describe the structural or static aspects of systems, and uses high-level Petri nets to describe their dynamic or behavioural aspects.

ICOs where originally devised for the modelling and implementation of event-driven interfaces. An ICO model of a system is made up of several communicating objects, where both behaviour of objects and communication protocol between objects are described by Petri nets.

In the ICO formalism, an object is an entity featuring four components: behaviour, services, state and presentation.

Behaviour : The behaviour of an ICO states how the object reacts to external stimuli according to its inner state. This behaviour is described by a high-level Petri net called the Object Control Structure (ObCS) of the object.
Services : An ICO offers a set of services that define the interface (in the programming language meaning) offered by the object to its environment. In the case of user-driven application, this environment may be either the user or other objects of the application. The ICO formalism distinguishes between two kinds of services: · services offered to the user (user services) and services offered to other objects.
State : The state of an ICO is the distribution and the value of the tokens (called the marking) in the places of the ObCS. This allows defining how the current state influences the availability of services, and conversely how the performance of a service influences the state of the object.
Presentation The Presentation of an object states its external look. This Presentation is a structured set of widgets organised in a set of windows. The user - system interaction will only take place through those widgets. Each user action on a widget may trigger one of the ICO's user services. The relation between user services and widgets is fully stated by the activation function that associates to each couple (widget, user action) the service to be triggered.

ICO are used to provide a formal description of the dynamic behaviour of an interactive application. An ICO specification fully describes the potential interactions that users may have with the application. The specification encompasses both the "input" aspects of the interaction (i.e. how user actions impact on the inner state of the application, and which actions are enabled at any given time) and its "output" aspects (i.e. when and how the application displays information that is relevant to the user).

An ICO specification is fully executable, which gives the possibility to prototype and test quickly an application before its is fully implemented. The specification can also be validated using analysis and prof tools developped within the Petri nets community.

Formal Definition

Formal definition of the ICO formalism is available here.

ICOs Environment

An environment is currently developed at LIHS for the edition, verification and execution of ICO models. Contact me for further information.

Related Bibliography

Palanque, Philippe, and Bastide, Rémi. "Task Models - System Models: a Formal Bridge Over the Gap." in Critical Issues in User Interface Systems Engineering. David Benyon, and Philippe Palanque, editors. Springer (1996) 65-79, Chapter IV.
Bastide, Rémi, and Palanque, Philippe. "A Visual and Formal Glue Between Application and Interaction." Journal of Visual Language and Computing 10, no. 3 (1999)
Palanque, Philippe, and Bastide, Rémi. "Synergistic Modelling of Tasks, Users and Systems Using Formal Specification Techniques." Interacting With Computers 9, no. 2 (1997) 129-53.
Bastide, Rémi, Palanque, Philippe, Le, Duc-Hoa, and Muñoz, Jaime. "Integrating Rendering Specifications into a Formalism for the Design of Interactive Systems." in 5th Eurographics Workshop on Design, Specification and Verification of Interactive Systems, DSV-IS'98, Abingdon, U. K. June 3-5,1998. Springer-Verlag (1998)
Bastide, Rémi, and Palanque, Philippe. "Implementation Techniques for Petri Net Based Specifications of Human Computer Dialogues." in 2nd Workshop on Computer Aided Design of User Interfaces, CADUI'96, Université Notre-Dame de la Paix, Namur (Belgium), 1996. Jean Vanderdonckt, Editor. Presses Universitaires de Namur (1996) 285-302.
Bastide, Rémi, and Palanque, Philippe. "Verification of an Interactive Software by Analysis of Its Formal Specification." 5th IFIP TC13 International Conference, Interact'95, Lillehamer, Norway, June 25-29 1995. Chapman et Hall (1995) 191-96.
Bastide, Rémi, and Palanque, Philippe. "A Petri-Net Based Environment for the Design of Event-Driven Interfaces." 16th International Conference on Applications and Theory of Petri Nets, ICATPN'95, Torino, Italy, June 1995. Giorgio De Michelis, and Michel Diaz, Volume editors. Lecture Notes in Computer Science, no. 935. Springer (1995) 66-83.
Bastide, Rémi, and Palanque, Philippe. "Petri Net Based Design of User-Driven Interfaces Using the Interactive Cooperative Objects Formalism." in Interactive Systems: Design, Specification, and Verification, DSV-IS'94. Fabio Paternò, Volume editor. Springer-Verlag (1994) 383-400.

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