an agent- and goal-oriented modelling framework   


"Social Modeling for Requirements Engineering"

i* Overview

i* Readings Roadmap




Related Projects

Related Publications

Further Readings

Related Doctoral Dissertations

Social Modeling for Requirements Engineering
                  (Cooperative Information Systems)November 15, 2010
From MIT Press: "This book offers a new approach to the requirements challenge, based on modeling and analyzing the relationships among stakeholders. The i* framework conceives of software-based information systems as being situated in environments in which social actors relate to each other in terms of goals to be achieved, tasks to be performed, and resources to be furnished. The book includes Eric Yu's original proposal for the i* framework as well as research that applies, adapts, extends, or evaluates the social modeling concepts and approach."
   Chapter 2 is a reprint of Eric Yu's doctoral dissertation from 1995.  It is followed by 18 chapters  authored by researchers from around the world who have applied, adapted, or extended the i* framework in various ways, and for diverse application contexts – from business processes to knowledge management to air traffic control, from information security to software development.
   Sneak preview - Chapter One.   
MIT PressAmazon.com.   Google books.


The i* framework is now part of an international standard!

International Telecommunication UnionNovember 13, 2008
The User Requirements Notation (URN) received final approval as an international standard today in Geneva, Switzerland, as ITU-T Recommendation Z.151. URN consists of the Goal-oriented Requirements Language (GRL), based on the i* modelling

 framework, and Use Case Maps (UCM), a scenario modelling notation. GRL provides a notation for modelling goals and rationales, and strategic relationships among social actors. It is used to explore and identify system requirements, including especially non-functional requirements. ITU is the UN agency for information and communication technologies.


The i
* framework proposes an agent-oriented approach to requirements engineering centering on the intentional characteristics of the agent.  Agents attribute intentional properties (such as goals, beliefs, abilities, commitments) to each other and reason about strategic relationships.  Dependencies between agents give rise to opportunities as well as vulnerabilities.  Networks of dependencies are analyzed using a qualitative reasoning approach.  Agents consider alternative configurations of dependencies to assess their strategic positioning in a social context.

The framework is used in contexts in which there are multiple parties (or autonomous units) with strategic interests which may be reinforcing or conflicting in relation to each other.  Examples of such contexts include: business process redesign, business redesign, information systems requirements engineering, analyzing the social embedding of information technology, and the design of agent-based software systems.

The name i* (pronounced eye-star) refers to the concept of distributed intentionality. 

Back to top  

Keywords: strategic relationships, intentional dependencies, multi-agent systems, autonomous agents, social networks, requirements engineering



Road map for readings on i* : 
For a quick overview, you may start with Social Modeling and i* and the introductory chapter of the book Social Modeling for Requirements Engineering.

RE97 which presents i* concepts using a pedagogical requirements engineering example.

A vision for strategic actors modelling in the context of Agent-Oriented Software Engineering is outlined in AOSE01. A similar overview for the Information Systems context is presented in WIj01.    

For a simple presentation of the framework in a Business Process Redesign context, you may start with either WITS94 or IEEE Expert 96.  Both provide an overview of the framework, with the latter including an example of ConGolog process modelling.  The COOCS93 paper focuses on the Strategic Dependency model (called the Actor Dependency model at the time). These papers should be enough to get you started in doing i* modelling.

CACM99 provides an overview of goal-oriented analysis, which is an important part of i*.  An earlier illustration of i* reasoning appeared in HICSS94 (This is now part of  the Strategic Rationale model.)

The ICSE94 paper is an application of the i* framework to Software Processes and Organizations. It has examples of the distinction among Agents, Roles, and Positions, and a discussion of enforcement, assurance, and insurance.  These are further illustrated in ICEIMT97.

IFAC99 offers examples of Business Modelling, with an example about IKEA.  These are further illustrated in ER01.  The latter also shows how i* modelling can be used to help reason about Patents in a strategic business context, with examples from e-commerce (online travel booking). The mechanisms for modelling patent protection is similar to those for modelling Trust and Security in Trust00.

The WIj01 paper provides a more detailed explanation of the premises behind the i* ontology.  The main arguments are summarized in the AOIS01 invited presentation.

COOCS95 compares several different approaches to modelling organizational work, including IBIS, KAOS, and Action Workflow (speech acts).
IWSSD98 and CoopIS95 provide examples of how i* may be used in conjunction with other modelling or specification languages in the context of software development.

The ER94 paper contains some partial schemas and axioms for the models.  More details are available in the PhD thesis [Yu95].


A set of Powerpoint slides assembles presentations slides from various papers and talks into a tutorial format.

Back to top

An International Standard


  • ITU-T Z.151 (2008-11).   i* is the basis for GRL (Goal-oriented Requirements Language), which together with UCM (Use Case Maps), constitute the User Requirements Notation URN.  URN was adopted as an international standard in November 2008. The full standards document "User Requirements Notation (URN) – Language definition" may be downloaded from here

International Telecommunication Union
ITU is the UN agency for information and communication technologies

Back to top

Software Tools

*new* Updated release, OpenOME version 3.4.2 is now available!

OpenOME is a software tool for supporting i* modeling. It may be downloaded from Sourceforge.
The developer site is at https://se.cs.toronto.edu/trac/ome
OME is an earlier software tool for supporing i* and NFR modelling. More information on the difference between the two can be found on the tools site.
See the i* tools

 page on the i* wiki for additional software tools for i* modeling and analysis.

Back to top

Events and ongoing research


  istar10-logoat caise

Back to top

Related projects


GRL - an elaborated version of i* , is part of the User Requirements Notation (URN), standardized under ITU-T Z.151.

Tropos is a methodology for agent-based software system development, with the i* framework as the basis and starting point.
Main project site:  www.troposproject.org
Other related project sites: Tropos at the Technical University of Aachen (RWTH), Germany   

Back to top 

Related publications

For more up-to-date listings, see CiteULike (tag: istar), and the publications pages on the i* wiki.

Some applications, extensions, or adaptations of i* :    (See also E. Yu Publications)
in selected areas:

Requirements Engineering

Process Analysis and Design, Reengineering

Evaluation, Verification and Validation  (See also the Tropos project.)

Agent-Oriented Systems Development  (See also the Tropos project.)

Trust in multi-agent systems

Security requirements engineering

Software engineering processes and organizations

Data Management Processes

Knowledge management

Systems and Organizational Architecture

Business modelling

Intellectual Property Management

 Back to top

Goal-Oriented Requirements Engineering

The  i*  agent-oriented approach builds on and extends Goal-Oriented Requirements Engineering (GORE)  [REFSQ98].  In particular the softgoal concept in i* draws on techniques for dealing with non-functional requirements in software engineering, as presented in

Some other related GORE frameworks include:

For discussions of goal-oriented requirements engineering, see  [Kavlaki02] [Rolland03] [vanLamsweerde00

Requirements Engineering

For an overview of Requirements Engineering, see:

Further Readings
Some recent papers which mention or discuss i*:    

Some recent papers concerning or mentioning the NFR framework:

Back to top


Related doctoral dissertations

For a more up-to-date list, see the Ph.D. dissertations page on the i* wiki.)

See: Katzenstein, G.J. and Lerch, F.J. (2001) Beneath the Surface of Organizational Processes: A Social Context Framework for Business Process Redesign. ACM Transactions on Information Systems, 18(4), 383-422.


Back to top

back to  University of Toronto :: KM lab  ::  Eric Yu  
Nedstat Basic - Free web site statisticsNedstat Basic - Free web site statistics

This page last modified on: September 6, 2011
Previous update: January 2, 2011