Towards an Explicit Bidirectional Requirement-to-Code Traceability

Meta-model for the PASSI Methodology

Mihoub Mazouz

, Farid Mokhati

and Mourad Badri

Department of Mathematics and Computer Science, University of Oum El Bouaghi, Oum El Bouaghi, Algeria

Department of Mathematics and Computer Science, University of Oum El Bouaghi, LAMIS Laboratory,

Oum El Bouaghi, Algeria

Department of Mathematics and Computer Science, Glog Laboratory, University of Quebec, Trois-Rivières, Canada

Keywords: Multi-agent System, Traceability, PASSI.

Abstract: Traceability plays an important role in the development of computing systems, specifically, the complex

ones. It provides several benefits to stakeholders and developers during the different phases of the systems

development life cycle, including verification & validation and maintenance. Unfortunately, there are very

few works in literature addressing the concept of traceability in multi-agent systems development

methodologies. Having an incremental and iterative process, the well-known PASSI (Process for Agent

Societies Specification and Implementation) methodology needs an explicit traceability in order to facilitate

the understanding of the MAS under development and to better manage the changes occurring during the

development process. In addition, it can lead to a requirement-based verification & validation. In this paper,

we propose a new traceability meta-model for the PASSI methodology by introducing explicit traceability

links of functional requirements through the various phases of the development life cycle.

1 INTRODUCTION

Tracing systems artifacts is a good factor to support

various activities in the development process of

computing systems (Spanoudakis, G, and A.

Zisman., 2004). The introduction of traceability

links between requirements and other systems

artefacts can help the developer to better understand

and manage the changes of any artifact on other

artefacts that are connected thereto. It also gives a

better development process visibility, as it facilitates

the maintenance and verification & validation

activities (Kannenberg et al., 2009). Integrating

traceability in the development processes increases

the quality of developed systems (Spanoudakis, G,

and A. Zisman., 2004). The agent paradigm has

demonstrated its effectiveness in modeling and

design of complex systems. Several methodologies

are now available in the literature to guide

developers in the development of agent-oriented

systems (e.g., PASSI (Cossentino, M., 2005,

Cossentino, M. and V. Seidita, 2014), Gaia

(Cernuzzi, L., et al., 2004), Prometheus (Winikoff,

M. and L. Padgham, 2004), Tropos (Giorgini, P., et

al., 2004).

Castro et al. reported in (Andréa C., et al., 2002)

that the success in the development of the next

generation of agent-oriented systems would be made

thanks to the adoption of requirements traceability.

Unfortunately, few works (Pinto, R., et al., 2007,

Cysneiros G. and A. Zisman., 2007a, Cysneiros G.

and A. Zisman., 2007b, Andréa C., et al., 2002,

Castro, J., et al., 2003, Cysneiros, G. and A. Zisman,

2008, Pinto, R, et al., 2005) being adopted the

traceability concept for multi-agent systems (MAS)

development methodologies and associated tools

exist. Introducing explicit traceability links between

the different artifacts composing a system during the

different phases of development facilitates the

development process.

In this paper, we propose a new traceability

meta-model for the well-known PASSI methodology

(Cossentino, M., 2005). Traceability information are

added to the specifications of the various system

artifacts produced during the development process,

allowing a bidirectional requirement-to-code

traceability from the identification of the functional

requirements in the domain requirement description

phase to the deployment of agents that will achieve

these requirements in the last phase of PASSI

203

Mazouz M., Mokhati F. and Badri M..

Towards an Explicit Bidirectional Requirement-to-Code Traceability Meta-model for the PASSI Methodology.

DOI: 10.5220/0005249102030209

In Proceedings of the International Conference on Agents and Artiﬁcial Intelligence (ICAART-2015), pages 203-209

ISBN: 978-989-758-073-4

 2015 SCITEPRESS (Science and Technology Publications, Lda.)

process, deployment configuration.

The remainder of this paper is organized as

follows. In Section 2, we give an overview of major

related work. In Section 3, we give a brief

description of the PASSI methodology. We

introduce, in Section 4, the proposed traceability

meta-model for the PASSI methodology. In Section

5, a case study is showed. Finally, Section 6 gives

some conclusions and future work directions.

2 RELATED WORK

Over the last years, very few works (Pinto, R., et al.,

2007, Cysneiros G. and A. Zisman., 2007a,

Cysneiros G. and A. Zisman., 2007b, Andréa C., et

al., 2002, Castro, J., et al., 2003, Cysneiros, G. and

A. Zisman, 2008, Pinto, R, et al., 2005) addressing

traceability in MAS development methodologies

have emerged in literature. G. Cysneiros et al.

(Cysneiros G. and A. Zisman., 2007a, Cysneiros G.

and A. Zisman., 2007b, Cysneiros, G. and A.

Zisman, 2008) address the Prometheus

methodology. The authors proposed a rule-based

approach supporting traceability and verification of

completeness of artefacts represented in the

Prometheus design models and JACK code

specification. They have identified some types of

traceability relationships between Prometheus

design models artefacts and JACK code. The

proposed rules allow the generation of traceability

relationships after the models are built in an

automatic way, which may neglect many

relationships.

The other works (Pinto, R., et al., 2007, Andréa

C., et al., 2002, Castro, J., et al., 2003, Pinto, R, et

al., 2005) address the Tropos methodology. The

authors have proposed an agent-oriented traceability

reference model and showed how it can be used in

the context of Tropos.

We present, in this paper, a new and explicit

bidirectional Requirement-to-Code traceability for

the PASSI methodology. Compared to the other

approaches quoted above, the creation of traceability

links we propose is performed when building PASSI

models, covering the whole PASSI Process.

3 THE PASSI METHODOLOY

3.1 Description

PASSI (Process for Agent Societies Specification

and Implementation) (Cossentino, M., 2005,

Cossentino, M. and V. Seidita, 2014), is a step-by-

step requirement-to-code methodology for designing

Figure 1: The PASSI design process. (Cossentino, M.,

2005).

and developing agent-oriented systems. The process

model of PASSI is iterative/incremental and

includes five models, each model includes one or

more phases (see Figure 1). The five models of

PASSI are:

 System Requirements Model: It is composed of

four phases: 1) Domain Requirements Description,

as a use case diagram, the functional requirements

of the system are described. 2) Agents

Identification, where the agents making up the

system to be developed are identified as packages

including their proper functionalities. 3) Roles

Identification, where the roles played by agents in

the different scenarios of the system are identified

in a series of sequence diagrams exploring the use

cases identified in the first phase. 4) Tasks

specification, where an activity diagram is used to

specify the plan of each agent.

 Agent Society Model: It is composed of four

phases: 1) Domain Ontology Description, where

the agent knowledge is described by an ontology

(in terms of Concept, Predicate, Action) and

represented as a class diagram. 2) Communication

Ontological description, where a class diagram is

used to represent all agents, all interactions

between them with the precision of the semantics

of each communication between agents (ontology

element, content language and the interaction

protocol). 3) Roles Description, where roles

already identified in the Role Identification phase

for each agent (a package here) are represented by

classes, each one is responsible for its own tasks

(class operations). 4) Protocols Description,

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AUML sequence diagrams are used to describe all

non-standard protocols.

 Agent Implementation Model: It is composed

of two phases: 1) Agent Structure Definition,

class diagrams are used to describe the system

architecture, 2) Agent Behaviour Description,

where activity diagrams or state-machines can be

used to describe the system behaviour. These two

phases are views of two different abstraction

levels: a) society, i.e. multi-agent abstraction

level; b) single agent abstraction level.

 Code Model: It is composed of two phases: 1)

Code-Reuse, in this phase, design patterns

already exist can be used directly, 2) Code

Production, where the skeleton of the source

code of the system is automatically generated by

the PTK (a Rational Rose plug-in that offers a

support for PASSI) and a manual completion of

the generated code is then achieved by the

developer.

 Deployment Model: It is composed of one

phase: Deployment Configuration, where

deployment diagram is used to describe the

allocation of agents to different processing units

and any constraints on agent migration and

mobility.

As illustrated by Figure 1, the PASSI process

includes a test activity divided into two different

levels: 1) single-agent test: when a framework built

on top of JADE is implemented (Caire, G, et al.,

2004). The most framework classes are “Test” class

for testing a specific task of an agent and

“TestGroup” class for testing all tasks composing a

specific agent. 2) society test: at this level,

integration verification is carried out together with

the validation of the overall results of the current

iteration (Cossentino, M., 2005).

3.2 The MAS Meta-Model of PASSI

The meta-model adopted for PASSI MAS is divided

into three areas (Cossentino, M. and V. Seidita,

2014):

 Problem domain: where the elements

describing the requirements that will be achieved

by the future system are included. These

elements are directly connected to the System

Requirements Model.

 Agency domain: where the elements describing

the multi-agent society in terms of environment

(defined by a set of ontological elements) and the

social aspect of agents (interaction between

them) are included. The items of this area are

connected directly to the Agent Society Model.

 Solution domain: where the elements describing

the architectural solution (respecting the

architecture of FIPA) of the problem in terms of

agent classes, task class, agent code and task

code are included. The elements of this area are

connected directly to the two models: Agent

Implementation and Code.

3.3 Traceability in PASSI

In (Cossentino, M. and V. Seidita, 2014), the authors

have mentioned dependencies between the different

artefacts produced during the PASSI process and

how the diagrams are constructed from the

preceding ones. These dependencies represent

implicit links between artefacts, i.e. links which

exist between artefacts having the same name, for

example, between Task and Agency_Task, between

Agent and Agency_Agent. However, no explicit

traceability links were adopted to follow functional

requirements since their identification in the Domain

Requirements Description phase until the

deployment of agents carrying out these

requirements in Deployment Configuration phase.

The lack of these traceability links causes some

difficulties in the development of MAS using PTK.

In fact, if the developer decides, using PTK, to

change the name of task (Agency_Task) the

corresponding task (Task) in Tasks Specification

phase remains with the first name, which needs

another modification. This takes more time. In the

next section, we propose an explicit traceability

links for the PASSI methodology, where it will be

possible to follow the requirements during the whole

PASSI development process. This will facilitate

changes management.

4 EXPLICIT TRACEABILITY

FOR PASSI

We introduce, in this section, a new traceability

meta-model (Figure 2) for supporting explicit

bidirectional Requirement-to-Code Traceability for

the PASSI methodology. To create traceability links

between the different artefacts, some information

has to be added to the specifications of these

artefacts in order to ensure traceability in both

backward & forward directions: 1) a unique

identifier "id" (ID according to the XML DTD

syntax); 2) a name, and 3) a reference (s) (IDREF /

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Figure 2: Requirement-to-Code Traceability Meta-model for PASSI.

Table 1: Functional requirement & Agent Life cycle.

System Requirements

Model

Agent Society Model Agent Implementation Model

Code

Model

Test

Deployment

Model

D.R.D.

A.Id.

R.Id.

T.Sp.

D.O.D.

Co.O.D.

R.D.

P.D.

M.A.S.D.

M.A.B.D.

S.A.S.D.

S.A.B.D

C.R.

C.P.

AgentTest

D.C.

FunctionalReq-

uirement

Functionnality

RoleSpecificSc-

enario i

Task_j

/ /

Agency_Task_j

Implementation_

Task_j

Implementation_

Task_j

Implementation_

Task_j

State

Machine_j:1..k

Pattern_j

Task_Code_j

Test_j

Agent

Role 1..*

Plan

Agency_Agent

Implementation

_Agent

Implementation

_Task 1..*

Implementation

_Agent

StateMachine

Pattern

Agent_Code

TestGroup

Node

IDREFS according to the XML DTD syntax)

towards the precedent element(s) and / or towards

the following element(s). Each functional

requirement identified in the domain requirement

description is assigned to a specific agent as a

functionality (agentREF attribute) in the agents

identification phase. One or more

RoleSpecificScenario (composed of one or more

“Role”) explore(s) each Functionality (use case) in

the Roles Identification phase. From each Role,

several Tasks are identified in the tasks specification

phase and so on until the Test phase. By creating

traceability links, the developer can know, at any

given moment, the origin of a Task class (the

functional requirement from which is identified) in

the single agent structure definition phase, and what

is the Test according to it.

The creation of traceability links is supposed to

be performed by the developer thanks to a new tool

(under development) that can replace the official

PTK by adding support for traceability introduced

for PASSI with other improvements.

After identifying functional requirements in the

first phase and during the Roles Identification phase,

the developer will have to associate each functional

requirement to a specific scenario

(RoleSpecificScenario) thanks to a GUI and the

links which will be created in both forward and

backward directions.

The developer will need during each phase to

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relate system artefacts.

Table 1 shows the life cycle of two PASSI

elements: Functional Requirement and Agent. These

two elements (and others) have to be followed up to

the PASSI process end. For example, each “agent”

(identified in Agent Identification phase) has to be

linked to a “plan” (described in Tasks Specification

phase), and so on (Agency_Agent,

Implementation_Agent,, Implementation_Tasks,

StateMachine, Pattern, Agent_Code, TestGroup)

until the “Node” element (identified in deployment

configuration phase). All these artefacts have to be

linked one to each other in the two directions.

5 CASE STUDY

In order to illustrate the use of the meta-model we

propose, we have selected a case study based on the

“Juul Møller Bokhandel A/S” problem designed in

(Cossentino, M., 2005) as an agent-oriented system

using the PASSI methodology. Among the

functional requirements that are presented in the

Domain Requirements Description diagram, the

« Provide Books » one (Figure 3).

Figure 3: A portion of the domain requirements

description diagram (Cossentino, M., 2005).

The functional requirement “Provide books”

becomes a functionality assigned to the agent

“PurchaserManager” in the agents identification

phase (figure 4).

The scenario “Announcement of the need of a

book purchase” (Figure 5) then explores the

functionality mentioned above. Several agent roles

participate in this scenario: PurchaseMonitor,

PurchaseManager, PurchaseAdvisor, Purchaser and

StoreUI. From each agent role, several tasks are

identified like “ReceivePurchaseRequest” and

“AskForAdvice” for the “BooksProvider” role

(Figure 6).

Figure 4: A portion of the agents’ identification diagram

(framed in bold, the functionality is assigned to the

PurchaseManager Agent) (Cossentino, M., 2005).

Figure 5: Roles identification diagram “Announcement of

the need of a book purchase” scenario (framed in bold, the

BooksProvider agent role) (Cossentino, M., 2005).

Figure 6: Tasks specification diagram for the agent

“Purchase Manager” (framed in bold, the two tasks related

to the “BooksProvider” role) (Cossentino, M., 2005).

Figure 7 shows a part of the traceability model

(instance of the meta-model we proposed) for the

functional requirement “providebooks”. naturally,

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Figure 7: A part of «Provide Books» Functional Requirement-To-Code traceability model.

all the concepts that appear in the obtained

traceability model (figure 6) are included in the

traceability meta-model we have proposed.

6 CONCLUSION AND FUTURE

WORK

Traceability is an important activity in the

development of high quality computing systems. In

this paper, we presented our attempt to introduce an

explicit traceability links between artefacts produced

during all the PASSI process. The existence of these

links adds the ability to follow system’s artefacts,

particularly, the functional requirements during all

the PASSI development phases. This will allow a

better management of changes. As future work, we

plan to: improve the traceability model proposed in

this paper and develop a supporting tool with other

additions to PTK.

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