DIALOGUE ACT MODELLING FOR ANALYSIS AND
SPECIFICATION OF WEB-BASED INFORMATION SYSTEMS
Ying Liang
School of Computing, University of Paisley, Paisley PA1 2BE, U.K.
Keywords: Dialogues, Dialogue acts, Dialogue act modelling, Object modelling
Abstract: Web-based information systems aim to enable people to live
and do things in society with help of computer
systems on internet. User interfaces and navigation structures of these systems become more important and
critical than the ones of traditional information systems to the user because of the nature and specific
characteristics of these systems. The experiences on requirements analysis and specification of these
systems have shown the need of gathering and specifying communicational requirements for these systems
in the analysis model as a basis for designing user interfaces and navigation structures. This paper addressed
this issue and proposes a dialogue act modelling approach that has focus on communicational requirements
with pragmatic and descriptive views in terms of the Speech Theory in social science and the object
modelling techniques in Software Engineering.
1 INTRODUCTION
Web-based information systems (WBIS) are a new
type of IS based on technology and standards of the
World Wed Web Consortium (W3C) and there are
many differences between them and traditional IS
(Deshpande et al., 2002). For example, WBIS must
address ethical, social and legal issues but this was
unnecessary to traditional IS. Deshpande et al. also
noticed that traditional IS dealt with largely data
transactions in predominantly numerical form with a
bit of textual information, but WBIS contain text and
multimedia in addition. Experiences of developing
WBIS have convinced that they have their own
characteristics in comparison with traditional IS
such as:
• They
include web pages. Developing web pages
with consultation with customers is vital to web
site success and, ideally, customers are consulted
repeatedly in order to understand their needs over
time (Lawrance et al., 1998).
• Th
ey have an unlimited number of varied users.
Traditional IS are used by a fixed number of users
working in organization and well trained for use
of systems. But WBIS are used by an unlimited
number of users (e.g., online customers) anywhere
in the world (Conallen, 2003). They cannot be
well trained in advance. Thus it is critical to
provide user-friendly systems to such users.
• Th
eir development process is volatile. This makes
requirements specification difficult (Baskerville
and Pries-Heye, 2001).
These specific characteristics increase difficulty of
devel
oping WBIS in general. It has been found that
traditional information system development methods
and techniques are not really proper or adequate to
WBIS development because of dynamic and
evolving nature of WBIS (Lang, 2002; Zelnic, 1998).
Experts in this field thus intend to set up a new
discipline Web Engineering for research and to
establish sound scientific, engineering and
management principles and systematic approaches to
successful development and maintenance of high
quality WBIS (Murugesan et al., 2001). Engineering
a web application is to diverse problems to
application domain analysis, navigational structures,
and user interface design (Conallen, 2003).
Application domain analysis is done at the analysis
stage with focus of problems and navigation
structures and user interfaces are constructed at the
design stage with focus of solutions in software
process. Modelling approaches for traditional IS
such as use case modelling, object modelling, and
behaviour modelling in UML (Booch et al., 1999)
have been used in application domain analysis for
web applications (Conallen, 2003). Requirements of
traditional IS often include functional requirements
that tell what the system should do and non-
functional requirements that specify constraints (e.g.,
89
Liang Y. (2005).
DIALOGUE ACT MODELLING FOR ANALYSIS AND SPECIFICATION OF WEB-BASED INFORMATION SYSTEMS.
In Proceedings of the Seventh International Conference on Enterprise Information Systems, pages 89-97
DOI: 10.5220/0002536200890097
Copyright
c
 SciTePress

performance and security) on functions of the
system. They are elicited and specified in
requirements analysis and specification of the
software process (Sommerville, 2004). However
observation on WBIS showed that online users were
often concerned with what are displayed on the
computer screen for them to communicate with the
system and how they can do this correctly and
efficiently. These concerns can become new
requirements on communications between users and
WBIS, apart of other types of requirements. We call
them communicational requirements in this paper. It
is important to elicit them as they have impact on
use of WBIS and can affect its navigation structures
and user interfaces significantly. Also elicitation of
them can help understand and clarify system
obligations and user responsibilities/commitments
within the business context. But current modelling
approaches (e.g., Conallen, 2003) do not support
analysis and specification of communicational
requirements as they focus on functional and non-
functional requirements only. Change of WBIS may
be inevitable later using these approaches as users’
concerns with communications are not considered in
analysis but at the late stages of WBIS development.
This paper addresses this issue and proposes a
dialogue act modelling approach that has focus on
communicational requirements in WBIS analysis.
The next section will describe communicational
requirements. The third section will explain
pragmatic view and descriptive view used in IS
analysis. The fourth section will show the approach
and the fifth section will describe the dialogue act
model. The final section will conclude the work.
2 COMMUNICATIONAL
REQUIREMENTS
We observe the following concerns of WBIS users
as communicational requirements of WBIS:
- Business contexts required to display on the
computer screen. They are business activities such
as “Car search” or business indexes such as “Cars”.
The business contexts may include same things if
users are concerned with the things in different
ranges, e.g., a, car company wants business context
“Car for sale”; while its customers want business
context “Cars” including car for sale. “Car for
sale” is concerned in different ranges in WBIS.
- Dialogues required to display on the screen while
users and WBIS communicate interactively. They
are the preference of users in collaborations with
system within a business context. For example, in
the business context “Cars”, car buyers want “car
list” to be displayed on screen for searching or
finding a car. User responsibilities/ commitments
and system obligations are elicited and specified
along the dialogues (see Figure 3).
We found that the Speech Act Theory (Austin,
1962) in the social science can help elicit
communicational requirements as communications
mean speech to act. According to it, a dialogue
between a user and a system means one or more acts
in an e-business society. Therefore communications
are useful to find roles of users and their
responsibilities/commitments and roles of the system
and its obligations. System obligations mean system
functions, and user responsibilities/commitments are
preconditions of the functions. Navigation structures
and user interfaces must be designed and validated
based on communicational requirements. We hope
that focus on these requirements can help reduce
changes in system maintenance because of failure of
elicitation of communicational requirements.
3 DESCRIPTIVE VIEW AND
PRAGMATIC VIEW
There are two modelling views in requirements
analysis and specification of traditional IS:
• Descriptive view used for observing the semantic
aspects of IS as image of reality. Examples using
this view are data modelling (Chen, 1976), process
modelling (DeMacro, 1978), and object modelling
(Booch, 1991; Coad, 1991; Rumbaugh, 1991;
Jacobson, 1992). In general this view has much
focus on business processes but little focus on
other business properties such as customers and
their responsibilities/commitments (pragmatic
concepts) in the business context. Thus the
analysis model built with this view does not
emphasis users’ responsibilities/commitments in
the business context.
• Pragmatic view used for observing the pragmatic
aspects of IS as part of reality within the business
context. Action workflow approach (Denning and
Medina-Mora, 1995) is an example using this
view. This view has much focus on pragmatic
concepts (Agerfalk, 2002; Erickson and Kellogg,
2000; Eriksen, 2002; Holm and Ljungberg, 1996).
Thus the analysis model built with this view
covers users’ responsibilities and commitments in
the business context. But it cover little semantics
of the system.
We regard both of these two views equally
important in requirements analysis and specification
of WBIS as WBIS need focus of both of semantic
and pragmatic aspects in order to create a complete
analysis model covering all concerns of WBIS users
and WBIS developers. We thus created a new
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modelling approach, for this need, that integrates the
two views using dialogue act modelling and object
modelling techniques in WBIS analysis.
4 DIALOGUE ACT MODELLING
AND SPEECH ACT THEORY
The speech theory was initially defined by Austin in
1962 (Austin, 1962) for describing the phenomenon
in a social society that people use speech to act such
as demanding or promising something. Then in 1969
Searle specifically defined a speech act with four
different sub-acts: utterance acts with uttering words,
prepositional acts with referring and predicating,
illocutionary acts with stating, questioning,
commanding, promising, and perlocutionary acts
with causing an effect on hearers (Searle, 1969).
This theory explains how people in a society use a
language for talk about events in the external world
as observers, and also for communication act within
the world as actors in the society (Agerfalk and
Erisson, 2004). In computer society, IS were even
defined as language systems in general used to
perform communication acts (Goldkuhl and
Lyytinen, 1982). IS Modelling approaches based on
this theory also include COMMODIOUS (Holm and
Ljungberg, 1996), conversion-for-action schema
(Winograd and Flores, 1987), DEMO (Dietz, 2001),
and action-oriented conceptual modelling (Agerfalk
and Erisson, 2004). The applications of these
approaches in IS analysis have shown the
significance of understanding of the pragmatic
aspects of IS using this theory. This encouraged us
to use it in WBIS analysis as WBIS also use a
language for communication and other things such
as demands and promises (i.e., dialogue to act). The
current approaches observe communications
between users and IS as data flows and acts as data
transformations through different medias such as a
computer screen. However WBIS not only deal with
data transformations but also provide textual
information and customer services. We thus observe
communications between users and WBIS as wider
than data flows as they can be information flows
(e.g., car list), organization flows (e.g., sales
department), and service flows (e.g., buy car). In our
approach all these kinds of communications are
termed 'dialogue’. A sequence of dialogues is
termed ‘dialogue flow’ and a speech act is termed
‘dialogue act’. They cause different acts in WBIS:
(a) Utterance act is production and communication of
physical written message such as “Buy car”
displayed on the computer screen or printed on paper.
(b) Prepositional act is performed by an object such as a
Car and its attributes.
(c) Illocutionary act is performed by a business service
(activity) such as sell car.
(d) Perlocutionary act such as buy car is performed by
the hearer. It has the effect on the business context.
The new dialogue act modelling approach was
created as described below based on the definitions.
5 DIALOGUE ACT MODELLING,
OBJECT MODELLING AND
BEHAVIOUR MODELLING
The new approach builds a dialogue act model using
dialogue act modelling, an object model and a
behaviour model using object modelling:
• Dialogue act modelling: It focuses on the
pragmatic aspects of WBIS and interactive
communications and collaborations between users
and the system within business contexts.
• Object modelling: It focuses on business entities
involved in collaborations and structure of the
system.
• Behaviour modelling: It focuses on behaviour of
business entities and interactions between them.
The modelling process defined by Sommerville
(Sommerville, 2004) is then used iteratively along
with these modelling in the approach as illustrated in
Figure 1.
dialogue act modelling, object modelling, behaviour modelling
(class diagram)
(business context map, dialogue act
diagrams, interface structure tree) (sequence diagram,
Requirements specification documents statecharts)
Business
case study
Requirements
analysis
System
specification
Specification
validation
Object model
(WBIS structure)
Dialogue act model
(user communication)
Behaviour model
(WBIS behaviour)
Business
contexts
Figure 1: Dialogue act modelling approach for WBIS requirements analysis and specification
DIALOGUE ACT MODELLING FOR ANALYSIS AND SPECIFICATION OF WEB-BASED INFORMATION
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5.1 Dialogue Act Modelling
The pragmatic aspects of WBIS concern business
properties such as customers (e.g., Car Buyer)
within the business context (e.g., Cars). Dialogue act
modelling describes such properties as speakers and
hearers of dialogues, performers of dialogue acts,
and seekers of business data in the dialogue act
model. Dialogue act modelling aims to generate a
dialogue act model for WBIS with following steps:
i) Elicit business contexts required by stakeholders
of business based on business case study.
ii) For each of the required business contexts,
(i) Identify business people/department (e.g.,
sales person/department) and stakeholders
(e.g., car buyer) who will communicate with
the system within the business context. They
are represented as actors of the business
context in the diagrams.
(ii) Identify dialogues between the system and
actors by asking actors:
• What things/terms/keywords do they want
to see/display on the computer screen?
• What conversations do they wish make with
the system?
• What conversations do they expect the system
to make with them?
Dialogues are linked by dialogue flows. Actors
involved in conversations are shown as the
speakers/hearers of the dialogues.
(iii) Identify dialogue acts by asking actors:
• What are actions of hearers?
• What do they promise/demand to do through
conversations?
Hearers are performers of the dialogue acts.
(iv) Describe states of the business context (i.e.,
effects of performance of dialogue acts).
We create a business context map (see Figure 2)
for WBIS to show business contexts (black rectangle
boxes) and connections (solid lines) with actors
(figures) requiring them, and a dialogue act diagram
(see notation and definition in Table 1) for each of
business contexts (e.g., Cars in Figure 3 as explained
by Table 2). Hierarchy of business contexts with
dialogues in WBIS can be illustrated as shown in
Figure 4, as a basis for designing user interface and
navigation structures in WIS development.
Hearer
Speaker
Dialogue
Name
Figure 2: Business context map
Table 1: Notation and definition of dialogue act diagram
Element Diagrammatic Notation Definition
Start dialogue First directed communication from speaker to hearer(s).
It must be displayed on computer screen for getting into
a business context in WBIS.
Following
dialogue
Directed communication from speaker to hearer(s). It
can be displayed on the computer screen to mean a
demand/promise for information/service.
Actor (speaker/
hearer)
Speaker/hearer of a dialogue.
A performer of a dialogue act.
Dialogue flow Connection of communications within the business
context.
Dialogue act Activity performed by hearer(s) as a consequence of a
dialogue. It is regarded as a precondition of the next
dialogue.
Cars
Dialogue act
Dialo
g
ue
Hearer
Speaker
Business
context
Car Bu
y
e
r
Car search
Contact
Car for sale
Car for hire
Company
services
Car Hire
r
Custome
r
Car Company
Custome
r
Car Company
Car Company
Actor
Business context, the start
dialogue in the dialogue act
diagram
Connection
De
p
artments
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Element Diagrammatic Notation Definition
Resource flow Resource sent through actors within the business
context.
Resource
State of business
context
Effect on the business context.
State
Figure 3: Dialogue act diagram for the business context “Cars”
Car Buyer
WBIS
Offered
Offer car
Car list
Bu
y
ca
r
Order car
Sell car
Demand
ca
r
Car Buyer
Car Buyer
WBIS
Order details
Order for
m
Ordering
WBIS
WBIS
Ordered
Pa
y
ment details
Demand
payment
Pa
y
ment for
m
Car Buyer
e-Bank
Pay
orde
r
Process
payment
Transfer
cash
Delivery
Clear
p
a
y
ment
Payment
confirmation
WBIS
Ca
r
Demand
deliver
y
Car Buyer
Deliver
ca
r
Paid
Delivered
Delivering
Paying
Car
Supplier
Car
Supplier
Complete
sale
Delivery
confirmation
WBIS
Cars
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Table 2: Cars business context
{precondition} Dialogue (meaning) Speaker-Hearer Dialogue act
performed by
hearer
Re-
source
State of
business
context
{} Cars (want to find a car) Car Buyer-WBIS Offer car
{Offer car} Car list(promise to offer cars) WBIS-Buyer Demand car
Offered
{Demand car}Buy car(want to own a car) Car Buyer-WBIS Sell car
{Sell car}Order form (demand order details) WBIS- Car Buyer Order car
Ordering
{Order car} Order details (promise to buy car) Car Buyer-WBIS Demand payment Ordered
{Demand payment} Payment form (want to get pay) WBIS- Car Buyer Pay order
{Pay order} Payment details (promise to pay) Car Buyer-WBIS Process payment
{Process payment} Clear payment (want to get cash) WBIS-e-Bank Transfer money
Paying
{Transfer cash} Payment confirmation (state pa
y
accepted)
e-Bank-WBIS Demand delivery Paid
{Demand delivery}Delivery(want to deliver car) WBIS-Car Supplier Deliver car Delivering
{Deliver car} Delivery confirmation (state delivery
done)
WBIS Complete car sale Car Delivered
User responsibility
User action on Hierarchy of business contexts with dialogues in WBIS
/commitment
computer screen
• Car buyer want to find a car
clicks on Car search (nested business context)
• Car buyer wants to buy a car
selects Buy car ( part of the Car for sale business context)
• Car buyer orders a car
fills Order form
• Car buyer pays order, e-bank
completes Payment form
transfers cash, car supplier
etc.
delivers car
…
Figure 4: Hierarchy of business contexts and dialogues
5.2 Object Modelling
WBIS is currently designed and implemented using
object-oriented technology in WBIS development.
Once the dialogue act model is created, object
modelling technique like UML class diagram
(Booch et al., 1999) is used to describe business
entities (classes) such as cars and orders involved in
the dialogues and dialogue acts. Some objects such
as Customer may be found from actors such as Car
Buyer if they need to play roles within the system.
Dialogues in the model are specified as user
interface (UI) classes in the diagram (see Figure 5).
Dialogue acts and properties of business entities
such as car details and order details are specified as
operations and attributes of the classes in this model.
5.3 Behaviour Modelling
Communications between objects of classes in
WBIS for a business context are abstracted from the
dialogue act model and represented using UML
sequence diagrams (Booch et al., 1999) as shown in
Figure 6. Dialogue acts and states of business
contexts are used to identify states and behaviour of
the objects in WBIS. They are represented using
statecharts (Harel, 1987) as shown in Figure 7.
Business context, the start dialogue in Figure 3
Cars
Ca
r
for sale
Ca
r
search
Dialogues in the Cars business context in Figure 3
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User interface
classes displaying
information on the
com
p
uter screen
Attributes o
f
classes
Figure 5: A class diagram for the Cars business context
Figure 6: Sequence diagram for the business context Cars
Figure 7: Statechart for objects of the class “Car”
6 CONCLUSIONS
By research we have found that WBIS have their
own characteristics that make them different from
traditional IS. Unlike traditional IS whose users are
limited employees working in the organization,
WBIS users are an unlimited number of varied users
such as online customers on internet. Therefore it is
impossible to train users of WBIS face-to-face in the
reality. This means that many users have to learn use
of these systems on their own with help facilities and
to understand system obligations and their own
responsibilities/commitments based on dialogues
(communications) displayed on the computer screen.
In this situation user interfaces of WBIS becomes
much more critical in WBIS development than in
traditional IS development as an important place
where users learn and find what and how they can
communicate and collaborate interactively with the
system correctly and efficiently. It is thus probably
inevitable for such users to make requirements on
this part of the system in WBIS analysis. This
requires a specific focus on this type of requirements
Actors
Communications
between actors
and objects with
dialogue acts
demand
p
a
y
men
t
payment confirmation
deliver
y
confirmation
Offered
Ordered
Paid
Delivered
Business entity classes
playing roles and
containing data and
operations acting on
data in
W
BI
S
Associations
between classes
O
p
erations o
f
classes
Objects
of
classes
Dialogue act Dialogue
State
State transition
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and to model them as communicational requirements
during WBIS analysis, apart of functional and non-
functional requirements.
There are two modelling views in traditional IS
analysis: descriptive view and pragmatic view. It has
been observed that, when using one of the two views
only, traditional IS modelling approaches either have
too much focus on the semantic aspects (i.e. system
semantics) and too little focus on the pragmatic
aspects (i.e. business contexts) of the systems, or
vice versa. Then analysis models built using these
approaches either do not show enough business
context concerns or do not include sufficient system
semantics. This paper has addressed this issue and
presented a dialogue act modelling approach that
aims to balance the focus of the two aspects in
analysis and specification of WBIS. This approach
focuses on pragmatic aspects with the pragmatic
view and semantic aspects with the descriptive view
in WBIS analysis. Specifically it provides a dialogue
act modelling for observing the pragmatic aspects of
the system in terms of the speech theory in the social
science, and it uses object modelling techniques in
Software Engineering for observing the semantic
aspects of the system in WBIS analysis, as outlined
in Table 3.
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Table 3: Dialogue act modelling approach for WBIS requirements analysis and specification
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