A Model-driven Approach for Empowering Advance Web Augmentation
From Client-side to Server-side Support
Matias Urbieta
1,2
, Sergio Firmenich
1,2
, Pedro Maglione
1
, Gustavo Rossi
1,2
and Miguel Angel Olivero
3
1
Facultad de Inform
´
atica, Universidad Nacional de La Plata, calle 50 y 120,1900, La Plata, Buenos Aires, Argentina
2
CONICET, La Plata, Argentina
3
Web Engineering and Early Testing Group, Computer Languages and Systems Department,
University of Seville ETSII, Avda. Reina Mercedes S/N, 41012, Seville, Spain
Keywords:
Model-driven Web Engineering, Augmentation, End-user Development, Separation of Concern.
Abstract:
Websites augmentations have been adopted as a mean for improving the User Experience of applications
that often are not owned by the user. The augmentations alter the page in order to add, modify and even
remove its content pursuing the satisfaction of a user’s need. However, these augmentations are limited to
page modification or transcluding content from another site on Internet. Moreover, advance server-side based
augmentations have been released only by developers because of the required technical skill for the task. In
this work, we have presented a novel approach for designing Web Augmentation coping client-side and server-
side using a Model-Driven Web Engineering approach. The approach rises the abstraction level for server-
side developments allowing end-users to design, and even implement the new functionalities. Additionally,
the approach uses advance separation of concern principles thus we provide a set of tools for designing the
composition of the core application and the augmentation. We show as running example an augmentation that
introduces a site community’s review support upon an agriculture e-commerce site.
1 INTRODUCTION
Web applications are often designed and developed
considering a small subset of stakeholders (managers,
internal users, product owners, and developers) with-
out an active listening of the crowd’s feedback and
awareness of their needs. The emergence of Web
personalization allowed introducing improvements to
an application that runs as a black box just consid-
ering those perceivable behaviors by the end-user.
Personalization usually is tied to recommender sys-
tems, which basically recommend information items
to users according to their user profiles (Brusilovsky
et al., 2007). However, beyond the information dis-
played, other approaches adapt the User Interface
(UI), such as the Adaptive Navigation Support de-
fined by Brusilosky (Brusilovsky, 2007). When these
mechanisms are chosen directly by users, then some
authors called them customizations (Aoki and Naka-
jima, 1999), that basically are systems allowing users
to customize how the application displays contents
and functionalities. In spite of which mechanisms
(personalization, customization, etc.) that a particu-
lar application supports, it is not realistic to determine
that the application idealized by a product owner cov-
ers every single users need. In this sense, users may
have unsatisfied requirements. To tackle this problem
a mechanism, very used nowadays, is to alter Web
page once these are loaded on the client-side. By
manipulating the Web site’s Document Object Model
(DOM), the user would perceive a variation of the
Website that may add, remove or change both con-
tents and functionalities. This technique, called Web
Augmentation (D
´
ıaz and Arellano, 2015), is very pop-
ular and is commonly deployed as Web browser ex-
tensions that package software artifacts able to access
these DOMs and altering it by using its interface.
For the sake of understanding, consider the exam-
ple of a simple but real augmentation artefact, called
Magic Actions for Youtube
1
. Magic Actions is a
browser extension (with more than one hundred thou-
sand users) designed to augment Youtube with func-
tionalities that originally are not supported by this ap-
plication, such as adaptive layout, volume control by
1
Magic Actions for Youtube https://goo.gl/AkFnOj
444
Urbieta, M., Firmenich, S., Maglione, P., Rossi, G. and Olivero, M.
A Model-driven Approach for Empowering Advance Web Augmentation - From Client-side to Server-side Support.
DOI: 10.5220/0006394604440454
In Proceedings of the 13th International Conference on Web Information Systems and Technologies (WEBIST 2017), pages 444-454
ISBN: 978-989-758-246-2
Copyright © 2017 by SCITEPRESS Science and Technology Publications, Lda. All rights reserved
scrolling, etc. Note that, at this point, we are in-
troducing the idea of adapting or customizing third-
party Web applications. Web augmentation has an
interesting combination of real use from part of the
users crowd of Web applications and some research
works aiming at conducting this activity promoting
good software development practices, such as reuse
(Garrido et al., 2013), robustness (D
´
ıaz et al., 2010),
etc.. Most of these approaches rely on client-side,
i.e. without the need of a back-end application for
performing the augmentation effect. However, since
this architecture limits the power of the augmentation
because it does not profit from collaborative features
(nowadays a de facto requirement) and the limited
resources provided by the browser (i.e. processing
power, storage alternatives, etc.), other approaches
have a traditional client-server architecture, allow-
ing, for instance, the synchronization of devices to
support distributed user interfaces (Firmenich et al.,
2016c), the use of complex services that cannot be de-
ployed only on client-side (such as the use of a recom-
mender system (Wischenbart et al., 2015)), and social
Web content management tools, such as Diigo (Di-
igo, 2017). The reader must note that all these back-
end counterparts are dedicated applications specifi-
cally designed and deployed for the particular kind
of augmentation, but, to our knowledge, there are not
approaches considering both client and server sides
in a more generic way. That is, the end-user only
contribute designing client-side improvements keep-
ing him-self excluded from contributing complex be-
havior at server-side because the lack of coding skills
that let him face technical challenges (e.g. Database
access, complex algorithms design and coding, and
User Interfaces component definition).
Current trends in agile software development
(Martin, 2003) rely on quick prototyping since it helps
to validate easily whether a new requirement meets
the users’ needs. For example, agile approaches pro-
mote the incremental development of Minimum Vi-
able Product (MVP) (Bosch et al., 2013; Torrecilla-
Salinas et al., 2015) delivered in a few Sprints con-
sidering the value-based contribution to the business.
Web augmentation approaches give support partially
if a development team wants to obtain a running ex-
ample of a User Experience improvement or the re-
sult of transcluding other website’s content. By using
Web pages’ augmentations it is possible to perform
advance A/B testing without the need of branching
current version of an application, coding a new fea-
ture, and build and release the application. This pa-
per presents a Web Augmentation modeling approach
contemplating a client-server application that hides
the back-end complexity to users. Existing studies
shows that end-users are able to create some simple
artifacts using client-side Web technologies (HTML,
CSS, and JavaScript) (Scaffidi et al., 2006), but there
are not similar reports for managing the logic on the
server-side. One manner to reduce the associated
complexity to this task is to rise up the level of ab-
straction required to specify this logic. With this in
mind, we propose the use of existing Web modeling
languages that may be used in a dedicated server to
create Web augmentation back-end counterparts in-
creasing abstraction level and reducing development
effort (DDway, 2016). On client-side, we propose
a specialized end-user development tool that allows
them to recreate an object model of the target appli-
cation (the one being augmented) by abstracting Web
contents. As we will discuss later, applications own-
ers could use our ideas and supporting tools also in
order to weave new functionalities without the need
of modifying the applications core. In this paper, we
present a novel approach to implement complex Web
augmentation based on client-side improvements sup-
ported by server-side developments. The main contri-
butions of our approach are: (1) a Model-driven ap-
proach for modeling augmentation that is not already
available on the Internet, (2) a full support for the
seamless introduction of augmentation, and (3) a de-
velopment process that combines WOA tool and We-
bRatio (WebRatio, 2017) platform for supporting our
approach . The paper is organized as follows. Section
2 describes the background. Then, the Section 3 in-
troduces the related works. Section 4 is an overview
of the approach. Section 5 shows a comprehensive ex-
ample. And Section 6 concludes and talks about the
future works.
2 BACKGROUND
2.1 Web Application Augmentation
As we mentioned before, Web augmentation is ac-
tually used by the users crowd. Besides of Web
browser stores, where thousands of extensions for
adapting existing Web content may be found, there
are some of these tools supported by communities
where end-users and other stakeholders with pro-
gramming skills interact in the creation, sharing and
improvement of artifacts. For instance, in the user-
styles community (http://userstyles.org) users share
artifacts that augment Web sites by adding further
CSS designs that may change any aspect of Web sites
content presentation. Similarly, in repositories be-
hind userscripts communities (such as greasyfork -
https://greasyfork.org/) artifacts written in JavaScript
A Model-driven Approach for Empowering Advance Web Augmentation - From Client-side to Server-side Support
445
may be found. In these cases beyond simple content
presentation (such as the achieved with userstyles),
Web sites may be augmented with new functionali-
ties, given the power of JavaScript. In these commu-
nities, in spite of the artifact kind, there is a depen-
dency between users with and without programming
skills. Then, some research works proposed End-User
Development (EUD) approaches to let users specify
their own augmentation artifacts, these are discussed
in the related work section.
2.2 Model-driven Web Engineering
Approaches
In most mature Web design approaches (Rossi et al.,
2008) , such as UWE, WebML, UWA, Hera, OOWS
or OOHDM, a Web application is designed with
an iterative process comprising at least conceptual
and navigational modeling. According to the state-
of-the-art of model-driven Web engineering tech-
niques (Arag
´
on et al., 2013; Dom
´
ınguez-Mayo et al.,
2014), these methods produce an implementation-
independent model that can be later mapped to dif-
ferent run time platforms. For the sake of clarity, we
will concentrate on the conceptual, navigational and
interface models as they are rather similar in different
design approaches.
2.2.1 Conceptual Design
The conceptual model of a Web application (a.k.a.,
application, domain, or content model) is focused on
defining the contents of the application with their at-
tributes and associated behavior. When it is defined
using the OOHDM method (or others such as UWE),
this model is an object-oriented model described with
UML and comprised of classes, with their attributes
and methods, and associations between classes.
2.2.2 Navigational Design
The navigational design of a Web application is aimed
at defining views, access structures and navigation
paths to contents in order to enable the user easily ac-
cessing and navigating them. Most of the Web engi-
neering methods base their navigational model on two
modeling primitives, namely Node and Link. IFML
(Brambilla and Fraternali, 2014) is no exception to
this, as it defines Pages as logical views on application
model classes and links as the hypermedia realization
of application model associations that defines either
browsing capabilities or triggering system behavior.
2.2.3 Abstract Interface Design
In OOHDM, the user interface is specified using Ab-
stract Data Views (ADVs) (Vilain et al., 2000) which
support an object-oriented model for interface ob-
jects. An ADV is defined for each node class, to
indicate how each node attribute or sub-node (if it
is a composite node) will be presented to the user.
An ADV can be seen as an Observer (Gamma et al.,
1995) of the node expressing its perception proper-
ties, in general, as nested ADVs or primitive types
(e.g. buttons). Using a configuration diagram (Vilain
et al., 2000) we express how these properties relate
with the node attributes and operations.
ADVs are also used to indicate how interaction
will proceed and which interface effects take place
as the result of user-generated events. These behav-
ioral aspects are specified using ADV-charts (Vilain
et al., 2000), a kind of statecharts representing states
and states transitions for a given ADV. ADV-charts
are useful when we need to model rich interface be-
haviors such as that of Rich Internet Applications
(RIA) (Niederhausen et al., 2009). ADV-Charts are
state machines diagrams that allow expressing inter-
face transformations occurring as the result of the user
interaction on a given ADV. ADV-Charts describe
interface behaviours through Event-Condition-Action
rules.
3 RELATED WORKS
3.1 Web Application Augmentation
End-User Development (EUD) was explored in the
field of Web Augmentation in order to let users with-
out advanced programming skills to specify their
own augmentation artifacts (D
´
ıaz and Arellano, 2012;
Bosetti et al., 2017). In previous work we presented
some WOA (Web Object Ambient) tool that allows
users to recreate an object model of Web sites on the
client-side (Firmenich et al., 2016d), however, since
we are focused on supporting complex augmenta-
tion applications that could not be work just on the
client-side, at the same time that with some mod-
eling skills, they can create the back-end counter-
part of these augmentations. This generic back-end
support will empower augmentation artifacts, given
that further features could be contemplated such as
more complex business logic, storage, social aspects.
Although several aspects about augmentation have
been addressed through modeling activities, such as
requirement specification (Firmenich et al., 2016a),
these usually aim to model the presentation layer,
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446
something that is not enough to represent the back-
end logic of the application. In this sense, this pa-
per propose an integration between our tool for ex-
tracting a model object from existing Web pages (Fir-
menich et al., 2016d) with an application that is mod-
eled using existing Web modeling languages. Web
Augmentation could be considered a foreign client-
side application mechanism, i.e. adapting existing
and third-party Web sites on the client-side. However,
Client-Side adaptation could be also be considered as
a core concern during application design. An inter-
esting approach that considers this aspect was pre-
sented before [Model-Driven Design of Web Applica-
tions with Client-Side Adaptation], focusing the use
of this mechanism in an e-learning system. However,
although this work also propose a modeling layer for
the client-side adaptation layer, it is not used from the
augmentation point of view, but that is defined by ap-
plication owners, and one more time, this could be
part of what end-users would like to change.
3.2 Separation of Concern in MDWE
Several existing Model-Driven Web Engineering
(MDWE) allows to seamlessly compose Web ap-
plications’ concerns such as our previous work to
tackle Volatile Functionalities in Web Applications
(Urbieta et al., 2012b; Frajberg et al., 2016), mod-
elling sepparation of concerns in Workflows (Urbieta
et al., 2012a), and supporting separation of Web-GIS
concerns in Web applications (Urbieta et al., 2014).
Additionally, other approaches support evolutive re-
quirements such as WebComposition Process Model
(Gaedke and Gr
¨
af, 2001), Distributed Concern De-
livery (Cerny et al., 2015) or, more general princi-
ples, such as refactoring (Fowler et al., 1999) and pat-
terns (Gamma et al., 1995). However, all of these ap-
proaches are focused to compose concerns at server
side only when the developer has access to the core
application which is not the case of Web augmenta-
tion’s purpose. Web
4 OUR APPROACH IN A
NUTSHELL
Our approach is based on the idea that even the sim-
plest functionality (e.g., a new community comment
feature) should be considered as a first-class func-
tionality and, as such, designed accordingly. At the
same time, their design and implementation have to
be taken separated from the host site (from now on
core application) and as much as possible decoupled
from that of core and stable functionalities which the
augmentations can not be introduced because the aug-
menter analyst is not part of the Application Webmas-
ter team. Building on the above ideas, our approach
can be summarized with the following design guide-
lines, which are shown schematically in Figure 1:
1. We decouple the augmentation from core appli-
cation by introducing a design layer (called Aug-
mentation Layer), which comprises a conceptual
model, a navigational model, and an interface
model.
2. We capture the basic conceptual model by tagging
data in host application pages using (Firmenich
et al., 2016d). The lack of access to the host appli-
cation’s underlying models requires the perceiv-
able conceptual model extraction. In this process,
data elements in the page are tagged and grouped
into an entity definition by an Augmentation ana-
lyst in such a way a simplified conceptual model
is obtained. The augmentation analyst is a skilled
end-user with advance knowledge of Web Appli-
cation who has as goal to improve the core ap-
plication. In further steps, the model instantia-
tion in a particular user session will be used for
giving contextual information to the augmentation
engine by providing model instances information
when triggering the augmentation.
3. Augmentation requirements are modeled using
Web engineering notations (e.g., use cases, user
interaction diagrams, etc.) and separately mapped
onto the following models using the heuristics de-
fined by the design approach (See for example
(Popovici et al., 2002)). Notice that, as shown in
Figure 1, augmentation requirements are not inte-
grated into the core requirements model, therefore
leaving their integration to further design activi-
ties.
(a) New behaviors, i.e. those which belong to
the Augmentation layer, are modeled as first
class objects in the Augmentation conceptual
model. It defines all the objects and behavior
corresponding to the new requirements. Ad-
ditionally, this model may include core appli-
cation conceptual classes (captured in step 2)
perceivable by the end-user allowing defining
relationships between augmentation business
model and the core application. Notice that this
strategy can be applied to any object-oriented
method, i.e., any method using a UML-like
specification approach.
(b) Nodes and links belonging to the augmenta-
tion navigational model may or may not have
links to the core navigational model. The core
navigational model is also oblivious to the aug-
A Model-driven Approach for Empowering Advance Web Augmentation - From Client-side to Server-side Support
447
Figure 1: Approach schema.
mentation navigational classes, i.e., there are no
links or other references from the core to the
augmentation layer. This principle can be ap-
plied in any Web design approach.
(c) We use a separate integration specification to
specify the connection between core and aug-
mentation nodes. As we show later in the paper,
the integration is achieved at run time as part of
a client side weaving engine. In other model-
driven approaches, the integration can be per-
formed during model transformation by imple-
menting the corresponding transformations.
(d) We design (and implement) the interfaces cor-
responding to each concern (core and augmen-
tation) separately; the interface design of the
core classes (described in OOHDM using Ab-
stract Data Views (ADV) (Vilain et al., 2000))
are oblivious with respect to the interface of
augmentation concerns. As in the navigational
layer, this principle is independent of the design
approach.
4. Core and augmentation interfaces (at the ADV
and implementation layers) are woven by execut-
ing an integration specification, which is realized
using DOM transformations. Again, the idea of
model weaving is generic and therefore the same
result can be obtained using other technical solu-
tion.
Once the augmentation requirements are modeled in
Step 3, the augmentation of another site will be quite
straightforward requiring to find and map the virtual
classes (Step 2) and to specify how to wave the aug-
mentation UI artifacts (Step 4).
Figure 2: Concept definition.
We next explain how these principles have been
put into practice in the OOHDM approach.
4.1 Core application Conceptual Model
extraction (Step 2)
Our approach is based on the creation of objects that
are specified by abstracting Web pages contents (Fir-
menich et al., 2016b).
In order to do it, we developed a visual program-
ming tool that allows users to select a DOM element
from which the abstraction process starts. For this
DOM element, the user must define which is the con-
ceptual class, which are the properties of that class
and also to select from which children DOM elements
are the values for these properties taken from. This
process is shown in Figure 2, our tool adds the neces-
sary controls that let users creating objects, no matter
what Web resource has been loaded in the browser.
The first step is enabling the DOM selection (Step
1). By clicking this option, every DOM element is
highlighted on a mouse-over event, so the user can
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448
clearly appreciate what is the current target element to
collect. Then, as shown in step 2, he can access via a
context menu to the options for extracting an element
in the current DOM. Once the DOM element is se-
lected, an UI form is opened at the sidebar, which lets
the user selecting a name for the concept, a seman-
tic tag, etc. Concerning the different instances that
could be extracted from a single Class, a combo is
filled with different XPaths applicable to the selected
element and allows to unequivocally reference it or
to reference a set of similar elements instead. Then,
the user may choose one or more elements, according
to his needs. Then to select one of the possible se-
lectors in the DOM, so, e.g. he can choose multiple
DOM elements by changing the selector. Properties
can be added in the same way; the only difference is
the addition of a combo for linking such property to
an existing concept. The result of this process is the
definition of a set of classes specifications which al-
low obtaining one or multiple instances according to
the selector the user has chosen during the authoring
process: if it refers to a single element in the DOM or
to several of them Once finished the abstraction pro-
cess, users may see the collected classes and instances
viewer panel, from where the use may also export the
specifications in JSON format. Further aspects of the
abstraction of Web contents as domain object may be
found in previous work (Firmenich et al., 2016d).
4.2 Augmentation Layer Modelling
The augmentation request is triggered by a page ac-
cess of core application. To provide the enhancement,
an application server runs application models (Con-
ceptual, Navigational and Interface) in order resolve
the request. Next, we introduce the guidelines for de-
signing each model.
4.2.1 Conceptual Model (Step 3a)
Augmentation functionalities like customized recom-
mendation systems or complex concern may involve
brand new content classes (e.g., the class modeling
a Comment from a user) or the enhancement of ex-
isting core application classes and application behav-
iors. In our approach, a class diagram is designed
defining new classes and the enrichments for virtual
classes extracted in Step 2. The new classes are new
pieces of information and behavior that must be in-
troduced whereas the virtual classes are representa-
tions of the information actually perceivable by the
end-user which are enhanced with new attributes (e.g.
a Product may be enriched with an ) or relationships
with other virtual classes or augmentation ones. Any
new feature of virtual classes will be woven automati-
cally and must be considered as a Decorators (Gamma
et al., 1995) because it allows adding new features
(properties and behaviors) to an application in a non
intrusive way. In our approach, augmentation func-
tionalities might be new behaviors which are added
to the conceptual model (and which might encompass
many classes) or full-fledged navigation models, con-
taining new nodes, links and even relationships with
conceptual classes. Each augmentation functionality
is treated as a self-contained sub-system and modeled
using the OOHDM method. The notation is similar
to symmetric approaches for separation of concerns
such as the one described in (Rossi et al., 2008).
4.2.2 Navigational Design (Step 3b)
At the navigational layer, Augmentation and core nav-
igational components are connected using an integra-
tion specification which indicates, for example, if the
augmentation features are inserted in the core node or
if they are connected with a hyperlink. This specifica-
tion also includes a query indicating which core nodes
will contain the extension. Nodes matching the query
are affected by (or enhanced with) the augmentation
functionality and represent the Affinity of the aug-
mentation functionality. It is possible to define one or
more affinities for the same augmentation functional-
ity, i.e., the same functionality might be incorporated
in different parts of the application, by following dif-
ferent rules. The affinities of an augmentation func-
tionality are specified with the same query language
used in OOHDM to define nodes (Rossi et al., 2006).
The language is based on object queries. Using this
query language the definition of an affinity assumes
the following form:
AFFINITY: AffinityName
FROM C1..Ci
WHERE Predicate
INTEGRATION: Extension | Linkage(V1..Vi)
In it, AffinityName is the name associated with the
affinity, C1..Ci indicate core node classes involved in
the query, Predicate is a logical expression defined
in terms of properties of model objects which deter-
mines the instances of the core node classes C1..Ci
that will be affected by the augmentation functional-
ity, and Extension / Linkage indicate the way the aug-
mentation functionality is integrated into core nodes
through the augmentation nodes V1..Vi. An extension
indicates that the core nodes are enhanced to contain
the new functionality information (and operations). In
a linkage integration, the core nodes just allow navi-
gation towards the augmentation nodes V1..Vi which
actually contain the augmentation functionality, and
A Model-driven Approach for Empowering Advance Web Augmentation - From Client-side to Server-side Support
449
therefore does not support new behaviors. In the case
of linkage integration, we can also specify additional
features such as attributes or anchors that have to be
added to the extended node (e.g., to make navigation
more clear).
4.2.3 Structural Weaving of Augmentation
(Step 3d)
As a consequence of inserting augmentation func-
tionalities into the conceptual model or the naviga-
tional model, new interface elements must be added
into the interface model, therefore introducing new
fields with data or control interface objects (anchors,
buttons, etc.). Though we described this process in
(Ginzburg et al., 2009), we briefly review it here for
completeness and readability reasons. Each concern
(core and augmentation) will comprise ADVs for its
corresponding nodes. During the interface design
stage and when a node should exhibit some augmenta-
tion functionality, we indicate the look and feel of the
final page by specifying how the augmentation inter-
face will be inserted into the core ADV. More specif-
ically, we indicate the relative position of the added
interface objects with respect to the core interface ob-
jects. To express the integration, we have defined a
simple specification language which allows indicat-
ing point-cuts and insertions at the abstract interface
level, i.e. the position where the augmentation ADV
has to be inserted in the core ADV. The specification
generalizes the idea of point-cuts in aspect-orientation
to the two dimensional space of Web interfaces. A
point-cut and the corresponding insertion are speci-
fied using the following template:
Integration: IntegrationName
Target: ADVTargetName
Add: ADVSourceName | InsertionSpecification
Relative to: ADV name
Position: [above | bottom | left | right]
The field Integration is an identification for this
specification. It may refer or not to a navigational
affinity since the same User Interface (UI) integra-
tion specification can be used with many navigational
affinities. The field Target indicates the names of the
ADVs (one or more) which will host the augmenta-
tion interface code. Inner ADVs may be specified us-
ing a . notation. As an example, we will write Prod-
uct.Reviews to indicate that the insertion will take
place in the ADV Reviews, which is a part of the
Product ADV. The Add field indicates which elements
must be inserted in the target, either an ADV or an
immediate specification which is used when the in-
serted field is simple enough to avoid the specifica-
tion of another (auxiliary) ADV. Finally, we indicate
the insertion position by using the Relative and Posi-
tion fields. It is worth to notice that the specification is
still abstract, thus leaving space to fine tuning during
implementation.
5 A COMPREHENSIVE
EXAMPLE
In this section, we show and describe an augmenta-
tion example performing all the steps proposed in the
approach. For example, we expect to improve a Web-
site that sells seeds for agriculture proposes. The ap-
plication lacks an end-user community reviews fea-
tures that let the end-users share their experience with
a given product. In following steps we detail our ap-
proach in practice.
5.1 Extracting Conceptual Model from
Core Application
The first step in the approach is to capture the under-
laying model perceivable by the end-user that will be
used later to be enhanced. For instance, in Figure 3
we highlight a particular part of the DOM that con-
tains information about an instance of the class Prod-
uct. Also, we can see that there other DOM elements
presenting other instances of the same class. All of
these instances seem to present similar information
responding to different properties of the Product vir-
tual class, such as the name, the price and a small
description. The main idea is to define the class Prod-
uct and its properties and how they are matched to
existing DOM elements to extract concrete values for
concrete instances.
Figure 3: Concept and instance identification in existing
Web content.
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450
5.2 Modeling Augmentation Layer
In order to give support to the augmentation aspects
that need to be performed on the server, we have de-
signed a Web application using IFML which com-
prises Conceptual, Navigational and Interface mod-
els. The application gives backend support to the
whole Augmentation experience.
Once the Virtual Classes are extracted, we design
the conceptual model that documents how Augmen-
tation enriches the core application model. In our
example, a Product will be enriched with a set of
Comments that represent community’s reviews. In
IFML, the first step is the description of conceptual
mode using Entity/Relationship modeling. In Figure
4, we show how a Product will be associated with its
comments. The Product virtual class which has doted
lines is augmented with a reference multi-valuated to
Comment entity. It is noteworthy that Comment en-
tity does not need to state all the information available
on the page; indeed, the basic set of information (e.g.
any information that identify the object such as an id
or a name) that let a basic lookup implementation is
required.
Figure 4: Entity relationship model.
Figure 5: Service represented on Web IFML.
Actions on client-side require, in addition to
the conceptual model enhancement, improvements
at navigational models to describe application be-
haviour. This is modeled using units, components,
and links as part of an IFML site view. In Figure 5
a Page is defined listing all available Comments for a
given product. Furthermore, a product’s id is required
for resolving the comments by browsing the relation-
ship depicted in Figure 5. At the bottom of Figure 5
there is an URL responsible of triggering the server-
side behaviour which sends the required id
¨
pankins
¨
.
Actually, the URL is triggered by the Augmentation
plugin running in the browser once the user access
the target page. The next step in the augmentation
design is the specification of how to achieve the com-
position the core application navigational model with
the augmentation. For such task, we use the affini-
ties (introduced in Section 4.2.2). In the following
specification, the affinity points out that the Product-
Detail node (the one perceived by the end-user) must
include all the behavior required for listing Product’s
comments:
AFFINITY: IncludeProductComment
FROM ProductDetail
WHERE Predicate
INTEGRATION: ProductComments
Finally, the designer must study the best experi-
ence to the end-user regarding the Comment list’s pre-
sentation. The visual point-cut is specified using inte-
gration rules (presented at Section 4.2.2 ):
Integration: Community review
Target: ProductDetail
Add: ProductComments
Relative to: ProductTitle
Position: bottom
This determines the user interface point-cut and
corresponding transclusion position to be done. Each
time a user access a page, the captured augmentation
model instance, in this case a Product, is sent to the
server for its processing and output rendering. The
outcome will be transcluded into the core application
page using the configuration set. As result of aug-
mentation execution on client-side, the web page is
modified listing the product’s comment as expected.
In Figure 6, the reader can appreciate how the the
comment block is inserted above product title. The
weaving of pages content is achieved by means of the
Web Object Ambient (WOA) Web browser extension
(Firmenich et al., 2016b) which will be who calls the
service and perform the augmentation on the client-
side based on users configuration. It is important to
highlight that special care must be taken in client side
object identification for matching with persisted ob-
ject, otherwise, you run the risk of not finding any
result and augmentation ends without effect.
A Model-driven Approach for Empowering Advance Web Augmentation - From Client-side to Server-side Support
451
Figure 6: Augmentation result.
5.3 Implementation
The architecture is composed of two parts, on one
hand there is a Web service which is intended to be
public showing how to interact with it, specifying in
and out parameters, and designed by WebRatio IDE
to take advantage of the benefits it brings on the ease
of its use for end user. This service should be part
of the communitys available augmentation options to
make it richer and create a collaborative context.
There are some client-side restrictions that have
been taken into account. One is Cross-origin resource
sharing (CORS)
2
because it can not be assumed that
its allowed to make a call to other domain from the
web where extension is running on. To resolve that
problem, a proxy is used which wraps the call adding
headers to enable cross domain calls by the insertion
of request headers, that way calls can be made to
bring augmentation services data. Furthermore, the
script is programmed in basic JavaScript to not have
dependencies in any possible client side library, like
2
Cross-origin resource sharing is a mechanism that al-
lows restricted resources (e.g. fonts) on a Web page to be
requested from another domain outside the domain of which
the first resource was served.
jQuery
3
.
6 CONCLUSIONS
In this work we have presented a novel approach for
designing Web Augmentation coping with client-side
and server-side behaviors. The augmentations are
modeled using IFML but our approach can be in-
stantiated with other approaches (Rossi et al., 2008)
such a UWE and OOHDM. The approach relies on
the separation of concerns principles thus we provide
the composition mechanism for each model (Concep-
tual, Navigational and User interface). We used as
running example the design of a Community review
feature instantiated, but not restricted to, at an agri-
culture e-commerce site. The new feature gives in-
formation to the decision making activities. We plan
to perform an evaluation for assessing the end-user
perception about the augmentation and how it im-
proves his site’s experience. On the other hand, we
will study how to improve the reuse of the augmen-
tations. We also consider to evaluate the approach
based on a quality framework for MDWE approaches
3
jQuery is a cross-platform JavaScript library designed
to simplify the client-side scripting of HTML.
APMDWE 2017 - 2nd International Special Session on Advanced practices in Model-Driven Web Engineering
452
(Dom
´
ınguez-Mayo et al., 2012). This will help to
improve our approach’s processes that let applying
and designing efficiently. Finally, we will study the
use of Model-Driven Web Augmentation in diverse
business domains such as Financial, Banking, Logis-
tic,etc.. Additionally, we instantiate our approach us-
ing OOHDM and UWE among other approaches.
ACKNOWLEDGEMENTS
Authors of this publication acknowledge the contribu-
tion of the Project 691249, RUC-APS: Enhancing and
implementing Knowledge based ICT solutions within
high Risk and Uncertain Conditions for Agriculture
Production Systems (www.ruc-aps.eu), funded by the
European Union under their funding scheme H2020-
MSCA-RISE-2015.
Additionally, this research has been partially sup-
ported by the POLOLAS project (code TIN2016-
76956-C3-2-R) of the Spanish Ministry of Science
and Innovation
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