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Artigo - Aplicações Interativas para TV Digital: Uma Proposta de Ontologia de Domínio.

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Artigo criado para a matéria de tópicos avançados em Engenharia de Software. Mestrado em Ciências da Computação. PROCC UFS

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Artigo - Aplicações Interativas para TV Digital: Uma Proposta de Ontologia de Domínio.

  1. 1. OntoAI Proposal of Ontology to Define Digital TV Interactive Application Diego Armando de Oliveira Meneses1, Antonio Aliberte de Andrade Machado1,Adicineia Aparecida de Oliveira1 and Rogerio Patricio Chagas Nascimento1 1Universidade Federal de sergipe, Sergipe, Brasil Keywords: Digital TV, Interactive Applications, Interactivity and Ontology. Abstract: Convergence of technologies has enabled the formation of the Digital TV infrastructure. The Brazilian Digital Television System (SBTVD) was developed with a layer of middleware called Ginga. This middleware sup-ports the development of applications and is responsible for supporting interactivity. This structure provides new opportunities and challenges. One of these challenges is the development process of interactive applica-tions for Digital TV. Develop interactive applications for Digital TV is a new and complex process. Create aid mechanisms to do this is necessary task. This paper proposes the development of an ontology that defines the concepts and relationships in an interactive application. The ontology was developed from the execution of a specific methodology and with the support of bibliographic references and systematic review. Multidis-ciplinary teams that produce interactive applications can use the ontology as supporting documentation or to understand the concepts of an application. Aiming to facilitate integration with other applications ontology was available in OWL format. The ontology created is simple and can be revised and altered depending on the context. 1 INTRODUCTION Today there are several technologies that converge on different devices, enabling new features and products. Television also going through this series of modifi-cations (Zuffo, 2006). The main change is the dig-ital signal. The digital signal together with the re-turn channel provides interactivity. The interactiv-ity allows you to control the viewer about the han-dling of applications and content creation (Montez and Becker, 2005). Development process of interactive application is complex and immature for Digital Television. Com-plexity exists because of the convergence of two dis-tinct areas: audio-visual and software development (Crocomo, 2007). Immaturity occurs due to lack of methodologies, techniques and development methods for this type of application. Teams multidisciplinary provides a complex domain. The lack of knowledge about this domain, affect the development of applica-tions. To solve this problem we suggest the creation of an ontology defining an interactive application of Digital TV. An ontology brings the benefit of being in-dependent technology and provide better understand-ing of the problem from the modeling performed in a higher level of abstraction (Gruber, 1993). This pa-per proposes an ontology for defining an interactive application of Digital TV. The ontology was created from the use of a methodology and compiling con-cepts raised through a literature search. 1.1 Related Work Works found during the systematic review. A sys-tematic review was performed from the string: ((on-tology) OR (ontologia)) AND (((”Digital TV”) OR (DTV) OR (”TV Digital”))). The research was con-ducted in SPRINGER and periodicals CAPES. The principle were found 237 papers. After application of the inclusion criteria, 5 (five) were selected for reading. The following are 3 of these articles. (Kim and Kang, 2013) proposes an ontology of IPTV pro-grams and viewers consumption behavior to improve the ability to recommend ads. (Saleemi and Lilius, 2014) proposes a methodology with ontology-based approach that helps to design and develop interactive TV applications. In Tsinaraki et al. (Tsinaraki et al., 2005) proposes a semantic indexing of audiovisual content-based indexing ontologies for MPEG-7 and TV-Anytime.
  2. 2. 1.2 Paper Structure The introduction contextualizes the problem, explains the difficulties, describes the motivations, presents the objectives to develop the work. Theoretical back-ground is the compilation of several concepts used in the construction of ontology. In Topic 3 we have the creation of ontology, from the execution of the steps of the methodology. In the topic brief analysis of the results is made evaluating the ontology based on qual-ity criteria and levels of care to these criteria. 2 THEORETICAL BACKGROUND This topic is done the compilation of concepts, Digital TV, Interactivity and Ontology. The concepts are im-portant because they provide the basis for the creation of OntoAI. 2.1 Digital TV Television is an electronic system for receiving sound images and snapshots. It works based on the conver-sion of light and sound into electromagnetic waves and their conversion into a receiver (TV). Digital TV offers new services that previously were not possi-ble in the conventional transmission system into elec-tromagnetic waves. Related to the digital television services are broadcast to multiple types of handset, record prgrams on your hard disk, computer systems, games and internet access. Access internet is the main way to promote the full interactivity in digital TV, this access is via the return channel, can use it as a com-munication: medium telephone line, dial-up, Asym-metric Digital Subscriber Line (ADSL) Power Line Communications (PLC), cable, satellite and mobile phones (Meloni, 2007). Digital TV is a new plat-form of communication, which over time will cause changes society (Montez and Becker, 2005). 2.2 Interactivity 2.2.1 Concept Interactivity is capacity (of equipment, communica-tion system, or computer, etc.) to interact and interact to allow. In Interactive Digital TV, the TV is no longer uni-directional and proceeds to allow greater user par-ticipation in selecting contents (Montez and Becker, 2005). This change provides interactivity makes the production process more complex content. For (Steuer, 1992), the interactivity depends on the extent how you can participate or influence the immediate change in form and content. 2.2.2 Features (Montez and Becker, 2005) describes five character-istics of interactivity. They are: Ability to stop, Gran-ularity, Soft Degradation, Limited Forecast and Non- Default. 2.2.3 Levels of Interactivity We categorizing interactivity from its scope in rela-tion to the ability to control the contents in ascending order (Montez and Becker, 2005). The categories are: Reactive, Proactive and coercive. 2.2.4 Types of Interactivity There are various types for interactivity. The most used was proposed by the research and development center in Telecommunications (CPqD) where there are 3 types: Local, Intermittent, Permanent. 2.2.5 Types of Interactive Applications (Montez and Becker, 2005) states that it is possible to classify the whole range of information incorporated by the term interactivity into seven major groups. They are: TV Advanced (Enhanced TV), Internet on TV, Individualized TV, Video On Demand, Personal Video Recorder (PVR), Walled Garden and Games Console. (Gawlinski, 2003) adds two new groups: Electronic Program Guide and Teletext Services. 2.3 Ontology 2.3.1 Concept (BlackBurn and Marcondes, 1997) describe ontology as ”the branch of metaphysics that concerns what exists.” Unlike philosophy, the term ontology has a sui generis meaning in information organization and computer science. To (Sowa, 2001), ontology is a ”catalog of types of things” where it is believed to be a domain, from the perspective of someone who uses a particular language. The ontology concept adopted in Computer Science is expressed by (Gruber, 1993), ”an ontology is a specification of a conceptualization, ie, an ontology is a description (like a formal specifi-cation of a program) of the concepts and relationships that can exist for an agent or a community of agents”. (Borst, 2001) is a description of simpler and complete ontology: ”An ontology is a formal, explicit specifi-cation of a shared conceptualization”. Where formal
  3. 3. specification has the meaning understood by comput-ers; explicit specification refers to the concepts, prop-erties, relations, axioms; the shared word means con-sensual knowledge (Almeida and Bax, 2003). In this article we adopted the concept of (Borst, 2001) as a basis to suggest OntoAI. 2.3.2 Features Ontology may represent the same area in different ways, this does not indicate that a diversity order is correct and another wrong, only indicates that a do-main can be represented in various ways depending on the perspective that same rate. Despite this diver-sity, ontologies have characteristics and basic compo-nents common to most of them (Almeida and Bax, 2003). The basic components of an ontology are: classes, relations, axioms, instances and functions (Gruber, 1993). 2.3.3 Uses, Benefits and Problems In computing, ontologies can be applied to: informa-tion retrieval on the Internet, natural language pro-cessing, knowledge management, semantic web, edu-cation (Morais and Ambrosio, 2007). To (Guizzardi, 2000) the benefits of using ontologies are: commu-nication, formal Specification (ontology) and knowl-edge representation and reuse. Guizzardi addresses the key issues such as choice of ontologies, creation and evolution of ontologies, ontology library and de-velopment methodologies, considered for the author as the problem worse. 2.3.4 Types (Almeida and Bax, 2003) says ontologies can be typ-ified as to their degree of formality, application, con-tent or function. The degrees of formality are highly informal, semi-casual, semi-formal and formal rigor-ously. Related to the application, can be neutral au-thorship, specification and access to information. Re-garding the content can be: terminology, informa-tion, modeling knowledge, application, domain, or generic or representation. With respect to their func-tion (Structure) can be: generic, domain, task, appli-cation or representation (Guarino, 1997). 2.3.5 Methodologies Develop ontologies is still considered an artistic pro-cess, so it is necessary the creation of methodolo-gies that aims to standardize and organize the con-struction and manipulation of ontologies (Lopez et al., 1999). (Guizzardi, 2000) proposes a systematic ap-proach based on 6 stages: identify the purpose and specify requirements, capture the ontology and for-malize the ontology, integrate with existing ontolo-gies and evaluate / document. Figure 1 shows the ac-tivity diagram and the iterative process of the method-ology, with the sequence in which the steps must be performed. Figure 1: Methodology activity diagram adapted from Morais e Ambrosio (2007). Source: Authors (2014). 2.3.6 Tools and Languages The most popular tool for building ontologies is the Prot´eg´e. Created by Stanford University is an open source tool that provides a graphical interface for building ontologies that supports several languages (Noy and McGuinness, 2001). The W3C (World Wide Web Consortium) recom-mends the use of three languages: Ontolingua (Cre-ated by the Knowledge Systems Laboratory at Stan-ford University, is considered it the most expressive), RDF (Developed by W3C) and OWL (Ontology Web Language) also developed by W3C. It is a language based on computational logic. It can be operated by computer programs, for example, verify the consis-tency of the knowledge (W3C, 2012). 3 BUILDING THE ONTOLOGY: ONTOAI The OntoAI was created from the Digital TV concepts and interactivity and also from a lived experience in a
  4. 4. real development process. The OntoAI can be used as a resource to assist the process of developing interac-tive applications. first step in the creation of ontology was sort your kind with regard to its function. The ontology was classified as domain ontology because it is a particular area of computing. For (Almeida and Bax, 2003) the construction of domain ontologies in-volves first defining its domain and its scope. The field of ontology OntoAI are the interactive applica-tions and the scope is the Digital TV. After defining these elements, it was necessary to choose a construc-tion methodology. In this paper we adopted the methodology pro-posed by (Guizzardi, 2000) to help systematize the construction of OntoAI. The iteration allowed by the methodology helped refine the ontology initially pro-posed. This refinement was possible from revisions made in OntoAI. The following topics describe the activities of the methodology. In each topic explains the activity and how it should be performed. In each activity is shown as we arrived to OntoAI. 3.1 Identify Purpose and Specify Requirements In this activity we identified the competence of the ontology, ie, its purpose and use. The main purpose is to assist the process of development of interactive applications for Digital TV. Other aims are: to serve as a base or generic definition of an interactive application, to provide a formal specification that can be understood by com-puter and can be searched from appropriate query lan-guages, sharing concepts involving such an applica-tion, integrate and reduce the ”differences” between the members of the multidisciplinary team provided by the domain. The ontology can be used as reference for the analysis requirements as a starting device directed to developing models, such as documentation to aid the development process. In this activity you can also identify potential users of the ontology, as system developers, analysts and software engineers, project managers, writers, producers audio visual, audio visual support team. The OntoAI ontology was created for a specific audience, but its simplicity makes it easy to use the same for anyone. 3.2 Capture Ontology For (Almeida and Bax, 2003) is the most important activity of the methodology, aims to capture the set of elements of a domain, based on the expertise and concepts that a involve. The description of the basic components of an on-tology defined by (Gruber, 1993) helped structure the capture. The classes (main element) were captured using a top-down approach, which first defines the generic concepts and then specialize them. Another technique used was the taxonomy to organize in sub-classes fa-cilitating the understanding. The more general classes captured in the process are listed below in order of importance: Interactive-Application; Interactivity; Media; Return-Channel; Viewer; Application-Type; Interactivity-Type; Interactivity-Level; Interactivity-Features; Interactivity-Location; Interactivity-Time; Interactivity-Access-Device. Then there was the specialization of classes. Some of these Return-Channel, Application- Type, Interactivity-Type, Interactivity-Level and Interactivity-Features were specialized based on the concepts of interactivity seen in the theoretical background. The class Interactivity is specialized based on def-initions provided in the Brazilian Digital TV stan-dard (SBTVD), where interactivity is only possible through the use of middlware swing and their special-izations Ginga NCL and Ginga-J. Other classes such as Media, Interactivity-Time, Interactivity-Access-Device are specialized, from ex-perience in developing this type of application. In Figure 2 you can see the class structure and some spe-cializations. This image shows the main structure of the ontology OntoAI. After defining the classes and their hierarchies, you must define the relationships and constraints (Cardinalities) between them. In OntoAI, the most important relationship is contained in the Interactive- Application class. This relationship defines the com-ponents of an interactive application. In Figure 3, one can see the relationships and cardinality of the class Interactive-Application with the other classes: In-teractivity, Media, Application-Type, Return-Channel and Viewer.
  5. 5. Figure 2: Ontology class structure. Source: Authors (2014). The class Interactive-Application has at least one (1) type of application. It has a return channel. It is composed of at least one (1) interactivity. It is composed of at least one (1) media. The Viewer class has a use relationship with the class Interactive- Application. Figure 3: Relationships and constraints (cardinality) of class Interactive-Application. Source: Authors (2014). Other important relationships are found in class Interactivity. This relationship is who defines interac-tivity, from their concepts. The class Interactivity has somento one (1) type of interactivity. The Interactiv-ity has one or more characteristics. Interactivity also has access device, location, level and time. Here rela-tions and cardinalities of intetatividade class in Figure 4. Figure 4: Relationships and constraints (cardinality) of class Interactivity. Source: Authors (2014). Also in Figure 4 one can see the relationship be-tween the Return-Channel and class Interactivity, this relationship states that the interactivity is provided by the use of the return channel in different levels. The class Viewer has a relationship that shows that an in-dividual (Instance) of this class interact with Interac-tivity. Other less important relationships are defined in the ontology. 3.3 Formalize Ontology This activity proposes specify the ontology language. For (Almeida and Bax, 2003) ontologies can be repre-sented formally (Mathematical Models) or informally (Natural Language). The language used to create the OntoAI ontology is the OWL language is used be-cause it has been easier to express meaning and se-mantics than XML, RDF and RDF (S) and represent interpretable content by machines. To consolidate the formalization of ontology, we use the Prot´eg´e tool. The tool was chosen because it supports the OWL and contains mechanisms for verification of logical con-straints, acquisition of information and etc. Figure 5 shows a snippet of the OWL ontology generated by Prot´eg´e tool. 3.4 Integrate With Existing Ontologies This activity is responsible for identifying possible ontologies already defined. During the capture pro-cess and formalization was not identified any on-tology that could be integrated to OntoAI ontology. Some classes could be references to other ontolo-gies, but no existing ontology was compatible with the needs of OntoAI ontology. It is worth noting that the reuse of ontologies is recommended when possi-ble.
  6. 6. Figure 5: Part of OWL OntoAI code. Source: Authors (2014). 3.5 Assess and Document These two activities occur throughout the cycle of the iterative method. The evaluation serves to verify that the requirements (Purpose) are in accordance with the final ontology. (Guizzardi, 2000) defines criteria for assessing the quality of ontology. They are: Clar-ity, Consistency, Extensibility and minimal ontolog-ical commitment. 4 BRIEF ANALYSIS OF RESULTS Figure 6 shows the evaluation of OntoAI ontology on the criteria and service levels. The clarity criterion is partially met because visually the class structure does not show all the relationships and constraints of the ontology. The consistency criterion is fully satisfied because all classes were captured from concepts al-ready established and referenced. The criterion on-tological commitments minimum and also fully satis-fied because the ontology although immature shown in accordance with the basic requirements of an on-tology. The extensibility criterion is partially met be-cause not all classes were created thinking about this feature, only some of them can be extended. For (Guizzardi, 2000) documentation is made throughout the development of the ontology. This work was not possible to document the entire pro-cess, the documented part refers to ontology created in Prot´eg´e tool. The Prot´eg´e tool provides a feature to export the ontology in OWL documentation, this documentation is generated in HTML pages. 5 CONCLUSIONS The choice of ontology can become a political pro-cess, since an ontology may not be entirely appro- Figure 6: Ontology was evaluated according to the criteria of Guizzardi (2000). Source: Authors (2014). priate for all individuals or related groups (Almeida and Bax, 2003). OntoAI is based on Digital TV concepts and interactivity, exposed in the theoretical background over the concepts and experiences gained in the development of a real application. Purpose of the ontology is to help people involved in the process of creating an interactive application of Digital TV, ie the ontology was created on the point of view of the developer and the audiovisual team, and not from the point of view of the viewer. Integration with existing ontologies facilitates new ontology development process. Some studies found during the protocol execution show the use of ontologies as a basis for TV recommender systems or defined ontology of TV programs. The development process of interactive applica-tions is still immature and complex. The creation of tools, methods and techniques facilitates the develop-ment process. This paper proposes an ontology that defines what a interactive applications for Digital TV. This ontology can be used to support the development process. The lack of ontologies that define an interactive application was a stimulus to create the OntoAI. The difficulties faced in the creation of ontology were for lack of mature methodologies that show the process of creating an ontology. The ontology first developed Ad-hoc without the use of a methodology, the difficul-ties in creating an ontology without a defined process were increasing, making the process in artistic. Be-cause of these difficulties a methodology was adopted to carry out the task of creation. The ontology can be further improved running other iterations of the methodology. In future work it is possible to ver-ify that the ontology can be used as the main artifact of a software development project designed to mod-els. The ontology is available inWebprotege from the link: http://goo.gl/dJcLx
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