Ana Carolina Salgado

Designing context-sensitive systems: An integrated approach

Context-sensitive systems (CSS) are computer systems that use context to provide more relevant services or information to support users performing their tasks, where context is any information that can be used to characterize the situation in which something exists or occurs. CSS demand that designers consider new aspects and challenges in comparison to traditional applications. In a preliminary experiment, we observed that developers find it difficult to include the concept of context in their applications. However, only few approaches offer integrated domain-independent support on developing CSS. This paper presents an integrated approach to assist the design of CSS. The originality of this work lies on the proposed way of thinking about context, on the proposed context metamodel and on the specification of a process for designing CSS. The metamodel supports building context models by making explicit the concepts related to context manipulation and by separating the context structure model from the CSS behavior model. The design process details the main activities related to context specification and the design of CSS, providing a systematic way to execute these tasks. This work also advances the state of the art related to the understanding of the concept of context (and its associated concepts). Three experimental studies were conducted to evaluate the proposal: its instantiation in the design of a context-sensitive Expert Recommender System, its usage by distinct designers on their CSS projects, and a qualitative evaluation of the overall proposal by experienced CSS developers. These studies showed a good acceptance of our approach and indicated the feasibility of using it on real projects.

Conceptual modeling of XML schemas

XML has become the standard format for representing structured and semi-structured data on the Web. To describe the structure and content of XML data, several XML schema languages have been proposed. Although being very useful for validating XML documents, an XML schema is not suitable for tasks requiring knowledge about the semantics of the represented data. For such tasks it is better to use a conceptual schema. This paper presents an extension of the Entity Relationship (ER) model, called X-Entity, for conceptual modeling of XML schemas. We also present the process of converting a schema, defined in the XML Schema language, to an X-Entity schema. The conversion process is based on a set of rules that consider element declarations and type definitions and generates the corresponding conceptual elements. Such representation provides a cleaner description for XML schemas by focusing only on semantically relevant concepts. The X Entity model has been used in the context of a Web data integration system with the goal of providing a concise and semantic description for local schemas defined in XML Schema.

Key issues in the design of an asynchronous system to support meeting preparation

Abstract A review is made of the most important decisions in the design of asynchronous systems to support the preparation of business decision meetings. These decisions are illustrated with the choices made for the development of SISCO, a system of this type. The presentation considers issues in the discussion model, the group memory, the communication and visualization mechanisms, and the development of a meeting preparation sequence: how to start a session, carry it out and close it. Issues concerning coordination, participation and awareness in meeting preparation sessions are also discussed.

Towards an ontology for context representation in groupware

An important issue in groupware is how to improve interaction and collaboration among participants. Through the analysis of the context a user is in or the context that surrounds an interaction, groupware systems can provide users with useful information in that situation. A relevant issue when using context is how to represent context information. Ontologies constitute an interesting method for representing context, since they enable information sharing and reuse. They can also be used by existing inference machines to reason about various contexts. In this paper we propose an ontology to formally represent context in groupware systems. We also present an example where this ontology is used by a logic-based reasoning mechanism for tool recommendation based on the current context of group members. We believe that this ontology could help to understand the role of context in collaboration and thus make the development of context-aware groupware systems easier.

Modelling and querying geographical data warehouses

A number of proposals for integrating geographical (Geographical Information Systems-GIS) and multidimensional (data warehouse-DW and online analytical processing-OLAP) processing are found in the database literature. However, most of the current approaches do not take into account the use of a GDW (geographical data warehouse) metamodel or query language to make available the simultaneous specification of multidimensional and spatial operators. To address this, this paper discusses the UML class diagram of a GDW metamodel and proposes its formal specifications. We then present a formal metamodel for a geographical data cube and propose the Geographical Multidimensional Query Language (GeoMDQL) as well. GeoMDQL is based on well-known standards such as the MultiDimensional eXpressions (MDX) language and OGC simple features specification for SQL and has been specifically defined for spatial OLAP environments based on a GDW. We also present the GeoMDQL syntax and a discussion regarding the taxonomy of GeoMDQL query types. Additionally, aspects related to the GeoMDQL architecture implementation are described, along with a case study involving the Brazilian public healthcare system in order to illustrate the proposed query language.

Investigating the specifics of contextual elements management: the CEManTIKA approach

In times where users need to process an ever increasing amount of information to perform more complex tasks in less time, the introduction of context in computer systems is becoming a necessity. However, building a context-sensitive system entails more work in comparison to traditional systems development: in the former, one must care for context-related tasks, such as the acquisition, processing, storage, manipulation and presentation of contextual elements. Context management proposes the separation of context related tasks from the applications business features. This paper presents a study on context management and discusses our proposal for a context manager, called CEManTIKA (Contextual Elements Management Through Incremental Knowledge Acquisition). A scenario is presented to illustrate its applicability.

A Semantic-Based Ontology Matching Process for PDMS

In Peer Data Management Systems (PDMS), ontology matching can be employed to reconcile peer ontologies and find correspondences between their elements. However, traditional approaches to ontology matching mainly rely on linguistic and/or structural techniques. In this paper, we propose a semantic-based ontology matching process which tries to overcome the limitations of traditional approaches by using semantics. To this end, we present a semantic matcher which identifies, besides the common types of correspondences (equivalence), some other ones (e.g., closeness). We also present an approach for determining a global similarity measure between two peer ontologies based on the identified similarity value of each correspondence. To clarify matters, we provide an example illustrating how the proposed approach can be used in a PDMS and some obtained experimental results.

Looking at both the present and the past to efficiently update replicas of web content

Since Web sites are autonomous and independently updated, applications that keep replicas of Web data, such as Web warehouses and search engines, must periodically poll the sites and check for changes.Since this is a resource-intensive task, in order to keep the copies up-to-date, it is important to devise efficient update schedules that adapt to the change rate of the pages and avoid visiting pages not modified since the last visit.In this paper, we propose a new approach that learns to predict the change behavior of Web pages based both on the static features and change history of pages, and refreshes the copies accordingly.Experiments using real-world data show that our technique leads to substantial performance improvements compared to previously proposed approaches.

Towards an Ubiquitous and Context Sensitive Public Transportation System

Transportation systems deal with dynamic and sometimes inconstant scenarios, which could involve events like traffic jams or accidents. Intelligent Transportation Systems (ITS) should be projected in a way that their behavior changes according to the real world that can be pictured surrounding it. Context is what allows the understanding of this dynamicity and how it impacts the way people decide to use the available transportation. This paper presents UbiBus, a system that aims to integrate the concepts of Computational Context and Ubiquitous Computing into the ITS domain. It considers the mobility of people and vehicles and the occurrence of dynamic factors that could affect the transportation and provide passengers with advanced information about the available public transportation in a city (e.g. the estimated arrival time of a bus, according to its current location and a given bus station, or route and bus recommendations according to the different needs of a passenger at a certain time). To verify the viability of the proposed ideas we developed an application that provides the current location and estimated arrival time of a bus. This application was evaluated after real data collection involving a route created for the city of Salvador, Bahia, which showed the potential of the proposed solution.

Towards a context ontology for geospatial data integration

Recently, Geospatial data and Geographic Information Systems (GIS) have been increasingly used As a result, the integration of geospatial data has become a crucial task for decision makers Since GIS and geospatial databases are designed by different organizations using different representation models and there are diverse levels of detail for the spatial features, it is much more complex to achieve data integration in geospatial databases To help matters, context information may be employed to improve two fundamental aspects in Geospatial Data Integration: (1) schema mapping generation and (2) query answering However, a relevant issue when using context is how to better represent context information Ontologies are an interesting approach to represent context, since they enable sharing and reusability and help reasoning In this paper, we propose a context ontology to formally represent context in geospatial data integration We also present an example where this context ontology is used to improve query processing.