Browsing by Author "Wijegunasekera, M.C."

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ER to Relational Model Mapping: Information Preserved Generalized Approach
(International Postgraduate Research Conference 2019, Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2019) Pieris, D.; Wijegunasekera, M.C.; Dias, N.G.J.
The Entity-Relationship (ER) model is widely used to create ER schemas to represent application domains in the Information Systems development field. However, when an ER schema is transformed to a Relational Database Schema (RDS), some critical information modeled on the ER schema may not be represented meaningfully on the RDS. This situation causes a loss of information during the transformation process. In our previous studies, we showed that the deficiencies that exist both in the ER model and the transformation algorithm cause this situation. Accordingly, we modified the ER model and the transformation algorithm to eliminate the deficiencies and thereby to preserve the information in the transformation process. We then showed that a mapping that is one-to-one and onto exists from the ER Schema to the RDS, and the information represented on the ER schema is preserved on the RDS. For this purpose, the ER schema should be created using the modified ER model and transformed to the RDS by the modified transformation algorithm. However, this concept has not yet been proved formally. It needs to be testified for any ER schema representing any application domain. Subsequently, following the modified ER model, we also proposed a generic ER schema ̶ an ER schema that represents any real-world phenomena in symbolic notation ̶ for using in a future proof creation process. Thus, in this work, we aim to create a formal proof for validating the work that we had done. For simplicity, we use a generic ER schema that consists of two regular (strong) entity types and a one-to-many-relationship-type. We first show that the generic ER schema can be partitioned into unique segments. We call them ER-construct-units, where each one represents a unique semantic meaning in the real world. The ER schema can be viewed to have been made up of the set of ER-construct-units. Both the ER schema and the ER-construct-unit set are equivalent. Second, we transform the generic ER schema to its corresponding RDS using the modified transformation algorithm. We then show that the RDS can also be partitioned into unique segments, which we call Relation-schema-units. Next, we show that a mapping that is one-to-one and onto exists from the set of ER-construct-units to the set of Relation-schema-units. In conclusion, we show that any ER-construct-unit in the ER schema has its own and unique Relation-schema-unit on the RDS. Therefore, any piece of information represented on the ER schema has its own and unique representation on the RDS. The proof can be expanded to any generic ER schema that is even bigger than the current one, and accordingly, the same result can be obtained. Since the generic ER schema means a generalized representation of any real-world ER schema, we conclude that information represented on any ER schema is preserved on its corresponding RDS.
An Improved Generic ER Schema for Conceptual Modelling of Information Systems
(Proceedings of the Asia International Conference on Multidisciplinary Research 2019, Vol.-1, 2019) Pieris, D.; Wijegunasekera, M.C.; Dias, N.G.J.
The Entity Relationship (ER) model is widely used for creating ER schemas for modelling application domains in the field of Information Systems development. However, when an ER schema is transformed to a Relational Database Schema (RDS), some important information on the ER schema may not be represented meaningfully on the RDS. This causes loss of information during the transformation process. Although, several previous researches have proposed solutions to remedy the situation, the problem still exists. Thus, in this on-going research we wish to improve the proposed solutions and maximize information preservation in the ER to relational transformation process. Cardinality ratio constraints, role names, composite attributes, and certain relationship types are among the information frequently lost in the transformation process. Deficiencies in the ER model and the transformation method seems causing this situation. We take the view that if the information lost is resolved; a one-to-one mapping should exist from the ER schema to its RDS. We modified the ER model and the transformation algorithm following a heuristic research method with a view to eliminating the deficiencies and thereby achieving a one-to-one mapping. We should show that the mapping exists for any real world application. We create a generic ER schema - an ER schema that represents any phenomena in symbolic form - and use it to show that a one-to-one mapping exists for any real world application. In this paper, we explore our generic ER schema and its advantages over its predecessors in view of representing any real world application.
Traveling Assistant Mobile Application Using Location-Based Service
(Faculty of Computing and Technology, University of Kelaniya, Sri Lanka, 2021) Dhananjaya, S.M.D.V.; Wijegunasekera, M.C.
Sri Lanka is a major tourist destination which has several historical places, rivers, waterfalls, and shrines, as well as many other places of interest,. Currently, several mobile apps have been added to the Google Play Store for the convenience of these travelers, but these apps do not meet the latest needs of travelers. As a result of this project, created a new mobile application called “Travel Lanka” that addresses the issues and new needs of the travelers. This project follows the Agile software development methodology. Travel guidance is provided by displaying data on a google map view [1]. People can find the places for food and drink, shopping, and service places using Google maps. But it has no method to find a nearby travelling place. This application automatically suggests and shows nearby places on the map that can be travelled based on user location using the have sine formula [2]. This application can automatically change the nearby places when the user moves from location to location. Also, users can find all places in a particular district or province and find any places by using place names. Travelers can filter places using place types as waterfalls, parks, mountains, beaches and so on. With the suggested places, users can view some important details about the places and receive navigation instructions. In addition to that, this mobile application facilitates users to view compass, use the suggested transport facility, currency converter and nine major languages are provided by this application. All the functions were tested using unit testing and integrated testing, Basically, how the user interfaces layout changes under different screen sizes was tested when creating this “Travel Lanka” application,. This app is designed to suit different screen sizes of different mobile phones. A responsive layout has been created to display this application correctly on all types of phones. For this, testing was done using the package called “Device Preview” [3]. This Device Preview package helped to test various screen sizes, change device orientation, check background running capability, and many more. Such facilities are not available for use in a single mobile application currently offered to the tourism industry in Sri Lanka. A major challenge for travelers has to install and use the number of applications to get these features. Travel Lanka app combines all general features available in other apps. Feedback and user evaluations were collected and considered under the categorizing as usability, accessibility, accuracy, and correctness. Positive user feedback and user evaluations show the success and the usefulness of the application for the users.