Michel E. Adiba

A Survey of Mobile Transactions

Transaction support is crucial in mobile data management. Specific characteristics of mobile environments (e.g. variable bandwidth, disconnections, limited resources on mobile hosts) make traditional transaction management techniques no longer appropriate. Several models for mobile transactions have been proposed but it is difficult to have an overview of all of them. This paper analyzes and compares several contributions to mobile transactions. The analysis distinguishes two groups of models. The first group includes proposals where transactions are completely or partially executed on mobile hosts. In this group we focus on ACID properties support. The second group considers transactions requested by mobile hosts and executed on the wired network. In this case, ACID properties are not compromised and focus is on supporting mobile host movements during transaction execution. Discussions pointing out limitations, interesting solutions and research perspectives complete this paper.

Analyzing mobile transactions support for DBMS

Focuses on transaction management in mobile environments. Mobility introduces new dimensions such as movement and disconnection that affect transaction management. Several proposals concerning mobile transactions have been done, but a detailed comparative analysis does not exist. We analyze and compare how mobility features have influenced the ACID properties and the execution model of some proposals. Furthermore, based on our analysis, we introduce a sketch of the design of a mobile transaction service.

STORM: An Object-Oriented Multimedia DBMS

Based upon the Object-Oriented approach, the STORM1 DBMS integrates structural and temporal aspects for managing different presentations of multimedia objects (i.e. Text, Audio, Image, Video). We provide a mapping between structural operators (e.g. tuple, list, set) and temporal relationships (e.g. before, after, equal) involved in presentations. Temporal aspects are modeled through the notion of Temporal Shadow which incorporates free or bound durations and/or delays. We extend the type system of an Object-Oriented data model for expressing and controlling synchronization between objects in order to provide sequential and parallel presentations. These presentations are themselves stored as database objects and can be derived automatically from the schema, updated and queried. We describe also several extensions to an object query language in order to deal with specific temporal and synchronization aspects of multimedia presentations. Our approach shows how current object-oriented DBMS architectures and functions should be revisited in order to provide an integrated environment to handle time-based multimedia data.

Spatio-Temporal Multimedia Presentations as Database Objects

In this paper, we present a database model and a prototype system which provide a general format for multimedia presentations with spatio-temporal aspects. This representation is independent of any description language and media type and can be used to interpret and to integrate heterogeneous multimedia data coming from different distributed sources. We put a special emphasis on spatial aspects and we provide both qualitative and quantitative relations to compose and query multimedia presentations. The originality of our approach is that presentations can be specified, stored as database objects, queried and executed.

Management of Multimedia Complex Objects in the '90s

It is always a very difficult exercise to predict the future and we did not do that! Rather, we tried to make a survey of the adequacies and inadequacies of the DBMS proposals at the beginning of this new decade. We tried to adopt a practical point of view and we gave some example which can help to understand how the field is going to evolve. As we have seen, we left a lot of problems open. Some of them are going to be addressed by the papers of the other sessions, and several solutions will be given. There is a huge amount of work in research and development in order to have systems which are both easy to use and efficient. We believe more in the integration of several different fields (e.g. programming languages and databases) rather than in the emergence of completely new fields.

Exploiting bitemporal schema versions for managing an historical medical data warehouse: a case study

Data warehouses integrate information from several data sources. Their main goal is to offer an efficient access to data sets and to enable users to make better and faster decisions. In this work, we present our proposition for the management, storage and visualization of a data warehouse (current and historical) in a medical environment using bitemporal schema versions. Changes in data sources concern either data or schema and must be propagated to the warehouse in order to have updated information. This process generates a maintenance transaction. Most research works use the version approach to keep information consistent according to its schema when a maintenance transaction is executed. In a medical context it is essential to manipulate current and historical data. However, we must consider the huge quantity of medical data and propose a mechanism for handling the data sets in an evolving environment. Our version model is placed above the database management system and is completely orthogonal to the DBMS data model.

Management of multimedia data using an object-oriented database system

A multimedia database management system (MMDBMS) must provide facilities to store, model and query multimedia data. In the context of the STORM (Structural and Temporal Object-oRiented Multimedia database system) project, we are developing an object-oriented client-server MMDBMS which addresses these problems. We use an object-oriented approach to develop reusable components which can be easily integrated in the general framework of multimedia database applications. In this paper, we present the main functionalities of our system and we focus on video objects and their integration in multimedia presentations.

Integrated Tools for Object Oriented Persistent Application Development

This paper presents the main characteristics of an integrated environment for object oriented, persistent application development. We first discuss the rationale of our approach and give our analysis of current database systems or persistent languages. Using such systems or languages is still a very difficult task because persistent application development combines the complexity of database schema design together with a software engineering problem.

Consistency Checking in Object Oriented Databases: a Behavioral Approach

This paper presents a mechanism to enforce consistency in object oriented DBMS using pre-conditions and post-conditions on methods. This mechanism is coupled with an exception mechanism to allow deferred controls and semantic tolerance. Conditions are defined using SQL-like expressions and methods composition. A prototype which has been implemented on the O2 object oriented database management system (DBMS) is also described in this paper.

An Object DBMS for Multimedia Presentations including Video Data

This demonstration shows how an OO DBMS can be extended for taking into account multimedia data. An integrated environment for multimedia presentation authoring and playback has been developed on top of the O2 OO DBMS. It consists of a library of classes which can be used and shared by several multimedia database applications. The system has been developed using C++ and multithreading is used for performing parallel tasks. In addition, a graphical interface has been developed which allows to easily and interactively build multimedia presentations. Also, a video data model has been specified and implemented. Finally, a query language like OQL is used to query video and presentation objects and to automatically generate dynamic multimedia presentations.