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A lot of Real-Time (RT) database research has been done to process transactions in a timely fashion using a large number of temporal data representing the current status of the real world. However, most existing RT database works are based on simulations which have limitations in modeling realistic environment. To address this problem, we design a RT object-oriented application development environment, called ODEA Object Database for Real-Time Application Development), atop a popular open-source object-oriented database. The aim of ODEA is to design a next-generation development tool for future RT database application programmers. The tool is based on the query language RTNQL (Real-Time Native Query Language), a powerful, new and high level RT object-oriented programming language tightly coupled with query capabilities. This paper presents design goals of ODEA and its fundamental mechanisms.

A real-time database usually requires maintaining a great quantities of temporal data items whose values remain valid only within their validity interval. Each data item in the database models the current status of a physical real-world entity. The freshness of these temporal data items is maintained by update transactions that need to be executed within their deadlines. In this paper, we propose a model-based data freshness management approach consisting of a model for expressing data freshness requirements. This approach is based on the TIME package of MARTE (Modeling and Analysis of Real-Time and Embedded systems) profile which provides capabilities of modeling concepts to deal with real-time and embedded systems features.

Real-time databases are different from conventional databases in that they have timing constraints on data and on transactions upon the data. The timing constraints of data require that the current status of the real world must be close enough to the state represented by the contents of the database. The timing constraints of transactions are typically expressed in the form of deadline which indicates a certain time in the future by which a transaction must be completed. Conventional data models can not be directly applied to describe the conceptual data model of a real-time database, since there is no mechanism to deal with the representation of timing constraints. A real-time data model should simultaneously satisfy many goals. It should clearly and concisely provide support for specifying timing constraints on data and transactions, semantics of real-time data and real-time transactions, concurrency control mechanisms, and transactions scheduling policies to meet the timing constraints defined by the real-time applications. This paper presents a real-time object-oriented data model and its use in designing real-time extensions to the DB4O database management system. This data model supports expression of time-constrained data, time-constrained transactions, concurrency control mechanisms, and transactions scheduling policies. It also can be integrated easily in existing object-oriented method and permits automatic code generation of all the real-time code of an application.

A real-time database is a database in which both the data and the operations upon the data may have timing constraints. The design of this kind of database must consider both temporal aspects of data and timing constraint of transactions. This paper proposes a new UML profile that extends UML with concepts related to real-time databases design. These extensions aim to accomplish the conceptual modeling of a real-time database. Our propositions is based on the HLAM (High Level Application Modeling) and NFPs (Non-Functional Properties) packages of MARTE (Modeling and Analysis of Real-Time and Embedded systems), which provides capabilities of modeling concepts to deal with real-time and embedded system features, in order to benefit from some concepts that we consider suited for real-time databases design. The proposed profile is illustrated by a case study in the context of Intelligent Transport System.

The design of real-time databases needs to incorporate methods specifically developed to represent the timing constraints of the system under consideration. Real-time databases have timing constraints on data and on transactions upon the data. During the last few years, several research approaches have been directed towards using the relational model as a data model for real-time databases. However, neither approach adds a temporal dimension to the data model. As realtime applications complexity grows, the real-time database community migrated towards object-oriented technology, both because one can use its rich data semantics in timing transactions processing and because complex real-time applications may benefit from its capabilities for modeling, storing and manipulating complex objects. In this paper we explore the realtime object-oriented data models for real-time databases, performing an overview of the existing models and presenting a set of features suitable to evaluate the quality of each model.

In recent years search for proper extensions of the object model to suit real-time database community has become a critical research issue. In this paper, we present such an extension of the object model, called RTO-RTDB. A concrete static and dynamic views of the model are presented. A major attraction of this model is in that it is effective not only in the use of the feedback control real-time scheduling theory but also in the accurate representation of realtime databases properties. It is used to demonstrate how to separate structural and concurrency concerns ensuring also high-level abstraction for parallelism modeling. In order to improve and to facilitate the RTO-RTDB object model specification, we have used the MARTE and UML-RTDB profiles as UML extensions to describe real-time aspects on one hand, and to express real-time database features on the other hand.

The object model is very promising for real-time applications that must handle complex real-world objects with short deadlines due to its capabilities for modeling, storing, and manipulating complex objects. However, real-time databases require tight control and, particularly, they need to take into account temporal aspects of data and timing constraints on transactions. This paper is about the application of the object-oriented technology to model complex objects in the context of real-time databases. It suggests a real-time object model that incorporates time-constrained data, timeconstrained transactions, and concurrency control mechanisms. This model can be integrated easily in existed object oriented method and permits automatic code generation of all the realtime code of an application.