Radosław Adamus

Object-Oriented wrapper for relational databases in the data grid architecture

The paper presents a solution of the problem of wrapping relational databases to an object-oriented business model in the data grid architecture. The main problem with this kind of wrappers is how to utilize the native SQL query optimizer, which in majority of RDBMS is transparent for the users. In our solution we use the stack-based approach to query languages, its query language SBQL, updateable object-oriented virtual views and the query modification technique. The architecture rewrites the front-end OO query to a semantically equivalent back-end query addressing the M0 object model that is 1:1 compatible with the relational model. Then, in the resulting SBQL query the wrapper looks for patterns that correspond to optimizable SQL queries. Such patterns are then substituted by dynamic SQL execute immediately statements. The method is illustrated by a sufficiently sophisticated example. The method is currently being implemented within the prototype OO server ODRA devoted to Web and grid applications.

Virtual Repository Supporting Integration of Pluginable Resources

The paper describes a dynamic integration mechanism for a virtual repository that transparently integrates distributed, heterogeneous and redundant resources. The repository is based on combination of a P2P network, object-oriented databases, a query language SBQL and virtual updateable views defined and used in SBQL. It is currently implemented as a prototype under .NET in C#. We also discuss a solution for an independent virtual P2P network integrating resources stored in databases and a novel global index mechanism

Autonomous layer for data integration in a virtual repository

The paper describes a self-operating integration mechanism for virtual repositorys distributed resources based on object-oriented databases in a grid architecture The core architecture is based on the SBA theory and its virtual updateable views Our virtual repository transparently processes heterogeneous data producing conceptually and semantically coherent results Our integration apparatus is explained by two examples with different types of fragmentations – horizontal and vertical A transparent integration process exploits a global index mechanism and an independent virtual P2P network for a communication between distributed databases Researches presented in the paper are based on a prototype integrator which is currently under development.

A generic proposal for a transparent integration of distributed data by an autonomous layer in a virtual repository

The article describes a solution to a problem of integration of distributed, heterogeneous and variously fragmented collections of data located in object-oriented databases. Basing on their investigation, authors present three methods of integration procedures for differently structured databases constituting virtual repositories in a data grid with a P2P architecture. The core of the described architecture is based on the Stack-Based Query Language (SBQL) and virtual updatable SBQL views. In the background, the system is based on a P2P architecture for data transporting and indexing. The article provides three short examples on how to apply the proposal in virtual repository. The procedures are implemented under the integrator prototype.

Tier aspect model based on updatable views

The tier aspect model addresses Aspect Oriented Programming (AOP) in the context of database applications. It is a new technique of separation of concerns through tiers implemented as virtual object-oriented updatable views. The code of an aspect related to particular objects is encapsulated within a separate view that overrides all generic operations performed on the objects. Aspect tiers form a chain of views. Such additional codes can do any extra action e.g. security, licensing, integrity constraints, monitoring and others. The idea is based on the Stack-Based Approach to object-oriented query languages and the novel idea of virtual updatable views.

Security Management Through Overloading Views

The model of overloading views is a facility allowing the programmer to separate some kinds of crosscutting concerns that occur during design, implementation and maintenance of database applications. In this paper we show how it can be used to manage data security. The model is based on updateable object views built within the stack-based approach to object-oriented query languages. After inserting the overloading view on top of the given population of objects all references to the objects come via the view. Thus the view can implement additional security semantics independently on the object implementation. Views allow one to add such new semantic to all the operations (retrieve, insert, update, delete) that can be performed on the objects. In our model overloading views are named encapsulated database entities that can be dynamically inserted, modified or deleted. Because virtual objects delivered by an overloading view are not distinguishable from stored objects, the overloading views model allows one to form a chain of views, where each next view adds new semantics (a specific concern) to the semantics introduces by the object implementation and previous views. In this way any new security requirement can be implemented independently from other requirements.

GENERIC APPROACH TO AUTOMATIC INDEX UPDATING IN OODBMS

In this paper, we describe a robust approach to the problem of the automatic index updating, i.e. maintaining cohesion between data and indices. Introducing object-oriented notions (classes, inheritance, polymorphism, class methods, etc.) in databases allows defining more complex selection predicates; nevertheless, in order to facilitate selection process through indices, index updating requires substantial revising. Inadequate index maintenance can lead to serious errors in query processing what has been shown on the example of Oracle 11g ORDBMS. The authors work is based on the Stack-Based Architecture (SBA) and has been implemented and tested in the ODRA (Object Database for Rapid Applications development) OODBMS prototype.

Relational to object-oriented database wrapper solution in the data grid architecture with query optimisation issues

This paper introduces a solution to the problem of integrating relational databases with the data grid architecture and presenting their contents as a purely object-oriented business model. It describes a dedicated wrapper constructed with the Stack-Based Approach (SBA) and updatable views concepts. The proposed architecture sustains the grids transparency and allows a grid user to operate in an object-oriented environment with SBQL the stack-based query language. The strength of the described wrapper is a possibility of employment of native SQL optimisers. A query entering the front-end of the wrapper (object-oriented business model) can be rewritten according to the powerful SBQL optimisation rules (within the wrapper) and then evaluated in the relational resource environment where appropriate SQL optimisers apply. This paper contains a description of the wrapper and its place in the grid architecture with a query optimisation procedure and an example of such a process.

Mapping SBQL Query Results to XML

Abstract The following paper presents a solution resolving inconsistencies in processing XML data-structures with SBQL objectoriented query and programming language. SBQL is based on Stack-Based Architecture (SBA) a formal approach reconstructing query languages’ concepts from the point of view of programming languages (Pls). The basic data store model AS0 defined in SBA can describe complex hierarchical data structures implied by XML. Nevertheless, in the classical approach to processing XML some use-case scenarios cannot be solved in satisfactory manner. In such cases SBQL queries return results either typologically obscure from the point of view of SBA or invalid from the point of view of expected XML tags formatting. The paper illustrates this problem on comprehensive examples, presents its cause and the solution.

Implementation of updateable object views in the ODRA OODBMS

The paper describes results of the research effort related to the implementation of the idea of Updateable Object Views for the ODRA project. ODRA (Object Database for Rapid Application development) is a prototype object-oriented database management system based on Stack Based Architecture (SBA) and Stack Based Query Language (SBQL). The updateable object views are one of the main features of the system that has great impact on its features. The paper focuses on the issues connected with views implementation related to external type system and optimization module.