Building object oriented applications which access relational data introduces a number of technical issues for developers who are making the transition to C++. We describe these issues and discuss how we have addressed them in Persistence, an application development tool that uses an automatic code generator to merge C++ applications with relational data. We use client-side caching to provide the application program with efficient access to the data. 1. INTERFACING C++ CLASSES WITH RELATIONAL DATA Object orientation promises dramatic benefits in software productivity, quality and reusability. Yet as with most technology innovations, it requires a significant break from the development practices of the past. Specifically, the difficulty of integrating objects with relational databases has emerged as a major barrier to adoption of object technology by developers who have a significant existing base of hierarchical or relational data. Today, C++ developers have to hand code an interface...

This paper presents an approach for architecting OO applications for high performance with relational databases. The key ideas of this approach are:

. The relational model supports the view concept, but relational views are limited in structure. OODBMSs do not support the view concept, so that all applications must share the same arrangement of object classes and inheritance. We describe the Penguin system and its support for the view concept. Each application can have its own arrangement of object classes and inheritance, and these are defined as views of an integrated, normalized conceptual data model, in our case the Structural Model. We define view-objects in a language-independent manner on top of the conceptual data model. These view-objects can be complex objects supporting a composite structure. We discuss the extension of Penguin to support PART-OF (reference) and IS-A graphs for composite view-objects. We also discuss the C++ binding to Penguin, where C++ code is generated for object classes corresponding to the view-objects along with basic operations on them (creation, query, navigate, browsing, and update). 1 Introduct...

We describe a two-level client-side cache for composite objects mapped as views of a relational database. A semantic model, the Structural Model, is used to specify joins on the relational database that are useful for defining composite objects. The lower level of the cache contains the tuples from each relation that have already been loaded into memory. These tuples are linked together from relation to relation according to the joins of the structural model. This level of the cache is shared among all applications using the data on this client. The higher level of the cache contains composed objects of data extracted from the lower level cache. This level of the cache uses the object schema of a single application, and the data is copied from the lower level cache for convenient access by the application. This two-level cache is designed as part of the Penguin system, which supports multiple applications, each with its own object schema, to share data stored in a common relational dat...

Research and products for the integration of heterogeneous legacy source databases in data warehousing have addressed numerous data quality problems in or between the sources. Such a solution is marketed by Team4 for the decision support of mobile sales representatives, using advanced view maintenance and replication management techniques in an environment based on relational data warehouse technology and Lotus Notes-based client systems. However, considering total information supply chain management, the capture of poor operational data, to be cleaned later in the data warehouse, appears sub-optimal. Based on the observation that decision support clients are often closely linked to operational data entry, we have addressed the problem of mapping the data warehouse data quality techniques back to data quality measures for improving OLTP data. The solution requires a warehouse-to-OLTP workflow which employs a combination of view maintenance and view update techniques. 1 Introduction T...

Lately, a need to integrate specialized data management systems such as geographic information systems (GIS), or multimedia systems has gained importance [6]. A large variety of different data sets are available in various specialized repositories, and users would like to access and manipulate these data sets in a uniform way. Additionally, it is desirable to make the specialized functionality provided by the individual repositories available to the user application through a homogeneous interface. At UCLA Data Mining Laboratory, we are developing geoPOM (geoscientific Persistent Object Manager), a heterogeneous geoscientific object system which provides a homogeneous interface to heterogeneous spatial data repositories [20]. geoPOM provides an object-oriented spatial data model for the definition of user-defined spatial object types. Internally, geoPOM maps user-defined spatial object types to different specialized spatial data repositories, and employs their storage, search and spat...

Lately, a need for uniform access to and integration of data stored in specialized, non-standard repositories such as GIS or multimedia storage servers has become apparent. In this paper, we provide an overview of a heterogeneous geoscientific persistent object manager (geoPOM) developed at the UCLA Data Mining Laboratory. GeoPOM provides users with the “illusion ” of a single object-oriented spatial data store even though the data is actually stored in several different spatial data repositories, thus, allowing users to define and handle spatial data in a uniform manner. The geoPOM data model is based on the ODMG-93 standard for object-oriented data models, and the Open Geodata Consortium’s (OGC) standardization effort for temporal-spatial object types (OGIS). 1

I authorize the University of Waterloo to lend this thesis to other institutions or individuals for the purpose of scholarly research. I further authorize the University of Waterloo to reproduce this thesis by photocopying or by other means, in total or in part, at the request of other institutions or individuals for the purpose of scholarly research. iii The University of Waterloo requires the signatures of all persons using or photocopying this thesis. Please sign below, and give address and date. Functional dependency analysis can be applied to various problems in query optimization: selectivity estimation, estimation of (intermediate) result sizes, order optimization (in particular sort avoidance), cost estimation, and various problems in the area of semantic query optimization. Dependency analysis in an ansi sql relational model, however, is made complex due to the existence of null values, three-valued logic, outer joins, and duplicate rows. In this thesis we define the notions of strict and lax functional dependencies, strict and lax equivalence constraints, and null constraints, which capture both a

juliano,luketucker¤ A great deal of corporate data is buried in network devices — such as PBX messaging/email platforms, and data networking equipment — where it is difficult to access and modify. Typically, the data is only available to the device itself for its internal purposes and it must be administered using either a proprietary interface or a standard protocol against a proprietary schema. This leads to many problems, most notably: the need for data replication and difficult interoperation with other devices and applications. MetaComm addresses these problems by providing a framework to integrate data from multiple devices into a metadirectory. The system allows user information to be modified through a directory using the LDAP protocol as well as directly through two legacy devices: a Definity R and a voice messaging system. In order to prevent data inconsistencies, updates to any system must be reflected appropriately in all systems. This paper describes how MetaComm maintains consistency when data integration is performed across several systems with no triggers and with extremely weak typing and transactional support. We also discuss implementation details and experiences.

Abstract. When a database view is to be updated, there are generally many choices for the new state of the main schema. One way of characterizing the best such choice is to minimize the distance between the old state of the main schema and the new one. In recent work, a means of representing such distance based upon semantics was forwarded in which the distance between two states is measured by the the difference of information between the two, with the information of a state defined as the set of sentences from a particular set which hold on that state. This approach proved to be highly useful in identifying optimal reflections of insertions and to a lesser extent deletions, provided that the reflections were themselves insertions or deletions. In this work, that investigation is extended to bidirectional view updates – those which involve both insertion and deletion. It is shown that the definition of distance must be crafted more carefully in such situations. Upon so doing, a result is obtained which provides update reflections which are information optimal for insertion and deletion optimal with respect to tuples but not necessarily information. 1