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From beginning of 1994 to the end of 1996, the IRO-DB ESPRIT project has developed tools for accessing in an integrated way relational and object-oriented databases, and for designing and maintaining integrated applications on large federations of heterogeneous databases. IRO-DB is based on the ODMG pivot object model and gives OQL/OML C++ interfac...
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... The IRO-DB (Interoperable Relational and Object Databases) [38] project developed a set of tools to achieve interoperability of pre-existing relational databases and new object-oriented databases. One of the main goals of the project was the provision of a path for integrating the relational database technology to object-oriented database technology. ...
Data integration requires managing heterogeneous schema information. A federated database system integrates heterogeneous, autonomous database systems on the schema level, whereby both local applications and global applications accessing multiple component database systems are supported. Such a federated database system is a complex system of systems which requires a well-designed organization at the system and software architecture level. A specific challenge that federated database systems face is the organization of schemas into a schema architecture. This paper provides a detailed, formal investigation of variability in the family of schema architectures, which are central components in the architecture of federated database systems. It is shown how the variability of specific architectures can be compared to the reference architecture and to each other. To achieve this, we combine the semi-formal object-oriented modeling language UML with the formal object-oriented specification language Object-Z. Appropriate use of inheritance in the formal specification, as enabled by Object-Z, greatly supports specifying and analyzing the variability among the studied schema architectures. The investigation also serves to illustrate the employed specification techniques for analyzing and comparing software architecture specifications.
... This approach has been motivated by views in object-oriented data models, which can be dated back to [10], and in particular by imaginary objects in [2]. [14] discussed federated OODBMS and views for objects in a distributed environment. [23] presented an algorithm for workflow view construction and verification, but does not discuss any of its applications. ...
Workflow technology has recently been employed not only within businesses but also as a framework for implementing services over the Internet. With the advancement and spreading of various mobile technologies and infrastructures, there is increasing demand for mobile users to connect to workflow management systems (WFMS). The basic requirement is to support SMS, WAP and web browsers on PDAs, in addition to regular web browsers on PCs. As the capabilities and bandwidth of these mobile devices are significantly inferior to computers over regular Internet connections, workflows have to be adapted to accommodate these limitations. Instead of redesigning or adapting workflows in an ad-hoc manner for different kinds of platforms, we propose a framework of workflow adaptation for mobile users based on three tiers of views: user interface views, data views and workflow views. User interface views provide alternative presentations of inputs and outputs. Data views summarize data over limited bandwidth and display them in different forms. Furthermore, we introduce a novel approach of applying workflow views to mobile workflow adaptation, where mobile users may execute a more concise version or modified procedures of a business process. The workflow view also serves as the centric mechanism for integrating user interface views and data views. We demonstrate the feasibility of our approach by extending a flexible web-based WFMS E-ADOME into ME-ADOME. The concepts are illustrated with a workflow of procurement approval.
... IV. M-SERVICE ADAPTATION WITH PROCESS VIEWS Motivated by views in federated object databases [26], we propose the use of process views as a fundamental mechanism for flexible m-service adaptation. A process view is a structurally correct subset of a process definition derived from a base process (as defined in [17], [28]). ...
With recent advances in mobile technologies and infrastructures, there are increasing demands for ubiquitous access to networked services. These services, generally known as m-services, extend supports from Web browsers on personal computers to handheld devices, such as mobile phones and PDAs. However, in general, the capabilities and bandwidth of these devices are significantly inferior to desktop computers over wired connections, which have been assumed by most Internet services. Instead of redesigning or adapting m-services in an ad-hoc manner for multiple platforms available in handheld devices, we propose a methodology for such adaptation based on three tiers: user interface views, data views, and process views. These views provide customization and help balance security and trust. User interface views provide alternative presentations of inputs and outputs. Data views summarize data over limited bandwidth and map heterogeneous data sources. In addition, we introduce a novel approach of applying process views to m-service adaptation, where mobile users may execute a more concise version or modified procedures of the original process. The process view also serves as the key mechanism for integrating user interface views and data views. In addition, we present a formal model on view consistency and integrity in our methodology. We demonstrate the feasibility of our methodology by extending a service negotiation subsystem into an m-service with multi-platform support.
... Most research on multidatabase systems has primarily been performed in the context of multiple relational database systems [5,41,52,56]. Only a few research projects, such as IRO-DB and METU [13,22] have been developed to address query techniques for the retrieval of data from heterogeneous database systems (e.g., relational and object-oriented data sources). Even within the domain of multiple relational databases, issues such as vertical fragmentation have been largely ignored. ...
... Another characteristic of previous multidatabase work is that most of what is reported in the literature is defined in terms of the relational data model [5,41,52,56]. More recent work supports the use of an object-oriented canonical data model in multidatabases [6,22,43] due to extended modeling capabilities such as encapsulation, inheritance, coupling and modular extension. In object-oriented (OO) multidatabase systems, it is possible to integrate a wider range of local components by providing an OO wrapper for each data source involved. ...
This paper presents an approach to query decomposition in a multidatabase environment. The unique aspect of this approach is that it is based on performing transformations over an object algebra that can be used as the basis for a global query language. In the paper, we first present our multidatabase environment and semantic framework, where a global conceptual schema based on the Object Data Management Group standard encompasses the information from heterogeneous data sources that include relational databases as well as object-oriented databases and flat file sources. The meta-data about the global schema is enhanced with information about virtual classes as well as virtual relationships and inheritance hierarchies that exist between multiple sources. The AQUA object algebra is used as the formal foundation for manipulation of the query expression over the multidatabase. AQUA is enhanced with distribution operators for dealing with data distribution issues. During query decomposition we perform an extensive analysis of traversals for path expressions that involve virtual relationships and hierarchies for access to several heterogeneous sources. The distribution operators defined in algebraic terms enhance the global algebra expression with semantic information about the structure, distribution, and localization of the data sources relevant to the solution of the query. By using an object algebra as the basis for query processing, we are able to define algebraic transformations and exploit rewriting techniques during the decomposition phase. Our use of an object algebra also provides a formal and uniform representation for dealing with an object-oriented approach to multidatabase query processing. As part of our query processing discussion, we include an overview of a global object identification approach for relating semantically equivalent objects from diverse data sources, illustrating how knowledge about global object identity is used in the decomposition and assembly processes.
... While the concept of workflow view is novel, our approach has been motivated by views in object-oriented data models which can be dated back to [8], and in particular by imaginary objects in [1]. [10] discusses federated OODBMS and views for objects in a distributed environment. Dartflow [2] is one of the first web-based WFMS, using transportable agents, CGI and Java technologies. ...
In an e-service environment, workflow involves not only a single organization but also a number of business partners. Workflow interoperability is therefore an important issue for workflow enactment in such an environment. In this paper, we introduce a novel concept of workflow views as a fundamental support for E-service workflow inter-operability and for controlled visibility by external parties. Furthermore, we develop a contract model based on workflow views and demonstrate how management of contracts can be facilitated, with an Internet start-up E-service inter-organization workflow example.
... While the concept of workflow view is novel, our approach has been motivated by views in object-oriented data models which can be dated back to [DayaI89], and in particular by imaginary objects in [Abitebou191]. [Gardarin97] discusses federated OODBMS and views for objects in a distributed environment. On the other hand, it is a relatively new approach to E-commerce / E-service enactment based on an advanced WFMS engine. ...
In an e-commerce or e-service environment, workflow involves not only a single organization but also a number of business partners. Workflow inter- operability is therefore an important issue for workflow enactment in such an environment. In this paper, we propose the use of workflow views as a fundamental support for workflow inter-operability and for visibility by external parties. We present taxonomy of workflow views, discuss various components of a workflow view, and their semantics with example usage. We also demonstrate how contracts can be facilitated with a supply-chain example.
... In this paper, we present an object-oriented view concept and its implementation complying with the ODMG-93 standard for object-oriented databases [Cat96]. It has been developed for database integration in the ESPRIT-III project IRO-DB [GFF97]. We follow the objectgenerating view approach, where view classes are populated with newly generated objects. ...
... Query processor and language binding can work independently from each other or can interact via the object manager. Additional modules of the IRO-DB system, like Transaction Manager, Security Manager, and Communication Layer are described in [GFF97]. ...
One major approach to realise database integration is to adapt and merge the database schemas by defining views. When integrating object-oriented databases, views need to adequately support the two main concepts of object-oriented data models: object identity and methods. View objects need to be identified on the basis of the objects they have been derived from. Methods require an efficient language binding and need to be substituted by declarative query mappings where possible. In this paper we present a view system that supports both declarative and procedural integration of object-oriented databases. We have extended the object definition language ODL of ODMG-93 and use simple OQL queries for instantiating the extents of derived classes and for performing simple attribute derivations. In addition, methods can be attached to view objects in order to provide more complex view semantics. A pre-processor is employed for consistently generating the declarative and the procedural parts fr...
... In this paper, we present an object-oriented view concept and its implementation complying with the ODMG-93 standard for object-oriented databases [Cat96]. It has been developed for database integration in the ESPRIT-III project IRO-DB [GFF97]. We follow the objectgenerating view approach, where view classes are populated with newly generated objects. ...
... Query processor and language binding can work independently from each other or can interact via the object manager. Additional modules of the IRO-DB system, like Transaction Manager, Security Manager, and Communication Layer are described in [GFF97]. ...
One major approach to realise database integration is to adapt and merge the database schemas by defining views. When integrating object-oriented databases, the views need to adequately support object identity and methods. View objects need to be identified on the basis of the objects they have been derived from. Methods must be callable from the query processor without impeding query optimisation. Our view system for ODMG-93 supports both declarative and procedural integration of object-oriented databases. It provides flexible integration semantics without sacrificing the optimisation potential. 1. Introduction Views are a powerful means to integrate heterogeneous databases. They serve to identify overlapping or related portions from several databases, and to overcome modelling differences in naming, scaling, structure, and semantics between the identified portions. Thereby applications can access heterogeneous databases like a single, integrated one. When integrating object-orient...
... Unsere Architektur (Abbildung 1)ähnelt der klassischen 3-tier Wrapper-Mediator-Architektur [24], die heute weit verbreitet ist und in einer Vielzahl von Papieren beschrieben wird (z.B. [14], [7], [5], [8]). Im Unterschied zur Wrapper-Mediator-Architektur wird in unserem System jedoch die Trennung in eine zu-griffsorientierte Wrapperschicht und eine darauf aufsetzende Mediatorlogik aufgegeben. ...
... Für klassische Datenbanksysteme wurden in [4] der Begriff des föderierten Datenbanksystems geprägt und verschiedene Grade der Koppelung solcher Datenbanksysteme eingeführt. Die klassische Architektur wurde erfolgreich in einer Vielzahl von Projekten mit unterschiedlichem Schwerpunkt angewandt (z.B. [14], [7], [5], [8]) und wird mittlerweile auch von industriellen Systemen eingesetzt. Für die Integration heterogener WWW-Informationsdienste, mit ihren limitierten Anfragemöglichkeiten [3], den nur teilweise strukturierten Daten [12], dem hohen Grad an Autonomie und der schieren Anzahl von Quellen hat sich jedoch gezeigt, daß die klassische Mediator-Architektur zu unflexibel ist und nicht skaliert [15]. ...
Die klassische 2-stuge Wrapper-Mediator-Architektur zur Koppelung heterogener Informationssysteme skaliert nicht fur das World Wide Web. Menge, Komplexitat, und hauge Ande- rung von WWW-Informationsdiensten erfordern exiblere Archi- tekturen. In diesem Papier stellen wir einen kompositionalen, oe- nen Ansatz zur modularen Koppelung heterogener WWW-Informa- tionsdienste vor. Grundlage des Ansatzes sind Dataows. Da- taows werden als gemeinsame Abstraktion f
... In this paper, we present an object-oriented view concept and its implementation complying with the ODMG-93 standard for object-oriented databases [Cat96]. It has been developed for database integration in the ESPRIT-III project IRO-DB [GFF97]. We follow the objectgenerating view approach, where view classes are populated with newly generated objects. ...
... Query processor and language binding can work independently from each other or can interact via the object manager. Additional modules of the IRO-DB system, like Transaction Manager, Security Manager, and Communication Layer are described in [GFF97]. ...
One major approach to realise database integration is to adapt and merge the database schemas by defining views. When integrating object-oriented databases, views need to adequately support the two main concepts of object-oriented data models: object identity and methods. View objects need to be identified on the basis of the objects they have been derived from. Methods require an efficient language binding and need to be substituted by declarative query mappings where possible. In this paper we present a view system that supports both declarative and procedural integration of object-oriented databases. We have extended the object definition language ODL of ODMG-93 and use simple OQL queries for instantiating the extents of derived classes and for performing simple attribute derivations. In addition, methods can be attached to view objects in order to provide more complex view semantics. A pre-processor is employed for consistently generating the declarative and the procedural parts fr...
