Jean-marie Legoff - Academia.edu (original) (raw)

Papers by Jean-marie Legoff

The CRISTAL (Cooperating Repositories and an Information System for Tracking Assembly Lifecycles)... more The CRISTAL (Cooperating Repositories and an Information System for Tracking Assembly Lifecycles) project is delivering a software system to facilitate the management of the engineering data collected at each stage of production of CMS. CRISTAL captures all the physical characteristics of CMS components as each sub-detector is tested and assembled. These data are retained for later use in areas such as detector slow control, calibration and maintenance. CRISTAL must, therefore, support different views onto its data dependent on the role of the user. These data viewpoints are investigated in this paper. In the recent past two CMS Notes have been written about CRISTAL. The first note, CMS 1996/003, detailed the requirements for CRISTAL, its relationship to other CMS software, its objectives and reviewed the technology on which it would be based. CMS 1997/104 explained some important design concepts on which CRISTAL is and showed how CRISTAL integrated the domains of product data man- ...

Interoperability of potentially heterogeneous databases has been an ongoing research issue for a ... more Interoperability of potentially heterogeneous databases has been an ongoing research issue for a number of years in the database community. With the trend towards globalization of data location and data access and the consequent requirement for the coexistence of new data stores with legacy systems, the cooperation and data interchange between data repositories has become increasingly important. The emergence of the eXtensible Markup Language (XML) as a database independent representation for data offers a suitable mechanism for transporting data between repositories. This paper describes a research activity within a group at CERN (called CMS) towards identifying and implementing database serialization and deserialization methods that can be used to replicate or migrate objects across the network between CERN and worldwide centres using XML to serialize the contents of multiple objects resident in object-oriented databases.

Software and Systems Modeling, 2003

One of the main factors driving objectoriented software development for information systems is th... more One of the main factors driving objectoriented software development for information systems is the requirement for systems to be tolerant to change. To address this issue in designing systems, this paper proposes a pattern-based, object-oriented, descriptiondriven system (DDS) architecture as an extension to the standard UML four-layer meta-model. A DDS architecture is proposed in which aspects of both static and dynamic systems behavior can be captured via descriptive models and meta-models. The proposed architecture embodies four main elements-firstly, the adoption of a multi-layered meta-modeling architecture and reflective meta-level architecture, secondly the identification of four data modeling relationships that can be made explicit such that they can be modified dynamically, thirdly the identification of five design patterns which have emerged from practice and have proved essential in providing reusable building blocks for data management, and fourthly the encoding of the structural properties of the five design patterns by means of one fundamental pattern, the Graph pattern. A practical example of this philosophy, the CRISTAL project, is used to demonstrate the use of description-driven data objects to handle system evolution.

Multimedia Tools and Applications

Highlighting important information of a network is commonly achieved by using random walks relate... more Highlighting important information of a network is commonly achieved by using random walks related to diffusion over such structures. Complex networks, where entities can have multiple relationships, call for a modeling based on hypergraphs. But, the limitation of hypergraphs to binary entities in co-occurrences has led us to introduce a new mathematical structure called hyperbaggraphs, that relies on multisets. This is not only a shift in the designation but a real change of mathematical structure, with a new underlying algebra. Diffusion processes commonly start with a stroke at one vertex and diffuse over the network. In the original conference article-(Ouvrard et al. 2018)-that this article extends we have proposed a two-phase step exchange-based diffusion scheme, in the continuum of spectral network analysis approaches, that takes into account the multiplicities of entities. This diffusion scheme allows to highlight information not only at the level of the vertices but also at the regrouping level. In this paper, we present new contributions: the proofs of conservation and convergence of the extracted sequences of the diffusion process, as well as the illustration of the speed of convergence and comparison between classical and modified random walks; the algorithms of the exchange-based diffusion and the modified random walk; the application to two use cases, one based on Arxiv publications and another based on Coco dataset images. All the figures have been revisited in this extended version to take the new developments into account.

Information Systems, 2014

Software engineers frequently face the challenge of developing systems whose requirements are lik... more Software engineers frequently face the challenge of developing systems whose requirements are likely to change in order to adapt to organizational reconfigurations or other external pressures. Evolving requirements present difficulties, especially in environments in which business agility demands shorter development times and responsive prototyping. This paper uses a study from CERN in Geneva to address these research questions by employing a 'description-driven' approach that is responsive to changes in user requirements and that facilitates dynamic system reconfiguration. The study describes how handling descriptions of objects in practice alongside their instances (making the objects self-describing) can mediate the effects of evolving user requirements on system development. This paper reports on and draws lessons from the practical use of a description-driven system over time. It also identifies lessons that can be learned from adopting such a self-describing description-driven approach in future software development.

In the web age systems must be flexible, reconfigurable and adaptable in addition to being quick ... more In the web age systems must be flexible, reconfigurable and adaptable in addition to being quick to develop. As a consequence, designing systems to cater for change is becoming not only desirable but required by industry. Allowing systems to be self-describing or description-driven is one way to enable these characteristics. To address the issue of evolvability in designing self-describing systems, this paper proposes a pattern-based, objectoriented, description-driven architecture. The proposed architecture embodies four pillars-first, the adoption of a multi-layered meta-modeling architecture and reflective meta-level architecture, second, the identification of four data modeling relationships that must be made explicit such that they can be examined and modified dynamically, third, the identification of five design patterns which have emerged from practice and have proved essential in providing reusable building blocks for data management, and fourth, the encoding of the structural properties of the five design patterns by means of one pattern, the Graph pattern. In this paper the fundamentals of the description-driven architecture are described-the multi-layered architecture and reflective meta-level architecture, remaining detail can be found in the cited references. A practical example of this architecture is described, demonstrating the use of description-driven data objects in handling system evolution.

In this paper, we propose a schema versioning mechanism to manage the schema evolution in tempora... more In this paper, we propose a schema versioning mechanism to manage the schema evolution in temporal object-oriented databases. The schema evolution management uses an object-oriented data model that supports temporal features and versions definition-the Temporal Versions Model-TVM. One interesting feature of our proposal is that TVM is used to control not only the schema versioning, but also the storage of extensional database and propagation of the changes performed on the objects. The extensional data level supports integration with the existing database, allowing the maintenance of conventional and temporal versioned objects. The instance propagation approach is proposed through the specification of propagation and conversion functions. These functions assure the correct instance propagation and allow the user to handle all instances consistently in both backward and forward schema versions. Finally, the initial requirements concerning data management in the temporal versioning environment, during schema evolution, are presented.

In data modelling, product information has most often been handled separately from process inform... more In data modelling, product information has most often been handled separately from process information. The integration of product and process models in a unified data model could provide the means by which information could be shared across an enterprise throughout the system lifecycle from design through to production. Recently attempts have been made to integrate these two separate views of systems through identifying common data models. This paper relates description-driven systems to multi-layer architectures and reveals where existing design patterns facilitate the integration of product and process models and where patterns are missing or where existing patterns require enrichment for this integration. It reports on the construction of a so-called description-driven system which integrates Product Data Management (PDM) and Workflow Management (WfM) data models through a common meta-model.

One of the main drivers in object-oriented design for information systems is the need for the reu... more One of the main drivers in object-oriented design for information systems is the need for the reuse of design artifacts in handling systems evolution. To be able to cope with change, systems must have the capability of reuse and to adapt as and when necessary to changes in requirements. To address the issues of reuse in designing evolvable systems, this

Optimising use of the Web (WWW) for LHC data analysis is a complex problem and illustrates the ch... more Optimising use of the Web (WWW) for LHC data analysis is a complex problem and illustrates the challenges arising from the integration of and computation across massive amounts of information distributed worldwide. Finding the right piece of information can, at times, be extremely time-consuming, if not impossible. So-called Grids have been proposed to facilitate LHC computing and many groups have embarked on studies of data replication, data migration and networking philosophies. Other aspects such as the role of 'middleware' for Grids are emerging as requiring research. This paper positions the need for appropriate middleware that enables users to resolve physics queries across massive data sets. It identifies the role of meta-data for query resolution and the importance of Information Grids for high-energy physics analysis rather than just Computational or Data Grids. This paper identifies software that is being implemented at CERN to enable the querying of very large collaborating HEP data-sets, initially being employed for the construction of CMS detectors.

Traditionally product data and their evolving definitions, have been handled separately from proc... more Traditionally product data and their evolving definitions, have been handled separately from process data and their evolving definitions. There is little or no overlap between these two views of systems even though product and process data arc inextricably linked over the complete software lifecycle from design to production. The integration of product and process models in an unified data model

Abstract The Compact Muon Solenoid (CMS) high energy physics experiment will comprise several lar... more Abstract The Compact Muon Solenoid (CMS) high energy physics experiment will comprise several large high resolution detectors each of which will be constructed out of over a million precision parts and will be produced and assembled during the next decade by ...

The construction process of detectors for the Large Hadron Collider (LHC) experiments is large sc... more The construction process of detectors for the Large Hadron Collider (LHC) experiments is large scale, heavily constrained by resource availability and evolves with time. As a consequence, changes in detector component design need to be tracked and quickly reflected in the construction process. With similar problems in industry engineers employ so-called Product Data Management (PDM) systems to control access to documented versions of designs and managers employ so-called Workflow Management software (WfMS) to coordinate production work processes. However, PDM and WfMS software are not generally integrated in industry. The scale of LHC experiments, like CMS, demands that industrial production techniques be applied in detector construction. This paper outlines the major functions and applications of the CRISTAL system (Cooperating Repositories and an Information System for Tracking Assembly Lifecycles) in use in CMS which successfully integrates PDM and WfMS techniques in managing large scale physics detector construction. This is the first time industrial production techniques have been deployed to this extent in detector construction.

... or duplication arc clcl'crrcd 10 the fi)llowing scction of this papcr. I n the lirst pha... more ... or duplication arc clcl'crrcd 10 the fi)llowing scction of this papcr. I n the lirst phase of prototypingCRISTAL has used the 0 2 TM product. Presently 0 2 is hascd on coinpiled C++ or C and thcrclorc the codc is not directly portable I'rom one inachinc to another. ...

... data warehouse. The meta-model approach to design reduces system complexity, provides model f... more ... data warehouse. The meta-model approach to design reduces system complexity, provides model flexibility and can integrate multiple, potentially heterogeneous, databases into the enterprise-wide data warehouse. A first prototype ...

As enterprises, data and functions become increasingly complex and distributed the need for infor... more As enterprises, data and functions become increasingly complex and distributed the need for information systems to be both customisable and interoperable also increases. Large scale engineering and scientific projects demand flexibility in order to evolve over time and to interact with external systems (both newly designed and legacy in nature) while retaining a degree of conceptual simplicity. The design of such systems is heavily dependent on the flexibility and accessibility of the data model describing the enterprise's repository. The model must provide interoperability and reusability so that a range of applications can access the enterprise data. Making the repository self-describing, based on 'meta-object' structures, ensures that knowledge about the repository structure is available for applications to interrogate and to navigate around for the extraction of application-specific data. In this paper, a large application is described which uses a meta-object based repository to capture engineering data in a large data warehouse. It shows that adopting a meta-modeling approach to repository design provides support for interoperability and a sufficiently flexible environment in which system evolution and reusability can be handled.

We discuss the requirements for information integration in large scientific collaborations and ar... more We discuss the requirements for information integration in large scientific collaborations and arrive at the conclusion that an architecture is needed that follows the declarative paradigm for reasoning completeness, maintainability and reuse of previously encoded knowledge but does not take the classical approach of integrating all sources against a single common “global” information model. Instead, we propose a local-as-view infrastructure that allows to make integrated information from remote sources available to ...

Database Engineering and …, 1998

At a time when many companies are embracing business process re-engineering and are under pressur... more At a time when many companies are embracing business process re-engineering and are under pressure to reduce "time-to-market" the management of product information from creative design through to manufacture has become increasingly important. Traditionally design engineers have employed Product Data Management systems to coordinate and control access to documented versions of product designs. However, these systems provide control only at the collaborative design level and are seldom used beyond design. Workflow management systems, on the other hand, are employed to coordinate and support the more complex and repeatable work processes of the production environment. Most commercial workflow products cannot support the highly dynamic activities found both in the design stages of product development and in rapidly evolving workflow definitions. The integration of Product Data Management with Workflow Management could provide support for product development from initial CAD/CAM collaborative design through to the support and optimisation of production workflow activities. This paper investigates such integration and proposes a philosophy for the support of product data throughout the full development and production lifecycle.

The CRISTAL (Cooperating Repositories and an Information System for Tracking Assembly Lifecycles)... more The CRISTAL (Cooperating Repositories and an Information System for Tracking Assembly Lifecycles) project is delivering a software system to facilitate the management of the engineering data collected at each stage of production of CMS. CRISTAL captures all the physical characteristics of CMS components as each sub-detector is tested and assembled. These data are retained for later use in areas such as detector slow control, calibration and maintenance. CRISTAL must, therefore, support different views onto its data dependent on the role of the user. These data viewpoints are investigated in this paper. In the recent past two CMS Notes have been written about CRISTAL. The first note, CMS 1996/003, detailed the requirements for CRISTAL, its relationship to other CMS software, its objectives and reviewed the technology on which it would be based. CMS 1997/104 explained some important design concepts on which CRISTAL is and showed how CRISTAL integrated the domains of product data man- ...

Interoperability of potentially heterogeneous databases has been an ongoing research issue for a ... more Interoperability of potentially heterogeneous databases has been an ongoing research issue for a number of years in the database community. With the trend towards globalization of data location and data access and the consequent requirement for the coexistence of new data stores with legacy systems, the cooperation and data interchange between data repositories has become increasingly important. The emergence of the eXtensible Markup Language (XML) as a database independent representation for data offers a suitable mechanism for transporting data between repositories. This paper describes a research activity within a group at CERN (called CMS) towards identifying and implementing database serialization and deserialization methods that can be used to replicate or migrate objects across the network between CERN and worldwide centres using XML to serialize the contents of multiple objects resident in object-oriented databases.

Software and Systems Modeling, 2003

One of the main factors driving objectoriented software development for information systems is th... more One of the main factors driving objectoriented software development for information systems is the requirement for systems to be tolerant to change. To address this issue in designing systems, this paper proposes a pattern-based, object-oriented, descriptiondriven system (DDS) architecture as an extension to the standard UML four-layer meta-model. A DDS architecture is proposed in which aspects of both static and dynamic systems behavior can be captured via descriptive models and meta-models. The proposed architecture embodies four main elements-firstly, the adoption of a multi-layered meta-modeling architecture and reflective meta-level architecture, secondly the identification of four data modeling relationships that can be made explicit such that they can be modified dynamically, thirdly the identification of five design patterns which have emerged from practice and have proved essential in providing reusable building blocks for data management, and fourthly the encoding of the structural properties of the five design patterns by means of one fundamental pattern, the Graph pattern. A practical example of this philosophy, the CRISTAL project, is used to demonstrate the use of description-driven data objects to handle system evolution.

Multimedia Tools and Applications

Highlighting important information of a network is commonly achieved by using random walks relate... more Highlighting important information of a network is commonly achieved by using random walks related to diffusion over such structures. Complex networks, where entities can have multiple relationships, call for a modeling based on hypergraphs. But, the limitation of hypergraphs to binary entities in co-occurrences has led us to introduce a new mathematical structure called hyperbaggraphs, that relies on multisets. This is not only a shift in the designation but a real change of mathematical structure, with a new underlying algebra. Diffusion processes commonly start with a stroke at one vertex and diffuse over the network. In the original conference article-(Ouvrard et al. 2018)-that this article extends we have proposed a two-phase step exchange-based diffusion scheme, in the continuum of spectral network analysis approaches, that takes into account the multiplicities of entities. This diffusion scheme allows to highlight information not only at the level of the vertices but also at the regrouping level. In this paper, we present new contributions: the proofs of conservation and convergence of the extracted sequences of the diffusion process, as well as the illustration of the speed of convergence and comparison between classical and modified random walks; the algorithms of the exchange-based diffusion and the modified random walk; the application to two use cases, one based on Arxiv publications and another based on Coco dataset images. All the figures have been revisited in this extended version to take the new developments into account.

Information Systems, 2014

Software engineers frequently face the challenge of developing systems whose requirements are lik... more Software engineers frequently face the challenge of developing systems whose requirements are likely to change in order to adapt to organizational reconfigurations or other external pressures. Evolving requirements present difficulties, especially in environments in which business agility demands shorter development times and responsive prototyping. This paper uses a study from CERN in Geneva to address these research questions by employing a 'description-driven' approach that is responsive to changes in user requirements and that facilitates dynamic system reconfiguration. The study describes how handling descriptions of objects in practice alongside their instances (making the objects self-describing) can mediate the effects of evolving user requirements on system development. This paper reports on and draws lessons from the practical use of a description-driven system over time. It also identifies lessons that can be learned from adopting such a self-describing description-driven approach in future software development.

In the web age systems must be flexible, reconfigurable and adaptable in addition to being quick ... more In the web age systems must be flexible, reconfigurable and adaptable in addition to being quick to develop. As a consequence, designing systems to cater for change is becoming not only desirable but required by industry. Allowing systems to be self-describing or description-driven is one way to enable these characteristics. To address the issue of evolvability in designing self-describing systems, this paper proposes a pattern-based, objectoriented, description-driven architecture. The proposed architecture embodies four pillars-first, the adoption of a multi-layered meta-modeling architecture and reflective meta-level architecture, second, the identification of four data modeling relationships that must be made explicit such that they can be examined and modified dynamically, third, the identification of five design patterns which have emerged from practice and have proved essential in providing reusable building blocks for data management, and fourth, the encoding of the structural properties of the five design patterns by means of one pattern, the Graph pattern. In this paper the fundamentals of the description-driven architecture are described-the multi-layered architecture and reflective meta-level architecture, remaining detail can be found in the cited references. A practical example of this architecture is described, demonstrating the use of description-driven data objects in handling system evolution.

In this paper, we propose a schema versioning mechanism to manage the schema evolution in tempora... more In this paper, we propose a schema versioning mechanism to manage the schema evolution in temporal object-oriented databases. The schema evolution management uses an object-oriented data model that supports temporal features and versions definition-the Temporal Versions Model-TVM. One interesting feature of our proposal is that TVM is used to control not only the schema versioning, but also the storage of extensional database and propagation of the changes performed on the objects. The extensional data level supports integration with the existing database, allowing the maintenance of conventional and temporal versioned objects. The instance propagation approach is proposed through the specification of propagation and conversion functions. These functions assure the correct instance propagation and allow the user to handle all instances consistently in both backward and forward schema versions. Finally, the initial requirements concerning data management in the temporal versioning environment, during schema evolution, are presented.

In data modelling, product information has most often been handled separately from process inform... more In data modelling, product information has most often been handled separately from process information. The integration of product and process models in a unified data model could provide the means by which information could be shared across an enterprise throughout the system lifecycle from design through to production. Recently attempts have been made to integrate these two separate views of systems through identifying common data models. This paper relates description-driven systems to multi-layer architectures and reveals where existing design patterns facilitate the integration of product and process models and where patterns are missing or where existing patterns require enrichment for this integration. It reports on the construction of a so-called description-driven system which integrates Product Data Management (PDM) and Workflow Management (WfM) data models through a common meta-model.

One of the main drivers in object-oriented design for information systems is the need for the reu... more One of the main drivers in object-oriented design for information systems is the need for the reuse of design artifacts in handling systems evolution. To be able to cope with change, systems must have the capability of reuse and to adapt as and when necessary to changes in requirements. To address the issues of reuse in designing evolvable systems, this

Optimising use of the Web (WWW) for LHC data analysis is a complex problem and illustrates the ch... more Optimising use of the Web (WWW) for LHC data analysis is a complex problem and illustrates the challenges arising from the integration of and computation across massive amounts of information distributed worldwide. Finding the right piece of information can, at times, be extremely time-consuming, if not impossible. So-called Grids have been proposed to facilitate LHC computing and many groups have embarked on studies of data replication, data migration and networking philosophies. Other aspects such as the role of 'middleware' for Grids are emerging as requiring research. This paper positions the need for appropriate middleware that enables users to resolve physics queries across massive data sets. It identifies the role of meta-data for query resolution and the importance of Information Grids for high-energy physics analysis rather than just Computational or Data Grids. This paper identifies software that is being implemented at CERN to enable the querying of very large collaborating HEP data-sets, initially being employed for the construction of CMS detectors.

Traditionally product data and their evolving definitions, have been handled separately from proc... more Traditionally product data and their evolving definitions, have been handled separately from process data and their evolving definitions. There is little or no overlap between these two views of systems even though product and process data arc inextricably linked over the complete software lifecycle from design to production. The integration of product and process models in an unified data model

Abstract The Compact Muon Solenoid (CMS) high energy physics experiment will comprise several lar... more Abstract The Compact Muon Solenoid (CMS) high energy physics experiment will comprise several large high resolution detectors each of which will be constructed out of over a million precision parts and will be produced and assembled during the next decade by ...

The construction process of detectors for the Large Hadron Collider (LHC) experiments is large sc... more The construction process of detectors for the Large Hadron Collider (LHC) experiments is large scale, heavily constrained by resource availability and evolves with time. As a consequence, changes in detector component design need to be tracked and quickly reflected in the construction process. With similar problems in industry engineers employ so-called Product Data Management (PDM) systems to control access to documented versions of designs and managers employ so-called Workflow Management software (WfMS) to coordinate production work processes. However, PDM and WfMS software are not generally integrated in industry. The scale of LHC experiments, like CMS, demands that industrial production techniques be applied in detector construction. This paper outlines the major functions and applications of the CRISTAL system (Cooperating Repositories and an Information System for Tracking Assembly Lifecycles) in use in CMS which successfully integrates PDM and WfMS techniques in managing large scale physics detector construction. This is the first time industrial production techniques have been deployed to this extent in detector construction.

... or duplication arc clcl'crrcd 10 the fi)llowing scction of this papcr. I n the lirst pha... more ... or duplication arc clcl'crrcd 10 the fi)llowing scction of this papcr. I n the lirst phase of prototypingCRISTAL has used the 0 2 TM product. Presently 0 2 is hascd on coinpiled C++ or C and thcrclorc the codc is not directly portable I'rom one inachinc to another. ...

... data warehouse. The meta-model approach to design reduces system complexity, provides model f... more ... data warehouse. The meta-model approach to design reduces system complexity, provides model flexibility and can integrate multiple, potentially heterogeneous, databases into the enterprise-wide data warehouse. A first prototype ...

As enterprises, data and functions become increasingly complex and distributed the need for infor... more As enterprises, data and functions become increasingly complex and distributed the need for information systems to be both customisable and interoperable also increases. Large scale engineering and scientific projects demand flexibility in order to evolve over time and to interact with external systems (both newly designed and legacy in nature) while retaining a degree of conceptual simplicity. The design of such systems is heavily dependent on the flexibility and accessibility of the data model describing the enterprise's repository. The model must provide interoperability and reusability so that a range of applications can access the enterprise data. Making the repository self-describing, based on 'meta-object' structures, ensures that knowledge about the repository structure is available for applications to interrogate and to navigate around for the extraction of application-specific data. In this paper, a large application is described which uses a meta-object based repository to capture engineering data in a large data warehouse. It shows that adopting a meta-modeling approach to repository design provides support for interoperability and a sufficiently flexible environment in which system evolution and reusability can be handled.

We discuss the requirements for information integration in large scientific collaborations and ar... more We discuss the requirements for information integration in large scientific collaborations and arrive at the conclusion that an architecture is needed that follows the declarative paradigm for reasoning completeness, maintainability and reuse of previously encoded knowledge but does not take the classical approach of integrating all sources against a single common “global” information model. Instead, we propose a local-as-view infrastructure that allows to make integrated information from remote sources available to ...

Database Engineering and …, 1998

At a time when many companies are embracing business process re-engineering and are under pressur... more At a time when many companies are embracing business process re-engineering and are under pressure to reduce "time-to-market" the management of product information from creative design through to manufacture has become increasingly important. Traditionally design engineers have employed Product Data Management systems to coordinate and control access to documented versions of product designs. However, these systems provide control only at the collaborative design level and are seldom used beyond design. Workflow management systems, on the other hand, are employed to coordinate and support the more complex and repeatable work processes of the production environment. Most commercial workflow products cannot support the highly dynamic activities found both in the design stages of product development and in rapidly evolving workflow definitions. The integration of Product Data Management with Workflow Management could provide support for product development from initial CAD/CAM collaborative design through to the support and optimisation of production workflow activities. This paper investigates such integration and proposes a philosophy for the support of product data throughout the full development and production lifecycle.