Florida Estrella

MammoGrid: A Service Oriented Architecture Based Medical Grid Application

The MammoGrid project has recently delivered its first proof-of-concept prototype using a Service-Oriented Architecture (SOA)-based Grid application to enable computing spanning national borders. The underlying AliEn Grid infrastructure has been selected because of its practicality and its emergence as a potential open source standards-based solution for managing and coordinating distributed resources. The resultant prototype is expected to harness the large amounts of medical image data needed to perform epidemiological studies, advanced image processing and ultimately tele-diagnosis over communities of ‘virtual organizations’. This paper outlines the MammoGrid approach in managing a federation of Grid-connected mammography databases in the context of the recently delivered prototype and describes the next phase of prototyping.

Experiences of engineering Grid-based medical software

OBJECTIVES Grid-based technologies are emerging as potential solutions for managing and collaborating distributed resources in the biomedical domain. Few examples exist, however, of successful implementations of Grid-enabled medical systems and even fewer have been deployed for evaluation in practice. The objective of this paper is to evaluate the use in clinical practice of a Grid-based imaging prototype and to establish directions for engineering future medical Grid developments and their subsequent deployment. METHOD The MammoGrid project has deployed a prototype system for clinicians using the Grid as its information infrastructure. To assist in the specification of the system requirements (and for the first time in healthgrid applications), use-case modelling has been carried out in close collaboration with clinicians and radiologists who had no prior experience of this modelling technique. A critical qualitative and, where possible, quantitative analysis of the MammoGrid prototype is presented leading to a set of recommendations from the delivery of the first deployed Grid-based medical imaging application. RESULTS We report critically on the application of software engineering techniques in the specification and implementation of the MammoGrid project and show that use-case modelling is a suitable vehicle for representing medical requirements and for communicating effectively with the clinical community. This paper also discusses the practical advantages and limitations of applying the Grid to real-life clinical applications and presents the consequent lessons learned. CONCLUSIONS The work presented in this paper demonstrates that given suitable commitment from collaborating radiologists it is practical to deploy in practice medical imaging analysis applications using the Grid but that standardization in and stability of the Grid software is a necessary pre-requisite for successful healthgrids. The MammoGrid prototype has therefore paved the way for further advanced Grid-based deployments in the medical and biomedical domains.

Meta-data Objects as the Basis for System Evolution

One of the main factors driving object-oriented software development in the Web-age is the need for systems to evolve as user requirements change. A crucial factor in the creation of adaptable systems dealing with changing requirements is the suitability of the underlying technology in allowing the evolution of the system. A reflective system utilizes an open architecture where implicit system aspects are reified to become explicit first-class (metadata) objects. These implicit system aspects are often fundamental structures which are inaccessible and immutable, and their reification as meta-data objects can serve as the basis for changes and extensions to the system, making it self-describing. To address the evolvability issue, this paper proposes a reflective architecture based on two orthogonal abstractions - model abstraction and information abstraction. In this architecture the modeling abstractions allow for the separation of the description meta-data from the system aspects they represent so that they can be managed and versioned independently, asynchronously and explicitly. A practical example of this philosophy, the CRISTAL project, is used to demonstrate the use of meta-data objects to handle system evolution.

The use of production management techniques in the construction of large scale physics detectors

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.

Pattern reification as the basis for description-driven systems

One of the main factors driving object-oriented 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, description-driven 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.

Handling Evolving Data Through the Use of a Description Driven Systems Architecture

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 are inextricably linked over the complete software lifecycle from design to production. The integration of product and process models in an unified data model provides the means by which data could be shared across an enterprise throughout the lifecycle, even while that data continues to evolve. In integrating these domains, an object oriented approach to data modelling has been adopted by the CRISTAL (Cooperating Repositories and an Information System for Tracking Assembly Lifecycles) project. The model that has been developed is description-driven in nature in that it captures multiple layers of product and process definitions and it provides object persistence, flexibility, reusability, schema evolution and versioning of data elements. This paper describes the model that has been developed in CRISTAL and how descriptive meta-objects in that model have their persistence handled. It concludes that adopting a description-driven approach to modelling, aligned with a use of suitable object persistence, can lead to an integration of product and process models which is sufficiently flexible to cope with evolving data definitions.

The Design of an Engineering Data Warehouse Based on Meta-Object Structures

Large scale engineering and scientific projects demand product and workflow management which may require integration and/or distribution over many separate organisations. The integration of such ‘islands of information’, which ultimately forms the basis of so-called ‘virtual enterprises’, 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 ensures that knowledge about the repository structure is available for applications to interrogate and to navigate around for the extraction of application-specific data. Herein a large application is described which uses a meta-object based repository to capture product and workflow data in an engineering data warehouse. It is shown that adopting a meta-object approach to repository design provides support for interoperability and a suitable environment on which to build data mining applications.

Promoting Reuse through the Capture of System Description

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 paper proposes a so-called description-driven system architecture. The proposed architecture is based on a twodimensional design approach founded on the adoption of a multilayered modeling architecture and on a reflective meta-level architecture. This paper discusses the need for capturing holistic system description when modeling large-scale distributed systems and the role of reflection as a method to cater for reuse in systems evolution. A practical example of the application of this design philosophy, the CRISTAL project, is used to demonstrate the reuse of descriptiondriven data objects to provide for evolution.

Managing Evolving Business Workflows through the Capture of Descriptive Information

Business systems these days need to be agile to address the needs of a changing world. In particular the discipline of Enterprise Application Integration requires business process management to be highly reconfigurable with the ability to support dynamic workflows, inter-application integration and process reconfiguration. Basing EAI systems on model-resident or on a so-called description-driven approach enables aspects of flexibility, distribution, system evolution and integration to be addressed in a domain-independent manner. Such a system called CRISTAL is described in this paper with particular emphasis on its application to EAI problem domains. A practical example of the CRISTAL technology in the domain of manufacturing systems, called Agilium, is described to demonstrate the principles of model-driven system evolution and integration. The approach is compared to other model-driven development approaches such as the Model-Driven Architecture of the OMG and so-called Adaptive Object Models.

Design patterns for description-driven systems in high energy physics

In data modeling, 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 between High Energy Physics (HEP) groups 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 through the CRISTAL project and reveals where existing design patterns facilitate the integration of product and process models, where patterns are missing or require enrichment for integration. It reports on the construction of a so-called description-driven system which integrates Product Data Management (PDM) and Workflow Management (WfM) models through a common meta-model.