F. Estrella

Towards next generations of software for distributed infrastructures: The European Middleware Initiative

The last two decades have seen an exceptional increase of the available networking, computing and storage resources. Scientific research communities have exploited these enhanced capabilities developing large scale collaborations, supported by distributed infrastructures. In order to enable usage of such infrastructures, several middleware solutions have been created. However such solutions, having been developed separately, have been resulting often in incompatible middleware and infrastructures. The European Middleware Initiative (EMI) is a collaboration, started in 2010, among the major European middleware providers (ARC, dCache, gLite, UNICORE), aiming to consolidate and evolve the existing middleware stacks, facilitating their interoperability and their deployment on large distributed infrastructures, establishing at the same time a sustainable model for the future maintenance and evolution of the middleware components. This paper presents the strategy followed for the achievements of these goals : after an analysis of the situation before EMI, it is given an overview of the development strategy, followed by the most notable technical results, grouped according to the four development areas (Compute, Data, Infrastructure, Security). The rigorous process ensuring the quality of provided software is then illustrated, followed by a description the release process, and of the relations with the user communities. The last section provides an outlook to the future, focusing on the undergoing actions looking toward the sustainability of activities.

An object model for product and workflow data management

In industry design engineers have traditionally 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 in industry to coordinate and support the more complex and repeatable work processes of the production environment. The integration of Product Data Management with Workflow Management can provide support for product development from initial CAD/CAM collaborative design through to the support and optimisation of production workflow activities. This paper investigates this integration and proposes a data model for the support of product data throughout the full development and production lifecycle and demonstrates its usefulness in the construction of large scale high energy physics detectors at the European Particle Physics laboratory at CERN.

Version management in a distributed workflow application

Most applications of workflow management in business are based on well-defined repetitively executed processes. Recently, workflow management principles have been applied to the scientific and engineering communities, where activities may dynamically change as the workflows are executed and may often evolve through multiple versions. These domains present new problems including tracking the progress of parts on which those activities are executed, particularly if the production process itself is distributed across multiple sites. A major requirement of the system is that the full production history of every part must be permanently stored. This paper reports on the activities of a large-scale distributed scientific workflow management project, entitled CRISTAL (Cooperating Repositories and Information System for the Tracking of Assembly Lifecycles), in which a product data management (PDM) system is used to store and maintain versions of workflow meta-objects and in which a light-weight workflow enactment component is implemented for execution. These versions must support the permanent recording of a constantly adapting production process. The workflow enactment component is based on Petri nets, which are designed to embody all aspects of the scientific workflow management.

On realizing the concept study ScienceSoft of the European Middleware Initiative: Open Software for Open Science

In September 2011 the European Middleware Initiative (EMI) started discussing the feasibility of creating an open source community for science with other projects like EGI, StratusLab, OpenAIRE, iMarine, and IGE, SMEs like DCore, Maat, SixSq, SharedObjects, communities like WLCG and LSGC. The general idea of establishing an open source community dedicated to software for scientific applications was understood and appreciated by most people. However, the lack of a precise definition of goals and scope is a limiting factor that has also made many people sceptical of the initiative. In order to understand more precisely what such an open source initiative should do and how, EMI has started a more formal feasibility study around a concept called ScienceSoft - Open Software for Open Science. A group of people from interested parties was created in December 2011 to be the ScienceSoft Steering Committee with the short-term mandate to formalize the discussions about the initiative and produce a document with an initial high-level description of the motivations, issues and possible solutions and a general plan to make it happen. The conclusions of the initial investigation were presented at CERN in February 2012 at a ScienceSoft Workshop organized by EMI. Since then, presentations of ScienceSoft have been made in various occasions, in Amsterdam in January 2012 at the EGI Workshop on Sustainability, in Taipei in February at the ISGC 2012 conference, in Munich in March at the EGI/EMI Conference and at OGF 34 in March. This paper provides information this concept study ScienceSoft as an overview distributed to the broader scientific community to critique it.

Reifying design patterns to facilitate systems evolution

In the Web age systems must be increasingly flexible, reconfigurable and adaptable in addition to being developed rapidly. As a consequence, designing systems to cater for change is becoming critical to their success. Allowing systems to be self-describing or description-driven is one way to enable this. To address the issue of evolvability in information systems, this paper proposes a pattern-based description-driven architecture. The proposed architecture embodies four pillars – firstly, the adoption of a multi-layered and reflective meta-level architecture, secondly, the identification of four modeling relationships that must be made explicit to be examined and modified dynamically, thirdly the identification of five patterns which have emerged from practice and have proved essential in providing reusable building blocks, and finally the encoding of the structural properties of these design patterns by means of one pattern, the Graph pattern. A practical example of this is cited to demonstrate the use of description-driven data objects in handling system evolution.