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.