The European Middleware Initiative (EMI) is a

computer software Software is a set of computer programs and associated documentation and data. This is in contrast to hardware, from which the system is built and which actually performs the work. At the lowest programming level, executable code consists ...

platform for high performance

distributed computing A distributed system is a system whose components are located on different computer network, networked computers, which communicate and coordinate their actions by message passing, passing messages to one another from any system. Distributed com ...

. It is developed and distributed directly by the ''EMI project''. It is the base for other grid middleware distributions used by scientific research communities and distributed computing infrastructures all over the world especially in

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

and

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...

. EMI supports broad scientific experiments and initiatives, such as the

Worldwide LHC Computing Grid The Worldwide LHC Computing Grid (WLCG), formerly (until 2006) the LHC Computing Grid (LCG), is an international collaborative project that consists of a grid-based computer network infrastructure incorporating over 170 computing centers in 42 co ...

(for the

Large Hadron Collider The Large Hadron Collider (LHC) is the world's largest and highest-energy particle collider. It was built by the European Organization for Nuclear Research (CERN) between 1998 and 2008 in collaboration with over 10,000 scientists and hundred ...

). The EMI middleware is a cooperation among three general purpose grid platforms, the

Advanced Resource Connector Advanced Resource Connector (ARC) is a grid computing middleware introduced by NorduGrid. It provides a common interface for submission of computational tasks to different distributed computing systems and thus can enable grid infrastructures of ...

, gLite and

UNICORE UNICORE (UNiform Interface to COmputing REsources) is a grid computing technology for resources such as supercomputers or cluster systems and information stored in databases. UNICORE was developed in two projects funded by the German ministry ...

and the ''dCache'' storage software.

Purpose

The purpose of the EMI distribution is to consolidate, harmonize and support the original software platforms, evolve and extend them. Redundant or duplicate services resulting from the merging are deprecated, in favour of new services added to satisfy user requirements or specific consolidation needs, standardizing and developing common interfaces. These include the adoption of a common structure for accounting, resource information exchange or authentication and authorization. Input for the development activities is taken from users, infrastructures projects, standardization initiatives or changing technological innovations. The software products will be adapted as necessary to comply with standard

open-source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized sof ...

guidelines to facilitate the integration in mainstream

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...

distributions.

Collaborations

A cooperation with FutureGrid, a US distributed testbed for

Cloud In meteorology, a cloud is an aerosol consisting of a visible mass of miniature liquid droplets, frozen crystals, or other particles suspended in the atmosphere of a planetary body or similar space. Water or various other chemicals may co ...

s, Grids and

high-performance computing High-performance computing (HPC) uses supercomputers and computer clusters to solve advanced computation problems. Overview HPC integrates systems administration (including network and security knowledge) and parallel programming into a mult ...

, was announced in December 2011. In January 2012, the EMI project formalized a partnership with the iMarine project to create an open data e-infrastructure for fisheries management and marine conservation.

Users

By 2008 the EMI software distribution provided most of the middleware components which support the execution and completion of the millions of computational jobs handled by the 350 centers of the

European Grid Infrastructure European Grid Infrastructure (EGI) is a series of efforts to provide access to high-throughput computing resources across Europe using grid computing techniques. The EGI links centres in different European countries to support international rese ...

and the tens of

petabyte The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit ...

s of data transfers occurring between the storage systems of those centers. EMI middleware was used in the WLCG infrastructure which supports, for example, the search for the

Higgs boson The Higgs boson, sometimes called the Higgs particle, is an elementary particle in the Standard Model of particle physics produced by the quantum excitation of the Higgs field, one of the fields in particle physics theory. In the Stand ...

(the ''God Particle'') and new types of matter searches of the physicists at LHC together with other research in

astronomy Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...

biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary i ...

computational chemistry Computational chemistry is a branch of chemistry that uses computer simulation to assist in solving chemical problems. It uses methods of theoretical chemistry, incorporated into computer programs, to calculate the structures and properties of m ...

and other sciences.

License

There is no common EMI license though all licenses used by EMI are

. Each product has a long history behind its own license. Most are Apache or BSD. dCache products are released under the dCache Software License but they adopted the

Affero General Public License The Affero General Public License (Affero GPL and informally Affero License) is a free software license. The first version of the Affero General Public License (AGPLv1), was published by Affero, Inc. in March 2002, and based on the GNU General Pu ...

from 1 January 2012.

Products

The EMI products (components of the release) can be grouped in four categories (areas): ''computing'', ''data'', ''security'' and ''infrastructure''. The first release of the software is composed of 56 products packaged for Scientific Linux 5 (32, 64bit). The second release is also made of 56 products which are available for Scientific Linux 5 64bit and Scientific Linux 6 64bit. A subset of services is also available for Debian 6 64bit with more planned with the updates. The third and final release contains 61 products for the Scientific Linux 5 64bit (480 packages), Scientific Linux 6 64bit (474 packages) and Debian 6 (233 packages) Linux distributions. All components are supported on the Scientific Linux platforms while some are not on Debian.

Releases

EMI releases are of two types. Major releases include most if not all components and Component Releases which is related to a single product. A collection of components may be released as an ''update'' to a major release.

Major releases

Major releases are delivered once per year. Three planned major releases were named after European mountains. ''Full Support'': updates are released to address issues in the code and new features are provided (lasts 12 months) ''Standard Updates'': updates are released to address issues in the code but no new features are provided (lasts 6 months) ''Security Updates and Support'': only updates targeting security vulnerabilities are provided (6 months) As older versions of the EMI products are superseded by newer versions, an ''end-of-life'' announcement is made which coincides with the end of the security updates and support period. As of May 2013, 24 updates were released for EMI 1 Kebnekaise, 13 for EMI 2 Matterhorn and 3 for EMI 3 Monte Bianco.

Component releases

''Minor Releases'': contain interface or functional changes that are backwards-compatible with those of the current major release. They are issued a few times per year. ''Revision Releases'': available every week or two weeks. They contain only bug fixes. ''Emergency Releases'': contain only very specific bug fixes, typically security-related and are available as need, using emergency release procedures.

References

{{Reflist, colwidth=30em