CERN Accelerating science



The vast majority of WLCG users are members of LHC experiments or affiliated research projects and should normally use the official software frameworks that are available per experiment or project.  Those frameworks in turn make use of more generic middleware components, which are different in the different infrastructures that make up WLCG: EGI (European Grid Infrastructure), NDGF (Nordic Data Grid Facility), OSG (Open Science Grid) and other partners.

For service administrators and operations managers each participating infrastructure has documentation on how to test services.  See below. 


Each participating site is affiliated with one of the infrastructures that make up WLCG and should normally comply with the corresponding regulations, recommended versions and configurations.

A site normally is expected to provide computing resources via one of the supported Computing Element types and a commensurate amount of storage via one of the supported Storage Element solutions.

Also the network bandwidth (internal and external) needs to be commensurate with the site's resources for the supported collaborations.

Additional services are usually needed (e.g. for the information system, authorization or accounting), depending on the infrastructure of which the site is a part.

The exact choice of middleware technologies to be deployed should typically be discussed in advance with the site's (main) customers.

Middleware products

For WLCG as a whole there exists a list of baseline versions for various middleware products:

EGI (European Grid Infrastructure) and partners rely on the Unified Middleware Distribution (UMD) available here:

That in turn relies in particular on releases from the European Middleware Initiative (EMI).  For some products or for early access to newer versions one may need to use the EMI repository directly:

NDGF (Nordic Data Grid Facility) relies on Advanced Resource Connector (ARC) middleware that is available through the EGI UMD, EMI and the NorduGrid site:

OSG (Open Science Grid) relies on the OSG software distribution: