The e-Science conceptual view leads to the following architectural view over a Grid infrastructure, as depicted in the Figure.

It is organized by the well-known layer pattern for implementing the inevitable separation of concerns.

• The Resource Layer contains all physical resources (computing elements, storage elements, instrument elements, sensor networks, communication networks) which are provided by the various partners in the HMR e-Science environment. Typically, these resources are provided over European e-infrastructures like DEISA, PRACE, EGI or the national NGIs, but operated locally by the providers.
• For accessing them a Grid middleware system like the Globus Toolkit, gLite, or UNICORE is required. Some of the resources may also be available in a Cloud (public or private). The middleware and the access services are part of the Infrastructure and Middleware Layer.
• In order to cope with the inherent heterogeneity of Grid resources and Grid middleware, an Interoperability Layer assists in transparently accessing the resources via the underlying layers. The interoperability layer is based on standards like those defined in the Open Grid Forum (OGF), or in the Organization for the Advancement of Structured Information Standards (OASIS) like the Security Assertion Markup Language (SAML).
• The HMR related services are comprised in the Service Layer which itself is separated in the Basic Service Layer and the Compound Service Layer. The Service Layer typically interacts with the Interoperability Layer to transparently access the HMR resources. However, it may also interact with the Middleware Layer directly.On top of the Service Layer, the Application Layercontains the specific HMR applications for simulations, experiments and e-Learning. The Application Layer uses (basic or compound) services from the Service Layer. It may, however, also interact directly with the Grid infrastructure.
  • The Basic Service Layer provides all services which are fundamental for the HMR community. Examples are data conversion, model access or task composition
  • As opposed to the Basic Service Layer, the Compound Service Layer provides more complex services assembled from basic services. Typical examples in the HMR context are the creation and the management of workflows, the management of model sets, or the visualization of simulation results.
• The Application Layer is accessed via the Access Layer which provides the required capabilities to authorize the access to the HMR applications via various portals or clients and through an authentication interface.

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