Virtual hubs - system architecture

The ENERGIC-OD project aims to build Virtual Hubs to facilitate the use of open geospatial data. Unfortunately, most of the concepts in this apparently clear statement of objectives are controversial. There are many different interpretations of geospatial data and open data, and there is not any clear definition of what a Virtual Hub is. To guide the design of the ENERGIC-OD architectural framework, we considered that the real keyword in ENERGIC-OD is "facilitate", and everything should then be interpreted in that direction. For this reason, for example, ENERGIC-OD cannot adopt a strict definition of open data limiting to "free-of-charge" data. ENERGIC-OD has to facilitate users lowering barriers to open data such as the existence of heterogeneous interfaces, variety of formats, including proprietary ones or different coordinate reference systems. The ENERGIC-OD Virtual Hub concept puts its basis on past experiences in building System of Systems through a brokering approach. In brokered architectures, dedicated components provide mediation and harmonization of interfaces and data models avoiding the need of changes in the data provider systems. As an innovation action, ENERGIC-OD focuses on loosely-coupled integration of mature technologies and tools, most of them provided or under control of ENERGIC-OD Consortium members. In particular, existing brokers - such as the GI-suite Brokering Framework adopted in the Global Earth Observation System of Systems - assure the basis to build advanced Virtual Hubs. The integration of tools in the Virtual Hub will be based on full server-side APIs, while applications development will be facilitated through simple client-side APIs based on widespread Web technologies (HTML5, Javascript and CSS). For greater flexibility, ENERGIC-OD will adopt an agile methodology allowing rapid development in response of new requirements. It will have three main yearly iterations with fixed objectives for demonstration in reviews and events. ENERGIC-OD will deploy five national VHs in France, Germany, Italy, Poland and Spain. However, the architecture is flexible and can accommodate different topologies, to address specific requirements, such as the need of a sixth European VH, or a central VH acting as a single-point-of-access, as it could be suggested by marketing reasons for better exploitation. By a technical point-of-view, the deployment will be possible on local infrastructures, possibly managed by one or more ENERGIC-OD partners, or on commercial or public clouds providing Infrastructure-as-a-Service (IaaS) and Platform-as-a-Service (PaaS) functionalities.