Common Data Index (CDI)
The Common Data Index (CDI) service gives users a highly detailed insight in the availability and geographical spreading of marine data sets, that are managed by the SeaDataNet data centres. Moreover it provides a unique interface for requesting access, and if granted, for downloading data sets from the distributed data centres across Europe.
The CDI Version 1 has been launched as pilot in 2008 and very good progress has been made with its population by all SeaDataNet data centres. In June 2010 a further upgrade has taken place to CDI Version 2 which has been achieved in cooperation between SeaDataNet and the Geo-Seas project. The CDI V2 supports detailed tracks and polygons which are relevant for describing e.g. bathymetric surveys and seismic surveys. In November 2013 the CDI V3 has been launched which makes use of the ISO 19139 Schema, is compliant to INSPIRE and is supported by the new version (NVS 2.0) of the SeaDataNet Common Vocabularies. Also a further harmonisation and relationship of the CDI metadata format has been achieved.
Note: registration in the SeaDataNet User Register is required for submitting data requests and downloading!
The CDI service has a major functionality: by means of a data shopping, tracking and download service mechanism users are provided with a unique and harmonised access to the data sets, that are managed at the distributed data centres. Furthermore, the data sets are delivered by all data centres in standard SeaDataNet data transport formats.
The CDI service has already been adopted by a number of other European projects and EMODNet lots which has resulted in now more than 90 Data Centres connected to the SeaDataNet CDI infrastructure, giving overview and access to an ever increasing volume of data sets. It is planned and actively promoted that more Data Centres will connect.
How does it work?
The process from search to getting access to requested data sets is illustrated and explained below. This allows users to retrieve data sets from distributed data centres in a common way via one unique portal.
The CDI V3 query interface enables to search by a set of criteria. The selected data sets are listed. Geographical locations are indicated on a map. Clicking on the display icon retrieves the full metadata of the data set. This gives information on the what, where, when, how, and who of the data set. It also gives standardised information on the data access restrictions, that apply. The interface features a shopping mechanism, by which selected data sets can be included in a shopping basket.
All users can freely query and browse in the CDI V3 directory; however submitting requests for data access via the shopping basket requires that users are registered in the SeaDataNet central user register , thereby agreeing with the overall SeaDataNet User Licence. The maximum number of data set requests per shopping basket action has been increased in CDI V3 from 500 to max 10.000 requests.
All data requests are forwarded automatically from the SeaDataNet portal to the relevant data centres. This process is controlled via the Request Status Manager (RSM) service at the portal, that communicates with the data centres. Users receive a confirmation e-mail of their data set requests and a link to the RSM service. By log-in to the RSM service users can check regularly the status of their requests and download data sets from the associated data centres, after access has been granted. On their turn, data centres can follow via the RSM service all transactions for their data sets online and can handle requests which might require their mediation.
Each CDI V3 metadata record includes a data access restriction tag. It indicates under which conditions the data set is accessable to users. Its values can vary from "unrestricted" to "no access" with a number of values in between. During registration every user will first be considered as a public user while its national NODC / Marine Data Centre might change that on short term into one or more SeaDataNet roles. The RSM service combines for each data set request the given data access restriction with the role(s) of the user as registered in the SeaDataNet central user register. This determines per data set request, whether a user gets direct access automatically, whether it first has to be considered by the data centre, that therefore might contact the user, or that no access is given.