• Retrieving CDI controlled lists
• SeaDataNet Vocabulary service description
• SeaVox Content governance
• Web services

Retrieving CDI controlled lists

The CDI-format is supported by a number of controlled lists of standardised terms or vocabularies that cover a broad spectrum of disciplines of relevance to the oceanographic and wider community. CDI partners can browse through these vocabularies and download the latest versions.
Retrieving the csv files for CDI can be done as follows:
Via the SeaDataNet Vocabulary service (recently upgraded to V1.1 of the Web services) this applies to:

• L021: SeaDataNet Geospatial Feature Types (use Entryterm)
• L031: SeaDataNet_Measurement_Periodicity_Classes (use Entrykey)
• L05: SeaDataNet device categories (use Entrykey)
• L061: SeaDataNet_Platform_Classes (use Entrykey)
• L071: Data_access_mechanisms (use Entrytermabbr)
• L081: SeaDataNet_Data_Access_Restriction_Policies (use Entrykey)
• L101: SeaDataNet_geographic_co-ordinate_reference_frames (use Entrykey)
• L111: Height and Depth Vertical Co-ordinate Reference Datums (use Entrykey)
• P021: BODC_Parameter_Discovery_Vocabulary (use Entrykey)

Via the EDMO Directory of Organisations this applies to:

• Organisations: cdi_originator_codes.csv (Use N_code)

Short explanation of List 4 - parameter codes:
A dedicated Parameter Discovery Vocabulary (PDV) (P021) was defined in a cooperation between BODC and IFREMER, which is maintained by BODC. The PDV contains a hierarchical structure to support the CDI User Interface. The hierarchy contains the following levels:

• P081: Discipline (at present 9 items)
• P031: Agreed Parameter Groups (at present 43 items)
• P021: Parameter Discovery Vocabulary (at present 335 items) <= CDI coding
• P011: BODC Parameter Usage Vocabulary (at present 20.000 + items)

Each level has a Broader Term – Narrow Terms relation. This implicates that each Discipline is related to a multiple of Agreed Parameter Groups, each of which on it’s turn is related to a multiple of PDV terms. The lowest level in the hierarchy is the BODC Parameter Usage Vocabulary (at present > 20.000 items). Each of these belong to a Parameter Group / PDV term. The PDV terms are used for coding the parameters in the CDI XML files! The hierarchical relations and broader levels are applied in the CDI User Interface to support users in formulating their queries. CDI partners must ‘map’ their parameters to the CDI’s PDV terms.

Note: It is advised to read the background information as included in the CDI guidance document and in the text below.

SeaDataNet Vocabulary service description

Within the framework of the SeaDataNet project, successor to the Sea-Search project, a service has been set-up to provide ‘controlled vocabularies’, which are used in the metadata and to label data. This SeaDataNet Vocabulary service provides access to lists of standardised terms that cover a broad spectrum of disciplines of relevance to the oceanographic and wider community. Using standardised sets of terms solves the problem of ambiguities associated with data markup and also enables records to be interpreted by computers. This opens up data sets to a whole world of possibilities for computer aided manipulation, distribution and long term reuse. The controlled vocabularies delivered contain the following information for each term:

• Key - a compact permanent identifier for the term designed for computer storage rather than human readability Term - the text string representing the term in human-readable form
• Abbreviation - a concise text string representing the term in human-readable form where space is limited
• Definition - a full description of what is meant by the term
• All of the vocabularies are fully versioned and a permanent record is kept of all changes made.

The SeaDataNet Vocabulary service is based upon the NERC DataGrid (NDG) vocabulary Web service, originally developed in 2006 and operated by BODC.The current version is a recently upgraded version (V1.1) of the Web services, which now is compliant to WS Basic Profile 1.1 of the Web Services Interoperability Organisation (WS-I). This Basic Profile has been adopted as standard for Web services in SeaDataNet. On top of this webservice a vocabulary Client Interface has been developed in 2006 and is operated by MARIS, to provide users the options to search and browse in the various vocabularies and to make and download export files of selected entries in csv format. These csv files can be used in conjunction with e.g. the JavaTool, that is available for the CDI generation. To harvest the latest versions of the lists from the NDG Web service an automatic UPDATE function is included that runs every time to load the latest updates into a local buffer for feeding the Search and Browse interface. Also this client interface has recently been upgraded using the latest BODC webservices.

SeaVox Content governance

Content governance of these vocabularies is very important to stay up-to-date and in sync with ongoing developments. Therefore a combined SeaDataNet and MarineXML Vocabulary Content Governance Group (SeaVoX) has been set up, moderated by BODC, and with active membership from experts from SeaDataNet, MMI, MOTIIVE, JCOMMOPS and more international groups. SeaVox operates by mailing list server.
SeaVox Terms of Reference:

• Content management of all controlled vocabularies for the SeaDataNet and the IOC ISO19139 profile EXCEPT specific platform identifiers (ship codes and the like). SeaVox Rules of engagement:
• The aim of the list is to reach consensus through discussion on the topics raised.
• A week of silence on a topic is taken as 'subject closed' and the decisions made on that topic will be implemented.
• If consensus cannot be reached then the decision becomes the responsibility of the IOC MarineXML Steering Group Chair (currently Roy Lowry - BODC).
• Once loaded vocabulary terms cannot be deleted and changes to term definitions can only broaden meanings.

Web services

The SeaDataNet Vocabulary service has at its basis a Web service. This is a collection of protocols and standards used for exchanging data between applications or systems. Software applications written in various programming languages and running on various platforms can use web services to exchange data over the Internet in a manner similar to inter-process communication on a single computer. This interoperability (e.g., between Java and Python, or Windows and Linux applications) is due to the use of open standards. In common usage the term usually refers to those services that use SOAP-formatted XML envelopes and have their interfaces described by WSDL.

• SOAP: "Simple Object Access Protocol". An XML-based, extensible message envelope format, with "bindings" to underlying protocols (e.g., HTTP, SMTP)
• WSDL: "Web Services Description Language" An XML format that allows service interfaces to be described, along with the details of their bindings to specific protocols. Typically used to generate server and client code, and for configuration. This means that WSDL describes the public interface to the web service.
• UDDI: "Universal Description, Discovery, and Integration" A protocol for publishing and discovering metadata about Web services, to enable applications to find Web services.

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