Integrated Systems > Partner Chart


 
  Access to products

The Partner Chart

General Overview WP2 Interface Document Glossary Useful links

A common unified framework for product coherency and standardisation
which is needed to facilitate the visibility, understanding and exchange of the ocean observing data.

Mersea is serving and communicating with different thematic communities. So, the challenge for Mersea is to find a balance and to merge the practices and experiences of these different thematic communities into a coherent set of ocean products that will take into account specific features of the products and provide simultaneously interoperability to these surrounding communities and networks. That is:

  1. to describe product in such manner it will help to reach coherency in MERSA product description, that will concern as well information on the web than discovery metadata to offer user friendly searching and navigation tools that lead to the data (catalogue & inventory function),

  2. to fulfil a common data format structure and harmonise and standardise its description, which will ease exchange and joint use of Mersea interdisciplinary data sets,

  3. to harmonise data transport and exchange procedures, that is the ability to access the data in an interoperable manner from client applications, relying on a decentralised but compatible system architecture for distribution on Internet,

  4. to offer user friendly tools to select, browse and manipulate the data and give the ability to evaluate the character of the data through common web browsers.

Find here D17.2 Report on interoperability requirements for FTS and action needed to put missing standard into effect

Information on the web

  • The Mersea web portal will allow the users to identify and access spatial or geographical information from a wide range of sources, from the local level to the global level, in an inter-operable way for a variety of uses. The main goal of the portal is 1- to provide appropriate updated information for external users and 2- to facilitate the access to qualified data and products within the project, both in real-time and delayed mode.
  • Since data and products will be generated in different institutions, efficient provision of information and products from a single user portal will require to distribute the Mersea WWW site among different locations. Access will be given from a single user portal (http://www.mersea.eu.org) lying on a network of 'virtual data centres'. The Internet domain name mersea.eu.org has been consequently distributed among these web sites.
  • The Top level navigation menu, headings and subheadings, is essential for an integrated Mersea web site, and to keep it coherent. It has been defined in RD1.
  • All pages have the same graphical chart (a javascript that implement the menu-bar, a style sheet for the look, a model page to build pages (cf. RD2). The webmaster kit is made available by . No modification of the graphical chart should be done at webmaster level.
    Note: to help upgrade and keep MERSEA web sites coherent, part of MERSEA web chart will not be later exported but centralised.
  • The Mersea WWW site is distributed to facilitate it's life and updates. Each Mersea sub-site must have a designated webmaster that agrees to follow the Mersea guidelines (see RD3, document describing needed actions to run MERSEA Ocean Forecasting TEP web sites at different places and keep integrated web site coherency - chart, information and data distribution -.). The webmaster will be responsible for web site management, information to be released and data distribution. First pages should be identical in the format for each TEP.
  • To help understand Forecast TEP web site, webmaster should write a document explaining the web site purpose, general presentation, meta name used, access conditions, and organisation (see for example RD4 and RD5).
  • To allow enough visibility on each web activities, webmaster should report every 3-month on web site status and uses (see for example RD6), that is:
    • Internet domain identification
    • Webmaster e-mail address (written at bottom of each page)
    • Site map
    • Web site evolution
    • Synthesis of log analysis
    • Data status and history

References:

Note: Restricted access, only for Mersea partners.
Please enter your Mersea name and password to retrieve the documents.

Discovery Metadata

  • The Product Catalogue will be instrumental in promotion and marketing of Mersea Products. Mersea interoperable catalogue will list and give properties of all the products provided by Mersea TEPs, directly or indirectly through data provider centers.
    Catalogues are accessible not only to human operators, but also applications and services via appropriate catalogue interfaces. Catalogue services are designed to help users of application software to find information that exists anywhere in a distributed computing environment.
  • The Product Inventory lists and describes individual releases of products, which are time-dependent and geographically - dependent. An inventory description identifies a particular release of a product (full description, rather exhaustive). The physical references of a product release (actual files, access URL, associated-complementary files) are also included in the inventory. The inventory will count numerous records, but concern releases of a limited number of products.
    Inventory will be used by search tools to refine a request.
  • A Product Line is a reference in Mersea product catalogue. It is associated to a unique time-independent description (product fact sheet). The product description should show general characteristics of a product regardless periods of release as well as the access conditions. It aims at making users understand the nature of the product and its possible applications.
    Catalogue is for users, therefore description should cover generic presentation and support easy and quick discovery as well as marketing and promotion aspects.
  • Mersea interoperable catalogue will be implemented as metadatabases and their entries will be described as Discovery Metadata.
    For purposes of standardization and international exchange it was decided to adopt the ISO 19115 metadata standard and to prepare the Mersea metadata as dedicated subsets of this standard to make them ISO compliant. The resulting metadata formats will be translated to XML schema's, because this will support the interoperability with other systems and networks. The ISO19115 XML schema will provide the basis and will be used as reference model.

Important Note:

    Mersea products and services must be declared to the Mersea Integrated System for different classes of users in order to granted the access to users. All data provider should consequently declare their data products to the catalogue by filling in the catalogue forms and sending them to .
    In the attached document, you will find a description of the Catalogue and its format. It also contains a number of examples, that already have been prepared by a few data provider, and that will support you in interpreting the format fields. The document annex comprise the Parameter Discovery Vocabulary (PDV), prepared and managed by BODC (UK) and a List of Geographic Datums, prepared and managed by EPSG

    Existing references for Mersea Integrated System:

Common Data Format Structure

  • Mersea first requirements and recommendations are issued from the current stage of existing data centers and their own requirements and revision process as well as results from the MERSEA-Strand-1 intercomparison framework.They can be resumed as follows:
    • NetCDF portable and self describing structure format,
    • Convention / standardisation: COARDS/CF for name, International System with some factor scales for units, and more (cf. global attributes) to reach a multidisciplinary ocean gridded NetCDF Format.
  • To achieve this goal and reach data harmonization, there is a need for an iteration process with strong coordination between the various actors. MERSEA guidelines for grided data products contains more guidelines to follow than requirements for Mersea data provider. It is very useful for first time generation (format specification) and benefits from all feedback from current data providers. It provides guidelines and recommendations as to where to put information, and they provide advice as to what information you might want to include. Extra attributes are not outlawed and MERSEA recommends you include as much information as possible.
  • To help the system performances, the data provider will also have to take care of the following points:
    • Volume and character of the data stream
    • Anticipated volume and data rates and retention period
    • Strength and limitation of dissemination and viewing services
    • Requirements for security and/or restricted access

Important Note:

    The attached document entitled "Guidelines for Mersea Data Provider: Gridded Data Product Format" is very useful for first time generation (format specification) and benefits from all feedback from current data providers. For existing products, it gives nice inputs for format revision. The first part of the NetCDF structure format is more a 'cosmetic issue' but it is time now to work on it so the products are homogeneously described. The second part show comments like 'mandatory' (which take into account the current stage, it is the base line), 'strongly advised' and' optional' items which we could be taken as requirements for product enhancements.
    We still are in an iteration process to produce a good reference document. Elements written in red are to be checked or written. For any correction or enhancements, please iterate with and help us improve this reference document.

    Existing references for data products:

Data Transport & Exchange Procedures

  • Mersea main recommandation was to let the data be managed independently at participating sites and to rely consequently on a decentralised but compatible system architecture for distribution on Internet. To allow synctatic and semantic operability, MERSEA selected the Opendap technology as a good vector. FTP can of course remain an excellent complement to Opendap technology. Data centres are also recommended to keep this offer to users.
  • "OpenDAP" stands for "Open-source Project for a Network Data Access Protocol". OpenDAP is both the name of a non-profit organization and the name of the protocol which the OpenDAP organization has developed (see http://www.opendap.org ). It has been widely used, serving the marine community since 1995 and serves already a broad range of data, including oceanographic, atmospheric, and even astronomical data (cf. the Opendap master data sets list).
    Open DAP is an operational component of IOOS for access to gridded data. OpenDAP servers are available for download without licensing costs.
    Note: OPeNDAP was formerly called DODS (Distributed Oceanographic Data System).
  • The Opendap technology allows the users, where ever he is, to access whatever data they require in a form they select (image, ASCII, NetCDF, etc.), using client applications they already are familiar with (IDL, Matlab, Ferret, netCDF Operators, spreadsheets operators, LAS , MapServer, etc.).Alternatively, a simple internet browser may be used as a client and allows to download data from the server.
  • OpenDAP data server is a middleware (XML native + java servlets) that has been designed to distribute large data sets on Internet (uniform access to scientific data on the Internet - HTTP protocol -) and minimize the barriers to sharing them. It converts transparently from a number of commonly used data formats (NetCDF, GRIB, HDF4, MATLAB®, ASCII), into the format appropriate for the analysis package. OpenDAP also allows a client to request only a subset of a dataset (and aggregation) (selection of parameters at given space and time windows, compose a time series) as well as function evaluation like statistics functions (basic operation between parameters, mean computation, use of thresholds, etc.). At the other end, an OPeNDAP client, integrated into familiar analysis and visualization software packages access the data.
  • The Opendap technology provides strong support for data stored in NetCDF as well as for users of NetCDF enabled programs.

Important Note:

    The attached document entitled "Guidelines for Mersea Data Provider: Quick OpenDAP Installation & Configuration Guide" (version C) gives guidelines to Mersea data provider on which OpenDAP to select, how to find easily the information as well as our feedback on the Grads and Aggregation Data Server (AS & GDS) for installation, configuration & Mersea federating operations.
    The document contains 3 main sections:

    1. Mersea recommendations for the OpenDAP technology for data dissemination together with an OpenDAP overview, the list of current OpenDAP servers and clients and pro's and con's between GRADS and AS.
    2. Guidelines for OpenDAP installation & configuration including information on where to find it, which version to use, where to get the installation & configuration documentation, and our feedback for AS and GrADS prerequisites, installation and configuration.
    3. Routine operations needed for individual OpenDAPs and Mersea Federation System to reach an operational Mersea Integrated System (e.g. monitoring function and synchronization with a front-end server like Live Access Server…).
    We still are in an iteration process to produce a good reference document. Elements written in red are to be checked or written. For any correction or enhancements, please iterate with and help us improve this reference document.


Tools to Select, Browse and Manipulate the Data

  • Above Opendap is the Live Access Server (LAS), an Opendap client applications which enables user-friendly visualisation and/or data extraction without specific knowledge of Opendap technology. LAS allows various ways to visualise the data (maps, sections, time evolution, etc.) and offers means for intercomparison between two kinds of comparable data (e.g. remote sensing data and model outputs) and for basic statistics (average and standard deviation).

 

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