Frequently Asked Questions

METAMOD was initially developed to support scientific projects with data management. Development has focused on a cost effective system where several projects or operational services can share the same backend while maintaining a custom built user interface specific for each project. One METAMOD implementation may support many METAMOD instances. The first instance always own the database and some maintenance and configuration aspects are only available through this instance.

METAMOD was developed to support data management focusing on:

1. Metadata handling
   1. Human and machine interfaces
   2. Import/export using standardised interfaces
2. Support for dataset uploading
   1. Interactive and automated
      1. Through web interface, FTP, scp etc
   2. Ad hoc and regular data streams
   3. Configurable conformance check of NetCDF/CF files uploaded
3. Automatic extraction of metadata from datasets uploaded
   1. When uploaded as NetCDF/CF following the convention of METAMOD
4. Connection to online datasets
   1. METAMOD is usually linked to a THREDDS Data Server actually serving the data sets

The runtime environment is generated during installation of the software (see the README file coming with the software for details). Basically the following procedure is used to set up a METAMOD instance:

1. Edit master_config.txt under app/<appname>
2. Run update_target.pl found in source code using the user owning the web server
   1. This creates a runtime source code tree located as defined within master_config.txt
3. If a first time set up, run create_and_load_all.sh located within the runtime source code tree directory init
4. Run prepare_runtime_env.sh located within runtime source code tree root directory
5. Start the system by running metamodInit.sh located in the runtime source code tree root directory

If changes are made to master_config.txt, repeat steps 1, 2, 4 and 5 and remember that all scripts need to be run as the user owning the web server. In step 5 use e.g. sudo -u wwwuser ./metamodInit.sh restart or the two step procedure of first stopping and then starting the server.

The visual appearance of METAMOD is determined by style sheets and contents of the master_config.txt file. Style sheets are located in the directory named htdocs within the runtime source code directory of METAMOD. Appearance of most of the web pages, including buttons can be changed by changing the corresponding style elements within the following style sheets:

1. htdocs/style.css - Main style sheet determining the appearance of main menus and containers.
2. htdocs/sch/style.css - Style sheet used by the search interface.
3. htdocs/upl/style.css - Style sheet used by the upload interface.
4. htdocs/qst/style.css - Style sheet used by the quest interface.

METAMOD has two main menu containers. One top left (available within all modules) and one left (mainly in the search module and the upload). The top left menu is set up using the APP_MENU tag of the master_config.txt.

The search module menu is configured using the SEARCH_CATEGORY_SEQUENCE of the master_config.txt. This is configured using numbers (defined within the file searchdata.xml) where the following mapping apply by default¹⁾:

1. Activity type
2. Area
3. Variables (hidden)
4. Topics and variables
5. TBW
6. TBW
7. Institutions
8. Datacollection period
9. Map search
10. Operational status

In addition the keyword Fulltext can be used.

In order to add new search categories the following sequence is required:

1. Edit the file searchdata.xml (located within directory app/<appname>/staticdata)
2. Reinitialise the static part of the database by running the script import_searchdata.pl which is located in the runtime directory <appname>/scripts with searchdata.xml as input

If several METAMOD instances are using the same database, this has to be done in the METAMOD instance that actually own the database. If the database has been running for a while, reinitialisation may take some time during which the METAMOD instances using the database will be unavailable.

Open Archive Initiative Protocol for metadata harvesting has been supported for a time. Support for ISO23950/Z39.50 (SRU implementation) is currently under implementation and is expected in the next release.

METAMOD use an internal metadata standard that is mapped to Dublin Core, GCMD DIF and ISO19115²⁾.

Information and schemata of the metadata-files used since Metamod 2.1 can be found under XML format for dataset descriptions.

http://your.metamod.installation/pmh/oai2.php?verb=ListRecords&metadataPrefix=iso19115

The metadata structure is configurable, so this question must relate to a specific application of the database. The answer below is based on the applications implemented at met.no, which corresponds more or less to the EXAMPLE application available as part of the SVN source tree.

The METAMODPMH module contain a translation from the database to DIF XML. For the time being, this translation is implemented in a PHP script oaidp-config.php. This script contains an array which defines the translation:

      $key_conversion = array(
         '!DS_name 1', 'Entry_ID', '',
         'title', 'Entry_Title', '',
         'PI_name', 'Data_Set_Citation Dataset_Creator', '',
         'title', 'Data_Set_Citation Dataset_Title', '',
         'institution', 'Data_Set_Citation Dataset_Publisher', '',
         'dataref', 'Data_Set_Citation Online_Resource', '',
         'variable', '*Parameters Category', 'EARTH SCIENCE',
         'variable 1', 'Parameters Topic', '',
         'variable 2', 'Parameters Term', '',
         'variable 3', 'Parameters Variable_Level_1', '',
         'variable', 'Parameters Detailed_Variable', '',
         'topiccategory', 'ISO_Topic_Category', '',
         'keywords', 'Keyword', '',
         'datacollection_period 1', 'Temporal_Coverage Start_Date', '',
         'datacollection_period 2', 'Temporal_Coverage Stop_Date', '',
         'southernmost_latitude', 'Spatial_Coverage Southernmost_Latitude', '',
         'northernmost_latitude', 'Spatial_Coverage Northernmost_Latitude', '',
         'westernmost_longitude', 'Spatial_Coverage Westernmost_Longitude', '',
         'easternmost_longitude', 'Spatial_Coverage Easternmost_Longitude', '',
         'area 1', '*Location Location_Category', '',
         'area 2', 'Location Location_Type', '',
         'area 3', 'Location Location_Subregion1', '',
         'area 4', 'Location Detailed_Location', '',
         'latitude_resolution 1', 'Data_Resolution Latitude_Resolution', '',
         'longitude_resolution 1', 'Data_Resolution Longitude_Resolution', '',
         '!DS_ownertag 1', 'Project Short_Name', '',
         'distribution_statement', 'Access_Constraints', '',
         'institution', 'Originating_Center', '',
         '', 'Data_Center Data_Center_Name Short_Name', 'met.no',
         '', 'Data_Center Data_Center_Name Long_Name', 'Norwegian Meteorological Institute',
         '', 'Data_Center Data_Center_URL', 'http://met.no/',
         '', 'Data_Center Personnel Role', 'DATA CENTER CONTACT',
         '', 'Data_Center Personnel First_Name', 'Egil',
         '', 'Data_Center Personnel Last_Name', 'Støren',
         '', 'Data_Center Personnel Phone', '+4722963000',
         '', 'Data_Center Personnel Contact_Address Address', "Norwegian Meteorological Institute\nP.O. Box 43\nBlindern",
         '', 'Data_Center Personnel Contact_Address City', 'Oslo',
         '', 'Data_Center Personnel Contact_Address Postal_Code', 'N-0313',
         '', 'Data_Center Personnel Contact_Address Country', 'Norway',
         'references', 'Reference', '',
         'abstract', 'Summary', '',
         '', 'Metadata_Name', 'CEOS IDN DIF',
         '', 'Metadata_Version', '9.7',
         '!DS_datestamp', 'Last_DIF_Revision_Date', '',
         '', 'Private', 'False',
      );

In this array, triples of three consecutive elements (starting with elements 0, 1 and 2 on the first line) constitute the translation of one metadata item in the database to one XML element in the DIF.

Each triple comprise the following components:

1. Name of metadata type in the database (or an empty string)
2. Sequence of element names used in the DIF
3. Constant value

If these three components has, for example, the following contenet:

'institution', 'Data_Set_Citation Dataset_Publisher', '',

and “METNO Norwegian Meteorological Institute” is the value in the database found for the 'institution' metadata type, then the following text will be part of the DIF XML:

<DIF ...>
  ...
  <Data_Set_Citation>
    ...
    <Dataset_Publisher>METNO Norwegian Meteorological Institute</Dataset_Publisher>
    ...
  </Data_Set_Citation>
  ...
</DIF>

The sequence of triples in the array define the sequence of the elements in the DIF XML. If possible, one triple will use the same higher level XML elements as the previous triple.

These points constitute the general rule, but some special rules apply:

1. If an '!' prepends the metadata type name, the name represents a field name in the Datasts table instead.
2. If the third component in the triple (the constant value) is non-empty, it is used as the value in the DIF XML. The first component will then usually be empty.
3. A number may follow the metadata type name. This indicate a spacial conversion of the metadata value in the database. This conversion is implemented in the get_exception.php routine.
4. If several consecutive triples have the same metadata type name, they will appear as consecutive elements in the DIF XML. When this is the case, different conversions of the metatdata value will take place (indicated by a number as explained above).
5. Several metadata values for the same metadata type and dataset, produce several DIF XML elements.
6. An asterix (*) prepending an element name in the sequence of element names will force the start of a new DIF XML element at this level. (Othervise, new elements will, if possible, add to an already started higher level element).

METAMOD has extended support for NetCDF/CF files where conformance checks and automatic extraction of metadata are supported. Some relevant information concerning NetCDF/CF can be found here:

• NetCDF
• NetCDF - best practises
• CF metadata standard
  • CF Overview (Talk)
  • CF Overview (Paper)
• NetCDF Operator provides useful software e.g. to concatenate files

Common Data Language provides an ASCII representation of NetCDF files. METAMOD do support direct upload of CDL files and will perform the same conformance checks in CDL as on NetCDF/CF files, as well as conversion to NetCDF/CF.

The following global attributes are required in NetCDF/CF files uploaded through METAMOD for proper stewardship. Please note that this is a minimum requirement and is subject to change (some proposed changes are indicated below).

Name	Purpose	Status	Comment
title	A short description of the data set	Active
abstract	A short summary of the data collection activity and data set. This element may alternatively be provided as the global attribute “comment” in a NetCDF file.	Active
topiccategory	A blank separated list of topic keywords describing the dataset.	Active
keywords	A blank separated list of keywords describing the dataset.	Active, TBR	Controlled vocabulary
gcmd_keywords	Newline separated list of GCMD scientific keywords describing the various variables. This will be used to categorize the datasets according to the “Topics and variables” menu selection in the metadata search facility. If proper standard names have been used for the variables, data will be mapped for search under Topics and variables even without the gcmd_keywords attribute.	Active	Controlled vocabulary
activity_type	Comma separated list of activity types.	Active	Controlled vocabulary
operational_status	Status of the dataset, being one of Experimental Pre operational Operational Scientific	Active	Controlled vocabulary
Conventions	The metadata convention used, should be CF-1.x where x=1, 2, or 3.
product_name	A product name of the dataset.	Active	Controlled vocabulary
history	Modification history of the dataset. Should be of the form: 2007-05-12 creation 2007-06-10 revision and separated by newlines.	Active
area	Area name describing the geographical area being studied.If several area names are used, separate them using comma.	Active	Controlled vocabulary
southernmost_latitude	Elements to describe a geographicalbounding box for the data. Should be a floating point value (decimal degrees).	Active
northernmost_latitude	Elements to describe a geographicalbounding box for the data. Should be a floating point value (decimal degrees).	Active
westernmost_longitude	Elements to describe a geographicalbounding box for the data. Should be a floating point value (decimal degrees) with positive values towards the East.	Active
easternmost_longitude	Elements to describe a geographicalbounding box for the data. Should be a floating point value (decimal degrees) with positive values towards the East.	Active
start_date	Start date and time of the dataset in the form 2007-06-12 12:30:00 UTC	Active
stop_date	Stop date and time of the dataset in the form 2007-06-12 12:30:00 UTC	Active
institution	Name of the institution responsible for the dataset.	Active	Controlled vocabulary
PI_name	Name of the person responsible for the data set.	Active
contact	email address to responsible user support or principal investigator. If the email address of the principal investigator is used, the variable PI_name should be set accordingly.	Active
distribution_statement	A distribution statement describing the conditions for distributing and access to the dataset.	Active	Controlled vocabulary
use_statement	A use statement describing conditions for using the dataset.	Proposed	Controlled vocabulary
project_name	Name of the project within which the data were collected. Several project dependencies can be indicated using comma separated project names.	Active	Controlled vocabulary