METAMOD: User database

Design

Database tables

User

U_id	A_id	U_name	U_email	U_password	U_institution	U_telephone	U_session

DataSet

DS_id	U_id	A_id	DS_name

Info

DS_id	I_type	I1_id	I2_id	I_attribute	I_content

File

DS_id	F_name	F_timestamp	F_size	F_status	F_errurl

The table details are presented below:

User

U_id	Unique user id (autoincremented number). Primary key
A_id	Application id. Many METAMOD applications share the same database. This field has the same value as the APPLICATION_ID in the master_config.txt file.
U_name	User name as given in registration form
U_email	User E-mail address as given in registration form
U_password	User password
U_institution	User institution acronym as given in registration form
U_telephone	User telephone number as given in registration form
U_session	User session id. Random string generated when the user initiate a new interactive session.

The U_session field is used to track the state of an interactive user session. The user may only have one interactive session active at any time. If the user initiate a new session when another session is already active, the old session disappears. If the user tries to continue the old session, an error message will be submitted. This is the same mechanism used in the old (METAMOD 2.3 and earlier) file-based version.

The A_id field connects the user to one of the METAMOD applications that share the same database. If the same person wants to be a user of more than one of these METAMOD applications, she/he must apply for a user account in each application, and the database will contain independent rows in the user table, one for each application.

DataSet

DS_id	Unique dataset id (autoincremented number). Primary key. Not same number as in the Metadata Database
U_id	Identifies the user owning the dataset.
A_id	Application id.
DS_name	Dataset name. Name of dataset as provided by the user. Not the same name as in the corresponding field in the Metadata Database. But the last part of the name found in the Metadata Database field (everything after '/') will correspond to this field.

The combination of the A_id and DS_name fields will provide an alternative unique key that can be used to find a dataset without knowing the owning user.

Info

This table is used to contain various information about a dataset. Each piece of information is identified by the dataset it belongs to (DS_id) and a type tag (I_type) that is a short acronym for a limited set of information types. One piece of information can be contained in one or several table rows (these are all the rows identified by a DS_id,I_type value pair).

Two extra identification fields are used to implement structure to each piece of information: I1_id and I2_id. These are integers >= 0. In the simplest case, when the piece of information is just a single entity represented as a text string, the piece of information is contained in one row where both of these integers are 0. By using several rows with different I1_id and I2_id, it is possible to implement various structures like:

Single entity (as described above).

Two-level hierarchy: Multiple entities where each entity has children or attributes.

Three-level hierarchy: Like a two-level hierarchy with an additional entity alone at the top. This entity may have its own attributes.

I1_id will always represent a consecutive set of integers starting from 0, and for each of these numbers, I2_id will comprise a similar consecutive set of integers starting from 0. The max value for I2_id will vary between different I1_id values.

DS_id	Identifiles the dataset this info-row belongs to
I_type	Type tag. Short acronym that identifies the information type.
I1_id	Major integer identifier (see above).
I2_id	Minor integer identifier (see above).
I_attribute	Attribute name. Optional acronym to identify an attribute. If found, the I_content field is interpreted as an attribute value that software may treat specially.
I_content	The actual text string representing an entity or attribute value.

For the time being, the following information types (I_type) will be needed:

DSKEY	Dataset key (also called directory key or dirkey) as provided by the user. Single entity
LOCATION	Location. Single entity. Absolute path to the directory under which all files belonging to the dataset are found. The files may be found directly in the location direcory, or in any subdirectory of the location directory at any level.
CATALOG	Partial URL to a THREDDS dataset. Single entity. Combined with the file name, this URL can be used to access the content of a file through a TDS server. It can also provide the URL that points to the THREDDS catalog containing the METAMOD dataset.
WMS_URL	URL to the WMS service that can display data from the dataset. Single entity.
WMS_PARAM	Parameter. Two-level hierarchy. Each entity at the top level (I1_id >= 0, I2_id == 0) identifies a parameter that can be displayed in WMS. Each parameter may have one attribute (I1_id >= 0, I2_id == 1) representing a palette (for example “BOXFILL/redblue”) found in a style element in the GetCapabilites document. If no attribute is found, a default palette is used for the parameter. The I_attribute field of the attribute rows are set to “palette”.

Additional information types may be added later, for example to implement projection information:

PROJECTION	Three-level hierarchy used to represent reprojection information. The top level entity (identified by I1_id,I2_id == 0,0) contains attributes: urlRegex (I1_id,I2_id == 0,1) and urlReplace (I1_id,I2_id == 0,2). The second level (I1_id > 0, I2_id == 0) represents each projection the user has asked for (“Lat/Long”, “Stereo” etc.). Each projection has attributes: method, projString, xAxis, yAxis and toDegree (I2_id > 0).

File

DS_id	Dataset this file belongs to. Part of primary key.
F_name	Name of file. Part of primary key.
F_timestamp	Timestamp of last change
F_size	File size (bytes)
F_status	Status (OK or errors)
F_errurl	URL to error report (if errors)

This table is used to display recent changes to the data provider. It will not contain a complete inventory of files in the repository. This table will be purged (rows with old timestamps removed) periodically.

API design

This paragraph defines a set of subroutine/function calls that are used to read and write information to/from the user database. These functions will be implemented in PHP and/or Perl as needed.

The functions are defined as methods in a Userbase class. Inside a Userbase object, there may be a current user and a current dataset. The current user will always own the current dataset. There may also be a current file that will belong to the current dataset.

Open/close functions

Method	Purpose	Parameters
new	Create a new Userbase object and set up a connection to the User database	OUT: Userbase object reference
close	Save any pending changes to the database, and close the connection	None
revert	Revert any changes to the database made by this Userbase object. Close the database connection.	None

User functions

Method	Purpose	Parameters
user_find	Search for an existing user in the database and make him/her the current user.	IN: User E-mail address, application id (A_id).
user_create	Create a new user and make it the current user.	IN: User E-mail address, application id (A_id).
user_set	Set user properties for the current user	IN: Property name (one of 'U_name', 'U_password', 'U_institution', 'U_telephone', 'U_session'), property value
user_get	Get user properties for the current user.	IN: Property name (one of 'U_name', 'U_password', 'U_institution', 'U_telephone', 'U_session'). OUT: property value
user_first	Make the first user in the database the current user.	OUT: true if found, false if no users exist.
user_next	Make the next user in the database the current one.	OUT: true if found, false if already last user.

Dataset functions

Method	Purpose	Parameters
dset_create	Create a new dataset and make it the current dataset. The current user will be the owner of the new dataset.	IN: Dataset name, dataset key.
dset_find	Find a dataset in the database and make it the current dataset. Also make the user that owns the dataset the current user.	IN: Application id, dataset name. OUT: true if the dataset is found, false otherwise.
dset_first	Make the first dataset (owned by the current user) the current dataset	OUT: true if found, false if no such dataset exists.
dset_next	Make the next dataset (owned by the current user) the current dataset.	OUT: true if found, false if already last dataset.

Dataset information functions

Method	Purpose	Parameters
info_get_structure	Get an integer array describing the structure of one “piece of information” in the current dataset.	IN: Information type (I_type). OUT: Integer array indexed by the I1_id values. Each array element represents the number of rows in the given “piece of information” where I1_id == the array index value. In other words: for each I1_id value, the correspnding number of I2_id values.
info_get	Get information from the current dataset.	IN: Information type (I_type), I1 (value for the I1_id field), I2 (value for the I2_id field). OUT (array of two elements): Attribute name (empty if no attribute), entity or attribute value.
info_get_by_attribute	Get information from the current dataset for a given attribute.	IN: Information type (I_type), I1 (value for the I1_id field), attribute name. OUT: attribute value, false if not found.
info_put	Add or replace entities/attributes in the current dataset.	IN: Information type (I_type), I1 (value for the I1_id field), I2 (value for the I2_id field), attribute name (empty means no attribute), attribute/entity value.

File functions

Method	Purpose	Parameters
file_find	Search for an existing file (owned by the curent dataset) and make it the current file.	IN: File name (F_name). OUT: true if found, false otherwise.
file_create	Create a new file (for the current dataset) and make it the current file.	IN: File name (F_name)
file_set	Set file properties for the current file	IN: Property name (one of 'F_size', 'F_status', 'F_errurl'), property value
file_get	Get file properties for the current file.	IN: Property name (one of F_name', 'F_size', 'F_status', 'F_errurl', 'F_timestamp'). OUT: property value
file_first	Make the first file (in the current dataset) the current file.	OUT: true if found, false if no files exist.
file_next	Make the next file in the database the current one.	OUT: true if found, false if already last file.