Application Architecture¶

This section contains technical details about the current implementation of the Canadian Aquatic Barriers Database (CABD) back-end application, including feature and vector tile services and the CABD data dictionary. The intended audience are software developers and similar technical users looking to upgrade/maintain the current system or use the API endpoints.

Existing Implementation¶

The current application runs on two Microsoft Azure Java Web App servers, cabd-web (for CABD data) and chyf-web (for CHyF data).

Features and Database Models¶

CABD Feature Model¶

Generic Feature Model¶

Features in CABD have an optional hierarchical structure. Feature types can be combined to form “super feature types”.

There are no structures in the software/database that enforce this model. The database views (see section below) are used to define the various feature types and super types. It would be possible for a feature type to be associated with multiple super types, if desired.

Implemented Feature Model¶

There are currently three feature types and one super type implemented in CABD. Adding additional feature types is expected and the instructions for this are outlined below (How to add new Feature Type).

Feature types:

barriers - a super feature type that includes dams, other structures, waterfalls, and modelled crossings.
dams - a feature type for features classified as a dam or other structure.
waterfalls - a feature type for features classified as a waterfall.
fishways - a feature type for features classified as a fish passage structure.
modelled crossings - a feature type for features classified as a modelled stream crossing.
stream crossings - a feature type for features classified as a stream crossing.

CABD Database Model¶

The database is structured into multiple schemas. Each feature type has its own schema, with a common cabd schema for shared data and feature metadata.

Feature Views¶

Each feature type and super feature type has two associated views which support the API - one view for Engligh (_en) and one view for French (_fr). These views should include all fields required for output (either for display on the UI or to support the future editing API).

The view cabd.all_features_view_<en/fr> supports all feature api endpoints.

Views are used to support the CABD APIs that list features. Each feature type is linked to a database view. When requesting features of a specific type the view associated with this type is queried. The fields returned by this view populate the attributes of the feature returned by the API. Feature type views will generally query a single data table (for example, the dams view queries the dams data table). Super feature types will generally query multiple data tables (for example, the barriers view queries both the dams data table and the waterfalls data table).

Feature Update View¶

By design each feature includes an updates_pending attribute that is populated with true or false depending on if there are feature updates pending review in the system. This field is populated by the system using the cabd.updates_pending view. This view should return a single column, cabd_id, for each feature that has a review pending in the database.

Core Tables¶

These tables are the core tables for the system and required regardless of the feature types loaded. They support the definition of feature types.

cabd.feature_types

Lists all the feature types supported by the system.

Column	Description
type	Unique identifier for feature type. Required.
data_view	The root name of the data view supporting the feature type. This is the view name without the language suffix (ex. dams_view). Required.
name_en	The English human readable name for the feature type. Required.
name_fr	The English human readable name for the feature type. Required.
attribute_source_table	The data table containing the attribute data source information for the feature type. This is optional and can be null.
default_featurename_field	The field in the data_view that represents the main feature name.
feature_source_table	The data table containing a link between the features and the data source information. This is optional and can be null.
data_version	The version number of the data for the feature type. This version number is included in exports.

cabd.attribute_set

Lists the attribute sets supported by the system. Attribute sets allows user to specify which attributes the want included in API results that list features.

Notes:

The attribute set should not have the name “vectortile”. The system generates a vectortile attribute set automatically that is linked to the include_vector_tile field in the cabd.feature_type_metadata and used for the vector tile service.
The attribute “url” which provides a url to link to the full CABD feature is included in all JSON output for all attribute sets. There is no option to remove it. It is NOT included in other export formats (shape, geopackage, kml).

Column	Description
name	The unique name of the attribute set.
ft_metadata_col	The name of the column in the cabd.feature_type_metadata table that identifiers which attributes are to be included and in what order. This column must exist in this table with values 1..n for attributes to be included in the results or null for attributes to be excluded.

cabd.feature_type_metadata

Lists all the attributes for a given feature view and the metadata details about the attribute.

Column	Description
view_name	The data view name.
field_name	The field name in the data view that represents this attribute.
name_en	The English name of the attribute.
name_fr	The French name of the attribute.
description_en	An English description of the attribute.
description_fr	A French description of the attribute.
is_link	Boolean. If true this attribute will be treated as a URL in the API. The value will be returned in URL format (For example: link to another feature).
data_type	The data type for the attribute. Valid values: varchar(xxx), text, boolean, array(type), integer, double, uuid, date, geometry.
value_options_reference	For columns that have a defined list of valid values in another database table (for example: `province_territory_code`), this field identifies what table the values can be loaded from and what fields in the table that provide the value, name, and description. This column should be null for fields that don’t reference tables. The string should be of the form `<tablename>;<valuefield>;<namefield>;<descriptionfield>;<geometryfield>`. Only `tablename` and `namefield` are required, all others can be blank. The `tablename` references the code table, the `valuefield` the value field in the code table, the `namefield` the human friendly name field in the table, and `descriptionfield` the description field in the table. The name and description fields should exclude the language suffix and each reference table should have both _en and _fr columns for the name and description fields. The `geometryfield` is for tables that include geometry boundaries (nhn_workunit) and for whose bounding box extends we want included in the metadata. If supplied the metadata output includes bbox field representing the bounding box of the geometry in lat/long (SRID 4617). For example: `dams.use_codes;code;name;description` or `cabd.province_territory_codes;code;name;` or `cabd.nhn_workunit;id;name;;polygon`
is_name_search	True if field to be included in the name API search. Should be set to true fo any attributes that represent the feature name or want to include when searching by name.
shape_field_name	The field name for shapefile exports of features.
vw_<attributeset>_order	Metadata for the UI. These fields represents the order the attribute should appear in the ui for a given attribute set. The value should be null for attributes to be excluded from the results for the given set. There should be one column for each attribute set listed in the cabd.attribute_set table.
include_vector_tile	Boolean. If true this attribute will be included in the vector tile service.

cabd.data_source

Lists data sources. Supports data source tracking for feature type attributes.

Column	Description
id	A unique identifier for the data source.
name	Name of the data source (matches short names listed on the data sources page).
version_date	Data source version date.
version_number	Data source version number (optional).
source	A link to the source data or full reference and description of where the source data came from.
comments	Any additional comments about the data source.
source_type	Type of data source (spatial or non-spatial).

cabd.contacts

A list of contacts relevant to the CABD database. Currently, contacts are only created when a user submits a feature update.

Column	Description
id	unique system generated number
email	Users email
name	Users name
organization	(Optional) Organization associated with the user
datasource_id	(Optional) Link to the cabd.data_source table which represents the datasource associated with this user.

cabd.user_feature_updates

Users can use the Features API to submit updates to features. All submissions are stored in this table.

Column	Description
id	unique system generated identifier
datetime	Date time of submission
contact_id	Link to the contact who submitted the change
cabd_id	Link to the feature the update references
cabd_type	CABD feature type
user_description	The user provided description of the update
user_data_source	The user provided data source
status	Internal field representing the status of the update. This is managed by the CABD administrators.

Shared Attribute Tables¶

All of these tables store data that are shared between multiple feature types. Generally, each of these tables have a unique code (for references), a name, and a description.

cabd.barrier_ownership_type_codes
cabd.fish_species
cabd.nhn_workunit
cabd.passability_status_codes
cabd.province_territory_codes
cabd.upstream_passage_type_codes
cabd.census_subdivisions

Feature Tables¶

The feature type data tables are found in their corresponding schema. Generally, there will be one feature data table and a number of reference tables that represent attribute values. Details for current feature types can be found in the Data Dictionary document.

Feature Type Attribute Data Sources¶

The CABD database has the option of storing the data source for each attribute associated with the feature type. This has been implemented by having <featuretype>.<featuretype>_feature_source and <featuretype>.<featuretype>_attribute_source tables for the feature type (e.g., dams.dams_feature_source and dams.dams_attribute_source).

For each cabd feature, the <featuretype>_feature_source table contains a link to the data sources and associated data source feature ids that the feature was found in. For example, a dam feature that was found in both the nrcan_canvec_mm and bceccs_fiss data sources would have two entries for its cabd_id in the <featuretype>_feature_source table.

<featuretype>_feature_source

Column	Description
cabd_id	The unique cabd feature identifier. This id must exist in the corresponding data table for the feature type.
datasource_id	A link to the data source id in the cabd.data_source table
datasource_feature_id	The identifier of the feature in the data source.

The <featuretype>_attribute_source table contains the cabd_id and one column for each attribute that requires data source tracking. The column, <attribute>_ds, links to the cabd.data_source table to identify the data source for the attribute value.

<featuretype>_attribute_source

Column	Description
cabd_id	The unique cabd feature identifier. This id must exist in the corresponding data table for the feature type.
<attribute1>_ds	A link to the data source id in the cabd.data_source table that <attribute1> comes from for the feature.
<attribute2>_ds	A link to the data source id in the cabd.data_source table that <attribute2> comes from for the feature.

Audit Log / Change Tracking¶

The CABD database has tracks changes to the following tables:

cabd.contacts
cabd.fish_species
cabd.data_source
dams.dams
dams.dams_attribute_source
dams.dams_feature_source
waterfalls.waterfalls
waterfalls.waterfalls_attribute_source
waterfalls.waterfalls_feature_source
fishways.fishways
fishways.fishways_attribute_source
fishways.fishways_feature_source
fishways.species_mapping

New feature types can also include change tracking by applying the appropriate triggers to any new database tables that require change tracking.

All changes are logged in the cabd.audit_log table. This table has the following columns:

Column	Description
revision	Unique incrementing revision number
datetime	The timestamp of associated with the change
username	The user who made the change. This is the postgresql user who made the change
schemaname	The schema of the modified table
tablename	The name of the modified table
action	INSERT, UPDATE, or DELETE
cabd_id	The CABD feature id if applicable or null if not applicable. This field will be populated for most changes but will not be populated for changes to the contacts, fish_species, and datasources tables.
datasource_id	The datasource id if applicable or null. This field will be populated with the table has a datasource_id field that is part of the primary key for the table.
id_pk	The primary key for the row being modified if applicable or null. This field is populated for tables whose primary keys are not cabd_id or datasource_id (for example contacts and fish_species).
oldvalues	The original values of the row (before updating). This only includes values that were modified.
newvalues	The new values for the row. This only include values that have been modified. Values that remain the same are not included.