HydroServer Data Model Data Dictionary

This document describes the Django model fields that back HydroServer's core data model.

Attribute names below use the persisted model field names in snake_case. Foreign keys are shown as the stored *_id values. The API uses camelCase aliases.

M = Mandatory O = Optional

Datastream

A Datastream groups a collection of Observations measuring the same ObservedProperty and produced by the same Sensor. Each instance of a Datastream represents the properties for a time series of Observations.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the Datastream.	UUID
M	name	A text name for the Datastream.	String
M	description	A text description for the Datastream.	Text
M	sensor_id	A foreign key identifier for the Sensor or method used to create the Datastream.	UUID
M	thing_id	A foreign key identifier for the Thing on which or at which the Datastream was created.	UUID
M	observed_property_id	A foreign key identifier for the ObservedProperty associated with the Datastream.	UUID
M	unit_id	A foreign key identifier for the Unit used for Observations within the Datastream.	UUID
M	processing_level_id	A foreign key identifier indicating the ProcessingLevel for the Datastream.	UUID
M	observation_type	The type of Observation recorded in the Datastream.	String
M	result_type	The type of result represented by the Datastream.	String
O	status	A text value indicating the status of the Datastream.	String
O	observed_area	The spatial extent associated with the Datastream. This field exists in the database but is currently unused.	String
M	sampled_medium	The environmental medium sampled by the Datastream.	String
O	value_count	The number of Observations within the Datastream.	Integer
M	no_data_value	A numeric value used to indicate the absence of data.	Float
O	intended_time_spacing	A numeric value indicating the intended spacing between Observations.	Float
O	intended_time_spacing_unit	A string indicating the unit for intended_time_spacing.	String
M	aggregation_statistic	A text string indicating the aggregation statistic for the Datastream.	String
M	time_aggregation_interval	A numeric value indicating the time interval over which recorded Observations were aggregated.	Float
M	time_aggregation_interval_unit	A string indicating the unit for time_aggregation_interval.	String
O	phenomenon_begin_time	The time at which the activity began that results in the Datastream's Observations.	Datetime
O	phenomenon_end_time	The time at which the activity ended that results in the Datastream's Observations.	Datetime
O	result_begin_time	The timestamp of the first Observation in the Datastream. This field remains in the model but is currently unused.	Datetime
O	result_end_time	The timestamp of the last Observation in the Datastream. This field remains in the model but is currently unused.	Datetime
M	is_private	An access control flag indicating whether the Datastream metadata and data are private by default.	Boolean
M	is_visible	An access control flag indicating whether the Datastream should be shown in normal data-discovery responses.	Boolean

Location

The Location entity stores the location of a Thing. In the context of Things that are monitoring sites, this is the physical location of the monitoring site.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the Location.	UUID
M	thing_id	A foreign key identifier for the Thing to which the Location belongs.	UUID
M	name	A text string name for the Location.	String
M	description	A text string description for the Location.	Text
M	encoding_type	The encoding type of the Location, usually application/vnd.geo+json.	String
M	latitude	The latitude of the Location using WGS84 coordinates.	Decimal
M	longitude	The longitude of the Location using WGS84 coordinates.	Decimal
O	elevation_m	The elevation of the Location in meters.	Decimal
O	elevation_datum	A text string indicating the elevation datum used for the Location.	String
O	admin_area_1	A text string indicating the first-level administrative area for the Location.	String
O	admin_area_2	A text string indicating the second-level administrative area for the Location.	String
O	country	A two-character ISO country code for the Location.	String

NOTE: The database allows a Thing to have multiple Location rows, but the current Data Management API treats location as a single nested object on a Thing.

Observation

An Observation is the act of measuring or otherwise determining the value of a property, including its numeric result and the date/time at which it was observed.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the Observation.	UUID
M	datastream_id	A foreign key identifier for the Datastream to which the Observation belongs.	UUID
M	phenomenon_time	A datetime value indicating the time instant when the Observation happened.	Datetime
M	result	The numeric value of the Observation.	Float
O	result_time	The time that the Observation's result was generated, if different from phenomenon_time.	Datetime
O	quality_code	A text code indicating the quality of the Observation.	String
O	result_qualifiers	A many-to-many relationship to ResultQualifier. This is stored in a join table, not as an array column on Observation.	Many-to-many

NOTE: quality_code is persisted in the database, but the current Data Management API does not include it in the main observation schema. The API also uses resultQualifierCodes rather than exposing the join table directly.

ObservedProperty

An ObservedProperty specifies the phenomenon of an Observation, such as flow, temperature, pH, or dissolved oxygen concentration.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the ObservedProperty.	UUID
O	workspace_id	A foreign key identifier for the Workspace that owns the ObservedProperty. If omitted, the ObservedProperty is shared system-wide.	UUID
M	name	A descriptive name for the ObservedProperty.	String
M	definition	A text definition of the ObservedProperty or a URL pointing to a controlled definition.	Text
M	description	A text description of the ObservedProperty.	Text
M	observed_property_type	The type of ObservedProperty.	String
M	code	A brief text code identifying the ObservedProperty.	String

Organization

An Organization is a body of people having a particular purpose, such as a business, agency, research group, or laboratory.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the Organization.	BigInteger
M	code	A brief text code or abbreviation for the Organization.	String
M	name	A descriptive name for the Organization.	String
O	description	A text description of the Organization.	Text
O	link	A URL pointing to a website for the Organization.	URL
M	organization_type	A text string indicating the type of Organization.	String

User

Individual users who own workspaces, collaborate on data management, or manage account information in HydroServer.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the User.	BigInteger
M	username	The Django username field. HydroServer keeps this synchronized to the user's email address.	String
M	password	The stored password hash.	String
O	last_login	The datetime when the User last logged in.	Datetime
M	is_superuser	A boolean value indicating whether the User bypasses explicit permission assignments.	Boolean
O	first_name	The User's first name.	String
O	middle_name	The User's middle name.	String
O	last_name	The User's last name.	String
M	email	The User's contact email address.	String
M	is_staff	A boolean value indicating whether the User can access the Django admin site.	Boolean
M	is_active	A boolean value indicating whether the account is active.	Boolean
M	date_joined	The datetime when the User account was created.	Datetime
O	phone	The User's contact phone number.	String
O	address	The User's physical mailing address.	String
O	link	A URL pointing to a website for the User.	URL
M	user_type	A text string indicating the type of User.	String
O	organization_id	A one-to-one identifier for the Organization with which the User is affiliated. Each User may be affiliated with at most one Organization, and each Organization may be affiliated with at most one User.	BigInteger
M	is_ownership_allowed	A boolean value indicating whether the User may own workspaces.	Boolean

NOTE: groups and user_permissions are also persisted through Django auth many-to-many join tables, but they are not columns on the User row itself.

ProcessingLevel

The degree of quality control or processing to which a Datastream has been subjected.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the ProcessingLevel.	UUID
O	workspace_id	A foreign key identifier for the Workspace that owns the ProcessingLevel. If omitted, the ProcessingLevel is shared system-wide.	UUID
M	code	A brief text code identifying the ProcessingLevel.	String
O	definition	A text definition of the ProcessingLevel.	Text
O	explanation	A longer text explanation of the ProcessingLevel.	Text

ResultQualifier

Data qualifying comments added to individual data values to qualify their interpretation or use.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the ResultQualifier.	UUID
O	workspace_id	A foreign key identifier for the Workspace that owns the ResultQualifier. If omitted, the ResultQualifier is shared system-wide.	UUID
M	code	A brief text code identifying the ResultQualifier.	String
M	description	A longer text description or explanation of the ResultQualifier.	Text

NOTE: The database enforces a unique constraint on (code, workspace_id), including the system-wide NULL workspace scope.

Sensor

A Sensor is an instrument, method, or procedure used to produce Observations for a Datastream.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the Sensor.	UUID
O	workspace_id	A foreign key identifier for the Workspace that owns the Sensor. If omitted, the Sensor is shared system-wide.	UUID
M	name	A descriptive name for the Sensor.	String
M	description	A longer text description of the Sensor.	Text
M	encoding_type	A string indicating how the Sensor information is encoded.	String
O	method_code	A brief text code identifying the Sensor or method.	String
M	method_type	A text string indicating the type of Sensor or method.	String
O	method_link	A URL pointing to documentation that defines or describes the Sensor or method.	String
O	manufacturer	The name of the Sensor manufacturer.	String
O	sensor_model	The name of the Sensor model.	String
O	sensor_model_link	A URL pointing to documentation for the Sensor model.	String

NOTE: HydroServer uses the Sensor entity for both physical instruments and derived methods or procedures, such as transformations or rating-curve-derived values.

Thing

A Thing is an object of the physical world or information world that is capable of being identified and integrated into communication networks. In the context of HydroServer, a Thing is typically a monitoring station or site.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the Thing.	UUID
M	workspace_id	A foreign key identifier for the Workspace that owns the Thing.	UUID
M	name	A text string giving a name for the Thing.	String
M	description	A text string giving a description for the Thing.	Text
M	sampling_feature_type	A text string specifying the type of sampling feature.	String
M	sampling_feature_code	A text string specifying a shortened code identifying the Thing.	String
M	site_type	A text string specifying the type of site represented by the Thing.	String
M	is_private	An access control flag indicating whether the Thing is discoverable and whether its metadata is publicly available.	Boolean
O	data_disclaimer	A text string displayed with the Thing's data to specify any disclaimer.	Text

ThingTag

A key-value tag associated with a Thing.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the ThingTag.	BigInteger
M	thing_id	A foreign key identifier for the Thing to which the tag belongs.	UUID
M	key	The tag key.	String
M	value	The tag value.	String

ThingFileAttachment

A file attached to a Thing, such as a site photo, document, or supporting artifact.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the ThingFileAttachment.	BigInteger
M	thing_id	A foreign key identifier for the Thing to which the file attachment belongs.	UUID
M	name	The name of the attached file.	String
O	description	A text description of the attached file.	Text
M	file_attachment	The stored file object for the attachment.	File
M	file_attachment_type	A text string identifying the type of file attachment.	String

NOTE: The database enforces a unique constraint on (thing_id, name).

Unit

The unit of measure associated with the Observations within a Datastream.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the Unit.	UUID
O	workspace_id	A foreign key identifier for the Workspace that owns the Unit. If omitted, the Unit is shared system-wide.	UUID
M	name	A descriptive name for the Unit.	String
M	symbol	An abbreviation or symbol used for the Unit.	String
M	definition	A URL or text definition for the Unit.	Text
M	unit_type	The type of Unit.	String

Workspace

A Workspace is the ownership and access-control boundary for most HydroServer-managed resources.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the Workspace.	UUID
M	name	A descriptive name for the Workspace.	String
M	owner_id	A foreign key identifier for the User who owns the Workspace.	BigInteger
M	is_private	An access control flag indicating whether the Workspace is private.	Boolean

NOTE: The database enforces a unique constraint on (name, owner_id).

WorkspaceTransferConfirmation

A pending transfer record used when ownership of a Workspace is being transferred to another User.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the WorkspaceTransferConfirmation.	BigInteger
M	workspace_id	A one-to-one foreign key identifier for the Workspace being transferred. Each Workspace may have at most one pending transfer.	UUID
M	new_owner_id	A foreign key identifier for the new owner.	BigInteger
M	initiated	The datetime when the transfer was initiated.	Datetime

WorkspaceDeleteConfirmation

A pending confirmation record used when a Workspace deletion has been initiated.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the WorkspaceDeleteConfirmation.	BigInteger
M	workspace_id	A one-to-one foreign key identifier for the Workspace to be deleted. Each Workspace may have at most one pending delete confirmation.	UUID
M	initiated	The datetime when deletion confirmation was initiated.	Datetime

Role

A Role is a named collection of permissions that can be assigned to collaborators or API keys.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the Role.	UUID
O	workspace_id	A foreign key identifier for the Workspace that owns the Role. If omitted, the Role is shared system-wide.	UUID
M	name	A descriptive name for the Role.	String
O	description	A text description of the Role.	Text
M	is_user_role	A boolean value indicating whether the Role may be assigned to a User collaborator.	Boolean
M	is_apikey_role	A boolean value indicating whether the Role may be assigned to an API key.	Boolean

Permission

A Permission associates a Role with an allowed action on a resource type.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the Permission.	BigInteger
M	role_id	A foreign key identifier for the Role to which the Permission belongs.	UUID
M	permission_type	The permitted action: *, view, create, edit, or delete.	String
M	resource_type	The resource type to which the Permission applies. One of *, APIKey, Role, Collaborator, Thing, Datastream, Observation, Sensor, ObservedProperty, ProcessingLevel, Unit, ResultQualifier, ETL, DataProduct, or DataMonitoring.	String

Collaborator

A Collaborator associates a User with a Workspace through a Role.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the Collaborator.	BigInteger
M	workspace_id	A foreign key identifier for the Workspace.	UUID
M	user_id	A foreign key identifier for the collaborating User.	BigInteger
M	role_id	A foreign key identifier for the Role assigned to the Collaborator.	UUID

NOTE: The database enforces a unique constraint on (user_id, workspace_id).

APIKey

An APIKey grants non-interactive access to a Workspace using an assigned Role.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the APIKey.	UUID
M	workspace_id	A foreign key identifier for the Workspace to which the API key belongs.	UUID
M	role_id	A foreign key identifier for the Role assigned to the API key.	UUID
M	name	A descriptive name for the API key.	String
O	description	A text description of the API key.	Text
M	created_at	The datetime when the API key was created.	Datetime
O	expires_at	The datetime when the API key expires.	Datetime
O	last_used	The datetime when the API key was last used.	Datetime
M	is_active	A boolean value indicating whether the API key is active.	Boolean
M	hashed_key	The stored hashed representation of the API key secret.	String

DatastreamTag

A key-value tag associated with a Datastream.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the DatastreamTag.	BigInteger
M	datastream_id	A foreign key identifier for the Datastream to which the tag belongs.	UUID
M	key	The tag key.	String
M	value	The tag value.	String

DatastreamFileAttachment

A file attached to a Datastream.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the DatastreamFileAttachment.	BigInteger
M	datastream_id	A foreign key identifier for the Datastream to which the file attachment belongs.	UUID
M	name	The name of the attached file.	String
O	description	A text description of the attached file.	Text
M	file_attachment	The stored file object for the attachment.	File
M	file_attachment_type	A text string identifying the type of file attachment.	String

NOTE: The database enforces a unique constraint on (datastream_id, name).

Orchestration

HydroServer's orchestration layer defines a base Task model that is extended by domain-specific task subclasses in the ETL, Data Products, and Data Monitoring apps. Each domain task is a multi-table-inheritance child of the base Task: its primary key is the inherited task_ptr_id (the parent Task's UUID), and the row in the subclass table joins with the row in the orchestration task table.

Task

A Task defines an automated HydroServer workflow. It holds the schedule and run state shared by every task subtype. Each concrete task subclass — EtlTask, DataProductTask, and MonitoringTask — extends this model through multi-table inheritance.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the Task. Domain task subclasses share this identifier.	UUID
M	name	A descriptive name for the Task.	String
O	description	A text description for the Task.	Text
O	periodic_task_id	A one-to-one identifier for the associated scheduler record in django_celery_beat. Each Task maps to at most one periodic task record.	BigInteger
O	next_run_at	The datetime when the Task is expected to run next.	Datetime

TaskRun

A TaskRun stores the execution history for a Task.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the TaskRun.	UUID
M	task_id	A foreign key identifier for the Task to which the run belongs.	UUID
M	status	A text string indicating the run status: PENDING, STARTED, SUCCESS, or FAILURE.	String
O	message	A text string describing the outcome or error message for the run.	Text
M	started_at	The datetime when the TaskRun started. Automatically populated on creation.	Datetime
O	finished_at	The datetime when the TaskRun finished.	Datetime
O	result	A JSON object storing execution result details.	JSON

ETL

The ETL app models the configuration used to extract data from an external source and load it into HydroServer Datastreams.

DataConnection

A DataConnection describes a single external data source: where to fetch payloads, how to authenticate, and how to interpret the timestamps in the response. A DataConnection is shared across one or more EtlTask instances and one optional notification configuration.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the DataConnection.	UUID
M	name	A descriptive name for the DataConnection.	String
O	description	A text description for the DataConnection.	Text
M	workspace_id	A foreign key identifier for the Workspace that owns the DataConnection.	UUID
M	source_url	The URL template fetched by the extractor. May contain placeholder variables resolved at run time.	Text
O	auth_header_name	The name of an HTTP header used to authenticate against the source URL (e.g. Authorization).	String
O	auth_header_value	The value sent with the auth header, such as an API token. Stored as plain text.	Text
M	timestamp_key	The field name or column key that identifies the timestamp in the source payload.	String
O	timestamp_format	An optional format string used to parse non-ISO timestamps from the source payload.	String
O	timezone_type	The kind of timezone interpretation applied to the timestamps: utc, offset, or iana.	String
O	timezone	The timezone value (an IANA name or an offset) used when timezone_type is offset or iana.	String

PlaceholderVariable

A PlaceholderVariable defines a named substitution that is resolved into the DataConnection's source_url at run time.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the PlaceholderVariable.	UUID
M	data_connection_id	A foreign key identifier for the DataConnection to which the placeholder belongs.	UUID
M	name	The placeholder name as it appears in the source_url template.	String
M	variable_type	The type of value substituted at run time: run_time, latest_observation_timestamp, or per_task.	String
O	timestamp_format	An optional format string used to render the substituted value when the value is a timestamp.	String

Payload

A Payload describes how the response body returned by the extractor should be parsed. Each DataConnection has at most one Payload row.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the Payload.	UUID
M	data_connection_id	A one-to-one foreign key identifier for the DataConnection to which the Payload belongs.	UUID
M	payload_type	The payload encoding: CSV or JSON.	String
O	header_row	For CSV payloads, the row index containing column headers.	Integer
O	data_start_row	For CSV payloads, the row index where data begins.	Integer
O	delimiter	For CSV payloads, the field delimiter: ,, \t, ;, |, or .	String
O	jmespath	For JSON payloads, a JMESPath expression used to select observation records out of the response body.	Text

DataConnectionNotification

A DataConnectionNotification records the configuration for the periodic data freshness notification associated with a DataConnection.

Required	Attribute	Definition	Data Type
M	data_connection_id	The primary key for the DataConnectionNotification — a one-to-one foreign key to DataConnection. Each DataConnection has at most one notification row.	UUID
O	periodic_task_id	A one-to-one identifier for the associated scheduler record in django_celery_beat.	BigInteger

DataConnectionNotificationRecipient

A notification email recipient associated with a DataConnectionNotification.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the DataConnectionNotificationRecipient.	UUID
M	notification_id	A foreign key identifier for the DataConnectionNotification.	UUID
M	email	An email address that receives notifications for the parent DataConnection.	Email

NOTE: The database enforces a unique constraint on (notification_id, email).

EtlTask

An EtlTask extends Task with the ETL-specific configuration that links the run to a DataConnection and any runtime overrides used by the extractor, transformer, and loader.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the EtlTask. Inherited from the parent Task row as task_ptr_id.	UUID
M	data_connection_id	A foreign key identifier for the DataConnection used by the EtlTask.	UUID
M	task_variables	A JSON object storing runtime variables substituted into the DataConnection placeholders for this Task.	JSON

EtlMapping

An EtlMapping associates a source identifier produced by the DataConnection with the target Datastream into which the values should be loaded. The previous TaskMapping / TaskMappingPath pair has been collapsed into this single model.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the EtlMapping.	UUID
M	etl_task_id	A foreign key identifier for the EtlTask to which the mapping belongs.	UUID
M	source_identifier	A text identifier representing an incoming source field or column.	String
M	target_datastream_id	A foreign key identifier for the Datastream that receives the mapped values.	UUID

Data Products

The Data Products app models derived Datastreams produced by transformations such as rating curves, expressions, and time-series aggregations.

DataProductTask

A DataProductTask extends Task with the data-product context — the Thing under which the derived Datastreams are organized.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the DataProductTask. Inherited from the parent Task row as task_ptr_id.	UUID
M	thing_id	A foreign key identifier for the Thing that owns the derived Datastreams produced by this task.	UUID

DataProductTransformation

A DataProductTransformation describes how a single derived (output) Datastream is computed from one or more input Datastreams.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the DataProductTransformation.	UUID
M	task_id	A foreign key identifier for the DataProductTask to which the transformation belongs.	UUID
M	output_datastream_id	A one-to-one foreign key identifier for the Datastream that receives the transformation output.	UUID
M	transformation_type	The type of transformation: rating_curve, expression, composite_expression, or aggregation.	String
O	rating_curve_id	A foreign key identifier for the RatingCurve used when transformation_type is rating_curve.	UUID
O	formula	An expression string used when transformation_type is expression or composite_expression.	Text
O	output_interval_units	The interval unit for aggregation outputs: minutes, hours, days, weeks, or months.	String
O	output_interval	The positive interval count corresponding to output_interval_units.	Integer
O	timezone_type	For interval-aligned aggregations, the timezone interpretation: utc, offset, or iana.	String
O	timezone	The timezone value (an IANA name or an offset) used when timezone_type is offset or iana.	String
O	aggregation_method	For aggregation transformations, the aggregation function: mean, sum, min, max, first, or last.	String
O	max_gap_interval_units	For aggregation transformations, the unit of the maximum allowed gap within a window.	String
O	max_gap_interval	For aggregation transformations, the positive count of max_gap_interval_units allowed within a window before the bin is dropped.	Integer
O	min_values	For aggregation transformations, the minimum number of input observations required per window.	Integer

DataProductTransformationInput

A DataProductTransformationInput records a single input Datastream consumed by a DataProductTransformation, optionally bound to a named variable in the formula.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the DataProductTransformationInput.	UUID
M	transformation_id	A foreign key identifier for the DataProductTransformation that consumes the input.	UUID
M	datastream_id	A foreign key identifier for the input Datastream.	UUID
O	variable_name	The variable name used in the transformation formula to reference this input.	String

NOTE: The database enforces a unique constraint on (transformation_id, variable_name) when variable_name is not null.

RatingCurve

A RatingCurve defines a mapping from input values to output values, used by rating_curve transformations to convert one Datastream (e.g. stage) to another (e.g. discharge).

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the RatingCurve.	UUID
M	thing_id	A foreign key identifier for the Thing to which the RatingCurve belongs.	UUID
M	name	A descriptive name for the RatingCurve.	String
O	description	A text description for the RatingCurve.	Text
M	fitting_method	The method used to fit the curve: linear or power_law.	String

RatingCurvePoint

A RatingCurvePoint defines a single (input, output) sample used to fit a RatingCurve.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the RatingCurvePoint.	UUID
M	rating_curve_id	A foreign key identifier for the RatingCurve to which the point belongs.	UUID
M	input_value	The input value of the point (e.g. stage).	Float
M	output_value	The output value of the point (e.g. discharge).	Float

Data Monitoring

The Data Monitoring app models scheduled checks that evaluate Datastreams against quality-control rules and notify recipients when rules are violated.

MonitoringTask

A MonitoringTask extends Task with the data-monitoring context — the Thing whose Datastreams are evaluated.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the MonitoringTask. Inherited from the parent Task row as task_ptr_id.	UUID
M	thing_id	A foreign key identifier for the Thing whose Datastreams are monitored by this task.	UUID

MonitoringRule

A MonitoringRule defines a single quality-control check applied to a Datastream by a MonitoringTask.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the MonitoringRule.	UUID
M	task_id	A foreign key identifier for the MonitoringTask to which the rule belongs.	UUID
M	datastream_id	A foreign key identifier for the Datastream evaluated by the rule.	UUID
M	rule_type	The type of rule: range, rate_of_change, persistence, or missing_data.	String
O	last_checked_at	The datetime when the rule was last evaluated.	Datetime
O	min_value	For range rules, the lower bound of the allowed range.	Float
O	max_value	For range rules, the upper bound of the allowed range.	Float
O	window_interval	For window-based rules, the positive number of window_interval_units evaluated by the rule.	Integer
O	window_interval_units	For window-based rules, the unit of the evaluation window: minutes, hours, or days.	String

NOTE: The database enforces a unique constraint on (task_id, datastream_id, rule_type).

MonitoringNotificationRecipient

A notification email recipient associated with a MonitoringTask.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the MonitoringNotificationRecipient.	UUID
M	task_id	A foreign key identifier for the MonitoringTask.	UUID
M	email	An email address that receives notifications for the MonitoringTask.	Email

NOTE: The database enforces a unique constraint on (task_id, email).

Reference Data

Controlled Vocabulary Tables

HydroServer also includes simple lookup tables that primarily store controlled vocabulary terms used by the main entities.

Table	Attributes	Data Type
UserType	id, name, public	BigInteger, String, Boolean
OrganizationType	id, name, public	BigInteger, String, Boolean
SiteType	id, name	BigInteger, String
SamplingFeatureType	id, name	BigInteger, String
FileAttachmentType	id, name	BigInteger, String
VariableType	id, name	BigInteger, String
SensorEncodingType	id, name	BigInteger, String
MethodType	id, name	BigInteger, String
UnitType	id, name	BigInteger, String
DatastreamAggregation	id, name	BigInteger, String
DatastreamStatus	id, name	BigInteger, String
SampledMedium	id, name	BigInteger, String

SensorThings Conceptual Entities

The current HydroServer SensorThings implementation still exposes SensorThings concepts that are not represented as first-class HydroServer database tables.

FeatureOfInterest

HydroServer currently derives FeatureOfInterest behavior from the Thing and Location context used by SensorThings responses rather than storing FeatureOfInterest as a first-class HydroServer model.

Required	Attribute	Definition	Data Type
M	id	A primary key unique identifier for the FeatureOfInterest in SensorThings responses.	UUID
M	name	A text string giving the name of the feature.	String
M	description	A text string providing a description of the feature.	String
M	encoding	A text string describing the encoding in which the feature is expressed.	String
M	feature	A GeoJSON encoding of the geometry of the feature.	Object

HistoricalLocation

HydroServer currently exposes HistoricalLocation through SensorThings but does not store it as a first-class HydroServer model in the main domain packages.

Required	Attribute	Definition	Data Type
M	thing_id	A foreign key identifier for the Thing for which the HistoricalLocation is specified.	UUID
M	time	The time when the Thing is known to be at the Location.	Datetime
M	location_id	A foreign key identifier for the Location.	UUID