Characteristics and Constraints

Characteristics Classes

Characteristics Classes describe abstract concepts that need to be made specific when they are used. So for example, the Enumeration Characteristic represents the concept "one of multiple predefined values". In order to use the Characteristic, an instance of it needs to be specified in the corresponding Aspect Model, that determines which values are valid for the respective Property.

The following diagram shows the Characteristics Classes defined in the scope of the BAMM Aspect Meta Model.

characteristics classes

Characteristic

Base class of all characteristics. This Characteristics Class can also be instantiated directly (i.e., without creating a subclass).

See declaring characteristics for usage in an Aspect model.

Attributes Description Required

bamm:name

Unique name of characteristic

bamm:preferredName

Human readable name in a specific language

bamm:description

Human readable description in a specific language

bamm:dataType

Reference to a scalar or complex (Entity) data type. See Section "Type System" in the Aspect Meta Model

Trait

The Trait is used to add one or more Constraints to another Characteristic, which is referred to as the "base Characteristic".

See declaring constraints for usage in an Aspect model.

Attributes Description Required

bamm-c:baseCharacteristic

The Characterstic that is being constrained

bamm-c:constraint

A Constraint that is applicable to the base Characteristic. This attribute may be used multiple times, to add multiple Constraints to the base Characteristic.

Quantifiable

A value which can be quantified and may have a unit, e.g., the number of bolts required for a processing step or the expected torque with which these bolts should be tightened.

See declaring characteristics for usage in an Aspect model.

Attributes Description Required

bamm-c:unit

Reference to a Unit as defined in the Unit catalog

Measurement

A measurement is a numeric value with an associated unit and quantity kind.

See declaring characteristics for usage in an Aspect model.

Attributes Description Required

bamm-c:unit

Reference to a Unit as defined in the Unit catalog

Enumeration

An enumeration represents a list of possible values.

See declaring enumerations for usage in an Aspect model.

Attributes Description Required

bamm-c:values

List of possible values. The dataType of each of the values must match the dataType of the Enumeration.

State

A state is subclass of Enumeration with a default value.

See declaring state for usage in an Aspect model.

Attributes Description Required

bamm-c:defaultValue

The default value for the state

Duration

A time duration.

Attributes Description Required

bamm-c:unit

Reference to a Unit as defined in the Unit catalog. The referenced unit or its referenceUnit must have the quantityKind unit:time. Currently, the following units can therefore be used: unit:centipoisePerBar unit:commonYear unit:day unit:henryPerKiloohm unit:henryPerOhm unit:hour unit:kilosecond unit:microhenryPerKiloohm unit:microhenryPerOhm unit:microsecond unit:millihenryPerKiloohm unit:millihenryPerOhm unit:millipascalSecondPerBar unit:millisecond unit:minuteUnitOfTime unit:month unit:nanosecond unit:pascalSecondPerBar unit:picosecond unit:poisePerBar unit:poisePerPascal unit:reciprocalMinute unit:secondUnitOfTime unit:shake unit:siderealYear unit:tropicalYear unit:week unit:year

Collection

A group of values which may be either of a scalar or Entity type. The values may be duplicated and are not ordered (i.e., bag semantics).

In the Collection characteristics and its sub-Characteristics List, Set and Sorted Set, the respective values for the attributes bamm-c:allowDuplicates and bamm-c:ordered have fixed values.

See declaring collections for usage in an Aspect model.

Attributes Description Required

bamm-c:allowDuplicates

Set to true

bamm-c:ordered

Set to false

bamm:dataType

Reference to a scalar or complex (Entity) data type. See Section "Type System" in the Aspect Meta Model.

bamm-c:elementCharacteristic

Reference to a Characteristic which describes the individual elements contained in the Collection.

List

A subclass of Collection which may contain duplicates and is ordered.

Attributes Description Required

bamm-c:allowDuplicates

Set to true

bamm-c:ordered

Set to true

Set

A subclass of Collection which may not contain duplicates and is unordered.

Attributes Description Required

bamm-c:allowDuplicates

Set to false

bamm-c:ordered

Set to false

Sorted Set

A subclass of Collection which may not contain duplicates and is ordered.

Attributes Description Required

bamm-c:allowDuplicates

Set to false

bamm-c:ordered

Set to true

Time Series

A subclass of Sorted Set containing values with the exact point in time when the values where recorded. The values for the allowDuplicates and ordered attributes are inherited from the Sorted Set.

See declaring time series for usage in an Aspect model.

Attributes Description Required

bamm:dataType

Set to bamm-e:TimeSeriesEntity. This Entity consists of two Properties, namely bamm-e:timestamp and bamm-e:value.

As such the structure for time series data is fixed to a collection of key/value pairs with the timestamp being the key and the value being the value.

The bamm-e:timestamp property has a fixed Characteristic of bamm-c:Timestamp. The Characteristic of the bamm-e:value Property is set in the specific Aspect Model giving the value domain specific semantics.

Code

Describes a Property which contains any kind of code. Note that this Characteristic does not define a bamm:dataType, this must therefore be done when instantiating the Characteristic.

Either

Describes a Property whose value can have one of two possible types (a disjoint union).

See declaring either for usage in an Aspect model.

Attributes Description Required

bamm-c:left

The left side of the Either. The attribute references another Characteristic which describes the value.

bamm-c:right

The right side of the Either. The attribute references another Characteristic which describes the value.

Single Entity

Describes a Property whose data type is an Entity. The Entity used as data type may be defined in the same Aspect Model or the shared Entity namespace of the BAMM Aspect Meta Model.

See declaring characteristics for usage in an Aspect model.

Structured Value

Describes a Property which contains a scalar string-like value space value with a well-defined structure. The Structured Value Characteristic allows the description of the parts of the Property’s value by linking to a separate Property definition for each part. To define the parts, the value is deconstructed using a regular expression.

See declaring structured value for usage in an Aspect model.

Attributes Description Required

bamm-c:deconstructionRule

The regular expression used to deconstruct the value into parts that are mapped to separate Properties. This regular expression must contain the same number of capture groups as there are Properties given in the elements list. The n​th capture group maps to the n​th Property in the elements list.

bamm-c:elements

A list of entries each of which can either be a Property reference or a string literal. The list must contain at least one Property reference.

Concatenating the values of the Properties in the elements list with the string literals in the given order should yield a value that corresponds to the original value that has this Structured Value Characteristic. While the deconstructionRule is used for deconstruction, the string literals in the elements list are used for construction. When the Property using the Structured Value Characteristic also defines an exampleValue, construction and deconstruction of the value are tested when validating the model.

Characteristics Instances

A number of concrete Characteristics are defined in conjunction with the Aspect Meta Model. They can be used as-is as Characteristics for Properties in Aspect Models. The following diagram shows the Characteristics Instances defined in the scope of the BAMM Aspect Meta Model.

characteristics instances

Timestamp

Describes a Property which contains the date and time with an optional timezone.

dataType: xsd:dateTime

Text

Describes a Property which contains plain text. This is intended exclusively for human readable strings, not for identifiers, measurement values, etc.

dataType: xsd:string

Multi-Language Text

Describes a Property which contains plain text in multiple languages. This is intended exclusively for human readable strings, not for identifiers, measurement values, etc.

dataType: rdf:langString

Boolean

Represents a boolean value (i.e., a "flag").

dataType: xsd:boolean

Locale

Describes a Property containing a locale according to IETF BCP 47 [bcp47], for example "de-DE".

dataType: xsd:string

Language

Describes a Property containing a language according to ISO 639-1 [iso639], for example "de".

dataType: xsd:string

Resource Path

Describes a Property that contains the path to a relative or absolute resource.

dataType: xsd:anyURI

MIME Type

Describes a Property that contains a MIME type as defined by RFC 2046 [rfc2046], for example "application/json", "application/xls" or "image/png".

dataType: xsd:string

Unit Reference

Describes a Property containing a reference to one of the units in the Unit catalog.

dataType: bamm:curie

Constraints

Constraint

Base class for other constraints that constrain a Characteristic in some way, e.g., the Range Constraint limits the value range for a Property.

The Constraint class has no attributes.

Language Constraint

Restricts a value to a specific language.

Attributes Description Required

bamm:languageCode

An ISO 639-1 [iso639] language code for the language of the value of the constrained Property, e.g., "de".

Locale Constraint

Restricts a value to a specific locale, i.e., a language with additional region information.

Attributes Description Required

bamm:localeCode

An IETF BCP 47 [bcp47] language code for the locale of the value of the constrained Property, e.g., "de-DE".

Range Constraint

Whether the bamm-c:maxValue and bamm-c:minValue are inclusive or exclusive can be defined using the bamm-c:upperBoundDefinition and bamm-c:lowerBoundDefinition attributes.

The values for maxValue and minValue must be given in the same effective dataType that the constrained Characteristic uses.
Attributes Description Required

bamm-c:maxValue

The upper bound of a range

bamm-c:minValue

The lower bound of a range

bamm-c:upperBoundDefinition

Defines whether the upper bound of a range is inclusive or exclusive. Possible values are bamm-c:AT_MOST and bamm-c:LESS_THAN

bamm-c:lowerBoundDefinition

Defines whether the lower bound of a range is inclusive or exclusive. Possible values are bamm-c:AT_LEAST and bamm-c:GREATER_THAN

When either the bamm-c:minValue or the bamm-c:maxValue is not given, the Range is defined as having an open lower or upper boundary.
The AT_LEAST and AT_MOST values for lowerBoundDefinition and upperBoundDefinition define that the values for minValue and maxValue are inclusive. The LESS_THAN and GREATER_THAN values for the lowerBoundDefinition and upperBoundDefinition define that the values for minValue and maxValue are exclusive.

This Constraint can be used to restrict Characteristics with one of two kinds of data types:

  • Characteristics that have a numeric data type; in this case the Constraint restricts the range of the value. The scalar data types that can be restricted are: xsd:double, xsd:float, xsd:decimal, xsd:integer, xsd:byte, xsd:short, xsd:int, xsd:long, xsd:unsignedByte, xsd:unsignedShort, xsd:unsignedInt, xsd:unsignedLong, xsd:positiveInteger , xsd:nonPositiveInteger, xsd:negativeInteger and xsd:nonNegativeInteger.

  • Characteristics that have a time and date data type;. In this case the Constraint restricts the scalar data types: xsd:date,xsd:time, xsd:dateTime, xsd:dateTimeStamp, xsd:gYear, xsd:gMonth, xsd:gMonthDay, xsd:duration, xsd:yearMonthDuration, xsd:dayTimeDuration.

Restricts the value range of a Property. At least one of bamm-c:maxValue or bamm-c:minValue must be present in a Range Constraint. By default both bamm-c:maxValue and bamm-c:minValue are inclusive.

Encoding Constraint

Restricts the encoding of a Property.

Attributes Description Required

bamm:value

Configures the encoding. This may be one of the following: bamm:US-ASCII, bamm:ISO-8859-1, bamm:UTF-8, bamm:UTF-16, bamm:UTF-16BE or bamm:UTF-16LE.

The default encoding for values with a string-like value space is UTF-8, therefore using an Encoding Constraint with a bamm:value of bamm:UTF-8 is only necessary when a Property’s encoding is changed during an Aspect model version increase from some other encoding to UTF-8 to indicate that the other encoding is not any longer used.

Length Constraint

This Constraint can be used to restrict two types of Characteristics:

  • Characteristics that have a string-like value space; in this case the Constraint restricts the length of the (string-) value. The scalar data types that can be restricted are: xsd:string, xsd:date, xsd:time, xsd:dateTime, xsd:dateTimeStamp, xsd:gYear, xsd:gMonth, xsd:gMonthDay, xsd:duration, xsd:yearMonthDuration, xsd:dayTimeDuration, xsd:hexBinary, xsd:base64Binary, xsd:anyURI, bamm:curie and rdf:langString.

  • Collection Characteristics (Collection, Set, Sorted Set, List). In this case the Constraint restricts the number of elements in the collection.

At least one of bamm-c:maxValue or bamm-c:minValue must be present in a Length Constraint.

Attributes Description Required

bamm-c:maxValue

The maximum length. Must be given as xsd:nonNegativeInteger.

bamm-c:minValue

The minimum length. Must be given as xsd:nonNegativeInteger.

Regular Expression Constraint

Restricts a string value to a regular expression as defined by XQuery 1.0 and XPath 2.0 Functions and Operators [xpath-functions].

Attributes Description Required

bamm:value

The regular expression

Fixed Point Constraint

Defines the scaling factor as well as the amount of integral numbers for a fixed point number. The constraint may only be used in conjunction with Characteristics which use the xsd:decimal data type.

Attributes Description Required

bamm-c:scale

The scaling factor for a fixed point number. Must be given as xsd:positiveInteger.

bamm-c:integer

The number of integral digits for a fixed point number. Must be given as xsd:positiveInteger.