Chapter 4. Decision Model and Notation (DMN)

Decision Model and Notation (DMN) is a standard established by the Object Management Group (OMG) for describing and modeling operational decisions. DMN defines an XML schema that enables DMN models to be shared between DMN-compliant platforms and across organizations so that business analysts and business rules developers can collaborate in designing and implementing DMN decision services. The DMN standard is similar to and can be used together with the Business Process Model and Notation (BPMN) standard for designing and modeling business processes.

For more information about the background and applications of DMN, see the OMG Decision Model and Notation specification.

4.1. DMN conformance levels

The DMN specification defines three incremental levels of conformance in a software implementation. A product that claims compliance at one level must also be compliant with any preceding levels. For example, a conformance level 3 implementation must also include the supported components in conformance levels 1 and 2. For the formal definitions of each conformance level, see the OMG Decision Model and Notation specification.

The following list summarizes the three DMN conformance levels:

Conformance level 1
A DMN conformance level 1 implementation supports decision requirement diagrams (DRDs), decision logic, and decision tables, but decision models are not executable. Any language can be used to define the expressions, including natural, unstructured languages.
Conformance level 2
A DMN conformance level 2 implementation includes the requirements in conformance level 1, and supports Simplified Friendly Enough Expression Language (S-FEEL) expressions and fully executable decision models.
Conformance level 3
A DMN conformance level 3 implementation includes the requirements in conformance levels 1 and 2, and supports Friendly Enough Expression Language (FEEL) expressions, the full set of boxed expressions, and fully executable decision models.

Red Hat Process Automation Manager provides design and runtime support for DMN 1.2 models at conformance level 3, and runtime-only support for DMN 1.1 and 1.3 models at conformance level 3. You can design your DMN models directly in Business Central or with the Red Hat Process Automation Manager DMN modeler in VSCode, or import existing DMN models into your Red Hat Process Automation Manager projects for deployment and execution. Any DMN 1.1 and 1.3 models (do not contain DMN 1.3 features) that you import into Business Central, open in the DMN designer, and save are converted to DMN 1.2 models.

4.2. DMN decision requirements diagram (DRD) components

A decision requirements diagram (DRD) is a visual representation of your DMN model. A DRD can represent part or all of the overall decision requirements graph (DRG) for the DMN model. DRDs trace business decisions using decision nodes, business knowledge models, sources of business knowledge, input data, and decision services.

The following table summarizes the components in a DRD:

Table 4.1. DRD components

ComponentDescriptionNotation

Elements

Decision

Node where one or more input elements determine an output based on defined decision logic.

dmn decision node

Business knowledge model

Reusable function with one or more decision elements. Decisions that have the same logic but depend on different sub-input data or sub-decisions use business knowledge models to determine which procedure to follow.

dmn bkm node

Knowledge source

External authorities, documents, committees, or policies that regulate a decision or business knowledge model. Knowledge sources are references to real-world factors rather than executable business rules.

dmn knowledge source node

Input data

Information used in a decision node or a business knowledge model. Input data usually includes business-level concepts or objects relevant to the business, such as loan applicant data used in a lending strategy.

dmn input data node

Decision service

Top-level decision containing a set of reusable decisions published as a service for invocation. A decision service can be invoked from an external application or a BPMN business process.

dmn decision service node

Requirement connectors

Information requirement

Connection from an input data node or decision node to another decision node that requires the information.

dmn info connector

Knowledge requirement

Connection from a business knowledge model to a decision node or to another business knowledge model that invokes the decision logic.

dmn knowledge connector

Authority requirement

Connection from an input data node or a decision node to a dependent knowledge source or from a knowledge source to a decision node, business knowledge model, or another knowledge source.

dmn authority connector

Artifacts

Text annotation

Explanatory note associated with an input data node, decision node, business knowledge model, or knowledge source.

dmn annotation node

Association

Connection from an input data node, decision node, business knowledge model, or knowledge source to a text annotation.

dmn association connector

The following table summarizes the permitted connectors between DRD elements:

Table 4.2. DRD connector rules

Starts fromConnects toConnection typeExample

Decision

Decision

Information requirement

dmn decision to decision

Business knowledge model

Decision

Knowledge requirement

dmn bkm to decision

Business knowledge model

dmn bkm to bkm

Decision service

Decision

Knowledge requirement

dmn decision service to decision

Business knowledge model

dmn decision service to bkm

Input data

Decision

Information requirement

dmn input to decision

Knowledge source

Authority requirement

dmn input to knowledge source

Knowledge source

Decision

Authority requirement

dmn knowledge source to decision

Business knowledge model

dmn knowledge source to bkm

Knowledge source

dmn knowledge source to knowledge source

Decision

Text annotation

Association

dmn decision to annotation

Business knowledge model

dmn bkm to annotation

Knowledge source

dmn knowledge source to annotation

Input data

dmn input to annotation

The following example DRD illustrates some of these DMN components in practice:

Figure 4.1. Example DRD: Loan prequalification

dmn example drd

The following example DRD illustrates DMN components that are part of a reusable decision service:

Figure 4.2. Example DRD: Phone call handling as a decision service

dmn example drd3

In a DMN decision service node, the decision nodes in the bottom segment incorporate input data from outside of the decision service to arrive at a final decision in the top segment of the decision service node. The resulting top-level decisions from the decision service are then implemented in any subsequent decisions or business knowledge requirements of the DMN model. You can reuse DMN decision services in other DMN models to apply the same decision logic with different input data and different outgoing connections.

4.3. Rule expressions in FEEL

Friendly Enough Expression Language (FEEL) is an expression language defined by the Object Management Group (OMG) DMN specification. FEEL expressions define the logic of a decision in a DMN model. FEEL is designed to facilitate both decision modeling and execution by assigning semantics to the decision model constructs. FEEL expressions in decision requirements diagrams (DRDs) occupy table cells in boxed expressions for decision nodes and business knowledge models.

For more information about FEEL in DMN, see the OMG Decision Model and Notation specification.

4.3.1. Data types in FEEL

Friendly Enough Expression Language (FEEL) supports the following data types:

  • Numbers
  • Strings
  • Boolean values
  • Dates
  • Time
  • Date and time
  • Days and time duration
  • Years and months duration
  • Functions
  • Contexts
  • Ranges (or intervals)
  • Lists
Note

The DMN specification currently does not provide an explicit way of declaring a variable as a function, context, range, or list, but Red Hat Process Automation Manager extends the DMN built-in types to support variables of these types.

The following list describes each data type:

Numbers

Numbers in FEEL are based on the IEEE 754-2008 Decimal 128 format, with 34 digits of precision. Internally, numbers are represented in Java as BigDecimals with MathContext DECIMAL128. FEEL supports only one number data type, so the same type is used to represent both integers and floating point numbers.

FEEL numbers use a dot (.) as a decimal separator. FEEL does not support -INF, +INF, or NaN. FEEL uses null to represent invalid numbers.

Red Hat Process Automation Manager extends the DMN specification and supports additional number notations:

  • Scientific: You can use scientific notation with the suffix e<exp> or E<exp>. For example, 1.2e3 is the same as writing the expression 1.2*10**3, but is a literal instead of an expression.
  • Hexadecimal: You can use hexadecimal numbers with the prefix 0x. For example, 0xff is the same as the decimal number 255. Both uppercase and lowercase letters are supported. For example, 0XFF is the same as 0xff.
  • Type suffixes: You can use the type suffixes f, F, d, D, l, and L. These suffixes are ignored.
Strings

Strings in FEEL are any sequence of characters delimited by double quotation marks.

Example

"John Doe"

Boolean values
FEEL uses three-valued boolean logic, so a boolean logic expression may have values true, false, or null.
Dates

Date literals are not supported in FEEL, but you can use the built-in date() function to construct date values. Date strings in FEEL follow the format defined in the XML Schema Part 2: Datatypes document. The format is "YYYY-MM-DD" where YYYY is the year with four digits, MM is the number of the month with two digits, and DD is the number of the day.

Example:

date( "2017-06-23" )

Date objects have time equal to "00:00:00", which is midnight. The dates are considered to be local, without a timezone.

Time

Time literals are not supported in FEEL, but you can use the built-in time() function to construct time values. Time strings in FEEL follow the format defined in the XML Schema Part 2: Datatypes document. The format is "hh:mm:ss[.uuu][(+-)hh:mm]" where hh is the hour of the day (from 00 to 23), mm is the minutes in the hour, and ss is the number of seconds in the minute. Optionally, the string may define the number of milliseconds (uuu) within the second and contain a positive (+) or negative (-) offset from UTC time to define its timezone. Instead of using an offset, you can use the letter z to represent the UTC time, which is the same as an offset of -00:00. If no offset is defined, the time is considered to be local.

Examples:

time( "04:25:12" )
time( "14:10:00+02:00" )
time( "22:35:40.345-05:00" )
time( "15:00:30z" )

Time values that define an offset or a timezone cannot be compared to local times that do not define an offset or a timezone.

Date and time

Date and time literals are not supported in FEEL, but you can use the built-in date and time() function to construct date and time values. Date and time strings in FEEL follow the format defined in the XML Schema Part 2: Datatypes document. The format is "<date>T<time>", where <date> and <time> follow the prescribed XML schema formatting, conjoined by T.

Examples:

date and time( "2017-10-22T23:59:00" )
date and time( "2017-06-13T14:10:00+02:00" )
date and time( "2017-02-05T22:35:40.345-05:00" )
date and time( "2017-06-13T15:00:30z" )

Date and time values that define an offset or a timezone cannot be compared to local date and time values that do not define an offset or a timezone.

Important

If your implementation of the DMN specification does not support spaces in the XML schema, use the keyword dateTime as a synonym of date and time.

Days and time duration

Days and time duration literals are not supported in FEEL, but you can use the built-in duration() function to construct days and time duration values. Days and time duration strings in FEEL follow the format defined in the XML Schema Part 2: Datatypes document, but are restricted to only days, hours, minutes and seconds. Months and years are not supported.

Examples:

duration( "P1DT23H12M30S" )
duration( "P23D" )
duration( "PT12H" )
duration( "PT35M" )
Important

If your implementation of the DMN specification does not support spaces in the XML schema, use the keyword dayTimeDuration as a synonym of days and time duration.

Years and months duration

Years and months duration literals are not supported in FEEL, but you can use the built-in duration() function to construct days and time duration values. Years and months duration strings in FEEL follow the format defined in the XML Schema Part 2: Datatypes document, but are restricted to only years and months. Days, hours, minutes, or seconds are not supported.

Examples:

duration( "P3Y5M" )
duration( "P2Y" )
duration( "P10M" )
duration( "P25M" )
Important

If your implementation of the DMN specification does not support spaces in the XML schema, use the keyword yearMonthDuration as a synonym of years and months duration.

Functions

FEEL has function literals (or anonymous functions) that you can use to create functions. The DMN specification currently does not provide an explicit way of declaring a variable as a function, but Red Hat Process Automation Manager extends the DMN built-in types to support variables of functions.

Example:

function(a, b) a + b

In this example, the FEEL expression creates a function that adds the parameters a and b and returns the result.

Contexts

FEEL has context literals that you can use to create contexts. A context in FEEL is a list of key and value pairs, similar to maps in languages like Java. The DMN specification currently does not provide an explicit way of declaring a variable as a context, but Red Hat Process Automation Manager extends the DMN built-in types to support variables of contexts.

Example:

{ x : 5, y : 3 }

In this example, the expression creates a context with two entries, x and y, representing a coordinate in a chart.

In DMN 1.2, another way to create contexts is to create an item definition that contains the list of keys as attributes, and then declare the variable as having that item definition type.

The Red Hat Process Automation Manager DMN API supports DMN ItemDefinition structural types in a DMNContext represented in two ways:

  • User-defined Java type: Must be a valid JavaBeans object defining properties and getters for each of the components in the DMN ItemDefinition. If necessary, you can also use the @FEELProperty annotation for those getters representing a component name which would result in an invalid Java identifier.
  • java.util.Map interface: The map needs to define the appropriate entries, with the keys corresponding to the component name in the DMN ItemDefinition.
Ranges (or intervals)

FEEL has range literals that you can use to create ranges or intervals. A range in FEEL is a value that defines a lower and an upper bound, where either can be open or closed. The DMN specification currently does not provide an explicit way of declaring a variable as a range, but Red Hat Process Automation Manager extends the DMN built-in types to support variables of ranges.

The syntax of a range is defined in the following formats:

range          := interval_start endpoint '..' endpoint interval_end
interval_start := open_start | closed_start
open_start     := '(' | ']'
closed_start   := '['
interval_end   := open_end | closed_end
open_end       := ')' | '['
closed_end     := ']'
endpoint       := expression

The expression for the endpoint must return a comparable value, and the lower bound endpoint must be lower than the upper bound endpoint.

For example, the following literal expression defines an interval between 1 and 10, including the boundaries (a closed interval on both endpoints):

[ 1 .. 10 ]

The following literal expression defines an interval between 1 hour and 12 hours, including the lower boundary (a closed interval), but excluding the upper boundary (an open interval):

[ duration("PT1H") .. duration("PT12H") )

You can use ranges in decision tables to test for ranges of values, or use ranges in simple literal expressions. For example, the following literal expression returns true if the value of a variable x is between 0 and 100:

x in [ 1 .. 100 ]
Lists

FEEL has list literals that you can use to create lists of items. A list in FEEL is represented by a comma-separated list of values enclosed in square brackets. The DMN specification currently does not provide an explicit way of declaring a variable as a list, but Red Hat Process Automation Manager extends the DMN built-in types to support variables of lists.

Example:

[ 2, 3, 4, 5 ]

All lists in FEEL contain elements of the same type and are immutable. Elements in a list can be accessed by index, where the first element is 1. Negative indexes can access elements starting from the end of the list so that -1 is the last element.

For example, the following expression returns the second element of a list x:

x[2]

The following expression returns the second-to-last element of a list x:

x[-2]

Elements in a list can also be counted by the function count, which uses the list of elements as the parameter.

For example, the following expression returns 4:

count([ 2, 3, 4, 5 ])

4.3.2. Built-in functions in FEEL

To promote interoperability with other platforms and systems, Friendly Enough Expression Language (FEEL) includes a library of built-in functions. The built-in FEEL functions are implemented in the Drools Decision Model and Notation (DMN) engine so that you can use the functions in your DMN decision services.

The following sections describe each built-in FEEL function, listed in the format NAME( PARAMETERS ). For more information about FEEL functions in DMN, see the OMG Decision Model and Notation specification.

4.3.2.1. Conversion functions

The following functions support conversion between values of different types. Some of these functions use specific string formats, such as the following examples:

  • date string: Follows the format defined in the XML Schema Part 2: Datatypes document, such as 2020-06-01
  • time string: Follows one of the following formats:

    • Format defined in the XML Schema Part 2: Datatypes document, such as 23:59:00z
    • Format for a local time defined by ISO 8601 followed by @ and an IANA Timezone, such as 00:01:00@Etc/UTC
  • date time string: Follows the format of a date string followed by T and a time string, such as 2012-12-25T11:00:00Z
  • duration string: Follows the format of days and time duration and years and months duration defined in the XQuery 1.0 and XPath 2.0 Data Model, such as P1Y2M
date( from ) - using date

Converts from to a date value.

Table 4.3. Parameters

ParameterTypeFormat

from

string

date string

Example

date( "2012-12-25" ) - date( "2012-12-24" ) = duration( "P1D" )

date( from ) - using date and time

Converts from to a date value and sets time components to null.

Table 4.4. Parameters

ParameterType

from

date and time

Example

date(date and time( "2012-12-25T11:00:00Z" )) = date( "2012-12-25" )

date( year, month, day )

Produces a date from the specified year, month, and day values.

Table 4.5. Parameters

ParameterType

year

number

month

number

day

number

Example

date( 2012, 12, 25 ) = date( "2012-12-25" )

date and time( date, time )

Produces a date and time from the specified date and ignores any time components and the specified time.

Table 4.6. Parameters

ParameterType

date

date or date and time

time

time

Example

date and time ( "2012-12-24T23:59:00" ) = date and time(date( "2012-12-24" ), time( "23:59:00" ))

date and time( from )

Produces a date and time from the specified string.

Table 4.7. Parameters

ParameterTypeFormat

from

string

date time string

Example

date and time( "2012-12-24T23:59:00" ) + duration( "PT1M" ) = date and time( "2012-12-25T00:00:00" )

time( from )

Produces a time from the specified string.

Table 4.8. Parameters

ParameterTypeFormat

from

string

time string

Example

time( "23:59:00z" ) + duration( "PT2M" ) = time( "00:01:00@Etc/UTC" )

time( from )

Produces a time from the specified parameter and ignores any date components.

Table 4.9. Parameters

ParameterType

from

time or date and time

Example

time(date and time( "2012-12-25T11:00:00Z" )) = time( "11:00:00Z" )

time( hour, minute, second, offset? )

Produces a time from the specified hour, minute, and second component values.

Table 4.10. Parameters

ParameterType

hour

number

minute

number

second

number

offset (Optional)

days and time duration or null

Example

time( "23:59:00z" ) = time(23, 59, 0, duration( "PT0H" ))

number( from, grouping separator, decimal separator )

Converts from to a number using the specified separators.

Table 4.11. Parameters

ParameterType

from

string representing a valid number

grouping separator

Space ( ), comma (,), period (.), or null

decimal separator

Same types as grouping separator, but the values cannot match

Example

number( "1 000,0", " ", "," ) = number( "1,000.0", ",", "." )

string( from )

Provides a string representation of the specified parameter.

Table 4.12. Parameters

ParameterType

from

Non-null value

Examples

string( 1.1 ) = "1.1"
string( null ) = null

duration( from )

Converts from to a days and time duration value or years and months duration value.

Table 4.13. Parameters

ParameterTypeFormat

from

string

duration string

Examples

date and time( "2012-12-24T23:59:00" ) - date and time( "2012-12-22T03:45:00" ) = duration( "P2DT20H14M" )
duration( "P2Y2M" ) = duration( "P26M" )

years and months duration( from, to )

Calculates the years and months duration between the two specified parameters.

Table 4.14. Parameters

ParameterType

from

date or date and time

to

date or date and time

Example

years and months duration( date( "2011-12-22" ), date( "2013-08-24" ) ) = duration( "P1Y8M" )

4.3.2.2. Boolean functions

The following functions support Boolean operations.

not( negand )

Performs the logical negation of the negand operand.

Table 4.15. Parameters

ParameterType

negand

boolean

Examples

not( true ) = false
not( null ) = null

4.3.2.3. String functions

The following functions support string operations.

Note

In FEEL, Unicode characters are counted based on their code points.

substring( string, start position, length? )

Returns the substring from the start position for the specified length. The first character is at position value 1.

Table 4.16. Parameters

ParameterType

string

string

start position

number

length (Optional)

number

Examples

substring( "testing",3 ) = "sting"
substring( "testing",3,3 ) = "sti"
substring( "testing", -2, 1 ) = "n"
substring( "\U01F40Eab", 2 ) = "ab"

Note

In FEEL, the string literal "\U01F40Eab" is the 🐎ab string (horse symbol followed by a and b).

string length( string )

Calculates the length of the specified string.

Table 4.17. Parameters

ParameterType

string

string

Examples

string length( "tes" ) = 3
string length( "\U01F40Eab" ) = 3

upper case( string )

Produces an uppercase version of the specified string.

Table 4.18. Parameters

ParameterType

string

string

Example

upper case( "aBc4" ) = "ABC4"

lower case( string )

Produces a lowercase version of the specified string.

Table 4.19. Parameters

ParameterType

string

string

Example

lower case( "aBc4" ) = "abc4"

substring before( string, match )

Calculates the substring before the match.

Table 4.20. Parameters

ParameterType

string

string

match

string

Examples

substring before( "testing", "ing" ) = "test"
substring before( "testing", "xyz" ) = ""

substring after( string, match )

Calculates the substring after the match.

Table 4.21. Parameters

ParameterType

string

string

match

string

Examples

substring after( "testing", "test" ) = "ing"
substring after( "", "a" ) = ""

replace( input, pattern, replacement, flags? )

Calculates the regular expression replacement.

Table 4.22. Parameters

ParameterType

input

string

pattern

string

replacement

string

flags (Optional)

string

Note

This function uses regular expression parameters as defined in XQuery 1.0 and XPath 2.0 Functions and Operators.

Example

replace( "abcd", "(ab)|(a)", "[1=$1][2=$2]" ) = "[1=ab][2=]cd"

contains( string, match )

Returns true if the string contains the match.

Table 4.23. Parameters

ParameterType

string

string

match

string

Example

contains( "testing", "to" ) = false

starts with( string, match )

Returns true if the string starts with the match

Table 4.24. Parameters

ParameterType

string

string

match

string

Example

starts with( "testing", "te" ) = true

ends with( string, match )

Returns true if the string ends with the match.

Table 4.25. Parameters

ParameterType

string

string

match

string

Example

ends with( "testing", "g" ) = true

matches( input, pattern, flags? )

Returns true if the input matches the regular expression.

Table 4.26. Parameters

ParameterType

input

string

pattern

string

flags (Optional)

string

Note

This function uses regular expression parameters as defined in XQuery 1.0 and XPath 2.0 Functions and Operators.

Example

matches( "teeesting", "^te*sting" ) = true

split( string, delimiter )

Returns a list of the original string and splits it at the delimiter regular expression pattern.

Table 4.27. Parameters

ParameterType

string

string

delimiter

string for a regular expression pattern

Note

This function uses regular expression parameters as defined in XQuery 1.0 and XPath 2.0 Functions and Operators.

Examples

split( "John Doe", "\\s" ) = ["John", "Doe"]
split( "a;b;c;;", ";" ) = ["a","b","c","",""]

4.3.2.4. List functions

The following functions support list operations.

Note

In FEEL, the index of the first element in a list is 1. The index of the last element in a list can be identified as -1.

list contains( list, element )

Returns true if the list contains the element.

Table 4.28. Parameters

ParameterType

list

list

element

Any type, including null

Example

list contains( [1,2,3], 2 ) = true

count( list )

Counts the elements in the list.

Table 4.29. Parameters

ParameterType

list

list

Examples

count( [1,2,3] ) = 3
count( [] ) = 0
count( [1,[2,3]] ) = 2

min( list )

Returns the minimum comparable element in the list.

Table 4.30. Parameters

ParameterType

list

list

Alternative signature

min( e1, e2, ..., eN )

Examples

min( [1,2,3] ) = 1
min( 1 ) = 1
min( [1] ) = 1

max( list )

Returns the maximum comparable element in the list.

Table 4.31. Parameters

ParameterType

list

list

Alternative signature

max( e1, e2, ..., eN )

Examples

max( 1,2,3 ) = 3
max( [] ) = null

sum( list )

Returns the sum of the numbers in the list.

Table 4.32. Parameters

ParameterType

list

list of number elements

Alternative signature

sum( n1, n2, ..., nN )

Examples

sum( [1,2,3] ) = 6
sum( 1,2,3 ) = 6
sum( 1 ) = 1
sum( [] ) = null

mean( list )

Calculates the average (arithmetic mean) of the elements in the list.

Table 4.33. Parameters

ParameterType

list

list of number elements

Alternative signature

mean( n1, n2, ..., nN )

Examples

mean( [1,2,3] ) = 2
mean( 1,2,3 ) = 2
mean( 1 ) = 1
mean( [] ) = null

all( list )

Returns true if all elements in the list are true.

Table 4.34. Parameters

ParameterType

list

list of boolean elements

Alternative signature

all( b1, b2, ..., bN )

Examples

all( [false,null,true] ) = false
all( true ) = true
all( [true] ) = true
all( [] ) = true
all( 0 ) = null

any( list )

Returns true if any element in the list is true.

Table 4.35. Parameters

ParameterType

list

list of boolean elements

Alternative signature

any( b1, b2, ..., bN )

Examples

any( [false,null,true] ) = true
any( false ) = false
any( [] ) = false
any( 0 ) = null

sublist( list, start position, length? )

Returns the sublist from the start position, limited to the length elements.

Table 4.36. Parameters

ParameterType

list

list

start position

number

length (Optional)

number

Example

sublist( [4,5,6], 1, 2 ) = [4,5]

append( list, item )

Creates a list that is appended to the item or items.

Table 4.37. Parameters

ParameterType

list

list

item

Any type

Example

append( [1], 2, 3 ) = [1,2,3]

concatenate( list )

Creates a list that is the result of the concatenated lists.

Table 4.38. Parameters

ParameterType

list

list

Example

concatenate( [1,2],[3] ) = [1,2,3]

insert before( list, position, newItem )

Creates a list with the newItem inserted at the specified position.

Table 4.39. Parameters

ParameterType

list

list

position

number

newItem

Any type

Example

insert before( [1,3],1,2 ) = [2,1,3]

remove( list, position )

Creates a list with the removed element excluded from the specified position.

Table 4.40. Parameters

ParameterType

list

list

position

number

Example

remove( [1,2,3], 2 ) = [1,3]

reverse( list )

Returns a reversed list.

Table 4.41. Parameters

ParameterType

list

list

Example

reverse( [1,2,3] ) = [3,2,1]

index of( list, match )

Returns indexes matching the element.

Parameters

  • list of type list
  • match of any type

Table 4.42. Parameters

ParameterType

list

list

match

Any type

Example

index of( [1,2,3,2],2 ) = [2,4]

union( list )

Returns a list of all the elements from multiple lists and excludes duplicates.

Table 4.43. Parameters

ParameterType

list

list

Example

union( [1,2],[2,3] ) = [1,2,3]

distinct values( list )

Returns a list of elements from a single list and excludes duplicates.

Table 4.44. Parameters

ParameterType

list

list

Example

distinct values( [1,2,3,2,1] ) = [1,2,3]

flatten( list )

Returns a flattened list.

Table 4.45. Parameters

ParameterType

list

list

Example

flatten( [[1,2],[[3]], 4] ) = [1,2,3,4]

product( list )

Returns the product of the numbers in the list.

Table 4.46. Parameters

ParameterType

list

list of number elements

Alternative signature

product( n1, n2, ..., nN )

Examples

product( [2, 3, 4] ) = 24
product( 2, 3, 4 ) = 24

median( list )

Returns the median of the numbers in the list. If the number of elements is odd, the result is the middle element. If the number of elements is even, the result is the average of the two middle elements.

Table 4.47. Parameters

ParameterType

list

list of number elements

Alternative signature

median( n1, n2, ..., nN )

Examples

median( 8, 2, 5, 3, 4 ) = 4
median( [6, 1, 2, 3] ) = 2.5
median( [ ] ) = null

stddev( list )

Returns the standard deviation of the numbers in the list.

Table 4.48. Parameters

ParameterType

list

list of number elements

Alternative signature

stddev( n1, n2, ..., nN )

Examples

stddev( 2, 4, 7, 5 ) = 2.081665999466132735282297706979931
stddev( [47] ) = null
stddev( 47 ) = null
stddev( [ ] ) = null

mode( list )

Returns the mode of the numbers in the list. If multiple elements are returned, the numbers are sorted in ascending order.

Table 4.49. Parameters

ParameterType

list

list of number elements

Alternative signature

mode( n1, n2, ..., nN )

Examples

mode( 6, 3, 9, 6, 6 ) = [6]
mode( [6, 1, 9, 6, 1] ) = [1, 6]
mode( [ ] ) = [ ]

4.3.2.5. Numeric functions

The following functions support number operations.

decimal( n, scale )

Returns a number with the specified scale.

Table 4.50. Parameters

ParameterType

n

number

scale

number in the range [−6111..6176]

Examples

decimal( 1/3, 2 ) = .33
decimal( 1.5, 0 ) = 2
decimal( 2.5, 0 ) = 2

floor( n )

Returns the greatest integer that is less than or equal to the specified number.

Table 4.51. Parameters

ParameterType

n

number

Examples

floor( 1.5 ) = 1
floor( -1.5 ) = -2

ceiling( n )

Returns the smallest integer that is greater than or equal to the specified number.

Table 4.52. Parameters

ParameterType

n

number

Examples

ceiling( 1.5 ) = 2
ceiling( -1.5 ) = -1

abs( n )

Returns the absolute value.

Table 4.53. Parameters

ParameterType

n

number, days and time duration, or years and months duration

Examples

abs( 10 ) = 10
abs( -10 ) = 10
abs( @"PT5H" ) = @"PT5H"
abs( @"-PT5H" ) = @"PT5H"

modulo( dividend, divisor )

Returns the remainder of the division of the dividend by the divisor. If either the dividend or divisor is negative, the result is of the same sign as the divisor.

Note

This function is also expressed as modulo(dividend, divisor) = dividend - divisor*floor(dividen d/divisor).

Table 4.54. Parameters

ParameterType

dividend

number

divisor

number

Examples

modulo( 12, 5 ) = 2
modulo( -12,5 )= 3
modulo( 12,-5 )= -3
modulo( -12,-5 )= -2
modulo( 10.1, 4.5 )= 1.1
modulo( -10.1, 4.5 )= 3.4
modulo( 10.1, -4.5 )= -3.4
modulo( -10.1, -4.5 )= -1.1

sqrt( number )

Returns the square root of the specified number.

Table 4.55. Parameters

ParameterType

n

number

Example

sqrt( 16 ) = 4

log( number )

Returns the logarithm of the specified number.

Table 4.56. Parameters

ParameterType

n

number

Example

decimal( log( 10 ), 2 ) = 2.30

exp( number )

Returns Euler’s number e raised to the power of the specified number.

Table 4.57. Parameters

ParameterType

n

number

Example

decimal( exp( 5 ), 2 ) = 148.41

odd( number )

Returns true if the specified number is odd.

Table 4.58. Parameters

ParameterType

n

number

Examples

odd( 5 ) = true
odd( 2 ) = false

even( number )

Returns true if the specified number is even.

Table 4.59. Parameters

ParameterType

n

number

Examples

even( 5 ) = false
even ( 2 ) = true

4.3.2.6. Date and time functions

The following functions support date and time operations.

is( value1, value2 )

Returns true if both values are the same element in the FEEL semantic domain.

Table 4.60. Parameters

ParameterType

value1

Any type

value2

Any type

Examples

is( date( "2012-12-25" ), time( "23:00:50" ) ) = false
is( date( "2012-12-25" ), date( "2012-12-25" ) ) = true
is( time( "23:00:50z" ), time( "23:00:50" ) ) = false

4.3.2.7. Range functions

The following functions support temporal ordering operations to establish relationships between single scalar values and ranges of such values. These functions are similar to the components in the Health Level Seven (HL7) International Clinical Quality Language (CQL) 1.4 syntax.

before( )

Returns true when an element A is before an element B and when the relevant requirements for evaluating to true are also met.

Signatures

  1. before( point1 point2 )
  2. before( point range )
  3. before( range point )
  4. before( range1,range2 )

Requirements for evaluating to true

  1. point1 < point2
  2. point < range.start or ( point = range.start and not(range.start included) )
  3. range.end < point or ( range.end = point and not(range.end included) )
  4. range1.end < range2.start or (( not(range1.end included) or not(range2.start included) ) and range1.end = range2.start )

Examples

before( 1, 10 ) = true
before( 10, 1 ) = false
before( 1, [1..10] ) = false
before( 1, (1..10] ) = true
before( 1, [5..10] ) = true
before( [1..10], 10 ) = false
before( [1..10), 10 ) = true
before( [1..10], 15 ) = true
before( [1..10], [15..20] ) = true
before( [1..10], [10..20] ) = false
before( [1..10), [10..20] ) = true
before( [1..10], (10..20] ) = true

after( )

Returns true when an element A is after an element B and when the relevant requirements for evaluating to true are also met.

Signatures

  1. after( point1 point2 )
  2. after( point range )
  3. after( range, point )
  4. after( range1 range2 )

Requirements for evaluating to true

  1. point1 > point2
  2. point > range.end or ( point = range.end and not(range.end included) )
  3. range.start > point or ( range.start = point and not(range.start included) )
  4. range1.start > range2.end or (( not(range1.start included) or not(range2.end included) ) and range1.start = range2.end )

Examples

after( 10, 5 ) = true
after( 5, 10 ) = false
after( 12, [1..10] ) = true
after( 10, [1..10) ) = true
after( 10, [1..10] ) = false
after( [11..20], 12 ) = false
after( [11..20], 10 ) = true
after( (11..20], 11 ) = true
after( [11..20], 11 ) = false
after( [11..20], [1..10] ) = true
after( [1..10], [11..20] ) = false
after( [11..20], [1..11) ) = true
after( (11..20], [1..11] ) = true

meets( )

Returns true when an element A meets an element B and when the relevant requirements for evaluating to true are also met.

Signatures

  1. meets( range1, range2 )

Requirements for evaluating to true

  1. range1.end included and range2.start included and range1.end = range2.start

Examples

meets( [1..5], [5..10] ) = true
meets( [1..5), [5..10] ) = false
meets( [1..5], (5..10] ) = false
meets( [1..5], [6..10] ) = false

met by( )

Returns true when an element A is met by an element B and when the relevant requirements for evaluating to true are also met.

Signatures

  1. met by( range1, range2 )

Requirements for evaluating to true

  1. range1.start included and range2.end included and range1.start = range2.end

Examples

met by( [5..10], [1..5] ) = true
met by( [5..10], [1..5) ) = false
met by( (5..10], [1..5] ) = false
met by( [6..10], [1..5] ) = false

overlaps( )

Returns true when an element A overlaps an element B and when the relevant requirements for evaluating to true are also met.

Signatures

  1. overlaps( range1, range2 )

Requirements for evaluating to true

  1. ( range1.end > range2.start or (range1.end = range2.start and (range1.end included or range2.end included)) ) and ( range1.start < range2.end or (range1.start = range2.end and range1.start included and range2.end included) )

Examples

overlaps( [1..5], [3..8] ) = true
overlaps( [3..8], [1..5] ) = true
overlaps( [1..8], [3..5] ) = true
overlaps( [3..5], [1..8] ) = true
overlaps( [1..5], [6..8] ) = false
overlaps( [6..8], [1..5] ) = false
overlaps( [1..5], [5..8] ) = true
overlaps( [1..5], (5..8] ) = false
overlaps( [1..5), [5..8] ) = false
overlaps( [1..5), (5..8] ) = false
overlaps( [5..8], [1..5] ) = true
overlaps( (5..8], [1..5] ) = false
overlaps( [5..8], [1..5) ) = false
overlaps( (5..8], [1..5) ) = false

overlaps before( )

Returns true when an element A overlaps before an element B and when the relevant requirements for evaluating to true are also met.

Signatures

  1. overlaps before( range1 range2 )

Requirements for evaluating to true

  1. ( range1.start < range2.start or (range1.start = range2.start and range1.start included and range2.start included) ) and ( range1.end > range2.start or (range1.end = range2.start and range1.end included and range2.start included) ) and ( range1.end < range2.end or (range1.end = range2.end and (not(range1.end included) or range2.end included )) )

Examples

overlaps before( [1..5], [3..8] ) = true
overlaps before( [1..5], [6..8] ) = false
overlaps before( [1..5], [5..8] ) = true
overlaps before( [1..5], (5..8] ) = false
overlaps before( [1..5), [5..8] ) = false
overlaps before( [1..5), (1..5] ) = true
overlaps before( [1..5], (1..5] ) = true
overlaps before( [1..5), [1..5] ) = false
overlaps before( [1..5], [1..5] ) = false

overlaps after( )

Returns true when an element A overlaps after an element B and when the relevant requirements for evaluating to true are also met.

Signatures

  1. overlaps after( range1 range2 )

Requirements for evaluating to true

  1. ( range2.start < range1.start or (range2.start = range1.start and range2.start included and not( range1.start included)) ) and ( range2.end > range1.start or (range2.end = range1.start and range2.end included and range1.start included) ) and ( range2.end < range1.end or (range2.end = range1.end and (not(range2.end included) or range1.end included)) )

Examples

overlaps after( [3..8], [1..5] )= true
overlaps after( [6..8], [1..5] )= false
overlaps after( [5..8], [1..5] )= true
overlaps after( (5..8], [1..5] )= false
overlaps after( [5..8], [1..5) )= false
overlaps after( (1..5], [1..5) )= true
overlaps after( (1..5], [1..5] )= true
overlaps after( [1..5], [1..5) )= false
overlaps after( [1..5], [1..5] )= false
overlaps after( (1..5), [1..5] )= false
overlaps after( (1..5], [1..6] )= false
overlaps after( (1..5], (1..5] )= false
overlaps after( (1..5], [2..5] )= false

finishes( )

Returns true when an element A finishes an element B and when the relevant requirements for evaluating to true are also met.

Signatures

  1. finishes( point, range )
  2. finishes( range1, range2 )

Requirements for evaluating to true

  1. range.end included and range.end = point
  2. range1.end included = range2.end included and range1.end = range2.end and ( range1.start > range2.start or (range1.start = range2.start and (not(range1.start included) or range2.start included)) )

Examples

finishes( 10, [1..10] ) = true
finishes( 10, [1..10) ) = false
finishes( [5..10], [1..10] ) = true
finishes( [5..10), [1..10] ) = false
finishes( [5..10), [1..10) ) = true
finishes( [1..10], [1..10] ) = true
finishes( (1..10], [1..10] ) = true

finished by( )

Returns true when an element A is finished by an element B and when the relevant requirements for evaluating to true are also met.

Signatures

  1. finished by( range, point )
  2. finished by( range1 range2 )

Requirements for evaluating to true

  1. range.end included and range.end = point
  2. range1.end included = range2.end included and range1.end = range2.end and ( range1.start < range2.start or (range1.start = range2.start and (range1.start included or not(range2.start included))) )

Examples

finished by( [1..10], 10 ) = true
finished by( [1..10), 10 ) = false
finished by( [1..10], [5..10] ) = true
finished by( [1..10], [5..10) ) = false
finished by( [1..10), [5..10) ) = true
finished by( [1..10], [1..10] ) = true
finished by( [1..10], (1..10] ) = true

includes( )

Returns true when an element A includes an element B and when the relevant requirements for evaluating to true are also met.

Signatures

  1. includes( range, point )
  2. includes( range1, range2 )

Requirements for evaluating to true

  1. (range.start < point and range.end > point) or (range.start = point and range.start included) or (range.end = point and range.end included)
  2. ( range1.start < range2.start or (range1.start = range2.start and (range1.start included or not(range2.start included))) ) and ( range1.end > range2.end or (range1.end = range2.end and (range1.end included or not(range2.end included))) )

Examples

includes( [1..10], 5 ) = true
includes( [1..10], 12 ) = false
includes( [1..10], 1 ) = true
includes( [1..10], 10 ) = true
includes( (1..10], 1 ) = false
includes( [1..10), 10 ) = false
includes( [1..10], [4..6] ) = true
includes( [1..10], [1..5] ) = true
includes( (1..10], (1..5] ) = true
includes( [1..10], (1..10) ) = true
includes( [1..10), [5..10) ) = true
includes( [1..10], [1..10) ) = true
includes( [1..10], (1..10] ) = true
includes( [1..10], [1..10] ) = true

during( )

Returns true when an element A is during an element B and when the relevant requirements for evaluating to true are also met.

Signatures

  1. during( point, range )
  2. during( range1 range2 )

Requirements for evaluating to true

  1. (range.start < point and range.end > point) or (range.start = point and range.start included) or (range.end = point and range.end included)
  2. ( range2.start < range1.start or (range2.start = range1.start and (range2.start included or not(range1.start included))) ) and ( range2.end > range1.end or (range2.end = range1.end and (range2.end included or not(range1.end included))) )

Examples

during( 5, [1..10] ) = true
during( 12, [1..10] ) = false
during( 1, [1..10] ) = true
during( 10, [1..10] ) = true
during( 1, (1..10] ) = false
during( 10, [1..10) ) = false
during( [4..6], [1..10] ) = true
during( [1..5], [1..10] ) = true
during( (1..5], (1..10] ) = true
during( (1..10), [1..10] ) = true
during( [5..10), [1..10) ) = true
during( [1..10), [1..10] ) = true
during( (1..10], [1..10] ) = true
during( [1..10], [1..10] ) = true

starts( )

Returns true when an element A starts an element B and when the relevant requirements for evaluating to true are also met.

Signatures

  1. starts( point, range )
  2. starts( range1, range2 )

Requirements for evaluating to true

  1. range.start = point and range.start included
  2. range1.start = range2.start and range1.start included = range2.start included and ( range1.end < range2.end or (range1.end = range2.end and (not(range1.end included) or range2.end included)) )

Examples

starts( 1, [1..10] ) = true
starts( 1, (1..10] ) = false
starts( 2, [1..10] ) = false
starts( [1..5], [1..10] ) = true
starts( (1..5], (1..10] ) = true
starts( (1..5], [1..10] ) = false
starts( [1..5], (1..10] ) = false
starts( [1..10], [1..10] ) = true
starts( [1..10), [1..10] ) = true
starts( (1..10), (1..10) ) = true

started by( )

Returns true when an element A is started by an element B and when the relevant requirements for evaluating to true are also met.

Signatures

  1. started by( range, point )
  2. started by( range1, range2 )

Requirements for evaluating to true

  1. range.start = point and range.start included
  2. range1.start = range2.start and range1.start included = range2.start included and ( range2.end < range1.end or (range2.end = range1.end and (not(range2.end included) or range1.end included)) )

Examples

started by( [1..10], 1 ) = true
started by( (1..10], 1 ) = false
started by( [1..10], 2 ) = false
started by( [1..10], [1..5] ) = true
started by( (1..10], (1..5] ) = true
started by( [1..10], (1..5] ) = false
started by( (1..10], [1..5] ) = false
started by( [1..10], [1..10] ) = true
started by( [1..10], [1..10) ) = true
started by( (1..10), (1..10) ) = true

coincides( )

Returns true when an element A coincides with an element B and when the relevant requirements for evaluating to true are also met.

Signatures

  1. coincides( point1, point2 )
  2. coincides( range1, range2 )

Requirements for evaluating to true

  1. point1 = point2
  2. range1.start = range2.start and range1.start included = range2.start included and range1.end = range2.end and range1.end included = range2.end included

Examples

coincides( 5, 5 ) = true
coincides( 3, 4 ) = false
coincides( [1..5], [1..5] ) = true
coincides( (1..5), [1..5] ) = false
coincides( [1..5], [2..6] ) = false

4.3.2.8. Temporal functions

The following functions support general temporal operations.

day of year( date )

Returns the Gregorian number of the day of the year.

Table 4.61. Parameters

ParameterType

date

date or date and time

Example

day of year( date(2019, 9, 17) ) = 260

day of week( date )

Returns the Gregorian day of the week: "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", or "Sunday".

Table 4.62. Parameters

ParameterType

date

date or date and time

Example

day of week( date(2019, 9, 17) ) = "Tuesday"

month of year( date )

Returns the Gregorian month of the year: "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", or "December".

Table 4.63. Parameters

ParameterType

date

date or date and time

Example

month of year( date(2019, 9, 17) ) = "September"

month of year( date )

Returns the Gregorian week of the year as defined by ISO 8601.

Table 4.64. Parameters

ParameterType

date

date or date and time

Examples

week of year( date(2019, 9, 17) ) = 38
week of year( date(2003, 12, 29) ) = 1
week of year( date(2004, 1, 4) ) = 1
week of year( date(2005, 1, 1) ) = 53
week of year( date(2005, 1, 3) ) = 1
week of year( date(2005, 1, 9) ) = 1

4.3.2.9. Sort functions

The following functions support sorting operations.

sort( list, precedes )

Returns a list of the same elements but ordered according to the sorting function.

Table 4.65. Parameters

ParameterType

list

list

precedes

function

Example

sort( list: [3,1,4,5,2], precedes: function(x,y) x < y ) = [1,2,3,4,5]

4.3.2.10. Context functions

The following functions support context operations.

get value( m, key )

Returns the value from the context for the specified entry key.

Table 4.66. Parameters

ParameterType

m

context

key

string

Examples

get value( {key1 : "value1"}, "key1" ) = "value1"
get value( {key1 : "value1"}, "unexistent-key" ) = null

get entries( m )

Returns a list of key-value pairs for the specified context.

Table 4.67. Parameters

ParameterType

m

context

Example

get entries( {key1 : "value1", key2 : "value2"} ) = [ { key : "key1", value : "value1" }, {key : "key2", value : "value2"} ]

4.3.3. Variable and function names in FEEL

Unlike many traditional expression languages, Friendly Enough Expression Language (FEEL) supports spaces and a few special characters as part of variable and function names. A FEEL name must start with a letter, ?, or _ element. The unicode letter characters are also allowed. Variable names cannot start with a language keyword, such as and, true, or every. The remaining characters in a variable name can be any of the starting characters, as well as digits, white spaces, and special characters such as +, -, /, *, ', and ..

For example, the following names are all valid FEEL names:

  • Age
  • Birth Date
  • Flight 234 pre-check procedure

Several limitations apply to variable and function names in FEEL:

Ambiguity
The use of spaces, keywords, and other special characters as part of names can make FEEL ambiguous. The ambiguities are resolved in the context of the expression, matching names from left to right. The parser resolves the variable name as the longest name matched in scope. You can use ( ) to disambiguate names if necessary.
Spaces in names

The DMN specification limits the use of spaces in FEEL names. According to the DMN specification, names can contain multiple spaces but not two consecutive spaces.

In order to make the language easier to use and avoid common errors due to spaces, Red Hat Process Automation Manager removes the limitation on the use of consecutive spaces. Red Hat Process Automation Manager supports variable names with any number of consecutive spaces, but normalizes them into a single space. For example, the variable references First Name with one space and First Name with two spaces are both acceptable in Red Hat Process Automation Manager.

Red Hat Process Automation Manager also normalizes the use of other white spaces, like the non-breakable white space that is common in web pages, tabs, and line breaks. From a Red Hat Process Automation Manager FEEL engine perspective, all of these characters are normalized into a single white space before processing.

The keyword in
The keyword in is the only keyword in the language that cannot be used as part of a variable name. Although the specifications allow the use of keywords in the middle of variable names, the use of in in variable names conflicts with the grammar definition of for, every and some expression constructs.

4.4. DMN decision logic in boxed expressions

Boxed expressions in DMN are tables that you use to define the underlying logic of decision nodes and business knowledge models in a decision requirements diagram (DRD). Some boxed expressions can contain other boxed expressions, but the top-level boxed expression corresponds to the decision logic of a single DRD artifact. While DRDs represent the flow of a DMN decision model, boxed expressions define the actual decision logic of individual nodes. DRDs and boxed expressions together form a complete and functional DMN decision model.

The following are the types of DMN boxed expressions:

  • Decision tables
  • Literal expressions
  • Contexts
  • Relations
  • Functions
  • Invocations
  • Lists
Note

Red Hat Process Automation Manager does not provide boxed list expressions in Business Central, but supports a FEEL list data type that you can use in boxed literal expressions. For more information about the list data type and other FEEL data types in Red Hat Process Automation Manager, see Section 4.3.1, “Data types in FEEL”.

All Friendly Enough Expression Language (FEEL) expressions that you use in your boxed expressions must conform to the FEEL syntax requirements in the OMG Decision Model and Notation specification.

4.4.1. DMN decision tables

A decision table in DMN is a visual representation of one or more business rules in a tabular format. You use decision tables to define rules for a decision node that applies those rules at a given point in the decision model. Each rule consists of a single row in the table, and includes columns that define the conditions (input) and outcome (output) for that particular row. The definition of each row is precise enough to derive the outcome using the values of the conditions. Input and output values can be FEEL expressions or defined data type values.

For example, the following decision table determines credit score ratings based on a defined range of a loan applicant’s credit score:

Figure 4.3. Decision table for credit score rating

dmn decision table example

The following decision table determines the next step in a lending strategy for applicants depending on applicant loan eligibility and the bureau call type:

Figure 4.4. Decision table for lending strategy

dmn decision table example2

The following decision table determines applicant qualification for a loan as the concluding decision node in a loan prequalification decision model:

Figure 4.5. Decision table for loan prequalification

dmn decision table example3

Decision tables are a popular way of modeling rules and decision logic, and are used in many methodologies (such as DMN) and implementation frameworks (such as Drools).

Important

Red Hat Process Automation Manager supports both DMN decision tables and Drools-native decision tables, but they are different types of assets with different syntax requirements and are not interchangeable. For more information about Drools-native decision tables in Red Hat Process Automation Manager, see Designing a decision service using spreadsheet decision tables.

4.4.1.1. Hit policies in DMN decision tables

Hit policies determine how to reach an outcome when multiple rules in a decision table match the provided input values. For example, if one rule in a decision table applies a sales discount to military personnel and another rule applies a discount to students, then when a customer is both a student and in the military, the decision table hit policy must indicate whether to apply one discount or the other (Unique, First) or both discounts (Collect Sum). You specify the single character of the hit policy (U, F, C+) in the upper-left corner of the decision table.

The following decision table hit policies are supported in DMN:

  • Unique (U): Permits only one rule to match. Any overlap raises an error.
  • Any (A): Permits multiple rules to match, but they must all have the same output. If multiple matching rules do not have the same output, an error is raised.
  • Priority (P): Permits multiple rules to match, with different outputs. The output that comes first in the output values list is selected.
  • First (F): Uses the first match in rule order.
  • Collect (C+, C>, C<, C#): Aggregates output from multiple rules based on an aggregation function.

    • Collect ( C ): Aggregates values in an arbitrary list.
    • Collect Sum (C+): Outputs the sum of all collected values. Values must be numeric.
    • Collect Min (C<): Outputs the minimum value among the matches. The resulting values must be comparable, such as numbers, dates, or text (lexicographic order).
    • Collect Max (C>): Outputs the maximum value among the matches. The resulting values must be comparable, such as numbers, dates or text (lexicographic order).
    • Collect Count (C#): Outputs the number of matching rules.

4.4.2. Boxed literal expressions

A boxed literal expression in DMN is a literal FEEL expression as text in a table cell, typically with a labeled column and an assigned data type. You use boxed literal expressions to define simple or complex node logic or decision data directly in FEEL for a particular node in a decision. Literal FEEL expressions must conform to FEEL syntax requirements in the OMG Decision Model and Notation specification.

For example, the following boxed literal expression defines the minimum acceptable PITI calculation (principal, interest, taxes, and insurance) in a lending decision, where acceptable rate is a variable defined in the DMN model:

Figure 4.6. Boxed literal expression for minimum PITI value

dmn literal expression example2

The following boxed literal expression sorts a list of possible dating candidates (soul mates) in an online dating application based on their score on criteria such as age, location, and interests:

Figure 4.7. Boxed literal expression for matching online dating candidates

dmn literal expression example3b

4.4.3. Boxed context expressions

A boxed context expression in DMN is a set of variable names and values with a result value. Each name-value pair is a context entry. You use context expressions to represent data definitions in decision logic and set a value for a desired decision element within the DMN decision model. A value in a boxed context expression can be a data type value or FEEL expression, or can contain a nested sub-expression of any type, such as a decision table, a literal expression, or another context expression.

For example, the following boxed context expression defines the factors for sorting delayed passengers in a flight-rebooking decision model, based on defined data types (tPassengerTable, tFlightNumberList):

Figure 4.8. Boxed context expression for flight passenger waiting list

dmn context expression example

The following boxed context expression defines the factors that determine whether a loan applicant can meet minimum mortgage payments based on principal, interest, taxes, and insurance (PITI), represented as a front-end ratio calculation with a sub-context expression:

Figure 4.9. Boxed context expression for front-end client PITI ratio

dmn context expression example2

4.4.4. Boxed relation expressions

A boxed relation expression in DMN is a traditional data table with information about given entities, listed as rows. You use boxed relation tables to define decision data for relevant entities in a decision at a particular node. Boxed relation expressions are similar to context expressions in that they set variable names and values, but relation expressions contain no result value and list all variable values based on a single defined variable in each column.

For example, the following boxed relation expression provides information about employees in an employee rostering decision:

Figure 4.10. Boxed relation expression with employee information

dmn relation expression example

4.4.5. Boxed function expressions

A boxed function expression in DMN is a parameterized boxed expression containing a literal FEEL expression, a nested context expression of an external JAVA or PMML function, or a nested boxed expression of any type. By default, all business knowledge models are defined as boxed function expressions. You use boxed function expressions to call functions on your decision logic and to define all business knowledge models.

For example, the following boxed function expression determines airline flight capacity in a flight-rebooking decision model:

Figure 4.11. Boxed function expression for flight capacity

dmn function expression example

The following boxed function expression contains a basic Java function as a context expression for determining absolute value in a decision model calculation:

Figure 4.12. Boxed function expression for absolute value

dmn function expression example2

The following boxed function expression determines a monthly mortgage installment as a business knowledge model in a lending decision, with the function value defined as a nested context expression:

Figure 4.13. Boxed function expression for installment calculation in business knowledge model

dmn function expression example3

The following boxed function expression uses a PMML model included in the DMN file to define the minimum acceptable PITI calculation (principal, interest, taxes, and insurance) in a lending decision:

Figure 4.14. Boxed function expression with an included PMML model in business knowledge model

dmn function expression example5

4.4.6. Boxed invocation expressions

A boxed invocation expression in DMN is a boxed expression that invokes a business knowledge model. A boxed invocation expression contains the name of the business knowledge model to be invoked and a list of parameter bindings. Each binding is represented by two boxed expressions on a row: The box on the left contains the name of a parameter and the box on the right contains the binding expression whose value is assigned to the parameter to evaluate the invoked business knowledge model. You use boxed invocations to invoke at a particular decision node a business knowledge model defined in the decision model.

For example, the following boxed invocation expression invokes a Reassign Next Passenger business knowledge model as the concluding decision node in a flight-rebooking decision model:

Figure 4.15. Boxed invocation expression to reassign flight passengers

dmn invocation example

The following boxed invocation expression invokes an InstallmentCalculation business knowledge model to calculate a monthly installment amount for a loan before proceeding to affordability decisions:

Figure 4.16. Boxed invocation expression for required monthly installment

dmn invocation example2

4.4.7. Boxed list expressions

A boxed list expression in DMN represents a FEEL list of items. You use boxed lists to define lists of relevant items for a particular node in a decision. You can also use literal FEEL expressions for list items in cells to create more complex lists.

For example, the following boxed list expression identifies approved credit score agencies in a loan application decision service:

Figure 4.17. Boxed list expression for approved credit score agencies

dmn list expression example

The following boxed list expression also identifies approved credit score agencies but uses FEEL logic to define the agency status (Inc., LLC, SA, GA) based on a DMN input node:

Figure 4.18. Boxed list expression using FEEL logic for approved credit score agency status

dmn list expression example2
dmn list expression example2a

4.5. DMN model example

The following is a real-world DMN model example that demonstrates how you can use decision modeling to reach a decision based on input data, circumstances, and company guidelines. In this scenario, a flight from San Diego to New York is canceled, requiring the affected airline to find alternate arrangements for its inconvenienced passengers.

First, the airline collects the information necessary to determine how best to get the travelers to their destinations:

Input data
  • List of flights
  • List of passengers
Decisions
  • Prioritize the passengers who will get seats on a new flight
  • Determine which flights those passengers will be offered
Business knowledge models
  • The company process for determining passenger priority
  • Any flights that have space available
  • Company rules for determining how best to reassign inconvenienced passengers

The airline then uses the DMN standard to model its decision process in the following decision requirements diagram (DRD) for determining the best rebooking solution:

Figure 4.19. DRD for flight rebooking

dmn passenger rebooking drd

Similar to flowcharts, DRDs use shapes to represent the different elements in a process. Ovals contain the two necessary input data, rectangles contain the decision points in the model, and rectangles with clipped corners (business knowledge models) contain reusable logic that can be repeatedly invoked.

The DRD draws logic for each element from boxed expressions that provide variable definitions using FEEL expressions or data type values.

Some boxed expressions are basic, such as the following decision for establishing a prioritized waiting list:

Figure 4.20. Boxed context expression example for prioritized wait list

dmn context expression example

Some boxed expressions are more complex with greater detail and calculation, such as the following business knowledge model for reassigning the next delayed passenger:

Figure 4.21. Boxed function expression for passenger reassignment

dmn reassign passenger

The following is the DMN source file for this decision model:

<dmn:definitions xmlns="https://www.drools.org/kie-dmn/Flight-rebooking" xmlns:dmn="http://www.omg.org/spec/DMN/20151101/dmn.xsd" xmlns:feel="http://www.omg.org/spec/FEEL/20140401" id="_0019_flight_rebooking" name="0019-flight-rebooking" namespace="https://www.drools.org/kie-dmn/Flight-rebooking">
  <dmn:itemDefinition id="_tFlight" name="tFlight">
    <dmn:itemComponent id="_tFlight_Flight" name="Flight Number">
      <dmn:typeRef>feel:string</dmn:typeRef>
    </dmn:itemComponent>
    <dmn:itemComponent id="_tFlight_From" name="From">
      <dmn:typeRef>feel:string</dmn:typeRef>
    </dmn:itemComponent>
    <dmn:itemComponent id="_tFlight_To" name="To">
      <dmn:typeRef>feel:string</dmn:typeRef>
    </dmn:itemComponent>
    <dmn:itemComponent id="_tFlight_Dep" name="Departure">
      <dmn:typeRef>feel:dateTime</dmn:typeRef>
    </dmn:itemComponent>
    <dmn:itemComponent id="_tFlight_Arr" name="Arrival">
      <dmn:typeRef>feel:dateTime</dmn:typeRef>
    </dmn:itemComponent>
    <dmn:itemComponent id="_tFlight_Capacity" name="Capacity">
      <dmn:typeRef>feel:number</dmn:typeRef>
    </dmn:itemComponent>
    <dmn:itemComponent id="_tFlight_Status" name="Status">
      <dmn:typeRef>feel:string</dmn:typeRef>
    </dmn:itemComponent>
  </dmn:itemDefinition>
  <dmn:itemDefinition id="_tFlightTable" isCollection="true" name="tFlightTable">
    <dmn:typeRef>tFlight</dmn:typeRef>
  </dmn:itemDefinition>
  <dmn:itemDefinition id="_tPassenger" name="tPassenger">
    <dmn:itemComponent id="_tPassenger_Name" name="Name">
      <dmn:typeRef>feel:string</dmn:typeRef>
    </dmn:itemComponent>
    <dmn:itemComponent id="_tPassenger_Status" name="Status">
      <dmn:typeRef>feel:string</dmn:typeRef>
    </dmn:itemComponent>
    <dmn:itemComponent id="_tPassenger_Miles" name="Miles">
      <dmn:typeRef>feel:number</dmn:typeRef>
    </dmn:itemComponent>
    <dmn:itemComponent id="_tPassenger_Flight" name="Flight Number">
      <dmn:typeRef>feel:string</dmn:typeRef>
    </dmn:itemComponent>
  </dmn:itemDefinition>
  <dmn:itemDefinition id="_tPassengerTable" isCollection="true" name="tPassengerTable">
    <dmn:typeRef>tPassenger</dmn:typeRef>
  </dmn:itemDefinition>
  <dmn:itemDefinition id="_tFlightNumberList" isCollection="true" name="tFlightNumberList">
    <dmn:typeRef>feel:string</dmn:typeRef>
  </dmn:itemDefinition>
  <dmn:inputData id="i_Flight_List" name="Flight List">
    <dmn:variable name="Flight List" typeRef="tFlightTable"/>
  </dmn:inputData>
  <dmn:inputData id="i_Passenger_List" name="Passenger List">
    <dmn:variable name="Passenger List" typeRef="tPassengerTable"/>
  </dmn:inputData>
  <dmn:decision name="Prioritized Waiting List" id="d_PrioritizedWaitingList">
    <dmn:variable name="Prioritized Waiting List" typeRef="tPassengerTable"/>
    <dmn:informationRequirement>
      <dmn:requiredInput href="#i_Passenger_List"/>
    </dmn:informationRequirement>
    <dmn:informationRequirement>
      <dmn:requiredInput href="#i_Flight_List"/>
    </dmn:informationRequirement>
    <dmn:knowledgeRequirement>
      <dmn:requiredKnowledge href="#b_PassengerPriority"/>
    </dmn:knowledgeRequirement>
    <dmn:context>
      <dmn:contextEntry>
        <dmn:variable name="Cancelled Flights" typeRef="tFlightNumberList"/>
        <dmn:literalExpression>
          <dmn:text>Flight List[ Status = "cancelled" ].Flight Number</dmn:text>
        </dmn:literalExpression>
      </dmn:contextEntry>
      <dmn:contextEntry>
        <dmn:variable name="Waiting List" typeRef="tPassengerTable"/>
        <dmn:literalExpression>
          <dmn:text>Passenger List[ list contains( Cancelled Flights, Flight Number ) ]</dmn:text>
        </dmn:literalExpression>
      </dmn:contextEntry>
      <dmn:contextEntry>
        <dmn:literalExpression>
          <dmn:text>sort( Waiting List, passenger priority )</dmn:text>
        </dmn:literalExpression>
      </dmn:contextEntry>
    </dmn:context>
  </dmn:decision>
  <dmn:decision name="Rebooked Passengers" id="d_RebookedPassengers">
    <dmn:variable name="Rebooked Passengers" typeRef="tPassengerTable"/>
    <dmn:informationRequirement>
      <dmn:requiredDecision href="#d_PrioritizedWaitingList"/>
    </dmn:informationRequirement>
    <dmn:informationRequirement>
      <dmn:requiredInput href="#i_Flight_List"/>
    </dmn:informationRequirement>
    <dmn:knowledgeRequirement>
      <dmn:requiredKnowledge href="#b_ReassignNextPassenger"/>
    </dmn:knowledgeRequirement>
    <dmn:invocation>
      <dmn:literalExpression>
        <dmn:text>reassign next passenger</dmn:text>
      </dmn:literalExpression>
      <dmn:binding>
        <dmn:parameter name="Waiting List"/>
        <dmn:literalExpression>
          <dmn:text>Prioritized Waiting List</dmn:text>
        </dmn:literalExpression>
      </dmn:binding>
      <dmn:binding>
        <dmn:parameter name="Reassigned Passengers List"/>
        <dmn:literalExpression>
          <dmn:text>[]</dmn:text>
        </dmn:literalExpression>
      </dmn:binding>
      <dmn:binding>
        <dmn:parameter name="Flights"/>
        <dmn:literalExpression>
          <dmn:text>Flight List</dmn:text>
        </dmn:literalExpression>
      </dmn:binding>
    </dmn:invocation>
  </dmn:decision>
  <dmn:businessKnowledgeModel id="b_PassengerPriority" name="passenger priority">
    <dmn:encapsulatedLogic>
      <dmn:formalParameter name="Passenger1" typeRef="tPassenger"/>
      <dmn:formalParameter name="Passenger2" typeRef="tPassenger"/>
      <dmn:decisionTable hitPolicy="UNIQUE">
        <dmn:input id="b_Passenger_Priority_dt_i_P1_Status" label="Passenger1.Status">
          <dmn:inputExpression typeRef="feel:string">
            <dmn:text>Passenger1.Status</dmn:text>
          </dmn:inputExpression>
          <dmn:inputValues>
            <dmn:text>"gold", "silver", "bronze"</dmn:text>
          </dmn:inputValues>
        </dmn:input>
        <dmn:input id="b_Passenger_Priority_dt_i_P2_Status" label="Passenger2.Status">
          <dmn:inputExpression typeRef="feel:string">
            <dmn:text>Passenger2.Status</dmn:text>
          </dmn:inputExpression>
          <dmn:inputValues>
            <dmn:text>"gold", "silver", "bronze"</dmn:text>
          </dmn:inputValues>
        </dmn:input>
        <dmn:input id="b_Passenger_Priority_dt_i_P1_Miles" label="Passenger1.Miles">
          <dmn:inputExpression typeRef="feel:string">
            <dmn:text>Passenger1.Miles</dmn:text>
          </dmn:inputExpression>
        </dmn:input>
        <dmn:output id="b_Status_Priority_dt_o" label="Passenger1 has priority">
          <dmn:outputValues>
            <dmn:text>true, false</dmn:text>
          </dmn:outputValues>
          <dmn:defaultOutputEntry>
            <dmn:text>false</dmn:text>
          </dmn:defaultOutputEntry>
        </dmn:output>
        <dmn:rule id="b_Passenger_Priority_dt_r1">
          <dmn:inputEntry id="b_Passenger_Priority_dt_r1_i1">
            <dmn:text>"gold"</dmn:text>
          </dmn:inputEntry>
          <dmn:inputEntry id="b_Passenger_Priority_dt_r1_i2">
            <dmn:text>"gold"</dmn:text>
          </dmn:inputEntry>
          <dmn:inputEntry id="b_Passenger_Priority_dt_r1_i3">
            <dmn:text>>= Passenger2.Miles</dmn:text>
          </dmn:inputEntry>
          <dmn:outputEntry id="b_Passenger_Priority_dt_r1_o1">
            <dmn:text>true</dmn:text>
          </dmn:outputEntry>
        </dmn:rule>
        <dmn:rule id="b_Passenger_Priority_dt_r2">
          <dmn:inputEntry id="b_Passenger_Priority_dt_r2_i1">
            <dmn:text>"gold"</dmn:text>
          </dmn:inputEntry>
          <dmn:inputEntry id="b_Passenger_Priority_dt_r2_i2">
            <dmn:text>"silver","bronze"</dmn:text>
          </dmn:inputEntry>
          <dmn:inputEntry id="b_Passenger_Priority_dt_r2_i3">
            <dmn:text>-</dmn:text>
          </dmn:inputEntry>
          <dmn:outputEntry id="b_Passenger_Priority_dt_r2_o1">
            <dmn:text>true</dmn:text>
          </dmn:outputEntry>
        </dmn:rule>
        <dmn:rule id="b_Passenger_Priority_dt_r3">
          <dmn:inputEntry id="b_Passenger_Priority_dt_r3_i1">
            <dmn:text>"silver"</dmn:text>
          </dmn:inputEntry>
          <dmn:inputEntry id="b_Passenger_Priority_dt_r3_i2">
            <dmn:text>"silver"</dmn:text>
          </dmn:inputEntry>
          <dmn:inputEntry id="b_Passenger_Priority_dt_r3_i3">
            <dmn:text>>= Passenger2.Miles</dmn:text>
          </dmn:inputEntry>
          <dmn:outputEntry id="b_Passenger_Priority_dt_r3_o1">
            <dmn:text>true</dmn:text>
          </dmn:outputEntry>
        </dmn:rule>
        <dmn:rule id="b_Passenger_Priority_dt_r4">
          <dmn:inputEntry id="b_Passenger_Priority_dt_r4_i1">
            <dmn:text>"silver"</dmn:text>
          </dmn:inputEntry>
          <dmn:inputEntry id="b_Passenger_Priority_dt_r4_i2">
            <dmn:text>"bronze"</dmn:text>
          </dmn:inputEntry>
          <dmn:inputEntry id="b_Passenger_Priority_dt_r4_i3">
            <dmn:text>-</dmn:text>
          </dmn:inputEntry>
          <dmn:outputEntry id="b_Passenger_Priority_dt_r4_o1">
            <dmn:text>true</dmn:text>
          </dmn:outputEntry>
        </dmn:rule>
        <dmn:rule id="b_Passenger_Priority_dt_r5">
          <dmn:inputEntry id="b_Passenger_Priority_dt_r5_i1">
            <dmn:text>"bronze"</dmn:text>
          </dmn:inputEntry>
          <dmn:inputEntry id="b_Passenger_Priority_dt_r5_i2">
            <dmn:text>"bronze"</dmn:text>
          </dmn:inputEntry>
          <dmn:inputEntry id="b_Passenger_Priority_dt_r5_i3">
            <dmn:text>>= Passenger2.Miles</dmn:text>
          </dmn:inputEntry>
          <dmn:outputEntry id="b_Passenger_Priority_dt_r5_o1">
            <dmn:text>true</dmn:text>
          </dmn:outputEntry>
        </dmn:rule>
      </dmn:decisionTable>
    </dmn:encapsulatedLogic>
    <dmn:variable name="passenger priority" typeRef="feel:boolean"/>
  </dmn:businessKnowledgeModel>
  <dmn:businessKnowledgeModel id="b_ReassignNextPassenger" name="reassign next passenger">
    <dmn:encapsulatedLogic>
      <dmn:formalParameter name="Waiting List" typeRef="tPassengerTable"/>
      <dmn:formalParameter name="Reassigned Passengers List" typeRef="tPassengerTable"/>
      <dmn:formalParameter name="Flights" typeRef="tFlightTable"/>
      <dmn:context>
        <dmn:contextEntry>
          <dmn:variable name="Next Passenger" typeRef="tPassenger"/>
          <dmn:literalExpression>
            <dmn:text>Waiting List[1]</dmn:text>
          </dmn:literalExpression>
        </dmn:contextEntry>
        <dmn:contextEntry>
          <dmn:variable name="Original Flight" typeRef="tFlight"/>
          <dmn:literalExpression>
            <dmn:text>Flights[ Flight Number = Next Passenger.Flight Number ][1]</dmn:text>
          </dmn:literalExpression>
        </dmn:contextEntry>
        <dmn:contextEntry>
          <dmn:variable name="Best Alternate Flight" typeRef="tFlight"/>
          <dmn:literalExpression>
            <dmn:text>Flights[ From = Original Flight.From and To = Original Flight.To and Departure > Original Flight.Departure and Status = "scheduled" and has capacity( item, Reassigned Passengers List ) ][1]</dmn:text>
          </dmn:literalExpression>
        </dmn:contextEntry>
        <dmn:contextEntry>
          <dmn:variable name="Reassigned Passenger" typeRef="tPassenger"/>
          <dmn:context>
            <dmn:contextEntry>
              <dmn:variable name="Name" typeRef="feel:string"/>
              <dmn:literalExpression>
                <dmn:text>Next Passenger.Name</dmn:text>
              </dmn:literalExpression>
            </dmn:contextEntry>
            <dmn:contextEntry>
              <dmn:variable name="Status" typeRef="feel:string"/>
              <dmn:literalExpression>
                <dmn:text>Next Passenger.Status</dmn:text>
              </dmn:literalExpression>
            </dmn:contextEntry>
            <dmn:contextEntry>
              <dmn:variable name="Miles" typeRef="feel:number"/>
              <dmn:literalExpression>
                <dmn:text>Next Passenger.Miles</dmn:text>
              </dmn:literalExpression>
            </dmn:contextEntry>
            <dmn:contextEntry>
              <dmn:variable name="Flight Number" typeRef="feel:string"/>
              <dmn:literalExpression>
                <dmn:text>Best Alternate Flight.Flight Number</dmn:text>
              </dmn:literalExpression>
            </dmn:contextEntry>
          </dmn:context>
        </dmn:contextEntry>
        <dmn:contextEntry>
          <dmn:variable name="Remaining Waiting List" typeRef="tPassengerTable"/>
          <dmn:literalExpression>
            <dmn:text>remove( Waiting List, 1 )</dmn:text>
          </dmn:literalExpression>
        </dmn:contextEntry>
        <dmn:contextEntry>
          <dmn:variable name="Updated Reassigned Passengers List" typeRef="tPassengerTable"/>
          <dmn:literalExpression>
            <dmn:text>append( Reassigned Passengers List, Reassigned Passenger )</dmn:text>
          </dmn:literalExpression>
        </dmn:contextEntry>
        <dmn:contextEntry>
          <dmn:literalExpression>
            <dmn:text>if count( Remaining Waiting List ) > 0 then reassign next passenger( Remaining Waiting List, Updated Reassigned Passengers List, Flights ) else Updated Reassigned Passengers List</dmn:text>
          </dmn:literalExpression>
        </dmn:contextEntry>
      </dmn:context>
    </dmn:encapsulatedLogic>
    <dmn:variable name="reassign next passenger" typeRef="tPassengerTable"/>
    <dmn:knowledgeRequirement>
      <dmn:requiredKnowledge href="#b_HasCapacity"/>
    </dmn:knowledgeRequirement>
  </dmn:businessKnowledgeModel>
  <dmn:businessKnowledgeModel id="b_HasCapacity" name="has capacity">
    <dmn:encapsulatedLogic>
      <dmn:formalParameter name="flight" typeRef="tFlight"/>
      <dmn:formalParameter name="rebooked list" typeRef="tPassengerTable"/>
      <dmn:literalExpression>
        <dmn:text>flight.Capacity > count( rebooked list[ Flight Number = flight.Flight Number ] )</dmn:text>
      </dmn:literalExpression>
    </dmn:encapsulatedLogic>
    <dmn:variable name="has capacity" typeRef="feel:boolean"/>
  </dmn:businessKnowledgeModel>
</dmn:definitions>