soft-arch/src/docs/fml/index.md

FML Documentation

The Feature Modeling Language (FML) is used to represent how features are decomposed in sub-features and which kind of constraints are there between them.

The language comes with two syntaxes: flat (.fml1) and nested (.fml2).

Flat syntax

Syntax

To create a feature: feature <id> <label>
To create a simple relation: <fromId> <relationKind> <toId>
where relationKind is one of:

• has: required sub-feature
• canHave: optional sub-feature

To create a composite relation: <fromId> <relationKind> [<toId1>, <toId2>, ...]
where relationKind is one of:

• hasOneOf: exclusive subfeatures, choose only 1
• hasSome: alternative subfeatures, chose at least 1

To add constraints: <fromId> <contraintKind> <toId>
where contraintKind is one of:

• requires
• excludes

Flat Syntax - Example

Nested syntax

Syntax

To create a feature: <id> <label> <modifier>
where modifier is one of:

• optional
• required

This modifier is used when the feature is being defiend as sub-feature to specify the relation kind

Each feature declaration CAN be followed by one of the following relations:

• has: used in combination with the modifier of the features defined in this scope
• hasOneOf: exclusive subfeatures, choose only 1
• hasSome: alternative subfeatures, chose at least 1.

AFTER the sub-features declaration (if present) we can define the constraints for the feature as <contraintKind> <toId>
where contraintKind is one of:

• requires
• excludes

We can create a complex structure of features by nesting feature declarations, see examples for more in detail exaplanation.

Examples

Simple feature with no sub-features

id "Simple feature"

Feature with both required and optional sub-features

NOTE: both subfeatures are just simple feature declarations like in the previous example

root "Root Feature"
  has
    req "Required sub-feature" required
    opt "Optional sub-feature" optional

Feature with constraint

NOTE: the contraints are not bi-directional, this only implies that if we want to select opt1 we also have to select op2.

root "Root Feature"
  has
    req "Required sub-feature" required
    opt1 "Optional sub-feature 1" optional
      requires opt2
    opt2 "Optional sub-feature 2" optional

If we want it bi-directional we have to use two constraints

root "Root Feature"
  has
    req "Required sub-feature" required
    opt1 "Optional sub-feature 1" optional
      requires opt2
    opt2 "Optional sub-feature 2" optional
      requires opt1

Nested Syntax - Example