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| − | Henshin's '''variability management''' feature allows to express variants of the same rule in a compact way, by making the commonalities and differences (variabilities) between the rules explicit. The key idea is to annotate rule elements (such as nodes and edges) with presence conditions over the ''features'' in which the variants differ. A presence condition specifies a condition under which an element is present. Since editing presence conditions by hand is cumbersome, we provide dedicated editing support to reduce that effort.
| + | #REDIRECT [[Variant Management]] |
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| − | === Example ===
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| − | Consider a family of three refactoring rules for refactoring a class diagram.
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| − | The rules, shown below, express variants of the ''move method'' refactoring for class models. The first rule specifies the relocation of a method between two classes.
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| − | The second one additionally creates a "wrapper" method of the same name in the source class.
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| − | The third one adds an annotation to mark the wrapper method as deprecated.
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| − | [[File:Henshin_vb_exampleClassic.png|thumb|none|500px]] | + | |
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| − | These three rule variants can be expressed using one rule with variability, shown below.
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| − | Several elements are annotated with presence conditions over the features ''wrapper'' and ''deprecate''.
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| − | The variants are obtained by configuring the rule, i.e., binding the features to ''true'' or ''false'' and removing elements whose presence condition evaluates to ''false''.
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| − | Configuration ''{wrapper=false; deprecate=false}'' yields the base rule, a rule isomorphic to rule ''moveMethod'' in the Figure above.
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| − | The rules induced by the configurations ''{wrapper=true; deprecate=false}'' and ''{wrapper=true; deprecate=true}'' produce the additional variants.
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| − | To avoid the illegal configuration ''{wrapper=false; deprecate=true}'', the rule has a constraint called ''feature model'', shown in the title bar, requiring ''wrapper'' to be true if ''deprecate'' is true.
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| − | [[File:Henshin_vb_exampleCompact.png|thumb|none|350px]]
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| − | === Integration with graphical editor ===
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| − | A user interface supporting the management of rules with variability is integrated with Henshin's [[Henshin/Graphical Editor|graphical editor]].
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| − | The main components of this user interface, a graphical editor and its attached ''properties'' view, are shown in the left of the image below.
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| − | As custom components, we provide the ''variability'' and ''sanitizing'' views, shown in the right.
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| − | The variability view comprises features for the definition and configuration of variability points.
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| − | The variant produced from the current configuration is displayed in the editor.
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| − | The sanitizing view can be used to sanitize legacy transformations.
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| − | <div><ul>
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| − | <li style="display: inline-block; margin-bottom: 10px;"> [[File:Henshin_vb_perspective.png|thumb|none|500px|'''Henshin VB perspective''']] </li>
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| − | </ul></div>
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| − | The variability view allows features in a rule to be created and deleted.
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| − | To view and edit variants individually, the user configures the rule by setting the bindings for these features. Three literals are supported: ''true'', ''false'', and
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| − | ''unbound''.
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| − | Per default, each variability point is ''unbound'', yielding the maximal rule, all elements regardless of their annotations.
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| − | Configurations are validated against the given variability model, ''deprecate -> wrapper'' in this case.
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| − | Invalid configurations and rules lead to error messages being displayed.
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| − | To navigate variants efficiently, frequently used configurations can be saved as favorites using the [[File:star_grey.png|15px]] button in the toolbar.
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| − | The star appears in yellow if a favored configuration is currently active.
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| − | Each configuration has a user-specified name.
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| − | In the figure to the right the user has created two favorites, ''WrapperWithDeprecate'' and ''WrapperWithoutDeprecate'',
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| − | the latter one being active.
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| − | Upon selection, the configuration is loaded and shown in the table at the bottom of the view.
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| − | A ''view mode'' feature allows to access distinguished variants rapidly.
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| − | In the ''maximum rule'' mode, represented by the [[File:rule_full.png|15px]] icon, all elements included in the rule are shown regardless of the configuration.
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| − | In the ''variant mode'' ([[File:rule_configured.png|15px]]), elements absent in the current configuration are concealed.
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| − | In the ''base rule'' mode ([[File:rule_base.png|15px]]), elements with a non-empty presence condition are concealed.
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| − | To further improve the handling of variability, the view allows the users to choose a ''concealing strategy'', depicted in the figure below. First, elements can be turned invisible. This avoids a cluttered representation of the rule and lets users focus on the variant at hand.
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| − | On the other hand, to allow the comparison of a variant with the full rule, users may choose to have the elements toned down instead.
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| − | <div><ul>
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| − | <li style="display: inline-block;"> [[File:Vbrule fade.png|thumb|none|300px|<br />'''Concealing strategy: town down''']] </li>
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| − | <li style="display: inline-block; width: 20px;"> </li>
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| − | <li style="display: inline-block;"> [[File:Vbrule invisible.png|thumb|none|300px|<br />'''Concealing strategy: invisible''']] </li>
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| − | </ul></div>
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| − | Using the [[File:creation_mode.png|15px]] button, users can select an ''editing mode'' to define which variants are affected by edits to the rule.
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| − | The supported options are: all variants, variants included in the selected configuration, or variants associated to the current view mode.
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| − | In particular, the editing mode determines which presence condition is assigned during the addition or deletion of elements to a rule.
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| − | '''Context menus''': Additional context menu entries allow to manage variability at the level of individual elements.
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| − | Multiple nodes, edges and attributes can be selected and simultaneously "moved to a different configuration" (that is, their presence conditions are updated to match the current configuration).
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| − | === Execution via API ===
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| − | ''To be added soon.''
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| − | [[category:Henshin]]
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