Multidimensional Separation of Concerns using HyperJ

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Multidimensional Separation of Concerns using
HyperJ

• by
• Neeraj Sangal

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Sources

• Using Multidimensional Separation of Concerns to
  (Re)Shape Evolving Software by Ossher et al Comm
  ACM October 2001
• Separating Concerns with Hyper/J An Experience
  Report by Lai et al ICSE 2000 Workshop
• HyperJ Manual

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Benefits

• Easier Evolution Handles unanticipated changes
  better
• Easier Maintenance - Changes are localized
  because concerns are localized
• Easier Reuse - Unit of reuse is a concern
• Easier Integration Concerned only with relevant
  interactions

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Comparison with AspectJ

• AspectJ supports augmentation of a single model
  Hyper/J allows you to integrate multiple models
• Each concern (called Hyperslice) can be
  understood in isolation
• No distinction between classes and aspects

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Example Combining Methods
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Example Class Hierarchy
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Example Combining Class Hierachies
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Concerns - Unit of Mapping

• Package Mapping
• Class Mapping
• Interface Mapping
• Operation Mapping
• Field Mapping
• Each unit can be in only one concern

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Operation mapping

• operation Pkg.Class.method Feature.concern
• operation foo Feature.Foo
• Implicit wild carding
• Currently methods are represented by name only

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Field Mapping

• Pkg.class.var Feature.concern
• field fooVar Feature.Foo
• Note the implicit wild carding

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Hyperspace File

• hyperspace hyperspaceName
• classFileSpecification
• classFileSpecification
• composable class pkg2. except pkg2.name
• composable class pkg3. including subclasses
• uncomposable class java.lang., java.io.

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Hypermodule File

• hypermodule hypermoduleName
• hyperslices
• dimensionName1.concernName1,
• relationships
• mergeByName nonCorrespondingMerge
• overrideByNam
• end hypermodule

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Composition Strategy

• mergeByName (most common)
• nonCorrespondingMerge
• overrideByName (only for methods)

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Equate

• equate class dimension1.concern1.class1,
• dimension2.concern2.class2
• equate operation Feature.Kernel.process,
• Feature.Check.check_process,
• Feature.Eval.eval_process
• into myProcess

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Order

• order action dim2.concern.class.foo
• before action dim2.concern2.class2.foo
• Used for methods. If class is specified then
  applies to all methods in the class

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Merge

• merge class dim1.concern1.class1,
• dim2.concern2.class2

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Bracket

• bracket .foo
• from action Appl.Concern.Class.bar
• before Feature.log.LogClass.invokeBefore(ClassNa
  me),
• after Feature.log.LogClass.invokeAfter(Operation
  Name)

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Other relationship directives

• NoMerge
• Override
• Match
• Summary Function

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Caching Example