Fluid AOP Join Point Models

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Fluid AOP Join Point Models

• Terry Hon
• Gregor Kiczales

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Fluid AOP

• Modularization of crosscutting concerns in IDE
• Aspect is alternative view
• modularizes crosscutting concern
• can be generated each time it is needed
• or can be stored as a metaobject

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Fluid vs. Linguistic AOP

• Linguistic AOP
• Aspects are programming language constructs
• Defined semantics only execution is woven
• Fluid AOP
• Aspects are IDE constructs
• It may look like programming language constructs
• Defined semantics IDE view is explicitly woven

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Experiments in Fluid AOP JPMs

• 2 Fluid AOP Join Point Models
• What are join points?
• How are they identified?
• How is crosscutting combined?
• Using Eclipse
• Edit time weaving

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1st JPM Block Linking

• Join points
• Code fragments in java files
• Method
• Constructor
• Field
• Means of identifying join points
• Pointcuts method, field or constructor
  signatures, type patterns
• Means of combining crosscutting
• Identical blocks
• All linked, any block can be edited

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Display Updating Aspect

• Canonical AspectJ example

public aspect DisplayUpdating pointcut change
execution(public void Shape.set())
after returning change

• Note has no advice/pointcut parameters

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Intertype Declarations

• Want to add a Display field for each Shape class
• Instead of calling static update method, we will
  call update on the Display object

public aspect DisplayUpdating pointcut change
execution(public void Shape.set())
after returning change
display.update() declare for Shape
protected Display display
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1st JPM Block Linking

• Join points
• Code fragments in java files
• Method
• Constructor
• Field
• Means of identifying join points
• Pointcuts method, field or constructor
  signatures, type patterns
• Means of combining crosscutting
• Identical blocks
• All linked, any block can be edited

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2ndJPM Overlay

• Join points
• Code fragments in java files
• Method
• Constructor
• Means of identifying join points
• Pointcuts method or constructor signatures, type
  patterns
• Means of combining crosscutting
• Join points are all different
• Editable merge

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Variable references (with different names) in
join points
Identical parts in join points
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Block Linking vs. Overlay

• Crosscutting effects are identical
• No context of JPs in aspect
• Edit in linked advice block
• Can recreate aspect by code inspection without
  Fluid AOP tool

• Crosscutting effects can be different
• Some context of JPs in aspect
• Edit in linked merged structure
• Cannot recreate aspect unless we know list of JPs

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Current Questions

• Block Linking JPM
• What happens when a developer changes an advice
  body outside of the aspect file?
• What happens if an advice body is deleted?

• Overlay JPM
• What are rules for merging and overlaying?
• How should overlay look?

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Open Issues

• What are other JPMs in Fluid AOP?
• What is the best way to show a ccc (modularizing
  both viewing and editing of JPs)?
• Possible intermediate step in AOP adoption or AOP
  solution qua itself?
• Java tools can be used on all but aspect files
• Aspect files are only meta files
• Edit time weaving

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Related Work

• Linked editing
• Toonim et. al. CodeLink
• Miller et. al. Simultaneous Editing
• Editable virtual views
• Chu-Carroll et. al. VSC
• Janzen et. al Decal
• Quitslund MView
• Linguistic
• Harrison et. al. CME
• Quitslund et. al. Java Traits

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Questions?

• Fluid AOP Join Point Models
• Terry Hontyehon_at_cs.ubc.ca