JAsCo Technology

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JAsCo Technology
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Technology Requirements Review

• Technology requirements
• Not dependent on source code
• No invasive changes at aspect application time
• First class aspects at run-time
• Dynamic

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JAsCo Technology (1)

• New Component Model with traps built-in.
• Enables run-time aspect application and removal.
• Backward compatible Automatic transformation
  from Java Beans to JAsCo beans.

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JAsCo Technology (2)
Hook1
Connector1
JAsCo Component
Hook2
method1
traps
ConnectorRegistry
method2
event 1
Hook3
Connector2
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JAsCo Dynamic AOP

• Central Connector Registry
• Remotely adding/removing aspects
• Precedence Strategies
• Combination Strategies
• Applying Aspects on Instances
• Dynamic Wildcard Matching

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JAsCo Dynamic AOP

• Central Connector Registry
• Remotely adding/removing aspects
• Precedence Strategies
• Combination Strategies
• Applying Aspects on Instances
• Dynamic Wildcard Matching

Main Problem Performance!
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Optimizing Dynamic AOP

• Two main parts
• Interception System
• Aspect Dispatcher
• Improving by
• HotSwap
• Jutta

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HotSwap Optimizing the Interception System (1)

• Run-time Instrumentation using Custom Framework
• Only traps at methods where aspects are applied
• Aspects added/removed dynamically ? corresponding
  traps added/removed by hotswapping classes if
  necessary
• Two Systems
• Java 1.4 JDI HotSwap
• Java 1.5 Instrumentation API

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HotSwap Optimizing the Interception System (2)
HotSwap 1 (JDI)

• Benefits
• Run-time overhead dramatically decreased.
• Drawbacks HotSwap
• Installing traps takes some time.
• Less portable (requires JVM 1.4).
• JVM has to run in debugging mode.
• Runs 2 JVMs

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HotSwap Optimizing the Interception System (3)
HotSwap 2 (JPLIS)

• HotSwap using Java 1.5 instrumentation API,
  available since JAsCo 0.6
• Benefits
• Run-time overhead dramatically decreased
• Less cumbersome than HotSwap 1
• Drawbacks HotSwap 2
• Installing traps takes some time.
• Less portable (requires JVM 1.5).

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Jutta Optimizing Aspect Dispatcher (1)

• Jutta Just in time compiler for AOP
• Generates highly optimized code fragment (in byte
  code) for each joinpoint
• Lazy generation
• Invalidated when aspects are added/removed

BASE APP
jp1
jp2
jp3
jp4
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Jutta Optimizing Aspect Dispatcher (2)

• Example code fragment (Java counterpart)

public Object executeJoinpoint(Joinpoint jp)
Object result null
hook1.before(jp) hook2.before(jp) try
resulthook0.around() catch(Exception
ex) hook1.after_throwing(ex,jp)throw ex
if(hook7.isApplicable(jp)) hook7.after()
return result
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Jutta Optimizing Aspect Dispatcher (3)

• Generating the code fragment takes some time
  (around 10ms).Therefore
• Sharing code fragment at different joinpoints
  where the same aspects are applicable.
• Preinstalled set of code fragments.
• Partial Evaluation of aspects depending on
  dynamic values (e.g. cflow).
• Combination Strategies cached away unless they
  implement jasco.runtime.DoNotCache

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JAsCo performance
JAC Benchmark
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JAsCo Load-time Performance
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JAsCo run-time weaver (1)
Run-time Weaver
Jutta HotSwap
BASE APP
BASE APP
jp1
jp1
jp2
jp3
jp3
jp4
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JAsCo run-time weaver (2)

• Performance of JAsCo still slower than AspectJ
• By combining HotSwap and Jutta, a genuine
  run-time weaver can be realized aspects inserted
  into target joinpoints.
• Additional optimizations are possible, e.g.
  static or dynamic joinpoint info.

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Performance of run-time weaver
AWBench Results
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TOOL SUPPORT
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JAsCo implementations

• JAsCo for Java
• Eclipse plugin IDE
• JAsCoME (J1ME or J2ME compliant devices)
• JAsCo.NET (technology proof of concept)

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More Info

• Website
• http//ssel.vub.ac.be/jasco
• Useful Links
• thisJoinPoint API
• http//ssel.vub.ac.be/jasco/nightly/doc/jasco/runt
  ime/MethodJoinpoint.html
• JAsCo language reference (included in Eclipse
  plugin)