Survey of AspectOriented Programming

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Survey of Aspect-Oriented Programming

• Neerja Bhatnagar

CS 203 Programming Languages Fall 2004
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Motivation for AOP

• Code continues to grow in size and complexity
• Code evolves to become unmodularized, and hence
  unclean
• Application logic gets intermingled with system
  code
• For example, business logic of processing credit
  card payment intermingled with code that logs the
  transaction
• AOP aims to improve software design and
  development via separation of concerns

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Conventional Logging

• Does not utilize aspects
• Utilizes java.util.logging
• import java.util.logging.
• static Logger logger Logger.getLogger(Log)
• public void setEmployeeAddress(String address)
  
• if (name ! null)
• logger.logp(Level.INFO, Employee,
• setEmployeeAddress, Address Changed)
• employeeAddress address

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Logging with Aspects

• import org.aspectj.lang.
• import java.util.logging.
• public aspect AspectLog
• Logger logger
• Logger.getLogger(Log)
• // specify point of execution for
• // logging. within matches methods
• pointcut logMethods() execution( .(..))
• within(AspectLog)
• // begin logging before reaching
• // join point
• before()logMethods()

• Java code remains unchanged!
• public class Employee
• public Employee()
• setEmployeeAddress(String
• address)

• Push functionality related to logging into
  aspect(s)
• Application logic remains unchanged.

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AOP Languages and Frameworks
Languages

• AspectJ (Aspects for Java)
• AspectC (Aspects for C, may be C)
• Weave.NET (Language Independent Aspects)

Frameworks

• Nanning (for Java) (http//nanning.codehaus.org)
• AspectWerkz (for Java) (http//aspectwerkz.codehau
  s.org)
• JBoss (for Java) (http//www.jboss.org)
• HyperJ (for Java) (www.research.ibm.com/hyperspace
  /hyperj)
• Others abc, AspectC, CLAW, AOP, AspectDNG

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AOP Terminology (Buzzwords)

• public class Employee
• public String employeeName
• public Employee()
• public void setEmployeeName(String name)
• if (name ! null)
• logger.logp(Level.INFO, "Employee",
• "setEmployeeName", "Name change")
• employeeName name

Point Cut
Crosscutting concern
Join Point
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AOP Terminology (Buzzwords), contd.

• import org.aspectj.lang.
• import java.util.logging.
• public aspect AspectLog
• Logger logger
• Logger.getLogger(Log)
• // specify point of execution for
• // logging. within matches methods
• pointcut logMethods() execution( .(..))
• within(AspectLog)
• // code that actually logs
• // begin logging before reaching
• // join point
• before()logMethods()

Aspect
Advice
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Thank You