The tech talk was given by Dmitry Vinnik, Salesforce Senior Software Engineer in May 2017.

1. Aspect Oriented Programming:
Hidden Toolkit That You Already Have
Dmitry Vinnik
Senior Software Engineer
dvinnik@salesforce.com
JEEConf 2017

2. Talk Outline
● AOP Overview
● Anatomy of AspectJ
● Spring AOP
● Java Agents Overview
● AOP Implementations

3. Talk Motivation
Everyday challenges: profiling, code coverage, HotSwap, and monitoring.
Aspect Oriented Programing (AOP) is a solution to all these problems.
AOP is a Hidden Toolkit that everyone knows, but very few use.
This talk aims to change that.

4. Aspect Oriented Programming
Overview

5. Aspect Oriented Programming (AOP)
Overview
AOP is Cross-Cutting Concerns paradigm
Answers Questions:
● What is my code coverage?
● Is my JVM even running?
● Ahh, do I have to restart my app again?
● How long does this process take?

6. Hidden Toolkit: AOP Simple Example
1: 1
2: 1
...
39: 63245986
40: 102334155
Process: 1837 ms
Code Sample: Output:

7. Hidden Toolkit: AspectJ
Overview

8. Hidden Toolkit: AspectJ Overview
Defining Aspect
1) Definition
3) Advice
2)
Pointc
ut

9. Hidden Toolkit: AspectJ
Pointcuts Overview

10. Hidden Toolkit: AspectJ Pointcuts
Anatomy of Pointcut
1) Definition
2)
Ty
pe
3)
Expressi
on

11. Hidden Toolkit: AspectJ Pointcuts - Continue
Methods/Constructors:
1) call(Signature)
2) execution(Signature)
Fields (specific to AspectJ):
1) get(Signature)
2) set(Signature)
Exceptions Handler:
1) handler(TypePattern)
Types of Pointcuts

12. Hidden Toolkit: AspectJ Pointcuts - Continue
1) Signature
1) TypePattern
Pointcut Expressions
3) Pointcut/Combination

13. Hidden Toolkit: AspectJ
Advices Overview

14. Hidden Toolkit: AspectJ Advice
Anatomy of AspectJ Advice
1) Advice Type
2) Pointcut
Binding
3) Main
Logic

15. Hidden Toolkit: AspectJ Advice - Continue
Types of Advices
1) Before
1) After
1) Around

16. Hidden Toolkit: AspectJ Advice - Continue
1. Single Pointcut
2. Joint Pointcuts
3. Inline Pointcut
4. Parameterized Pointcut
Pointcut Binding

17. Hidden Toolkit: AspectJ
Additional Information

18. Hidden Toolkit: AspectJ - Advanced
1) Generics
2) Abstract Aspects
3) Declare Parents
4) Declare Soft
Generics and Declarations

19. Hidden Toolkit: AspectJ Execution
1) Switching to ‘ajc’ compiler
Aspect Process started
1: 1
2: 1
...
39: 63245986
40: 102334155
Aspect Process took: 1845 ms
2) Run function bound by the Aspect
3) Output:

20. Hidden Toolkit: AspectJ
Annotations Development Style

21. Hidden Toolkit: AspectJ - Annotations Usage
1) Aspect Initialization
1) Pointcut Definition
Annotations Development Style - Aspect Core

22. Hidden Toolkit: AspectJ - Annotations Usage
1) Before
1) After
1) Around
Annotations Development Style - Advices

23. Hidden Toolkit: Spring AOP
Spring AOP Overview

24. Hidden Toolkit: Spring AOP - Configuration
@Configuration and XML
XML@Configuration

25. Hidden Toolkit: Spring AOP - AspectJ Annotation
Native AspectJ Support:
1. Aspect
2. Pointcut
3. Before
4. After
5. Around
Spring AspectJ Support

26. Hidden Toolkit: Spring AOP - Schema-Based Aspects
XML Aspects:
1. Aspect
2. Pointcut
3. Before
4. After
5. Around
Spring XML-based Aspects

27. Hidden Toolkit: Spring AOP - AspectJ vs. Schema
AspectJ Annotations:
● (+) DRY by-design
● (+) Pointcut combination
● (+) Reusable outside of Spring
● (-) Requires >Java 5 support
Spring XML:
● (+) Best for Enterprise services
● (+) Summary of enabled aspects
● (-) No separation of concerns
● (-) No Pointcut combinations
Comparing Two Approaches

28. Hidden Toolkit: Spring AOP - Limitations
● No Field-level interception allowed (i.e. #set(), #get())
● Limited support for objects not managed by Spring
● No support for certain general pointcuts (ex. handler, call)
Limitation of Spring In Comparison With Native AspectJ

29. Hidden Toolkit:
Anatomy of Java Agents
Overview

30. Hidden Toolkit: Anatomy of Java Agents
Building Java Agents
1) Premain Java Agent class
2) Implement ClassFileTransformer (next slide)
3) Compile java agent and run as:
java -javaagent:simple-agent.jar -jar test-app.jar

31. Hidden Toolkit: Building Java Agents
Defining Class Transformer

32. AOP Implementations
Overview

33. AOP Implementations
Main Types:
1. Code Coverage: JaCoCo, Clover
2. Benchmarks/Profilers: JMH, AppDynamics
3. Improved Compilation: HotswapAgent, JRebel
4. Application Monitoring: AppDynamics
Main Types of AOP Implementations

34. AOP Implementations
Code Coverage

35. AOP Implementation: Code Coverage
JaCoCo[1]
Report:
Class Info:

36. AOP Implementation: Code Coverage - Continue
● No setup required (i.e. Java Agent)
● Produces detailed reports of Code Coverage
● Highlights coverage down to code lines
● Instruments Running/Pre-Execution code
Why AOP with JaCoCo?

37. AOP Implementation: Code Coverage - Continue
● Classes are instrumented on the fly by Java Agent
a. Performs in-memory pre-processing of all files
b. Instruments using java.lang.instrument.Instrumentation
● Collects coverage data into .exec files
● Process collected data into .html reports
How It Actually Works

38. AOP Implementations
Benchmarks

39. AOP Implementation: Benchmarks
# Benchmark mode: Throughput, ops/time
# Benchmark:
org.sample.MyBenchmark.testMethod
# Run progress: 0.00% complete, ETA
00:06:40
# Fork: 1 of 10
# Warmup Iteration 1: 0.414 ops/s
# Warmup Iteration 2: 0.416 ops/s
# Warmup Iteration 3: 0.417 ops/s
Java Microbenchmark Harness, JMH[1]
Code Sample: Output:

40. AOP Implementation: Benchmark - Continue
● Reliable measure of individual units (ex. microservices)
● Supported by Oracle
● Highly customizable:
• State
• Time Unit
• Mode
Why AOP with JMH?

41. AOP Implementations
Improved Compilation

42. AOP Implementation: Improved Compilation
Default Java Hotswap handles re-compilation of java files.
Does Not Handle:
● Renaming/Addition/Deletion of Methods
● Changes to Static/Non-Static Fields
● Changes to Enum Classes
● Changes to Class Hierarchy (interfaces/superclasses)
Java Hotswap

43. AOP Implementation: Improved Compilation
● Java Agent that handles imperfections of Java Hotswap.
● Can be run as a javaagent on a start of JVM:
• java -XXaltjvm=dcevm -javaagent:hotswap-agent.jar test-app.jar
● Can be attached to running JVM via com.sun.tools.attach.VirtualMachine calls
● Currently in beta version
Note: Java agents like HotswapAgent do not directly change main binaries, but
rather modify proxied copy of the binaries.
HotswapAgent[1]

44. AOP Implementation: Improved Compilation
● No setup required (i.e. Java Agent)
● Productivity Booster (especially in enterprise)
● More Control over JVM
● Verbose Logging
Why AOP with HotswapAgent?

45. AOP Implementations
Other Solutions

46. AOP Implementations: Other Solutions
● Atlassian Clover (Code Coverage)
● JCov (Code Coverage)
● AppDynamics (Benchmark, Monitoring)
● Statsd-JVM (Profiler)
● JRebel (Improved Compilation)

47. Q/A

48. About Speaker
Twitter: @DmitryVinnik
LinkedIn: in/dmitry-vinnik/
Email: dvinnik@salesforce.com
Dmitry Vinnik