AOP and AspectJ

Technokratos Android Meetups #1. By Kazakov Anton.

Transcript

1. AOP & AspectJ Anton Kazakov @antonkazakov
2. Code tangling problem Business Logic Analytics Security One module - many concepts implemented (single responsibility break)
3. Accounts Module Code scattering problem Authorization Module Maps module Analytics Module Single functionality in many modules (code duplication)
4. Analytics Aspect Analytics module call Accounts Module Maps Module Authorization Module Woven invocations Woven invocations AOP way
5. Main concepts of AOP systems • Identifiable execution points in system • Construct to select these points • Construct to dynamically change app behaviour • Construct to alter static structure of the system • Module to gather all contracts in one place
6. Constructor execution jp Fields write-access jp Fields read-access jp Join point model
7. Join point model Method call jp Method execution jp Exception handle jp Class initialization jp
8. Type signature
9. More pointcuts
11. will be removed in cflowbelow
12. within/withincode this vs target
13. Before() advice
14. After()* advice
16. Around()
17. Capturing context
18. • thisJoinPoint: target object execution object arguments annotations • thisJoinPointStaticPart source location signature of join point type of join point • thisEnclosingJoinPointStaticPart enclosing joint point Reflective access
19. Type hierarchy modifier
20. Annotation supplementation
21. Custom build time checks
22. Softening exceptions
23. Softening exceptions
24. Aspect associations • Singleton (default) • Per object • Per cflow/cflowbelow • Per type
25. Aspects precedence • Higher priority before() advices weaves BEFORE Aspects with lower priority • Higher priority after*() advices weaves AFTER Aspects with lower priority • Higher priority around advices incapsulate advice with lower priority
27. SOURCE CODE WEAVING BYTE CODE WEAVING BUILD TIME WEAVING ✅ ✅ LOAD TIME WEAVING ❌ ONLY IN XML FILES, WITH LIMITATIONS ✅ AspectJ Weaving Models comparison
28. Woven code .jar/.class Java source files AspectJ source files AspectJ .aj files ajc Build-time source code weaving
29. Java source files AspectJ source files AspectJ .aj files Java bytecode AspectJ bytecode AspectJ with native syntax bytecode javac/ajc javac/ajc ajc Build-time source code weaving Woven code .jar/.class ajc
30. aop.xml Unwoven classes and aspects Java Agent JVM Weaving Load time weaving
31. AspectJ @AspectJ Simple and plain; Lot of annotations with String body Support Exception softening Method and data introduction Privileged access Low ITD abilities Doesn’t need AJC to compile code. Additional step to build process Need ajc Poor support in Android Studio Good IDE/Plugins support/Spring intro AspectJ vs @AspectJ
32. ajc + aspetjrt.jar HujiangTechnology/ aspectjx 1000⭐ Archinamon/android- gradle-aspectj 160⭐ command-line access to ajc small size good for pure java projects not good for android works with multidex and lambda native toolchain can weave kotlin/scala/ groovy support Instant run Gradle 2/3/4 support do not support AspectJ native syntax docs/issues in Chinese written in Groovy works with multidex 100% Kotlin supports both syntaxes highly customisable supports instrumented tests issues with native lambda(milestone to 3.3.0) Plugins
33. Cons •Not obvious app behaviour/lack of visibility •Problems with tooling especially in Android •Increased binary file size •Would be better if aspects was language feature •Increased build time/class load time Pros … Pros and cons
34. AspectJ in Action eclipse.org/aspectj Where to learn
35. Thank you Anton Kazakov @antonkazakov