lessons

Lessons:

• 01-03-2022 - Lesson 01 - Introduction and Modern VMs, e.g. JVM, Node
• 03-03-2022 - Lesson 02 - Java Type System, Components and Metadata
• ..-03-2022 - Lesson 04 - Programming with Metadata

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Lesson 01 - Introduction and Modern VMs, e.g. JVM, Node

• Bibliography and Lecturing methodology: github and slack.
• Tools: javac, javap, kotlinc, JDK 17 and gradle.
• Program outline in 3 parts:
  1. Java Type System and Reflection;
  2. Metaprogramming and Performance;
  3. Iterators versus Sequences (yield). Generics and Reified type parameters.
• Project in 3 parts according to program outline.

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• Managed Runtime or Execution Environment.
• Informally virtual machine (VM) or runtime
• Historic evolution since Java to nowadays
• Examples of languages targeting JVM: Java, kotlin, Scala, Clojure.
• Examples of languages targeting Node: JavaScript, TypeScript, Kotlin.
• Java syntax similar to C and C++.
• Distinguish between Programming Language <versus> VM

Lesson 02 - Java Type System, Components and Metadata

• Type System - Set of rules and principles that specify how types are defined and behave.
• Module .classfor each class definition
• CLASSPATH
  • e.g. -cp . - local folder
  • e.g. -cp .:JetBrains/IntelliJIdea2022.2/plugins/Kotlin/lib/*
  • (for windows use ; rather than :)
• Class have Members
• Members may be: Fields, Constructors or Methods.
• Constructor is a function with name "<init>" returning void.
• Using javap -p Student.class to inspect metadata
• Using javap -c -p AppKt.class to inspect metadata and bytecodes definition of data class Point
• Analyzing kotin properties in Java.
• There are NO properties in Java Type System.
• A Kotlin property may generate:
  • Backing field -- accessed with getfield bytecode.
  • Getter, i.e. function get... -- called with invoke... bytecode.
  • Setter, i.e. function set... (if defined with var).
• Kotlin val <=> Java final.
• FIELDS => MEM
• bytecode invokevirtual to call e.g. getNr() and print()

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• Component - Reusable software unit, with:
  • IR - code in intermediate representation (e.g. bytecodes, IL, other)
  • Metadata - auto description
  • Ready to use => does not require static compilation.
  • API => conforms to a public interface.
  • Indivisible => 1 module (file)
• Software development by Components:
  • Reduce Complexity;
  • Promote Reuse.
• Developer roles:
  • Provider - provides a component with a well-known API (e.g. Point)
  • Client - uses the component from a provider to build an Application, or another component (e.g. App).
• Managed Runtime:
  • Software components = Metadata + IR (intermediate representation) (e.g. bytecodes)
  • Interoperability supported at bytecode and metadata level e.g. Java <> Kotlin
  • Portability - Compile once and run everywhere with VM, e.g. JRE.
  • Jitter - Just-in-time compiler
  • Safety - NO invalid memory accesses
  • GC - Garbage Collector.
  • ClassLoader and CLASSPATH - dynamic and lazy load.

Lesson 03 - Managed versus Unmanaged

Lesson 04 - Programming with Metadata