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Modularity andAPI Design

January 2015Johannes Kepler University Linz, Austriahttp://www.jku.at

Jaroslav Tulach (@JaroslavTulach)

Lukas Stadler

Thomas Wuerthinger (@thomaswue)

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Goals

● Why is modularity essential?

● How to scale the development of a large software system?

● Why are APIs like stars?

● How to design an API that is extensible without breaking backwards

compatibility?

● What modularity and API design concepts are relevant in languages other

than Java?

● What are modularity concepts in NetBeans?

● Project

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Don't reinvent the wheel!

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Learning Curve

Results

Effort

Reuse

Reinvent

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Object Oriented Spaghetti Code

≈ O(n2) dependencies

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Module System

≈ O(n) dependencies

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Tracking impacts

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Information Hiding

Public API

Module B

Implementation

Module A

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Limits are your friend!

Restrict dependencies

Small public API

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Clean Structure

Results

Effort

Quick & Dirty

Clean & Modular

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Distributed Development

Public API

Implementation

Module User Module Developer

sees publishes

creates

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Mechanisms in Java

Access modifiers only at class level -

Custom class loaders!

JDK9: New modularized JDK

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GOTO vs IF, WHILE, …

=

unrestricted OOP vs modular programming

?

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Application

Architecture Eclipse/NetBeans

Platform

Swing / JDK

Java VM

IDE

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Detailed Architecture

Swing / JDK

Java VM

Application

Platform

IDE

● Standalone: Deployment including required platform / IDE modules

● Plugin: Deployment only with user-defined modules