Introduction to API Design: REST and Java

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Introduction to API Design:REST and Java

Philip Johnson

Collaborative Software Development Laboratory

Information and Computer Sciences

University of Hawaii

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What is an API?

Specifies a boundary between 2 systems•What you can do•What you can't do

The boundary is defined by:•Functions you can invoke•Objects passed & returned

APIs can exist:•Within a single program•Between independent programs

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Advantages of APIs

Simplifies design by creating partitions Enables change without "ripple effect" Enables multiple implementations Enables development to scale•Larger development teams•Concurrent development

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Disadvantages of APIs

Increases implementation complexity Creates boundaries that can make certain changes hard to accomplish

Can impede performance optimization

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Kinds of APIs

Within a program•Separates components.•Creates "public" and "private" areas.

Between programs•Specifies a "protocol"•How to send and receive information.

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Example in-Program API: Java Collections Framework

Interface java.util.Collection•boolean add (Object o)•void clear()•boolean equals(Object o)•boolean isEmpty()

This API is implemented by:•HashSet, LinkedList, TreeSet, etc.

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Example between-program (REST)API: Twitter

The Twitter API is a RESTful protocol:

http://api.twitter.com/version/statuses/public_timeline.format•Operations: GET•Formats: json, xml, rss, atom•Authentication: none•Parameters: trim_user, include_entities

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Example between-program (REST)API: WattDepot

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The Solar Decathlon iHale System

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The Solar Decathlon iHale System

Within-program between-program

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On to the demo