Developing Eclipse Plugins

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Liran.zelkha@alunasoft.com

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Eclipse plug-in architectureSome of this material was taken from a

plug-in course developed by the ECESIS project .

Eclipse plug-in architectureFlexible, structured around extension

points and plug-insThis architecture allows for:

◦Other tools to be used within the platform◦Other tools to be further extended◦Integration between tools and the platform

No need to wait for new product releases

Eclipse plug-in architecture

Eclipse Platform

Platform Runtime

…

Tool(plug-in)

Tool(plug-in)

Tool(plug-in)

Workbench

Workspace

Help

Team

JFace

SWT

Plug-in Developer

Environment(PDE)

Java Development

Tooling(JDT)

Eclipse SDK

Platform runtimeIn the Eclipse, everything is plug-in except

the Platform Runtime (the kernel)All other subsystems build up on the

Platform Runtime following the rules of plug-ins

The Basic platform includes:◦Resources Management◦Workbench◦Team◦Debug◦Help

Extension pointsDescribe additional functionality that

could be integrated with the platform◦External tools extend the platform to bring

specific functionality◦Java Development Tooling (JDT) and Plug-in

Development Environment (PDE) are external tools integrated with the platform

Extension pointsThere are two levels of extending Eclipse:

◦Extending core platform◦Extending existing extensions

Extension points may have a corresponding API interface

◦Describes what should be provided in the extension

Plug-insDefine extension points

◦Each plug-in defines its own set of extension points

Implement specialized functionality◦Usually key functionality that does not already

exist in the platformProvide their own set of APIs

◦Used for further extension of their functionalities

Are external, but fully integrated

Plug-insImplement behavior defined through

extension point API interfaceCan extend named extension points from

Eclipse or extension points of other plug-ins

Can declare an extension point and provide an extension to it

Are developed in Java programming language

What's in a plug-in?A JAR file

◦An archive with the plug-in codeplugin.xml

◦Manifest that describes plug-inabout.html

◦Textual description of the plug-inplugin.properties

◦Plugin-in properties

Describing plug-insAn extension to the platform has to be

registered somewhereEach plug-in has a manifest file that

describes:◦Location of the plug-in code◦Extensions added by the plug-in

Describing plug-insThe manifest file is plugin.xml .

◦There are Eclipse tools that make it easy to edit the file without using XML directly.

The manifest describes:◦Name, id, and version of the plug-in◦List of other plug-ins (and versions) required by

the plug-in described◦Extension points◦Where the plug-in code is located

Example manifest file

?<xml version="1.0" encoding="UTF-8>?"?<eclipse version="3.0>?"

<plugin name="Helloworld plug-in " id="com.examples.helloworld " version="1.0.0“

provider-name="EXAMPLE" class="com.example.helloworld.HelloworldPlugin > >"

< requires>< import plugin="org.eclipse.ui>/"< import plugin="org.eclipse.core.runtime>/"< import plugin="org.eclipse.core.runtime.compatibility>/" /< requires >< runtime>

< library name="helloworld.jar>"< export name>/"*"=/< library >/< runtime >< extension point="org.eclipse.ui.views>"< category name="Hello Category" id="com.example.helloworld"> </category >< view name="Hello View" icon="icons/sample.gif" category="com.example.helloworld"

class="com.example.helloworld.HelloWorldView" id="com.example.helloworld.HelloWorldView >"/< view >/< extension> /<plugin>

Packaging plug-insPlug-ins are packaged as Java Archives –

JAR filesArchives are named using naming

convention:◦<id>_<version>.jar

<id> is the identifier<version> is the full version number from the

manifest file◦For example: org.eclipse.demo.

plugin.simple_1.0.jar

Publishing plug-insUsed for preparing plug-in for deployment

on a specific platformManual publishing makes use of Ant

scripts◦Ant is a open source build tool, commonly used

in building processes with Java code◦Ant scripts are Java based (platform

independent) with XML configuration◦Ant is supported in Eclipse

Publishing plug-insAutomatic publishing is available by using

Eclipse wizards◦You don't have to use Ant scripts ◦Wizards allow publishing in a single zip file. A

single zip file can contain multiple plug-ins.

Installing plug-insPlug-ins are installed under the plugins

directory under the Eclipse installation directory

◦Usually c:\eclipse\plugins on Windows platforms

Plug-in fragmentsUsed for extending existing plug-ins

◦Provide an additional functionality to existing plug-ins

◦Ideal for providing add-on functionality to plug-ins

Packaged in separate files◦Fragment content is treated as it was original

plug-in archive◦At runtime the platform detects fragments and

merges their content with the original plug-in

Plug-in fragmentsDescribed in fragment.xml files

◦Similar to plug-in manifest files◦Plug-in archive can contain plug-ins or

fragments

Eclipse APIMeant to be used by plug-in developersAPI elements are documented and

completely specifiedThe API elements specify what they are

supposed to do and how they are intended to be used.

Eclipse APIThe Eclipse platform code is separated

into:◦API packages

Contain API elements◦Non-API packages

Contain internal platform implementation

Using the Eclipse APIThe API can be used by doing one of the

following:◦Instantiating platform API classes◦Subclassing platform API classes◦Calling public API methods

Most commonly used◦Calling protected API methods

Possible from API subclasses

Using the Eclipse APIMore ways to use the API:

◦Overriding API methodsAllowed for some methods◦Implementing platform API interfaces◦Accessing Fields in API classes and interfaces

Mainly final, read-only fields