Transcript OSGi final summary. Eclipse plug-ins

OSGi:
Final summary and discussion
https://www.osgi.org/
Outline
• Review: Origins of OSGi
– Consortium
– Goals
• Review: What is OSGi
– Dynamic Modules for Java
– Advanced Component Models over OSGi
• OSGi adoption in practice and success stories
– Application servers
– Eclipse
• Eclipse plug-ins
• OSGi criticism
Review: The OSGi Alliance
• OSGi is a set of specifications by the OSGi-Alliance
• The Open Service Gateway Initiative
• Initial goal: Facilitate the componentization of software and assure
remote management and interoperability of applications and
services over a broad variety of devices
• Application domains: Home automation, Mobile devices, Enterprise
applications
• Current members of the OSGi alliance:
– Strategic members: Adobe, Deutsche Telekom, Hitachi, IBM, Liferay,
NTT, Oracle, Paremus, Ltd., ProSyst Software, Salesforce.com, Software AG ,
TIBCO
– Principal members: Cloudyle, Luminis, Makewave, Sumitomo Electric
Industries, Ltd.
– Contributing associates: Eclipse Foundation, Inc., Intuit Inc., Mitsubishi
Electric, NEC, Orange, Red Hat, Sagemcom SAS, Schneider Electric, Telecom
Italia S.p.A, Unify GmbH & Co. KG
OSGi specifications
• developed in expert groups
– Core platform (CPEG)
– Vehicle (VEG) OSGi in vehicles
– Mobile (MEG) OSGi in mobile devices
– Enterprise (EEG) OSGi in enterprise solutions
– Residential (REG) OSGi in home automation
• structured into 2 documents
– Core Specification : framework
– Service Compendium : standard services
OSGi specification releases
•
OSGi Release 1 (R1): May 2000
•
OSGi Release 2 (R2): October 2001
•
OSGi Release 3 (R3): March 2003
•
OSGi Release 4 (R4): October 2005 / September 2006
–
Core Specification (R4 Core): October 2005
–
Mobile Specification (R4 Mobile / JSR-232): September 2006
•
OSGi Release 4.1 (R4.1): May 2007 (AKA JSR-291)
•
OSGi Release 4.2 (R4.2): September 2009
–
•
•
OSGi Release 4.3 (R4.3): April 2011
–
Core: April 2011
–
Compendium and Residential: May 2012
OSGi Release 5 (R5): June 2012
–
•
Enterprise Specification (R4.2): March 2010
Core and Enterprise: June 2012
OSGi Release 6: July 2014
Review: What is OSGi now
• OSGi = Dynamic Modules for Java
• A set of specifications of the OSGi Alliance (currently
Release 6)
• A set of different implementations of these
specifications
– Equinox, Felix, Knopplerfish
• Advanced component models over OSGi, developed
independently by external parties (not included in OSGi
specifications)
– iPOJO, Spring DM
Review: OSGI – a component framework for Java
Bundle
Bundle
Bundle
Bundle
OSGi Framework
Java Runtime Environment (JRE)
Operating System (OS)
Hardware
Bundle
Review: OSGI Layered Architecture
Service
Bundles
Lifecycle
Module
Execution Environment
HW / OS
Review: Greeting Example - Modules
org.foo.hello.helper
Helper
org.foo.hello
org.foo.hello.cli
import
Client
Import
org.foo.hello
Greeting
export
org.foo.hello
Review: Greeting Example - Services
org.foo.hello
Greeting
org.foo.hello
import
org.foo.hello.cli
Client
get
Activator
org.foo.hello.impl
GreetingImpl
Import
org.osgi.*
register
Activator
Import
org.osgi.*
Review: Greeting Example - with DS
IGreeting
GreetingImpl1
IGreeting
[0..n]
GreetingConsumer
IGreeting
GreetingImpl2
OSGi adoption
• The OSGi component system is used to build
highly complex applications like:
– IDE’s, application servers, application frameworks,
telecom and service solutions, industrial automation,
residential gateways, onboard telematics
systems, etc
Java EE application servers
• vendors look for ways to make their application server
products more modular and flexible
–
–
–
–
–
IBM's WebSphere
Red Hat’s JBoss
Oracle’s GlassFish Enterprise Server
ObjectWeb’s JOnAS, and
Apache’s Geronimo
Eclipse
• Eclipse: an open development platform comprised of
extensible frameworks, tools and runtimes for building,
deploying and managing software across the lifecycle
Eclipse architecture
Figure from: http://www.hs-augsburg.de/~meixner/saj/skript/osgi/eclipseplugins.html
Different types of Eclipse plug-ins
• C++ IDE (CDE)
• Visual UI Editor (SWT/Swing Designer)
• UML modeling tools
• Colaborative tools (SVN)
• Aspect oriented language extension (AspectJ)
Eclipse plug-ins
• All written in Java
• Found at Eclipse launch - can not dynamically swap
plug-ins
• Load-on-demand strategy - makes it possible to have
many different plug-ins and still manage to obtain
reasonable performance
Eclipse plug-in architecture
• Multi-layered extensibility:
– Plugins,
– Extension points,
– Extensions
Figure from: http://www.hsaugsburg.de/~meixner/saj/skript/osgi/eclipseplugins.html
Create an Eclipse HelloWorld plugin
• Example: create an Eclipse plugin that adds a new Menu
entry; when activated, it displays a window with a
message
• Eclipse -> New ->Project
• Project wizard -> Plug-in-project -> select target = Eclipse
• Select Create plugin using one of the templates -> Plugin
with a popup menu
• Generated files:
– Source code: Activator.java, SampleAction.java
– Metadata: MANIFEST.MF, plugin.xml
• You may already run the plugin (Run As -> Eclipse
Application)
Manifest file for HelloWorld example
Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: Myeclipseplugin
Bundle-SymbolicName: org.foo.myeclipseplugin; singleton:=true
Bundle-Version: 1.0.0.qualifier
Bundle-Activator: org.foo.myeclipseplugin.Activator
Require-Bundle: org.eclipse.ui,
org.eclipse.core.runtime,
org.eclipse.core.resources
Bundle-ActivationPolicy: lazy
Bundle-RequiredExecutionEnvironment: JavaSE-1.7
An Eclipse plugin is an OSGi bundle !
OSGi for Eclipse Developers
org.foo.myeclipseplugin.Activator
public class Activator extends AbstractUIPlugin {
public static final String PLUGIN_ID = "org.foo.myeclipseplugin";
private static Activator plugin;
public Activator() { }
public void start(BundleContext context) throws Exception {
super.start(context);
plugin = this;
}
public void stop(BundleContext context) throws Exception {
plugin = null;
super.stop(context);
}
public static Activator getDefault() {
return plugin;
}
public static ImageDescriptor getImageDescriptor(String path) {
return imageDescriptorFromPlugin(PLUGIN_ID, path);
}
}
Two manifest files
MANIFEST.MF
plugin.xml
Classical OSGi manifest:
• Bundle identification
• Extension points
• Dependencies
• Activator
• Extensions
Plugin.xml for HelloWorld example
<?xml version="1.0" encoding="UTF-8"?>
<?eclipse version="3.4"?>
<plugin>
<extension point="org.eclipse.ui.popupMenus">
<objectContribution
objectClass="org.eclipse.core.resources.IFile"
id="org.foo.myeclipseplugin.contribution1">
<menu label="New Submenu"
path="additions"
id="org.foo.myeclipseplugin.menu1">
<separator name="group1"> </separator>
</menu>
<action
label="New Action"
class="org.foo.myeclipseplugin.popup.actions.NewAction"
menubarPath="org.foo.myeclipseplugin.menu1/group1"
enablesFor="1"
id="org.foo.myeclipseplugin.newAction">
</action>
</objectContribution>
</extension>
</plugin>
org.foo.myeclipseplugin.
popup.actions.NewAction
package org.foo.myeclipseplugin.popup.actions;
public class NewAction implements IObjectActionDelegate {
private Shell shell;
public NewAction() {
super();
}
public void setActivePart(IAction action,
IWorkbenchPart targetPart) {
shell = targetPart.getSite().getShell();
public void run(IAction action) {
MessageDialog.openInformation(
shell,
"Myeclipseplugin",
"New Action was executed.");
}
public void selectionChanged(IAction action,
ISelection selection) {}
}
}
OSGi Criticism
• Most of the success stories of OSGi adoption are with
(dynamic) plug-in architectures
• OSGi is suited for applications where modularity and
dynamic extensibility are particularly important
• OSGi may be too complex if the interest is on modularity
only
• Using independent Java libraries (available as “normal”
jars) from OSGi applications is difficult
• JRE will not adopt OSGi: if the JRE will be organized in a
modular way, this will have to come from itself, not from
an external container
Java modularity alternatives
• Goals:
– Introducing the concept of module for programmers
– Refactoring of the JDK/ JRE in a modular way (current JRE is
monolithic)
• Project Jigsaw: has as a goal to design and implement a
standard module system for the Java SE Platform, and
to apply that system to the Platform itself and to the JDK.
– It was postponed many times, it is now planned for java 9