Difference between revisions of "OSGi : Develop Simple Apps"

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{{Ecl_activities|type=OSGi|type-repo=osgi}}
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{{Ecl_activities|type=OSGi|type-repo=osgi}}__NOTOC__
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<h2>Bundels and Java Applications</h2>
 
# Check out the [https://guest:1673852@zenit.senecac.on.ca/svn/ecl500/Lectures/trunk/w11-osgi-simple-interface/ Service Interface]
 
# Check out the [https://guest:1673852@zenit.senecac.on.ca/svn/ecl500/Lectures/trunk/w11-osgi-simple-interface/ Service Interface]
 
# Check out the [https://guest:1673852@zenit.senecac.on.ca/svn/ecl500/Lectures/trunk/w11-osgi-simple-serviceprovider/ Service Provider]
 
# Check out the [https://guest:1673852@zenit.senecac.on.ca/svn/ecl500/Lectures/trunk/w11-osgi-simple-serviceprovider/ Service Provider]
 
# Check out the [https://guest:1673852@zenit.senecac.on.ca/svn/ecl500/Lectures/trunk/w11-osgi-simple-serviceconsumer/ Service Consumer]
 
# Check out the [https://guest:1673852@zenit.senecac.on.ca/svn/ecl500/Lectures/trunk/w11-osgi-simple-serviceconsumer/ Service Consumer]
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<h3>[[Steps for Building Applications from Bundels]]</h3>
  
<strong>Steps for Building Bundels</strong>
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[[File:OSGi-DS.png|border|SOA in JVM|400px| ]]
  
<h4>1. Study the Interfaces</h4>
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<h2>Bundels and the Declarative Services</h2>
 
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# Check out the [https://guest:1673852@zenit.senecac.on.ca/svn/ecl500/Lectures/trunk/w11-osgi-simple-declarativeservice-consumer Declarative Service Consumer]
* [http://www.osgi.org/javadoc/r4v42/org/osgi/framework/Bundle.html Bundle]
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# Check out the [https://guest:1673852@zenit.senecac.on.ca/svn/ecl500/Lectures/trunk/w11-osgi-simple-declarativeservice-provider Declarative Service Provider]
* [http://www.osgi.org/javadoc/r4v42/org/osgi/framework/BundleContext.html BundleContext]
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<h3>[[Steps for Building Declarative Services]]</h3>
* [http://www.osgi.org/javadoc/r4v42/org/osgi/framework/BundleActivator.html BundleActivator]
 
 
 
<h4>2. Define the Bundle Service Provider</h4>
 
<h5> 2.1 Define the Generic Bundle Service Provider</h5>
 
 
 
<h5>2.1.1 Define the Java Interface that exposes the services</h5>
 
Let us suppose that you want to define a service that allows the user to find a book from the book isbn. Then the interface should look similare with this one:
 
<source lang="java">
 
package cs.ecl.osgi.simple.bookfinder;
 
 
 
public interface BookFinder {
 
Book findBook(int isbn) throws BookNotFoundException;
 
}
 
</source>
 
Define in the same bundle the classes that you need such as: Book and BookNotFoundException
 
<source lang="java">
 
package cs.ecl.osgi.simple.bookfinder;
 
 
 
public class Book {
 
private int isbn;
 
private String title;
 
 
public Book(int isbn, String title) {
 
super();
 
this.isbn = isbn;
 
this.title = title;
 
}
 
 
 
public String getTitle() {
 
return title;
 
}
 
 
 
public void setTitle(String title) {
 
this.title = title;
 
}
 
 
 
public int getIsbn() {
 
return isbn;
 
}
 
 
 
public void setIsbn(int isbn) {
 
this.isbn = isbn;
 
}
 
}
 
 
 
package cs.ecl.osgi.simple.bookfinder;
 
 
 
public class BookNotFoundException extends Exception {
 
private static final long serialVersionUID = -6184839510952070091L;
 
 
 
public BookNotFoundException() {
 
super();
 
}
 
 
 
public BookNotFoundException(String arg0) {
 
super(arg0);
 
}
 
}
 
</source>
 
 
 
 
 
Define in the MANIFEST.MF that cs.ecl.osgi.simple.bookfinder is the '''Exported-Package'''
 
<source lang="xml">
 
Manifest-Version: 1.0
 
Bundle-ManifestVersion: 2
 
Bundle-Name: Bookfinder
 
Bundle-SymbolicName: cs.ecl.osgi.simple.bookfinder
 
Bundle-Version: 1.0.0.qualifier
 
Bundle-RequiredExecutionEnvironment: JavaSE-1.6
 
Bundle-Vendor: Seneca College - Eclipse Course
 
Export-Package: cs.ecl.osgi.simple.bookfinder
 
</source>
 
 
 
<h5>2.2 Define a Concrete Bundle Provider</h5>
 
<h6>2.2.1 Define the Activator class</h6>
 
<source lang="java">
 
package cs.ecl.osgi.simple.bookfinderservice;
 
 
 
import org.osgi.framework.BundleActivator;
 
import org.osgi.framework.BundleContext;
 
 
 
import cs.ecl.osgi.simple.bookfinder.BookFinder;
 
import cs.ecl.osgi.simple.bookfinderservice.internals.BookFinderImplementation;
 
 
 
 
 
public class Activator implements BundleActivator {
 
 
 
private static BundleContext context;
 
 
 
static BundleContext getContext() {
 
return context;
 
}
 
 
public void start(BundleContext bundleContext) throws Exception {
 
Activator.context = bundleContext;
 
BookFinder bookService = new BookFinderImplementation();
 
 
context.registerService(BookFinder.class.getName(), bookService, null);
 
System.out.println(" Bookfinder service registered ");
 
}
 
 
public void stop(BundleContext bundleContext) throws Exception {
 
Activator.context = null;
 
System.out.println(" Bookfinder service stopped ");
 
}
 
}
 
</source>
 
 
 
<h6>2.2.1 Define the internal implementation class (the class BookFinderImplementation <u>will not be exposed to the outside world</u>)</h6>
 
 
 
<source lang="java">
 
package cs.ecl.osgi.simple.bookfinderservice.internals;
 
 
 
import cs.ecl.osgi.simple.bookfinder.Book;
 
import cs.ecl.osgi.simple.bookfinder.BookFinder;
 
import cs.ecl.osgi.simple.bookfinder.BookNotFoundException;
 
 
 
public class BookFinderImplementation implements BookFinder {
 
private static final Book[] BOOKS = new Book[] {
 
new Book(1234, "Java Programming Language"),
 
new Book(5678, "OSGi") };
 
 
 
public Book findBook(int isbn) throws BookNotFoundException {
 
Book found = null;
 
 
 
for (Book b : BOOKS)
 
if (b.getIsbn() == isbn) {
 
found = b;
 
break;
 
}
 
if (found == null)
 
throw new BookNotFoundException("No book with isbn = " + isbn);
 
 
 
return found;
 
}
 
}
 
//This could be any implementation: database, file system, distributed, etc.
 
 
 
</source>
 
 
 
Define in the MANIFEST.MF for cs.ecl.osgi.simple.bookfinderservice
 
<source lang="xml">
 
Manifest-Version: 1.0
 
Bundle-ManifestVersion: 2
 
Bundle-Name: Bookfinderservice
 
Bundle-SymbolicName: cs.ecl.osgi.simple.bookfinderservice
 
Bundle-Version: 1.0.0.qualifier
 
Bundle-Activator: cs.ecl.osgi.simple.bookfinderservice.Activator
 
Bundle-ActivationPolicy: lazy
 
Bundle-RequiredExecutionEnvironment: JavaSE-1.6
 
Import-Package: org.osgi.framework;version="1.3.0"
 
Bundle-Vendor: Seneca College -  Eclipse Course
 
Export-Package: cs.ecl.osgi.simple.bookfinderservice
 
Require-Bundle: cs.ecl.osgi.simple.bookfinder;bundle-version="1.0.0"
 
</source>
 
 
 
The bundle export the package cs.ecl.osgi.simple.bookfinderservice Meanwhile, the implementation package - cs.ecl.osgi.simple.bookfinderservice.internals -  <strong>is hidden to the outside world and can be change dynamically</strong> and can be changed dynamically anytime a better implementation is created.
 
 
 
The bundle requires the osgi framework and the interface bundle (e.g. bookfinder bundle)
 
 
 
: Require-Bundle: cs.ecl.osgi.simple.bookfinder;bundle-version="1.0.0"
 
: Import-Package: org.osgi.framework;version="1.3.0"
 
 
 
The bundle export its service (for instance, the bood finder service - cs.ecl.osgi.simple.bookfinderservice)
 
 
 
: Export-Package: cs.ecl.osgi.simple.bookfinderservice
 

Latest revision as of 23:56, 24 January 2011


OSGi Activities



Start the lab activities in the order defined below:

Bundels and Java Applications

  1. Check out the Service Interface
  2. Check out the Service Provider
  3. Check out the Service Consumer

Steps for Building Applications from Bundels

OSGi-DS.png

Bundels and the Declarative Services

  1. Check out the Declarative Service Consumer
  2. Check out the Declarative Service Provider

Steps for Building Declarative Services