osgi world congress workshop exercise by peter kriens ceo aqute osgi technology officer

OSGi World CongressOSGi World CongressWorkshop ExerciseWorkshop Exercise

By Peter KriensBy Peter Kriens

CEO aQuteCEO aQute

OSGi Technology OfficerOSGi Technology Officer

www.aQute.sewww.aQute.se - 2002 OSGi World - 2002 OSGi World Congress - Congress - 22

Functional Description Functional Description ProgramProgram

““See your buddies” web page viewerSee your buddies” web page viewer At the end, each participant adds a At the end, each participant adds a

web page to the portal of all other web page to the portal of all other participantsparticipants

Zero Administration …Zero Administration …


ArchitectureArchitecture

app2

app3 app1

app4

Browser

app 1app 2app 3app 4

SP 2

SP 3

SP 4

SP 1

multicast


Architecture: ClassesArchitecture: Classes

ActivatorDistributor

Link

HttpTrackerTracks httpservers

findsbuddies

<<interface>>Http Service

ServiceTracker

Thread<<interface>>BundleActivator

Tracks buddies Registers page

Portal Tracks portal entries

Registers /portal page

LogService

Logs messages


Start: Hello WorldStart: Hello World

Activator

The Activator class will print “Hello The Activator class will print “Hello World” when the bundle is started World” when the bundle is started and “Goodbye World” when it stops.and “Goodbye World” when it stops.

<<interface>>BundleActivator


Getting StartedGetting Started

AssumptionsAssumptions– Eclipse 2.0.1 (check in Help:About, 2.0.0 Eclipse 2.0.1 (check in Help:About, 2.0.0

does not work!) installeddoes not work!) installed– unzipped fwx.zipunzipped fwx.zip

fwx.exefwx.exe load directoryload directory osgi.jarosgi.jar servlet.jarservlet.jar

– Started EclipseStarted Eclipse


EclipseEclipse


Getting StartedGetting Started

Create new Java ProjectCreate new Java Project– File:New:ProjectFile:New:Project– Java Project, NextJava Project, Next– Name is “ws”Name is “ws”– Default location, NextDefault location, Next– Libraries, Add external jars, Libraries, Add external jars,

servlet.jar, osgi.jar servlet.jar, osgi.jar (from where you unzipped fwx.zip, e.g. c:\fwx\(from where you unzipped fwx.zip, e.g. c:\fwx\osgi.jar)osgi.jar)

– Attach source (select osgi.jar), FinishAttach source (select osgi.jar), Finish


Add External JarAdd External Jar


Setup Activator classSetup Activator class

Add PackageAdd Package– File:New:PackageFile:New:Package– Name, aQute.world.congressName, aQute.world.congress


Setup Activator classSetup Activator class

Add new classAdd new class File:New:ClassFile:New:Class

– Package, aQute.world.congressPackage, aQute.world.congress– Name, ActivatorName, Activator– InterfacesInterfaces

Add BundleActivatorAdd BundleActivator

FinishFinish Eclipse will open a generated Eclipse will open a generated

source filesource file


Activator class setupActivator class setup


Write Hello/Goodbye Write Hello/Goodbye WorldWorld

Fill in the System.out.println(“...”) in Fill in the System.out.println(“...”) in the appropriate placesthe appropriate places

Save the file (File:Save or control-S)Save the file (File:Save or control-S)– This automatically compiles, so correct This automatically compiles, so correct

any errorsany errors


Create The ManifestCreate The Manifest

We only define what class to start: We only define what class to start: ActivatorActivator

File:New:File, name it Manifest.mf File:New:File, name it Manifest.mf – Store in aQute.world.congress package/dirStore in aQute.world.congress package/dir

Manifest MUST end with 2 empty lines!!Manifest MUST end with 2 empty lines!! Fill in (and save):Fill in (and save):

Manifest-Version: 1.0 Bundle-Activator: aQute.world.congress.Activator Import-Package: org.osgi.framework


Create ManifestCreate Manifest


Create Bundle JAR file!Create Bundle JAR file!

Select “ws” in left paneSelect “ws” in left pane Press right mouse buttonPress right mouse button Select ExportSelect Export Select JAR FileSelect JAR File NextNext


Create JAR FileCreate JAR File

Export DestinationExport Destination– Name it ws.jarName it ws.jar– Save the JAR in the load directorySave the JAR in the load directory

where you unzipped fwx.zip,where you unzipped fwx.zip,e.g. c:\fwx\loade.g. c:\fwx\load

NextNext


Create JAR fileCreate JAR file

Deselect “with compile Deselect “with compile errors”errors”

Save the description in theSave the description in the“ws” workspace, under the“ws” workspace, under thename bundle.jardescname bundle.jardesc

NextNext


Create JAR fileCreate JAR file

Set to use existing ManifestSet to use existing Manifest– Select Manifest.mfSelect Manifest.mf

FinishFinish


Starting A FrameworkStarting A Framework

The fwx.exe is the OSGi Reference Framework The fwx.exe is the OSGi Reference Framework with all the R2 services reference with all the R2 services reference implementationsimplementations– This Framework is not optimized, nor industrializedThis Framework is not optimized, nor industrialized– It expires December 1It expires December 1– Contact a vendor for a real frameworkContact a vendor for a real framework

To start it, open a window on its directory and To start it, open a window on its directory and double click itdouble click it

It will automatically start all bundles in the load It will automatically start all bundles in the load directorydirectory


Starting the FrameworkStarting the Framework


RestartingRestarting

You can restart the bundle by You can restart the bundle by – select the bundle.jardescselect the bundle.jardesc– Right mouse: Create JarRight mouse: Create Jar


Using The Log ServiceUsing The Log Service

Activator

We will now use a service: The Log We will now use a service: The Log ServiceService


LogService

Logs messages


Prepare for the Log Prepare for the Log ServiceService

Save the BundleContext parameter Save the BundleContext parameter in a context instance variablein a context instance variable

BundleContext context; public void start(BundleContext context) {

this.context = context; ...}


The log() methodThe log() method

Add a new method to the Activator Add a new method to the Activator class: class: void log( String msg, Throwable exception ) {

ServiceReference r = context.getServiceReference( LogService.class.getName() ); LogService log =(LogService)context.getService(r); if ( log != null ) { if ( exception == null ) log.log( LogService.LOG_INFO, msg ); else log.log( LogService.LOG_ERROR, msg, exception ); } else System.out.println( msg + " : " + exception ); context.ungetService( r );}


Use the log methodUse the log method

Replace the calls to System.out with Replace the calls to System.out with calls to the log methodcalls to the log method

public void start(BundleContext context) { this.context = context; log( "Hello world", null );}public void stop(BundleContext context){ log( "Goodbye world", null );}


Organize ImportsOrganize Imports

Source:Organizer ImportsSource:Organizer Imports This will automatically add the This will automatically add the

necessary import statementsnecessary import statements


Modify The ManifestModify The Manifest

Edit Manifest.mfEdit Manifest.mf Add Import-Package forAdd Import-Package for

– org.osgi.service.logorg.osgi.service.logManifest-Version: 1.0Bundle-Activator: aQute.world.congress.ActivatorImport-Package: org.osgi.framework, org.osgi.service.log


Using the Log ServiceUsing the Log Service

Save the source file (correct compile Save the source file (correct compile errors)errors)

Select bundle.jardesc, right menu, Select bundle.jardesc, right menu, Create JARCreate JAR

Check the console of fwx:Check the console of fwx:– Goodbye worldGoodbye world– But no Hello world … This is now in the logBut no Hello world … This is now in the log– Where is the log????Where is the log????


Reading the Log ServiceReading the Log Service

Open a telnet sessionOpen a telnet session– Start:Run:telnet localhost 2011Start:Run:telnet localhost 2011

This opens a simple OSGi This opens a simple OSGi console/debuggerconsole/debugger

TypeType– loglog


Publishing a pagePublishing a page



ServiceTracker

Registers page

Portal


Activator


LogService

Logs messages


Write An Html PageWrite An Html Page File:New:FileFile:New:File

– Directory, aQute/world/congressDirectory, aQute/world/congress– Call it page.htmlCall it page.html

Edit it (select page.html, Open With:Text Editor)Edit it (select page.html, Open With:Text Editor)

<html> <head> <title>My Demo HTML page</title> </head> <body> <h1>My Demo</h1> This is aQute's (use your own name!) demo page </body></html>


Create an HTML fileCreate an HTML file


Create HttpTrackerCreate HttpTracker

HttpTracker tracks Http Service objects and HttpTracker tracks Http Service objects and adds a “page.html” to every Http Serviceadds a “page.html” to every Http Service

It extends ServiceTracker to simplify trackingIt extends ServiceTracker to simplify tracking– Object addingService(ServiceReference)Object addingService(ServiceReference)– void modifiedService(ServiceReference,Object)void modifiedService(ServiceReference,Object)– void removedService(ServiceReference,Object)void removedService(ServiceReference,Object)

Create new class Create new class aQute.world.congress.HttpTracker that aQute.world.congress.HttpTracker that extends ServiceTracker, implements extends ServiceTracker, implements HttpContextHttpContext


Add HttpTracker classAdd HttpTracker class



And it needs a variable, constructor, And it needs a variable, constructor, add:add:Activator activator;

public HttpTracker( Activator activator, BundleContext context ) { super( context, HttpService.class.getName(),null); this.activator = activator;}



addingServiceaddingService

public Object addingService( ServiceReference reference ) { HttpService http = (HttpService)super.addingService(reference); try { http.registerResources("/mydemo", "", this ); } catch( NamespaceException e ) { activator.log( "Cannot register because “

+ “name is already in use /mydemo", e ); } return http;}



Modify the getResource method to Modify the getResource method to return resources from the packagereturn resources from the package

public URL getResource(String name) { try { URL url = getClass().getResource( name.substring(1) ); return url; } catch( Exception e ) { e.printStackTrace(); } return null;}



handlSecurity returns false. This handlSecurity returns false. This means deny access, change it to means deny access, change it to return true.return true.public boolean handleSecurity(

HttpServletRequest request, HttpServletResponse response) throws IOException { return true;}



Organize ImportsOrganize Imports Save itSave it Add an instance variable for the Http Add an instance variable for the Http

Tracker to ActivatorTracker to Activator

And add the following line to the And add the following line to the start method start method http = new HttpTracker( this, context );

http.open();

HttpTracker http;


Clean-upClean-up

// Add to stop methodhttp.close();


Modify The ManifestModify The Manifest

Add Import-Package forAdd Import-Package for– org.osgi.util.trackerorg.osgi.util.tracker– org.osgi.service.httporg.osgi.service.http– javax.servlet.http, javax.servletjavax.servlet.http, javax.servlet

Manifest-Version: 1.0Bundle-Activator: aQute.world.congress.ActivatorImport-Package: org.osgi.framework, org.osgi.service.log,org.osgi.util.tracker, org.osgi.service.http,javax.servlet.http, javax.servlet



Save open filesSave open files Select bundle.jardescSelect bundle.jardesc

– Create JARCreate JAR Open a browser and surf intoOpen a browser and surf into

– http://localhost/mydemo/page.htmlhttp://localhost/mydemo/page.html Ensure that your HTTP proxy is off!Ensure that your HTTP proxy is off!

– IE : Tools : Internet Options : IE : Tools : Internet Options : Connections : Lan settings Connections : Lan settings


Finding Your BuddiesFinding Your Buddies



ServiceTracker

Registers page

Portal


Activator


LogService

Logs messages

Distributor

Link

findsbuddies

Thread

Tracks buddies

Tracks portal entries


Add Distributor classAdd Distributor class

Add a new class DistribitorAdd a new class Distribitor– Package aQute.world.congressPackage aQute.world.congress– Extends ThreadExtends Thread

This class will open a UDP socketThis class will open a UDP socket Will listen to all Datagram’s on port 2014Will listen to all Datagram’s on port 2014 Forwards all datagrams to the activatorForwards all datagrams to the activator Sends an announce datagram every 5 secondsSends an announce datagram every 5 seconds Simple mechanism to dynamically discover Simple mechanism to dynamically discover

othersothers


Add Distributor classAdd Distributor class

Add Instance variable declarationsAdd Instance variable declarations

boolean active = true;DatagramSocket socket;byte outgoing[];Activator activator;


Add Distribitor classAdd Distribitor class

Add ConstructorAdd Constructor

Distributor( Activator activator, String outgoing ) { super("distributor"); this.activator = activator; this.outgoing = outgoing.getBytes();}


Add Distribitor classAdd Distribitor classpublic void run() { while ( active ) try { socket = new DatagramSocket( 2014 ); socket.setSoTimeout( 5000 ); activator.log("Discovery starts.", null); … inner loop … see next slide socket.close(); socket = null; } catch(Exception e) { activator.log( "Main discover loop exit", e ); if ( active ) try { Thread.currentThread().sleep(1000); } catch( Exception x) {} } activator.log("Discovery quits.", null);}


Add Distribitor classAdd Distribitor classwhile ( active ) try { DatagramPacket packet = new DatagramPacket(new byte[256], 256); socket.receive(packet); String incoming = new String( packet.getData(), 0, packet.getLength()); activator.process( new Link(incoming) ); }catch(InterruptedIOException e) { announce();} catch(Exception e) { if ( active ) activator.log( "Receving remote “

+ “service packets, ignoring ", e );}



The announce methodThe announce method

void announce() throws IOException { DatagramSocket announce = new DatagramSocket(); DatagramPacket packet = new DatagramPacket( outgoing, outgoing.length, InetAddress.getByName("255.255.255.255"), 2014 ); announce.send(packet); }



And the last close methodAnd the last close method

Organize importsOrganize imports SaveSave

– Unresolved method in Activator: processUnresolved method in Activator: process

void close() { active = false; socket.close();}


Add Link classAdd Link class

Add linke classAdd linke class The link class just holds the buddy The link class just holds the buddy

info together.info together.Hashtable properties = new Hashtable();ServiceRegistration registration;

Link( String msg ) { StringTokenizer tz =

new StringTokenizer( msg, "|" ); properties.put( "title", tz.nextToken() ); properties.put( "description",tz.nextToken()); properties.put( "url", tz.nextToken() ); }



Register method, for a new discovered Register method, for a new discovered buddybuddy

Modify method, when old buddy, new Modify method, when old buddy, new messagemessage

void register( BundleContext context ) { registration = context.registerService( Link.class.getName(), this, properties );}

void modify( Link link ) { registration.setProperties(link.properties);}



Unregister when link is goneUnregister when link is gone

To get the unique key To get the unique key

void unregister() { registration.unregister();}

Object getUrl(){ return properties.get( "url" ); }


Add process method in Add process method in ActivatorActivator

The process method must add buddy The process method must add buddy to the portalto the portal

The portal tracks “url” service The portal tracks “url” service property.property.

Edit Activator, add process methodEdit Activator, add process methodHashtable links = new Hashtable();void process( Link link ) { Link existing = (Link) links.get( link.getUrl() ); if ( existing != null ) existing.modify( link ); else { link.register( context ); links.put( link.getUrl(), link ); existing = link; }}


Add and Start the Add and Start the DistributorDistributor

// Add to start methodString host= InetAddress.getLocalHost().getHostAddress();if ( System.getProperty(

"org.osgi.service.http.port" ) != null )host += ":" + System.getProperty(

"org.osgi.service.http.port" );

distributor = new Distributor( this, "My Title|My Own Description|http://" + host + "/mydemo/page.html"

);distributor.start();


Clean-up (stop method)Clean-up (stop method)

// Add to stop methoddistributor.close();


Find the buddiesFind the buddies

Organize imports for all filesOrganize imports for all files Build JARBuild JAR Browse to:Browse to:

– http://localhost/portalhttp://localhost/portal You should see your own page, and You should see your own page, and

with any luck pages from your with any luck pages from your buddiesbuddies


Advanced ExerciseAdvanced Exercise

Links are not cleaned up when the Links are not cleaned up when the buddy stops sendingbuddy stops sending

Cleanup the links when no message Cleanup the links when no message has been received for 30 secondshas been received for 30 seconds


ConclusionConclusion

Surprisingly little code is necessary to Surprisingly little code is necessary to perform interesting functionsperform interesting functions

Coupling to other parts is minimal Coupling to other parts is minimal because OSGi specified interfaces are because OSGi specified interfaces are intermediatesintermediates

Tools are available to simplify Tools are available to simplify creation of manifest and bundle filescreation of manifest and bundle files

This is only the beginning ...This is only the beginning ...


Vendors With Tools & Vendors With Tools & CoursesCourses

Acunia - www.acunia.comAcunia - www.acunia.com aQute - www.aQute.seaQute - www.aQute.se IBM - www.ibm.com/embeddedIBM - www.ibm.com/embedded Gatespace - www.gatespace.comGatespace - www.gatespace.com ProSyst - www.prosyst.comProSyst - www.prosyst.com

See for more www.osgi.org See for more www.osgi.org


aQute

www.aQute.se

+46 300 39800, [email protected]

e

osgi world congress workshop exercise by peter kriens ceo aqute osgi technology officer

Documents

world activator

file file

hello world

hellogoodbye world

activator file

manifest slide

framework slide

new class file