Sunday, December 20, 2015

Open Services Gateway Initiative (OSGi) Introduction

The Open Services Gateway Initiative (OSGi) is specification that defines modular based software management and its execution. OSGi makes software management and its execution simpler by making large application into small bunch of pieces and we call it as module. These modules are working independent way so that when we need we can start module and we can stop module. As for OSGi a module is Bundle or Plugin-in

OSGi provides execution environment so that we can install, start and stop module whenever we required such a way OSGi provides OSGi containers to manage lifecycle of these bundles.

Bundle/Plug-In/Software component

Bundle is a collection Java classes and resources make it as package then we call it as bundle and these bundle can be working as independent or it can be depends on other bundle or plugin. We can say bundle is small piece of software and as for OSGi we can specify as OSGi bundle.


As for our understand bundle is java jar file.

OSGi specification

OSGi implementations

After release of OSGi specification by OSGi Alliance in March 1999 then people implemented specifications as software and the following are popular implementation software open source groups.


Equinox is reference implementation of OSGi from eclipse and they have implanted OSGi software so that it provides runtime environment for OSGi based software development.

Apache Felix

Felix is also implemented OSGi specification from Apache and its open source implementation.


Knopflerfish is another Open source Implementation for OSGi


All above implementation covered all specifications of OSGi R3 and OSGi R4 specifications.

Software Developers can use any one of the implementation to implement their software as modular based way. We can also inherited features from above all implementations.

All OSGi implementations they packages as jar file so that it will provide execution environment for OSGi bundles. OSGi have basic standalone container to execute bundles and if we want other environments support we need to take relevant environment support bundle so that it will provide execution environment for different kind of environment.

Basic OSGi implementation Jars

From Apache Felix


Start the framework

From the installation directory by typing in the terminal

java -jar bin/felix.jar

From Eclipse Equinox


Start OSGi Framework

java -jar org.eclipse.osgi_3.2.0.jar –console

The above implementation jars covered all specification that defined by OSGi so that we can develop OSGi bundles then we can run it on OSGi containers.

OSGi bundle Lifecycle

As for software development mode each software component have its own lifecycle same way OSGi bundle also have its own lifecycle and these lifecycle will be manged by OSGi Framework implementation software or we can say OSGi containers.
The following are OSGi bundle lifecycle stages



Install is start point to OSGi bundle and we need to install OSGi bundle with help OSGi commands then Bundle will be available in OSGi container.


In the resolve stage it will check all dependent bundles and its required bundles if everything satisfied then it will moved to other stage otherwise it will be uninstalled.


Uninstall is completely removing OSGi bundle from OSGi container and this we can manually uninstall with command or If the bundle not resolved by all decencies then it’s automatically uninstalled.


After all dependencies and required bundles are resolved then bundle will be started, once bundle is started then it will be available for use.


Once bundle available to use in OSGi container then we will make it active so that it will be under real usage and it we can experience as end user.


Stop stage we can make OSGi bundle inactive so that it will not available for real use but still Bundle available for OSGi container.

The following are the commands to working with OSGi Bundle lifecycle

Apache Felix

The following are the commands to working with bundle lifecycle and we need to provide bundle path as variable for each command.

felix:install file:/path/to/bundle/bundle.jar

felix:start file:/path/to/bundle/bundle.jar

felix:stop file:/path/to/bundle/bundle.jar

felix:update file:/path/to/bundle/bundle.jar

felix:uninstall file:/path/to/bundle/bundle.jar

To work with shell based commands Apache Felix uses another OSGi bundle called Apache Felix GOGO

Apache Felix GOGO

Apache Felix GOGO is sub project of Apache Felix and it provide command based interface to working with OSGi bundles lifecycle.

The Gogo subproject of Apache Felix and its consists of three bundles


Implements the core command processing functionality.

The following is Bundle implemented Runtime



 Provides a simple textual user interface to interact with the command processor.
The following is Bundle implemented Shell


 Implements a set of basic commands.



Apache Felix GoGo is already included in the Apache Felix Framework Software so as soon as we start Felix OSGi jar file then it will be available as console so that we can use above specified commands to manage bundle lifecycle.

Example Gogo Console

Open your terminal in you system start Felix Framework jar file then you can see Apache Felix GoGo console.

$ cd felix-framework-3.0.0
$ java -jar bin/felix.jar
Welcome to Apache Felix Gogo

g! lb
   ID|State      |Level|Name
    0|Active     |    0|System Bundle (3.0.0)
    1|Active     |    1|Apache Felix Bundle Repository (1.6.2)
    2|Active     |    1|Apache Felix Gogo Command (0.6.0)
    3|Active     |    1|Apache Felix Gogo Runtime (0.6.0)
    4|Active     |    1|Apache Felix Gogo Shell (0.6.0)
    5|Installed  |    1|Example Bundle (1.0.0)
g! start 5
Hello from Bundle 5.

lb command list the available bundle in OSGi container and to start the bundle we can specify the bundle order number as argument.


Similar to Apache Felix equinox also have similar commands and its console to work with bundle lifecycle

install <bundle URL>

Installs the bundle from the given URL

start <bundle # or bundle name>

Starts the bundle with the given numeric or symbolic id

stop <bundle # or bundle name>

Stops the bundle with the given numeric or symbolic id


Reports a summary status of all installed bundles

diag <bundle # or bundle name>

 Reports any resolution problems for the bundle with the given numeric or symbolic id

Equinox also implemented OSGi console using following bundle


Internally Equinox also used Apache Felix gogo to provide command line interface and along with Equinox console.

Example of Equinox Console

osgi> ss
"Framework is launched."

id         State       Bundle
0          ACTIVE      org.eclipse.osgi_3.10.0.v20140606-1445
1          ACTIVE      org.apache.felix.gogo.runtime_0.10.0.v201209301036
2          ACTIVE      org.apache.felix.gogo.command_0.10.0.v201209301215
3          ACTIVE      com.meera.sample.HelloWorld_1.0.0.qualifier
4          ACTIVE      org.apache.felix.gogo.shell_0.10.0.v201212101605
5          ACTIVE      org.eclipse.equinox.console_1.1.0.v20140131-1639

osgi> stop 3
Goodbye World!!

osgi> start 3
Hello World!!

SS will use to list available bundles in OSGi container and we will use Bundle number in to start or stop bundle.

To work with Basic OSGi development using Apache Felix we need following bundles


To work with Basic OSGi development using Equinox we need following bundles


If we want work with other environments such as web applications we should have other OSGi bundle to provide execution run time environment.


To work with web application environment using OSGi we need following OSGi implementation bundles

Apache Felix HTTP Service

Apache Felix Web Console

Apache Felix Log

Similarly we need different implementation OSGi bundle to provide different types of environments.

In this case we need to setting up required bundles so that we can create execution environment rather than this there is project from Apache called Apache Arise it will provide all types of pluggable OSGi plugins to create different types of execution environment

Apache Aries

The Aries project consists of a set of pluggable Java components enabling an enterprise OSGi application programming model. This includes implementations (and extensions) of the following Enterprise OSGi specifications

Asynchronous Services and Promises Specification
Blueprint Specification
JTA Transaction Services Specification
JMX Management Model Specification
JNDI Services Specification
JPA Service Specification
Service Loader Mediator Specification
Subsystem Service Specification

Monday, November 23, 2015

Email forms using Liferay Web Content

Liferay have mail API to send emails in portlets and liferay also have web forms portlet to create email forms.

If we want create custom email form we need to develop custom portlet and need to design email form as for our requirement and its needed some development effort.

If we use web form portlet then we cannot make much look and feel design to forms and its separate portlet and we cannot use much convenient way in web content combination.

Out of box we can send email using web content so that we design email forms with good look and feel and we can send emails.

Here we have some custom portlet that will take care the email sending functionality we will use Ajax based mechanism to send email on behalf of our mail sender portlet through web content.

We will design email form in Liferay web content and we use AUI Ajax call to send emails.

The following are the steps you need to follow.

Step: 1

Download portlet from following location and deploy in your portal server and it should be successfully deployed.

Step: 2

Add following property in your file and restart Liferay portal server.



The above property should in single line in the properties file

Step: 3

Drag and Drop Liferay web content Display portlet in your desired page.

Create Liferay web content using following html content and publish it.

<style type="text/css">.mail-container{
<div class="mail-container">
<div id="successMessage">&nbsp;</div>

<div id="errorMessage">&nbsp;</div>

<form action="#" enctype="text/plain" method="post">Receiver Name:<br />
<input id="receiverName" name="receiverName" type="text" value="" /><br />
Receiver Email:<br />
<input id="receiverEmail" name="receiverEmail" type="text" value="" /><br />
Sender Name:<br />
<input id="senderName" name="senderName" type="text" value="" /><br />
Sendw Email:<br />
<input id="senderMail" name="senderMail" type="text" value="" /><br />
Subject<br />
<input id="mailSubject" name="mailSubject" type="text" value="" /><br />
Mail Body<br />
<textarea cols="50" id="mailBody" name="mailBody" rows="4"></textarea><br />
<br />
<input id="mailSend" type="button" value="mailSend" /> <input type="reset" value="Reset" />&nbsp;</form>
YUI().use('aui-base','aui-io-request', function(A){"#mailSend").on('click',function(){"#errorMessage").set("innerHTML","");"#successMessage").set("innerHTML","");
//alert("This click Event from AUI");
//aui ajax call to get updated content'http://localhost:8080/?p_p_id=AjaxMailSender_WAR_AjaxMailSenderportlet&p_p_lifecycle=2',{
dataType: 'json',
method: 'GET',
data: {
on: {
success: function() {
// response data will be received here
var data = this.get('responseData');

Finally you can see email form in web content display portlet as follows

You can see success message after send email

You can see error message if some get failed

The following portlet Java class we can customize the way we required.

package com.iamsuraj.mailsender;
import javax.mail.internet.InternetAddress;
import javax.portlet.PortletException;
import javax.portlet.ResourceRequest;
import javax.portlet.ResourceResponse;
import com.liferay.mail.service.MailServiceUtil;
import com.liferay.portal.kernel.json.JSONFactoryUtil;
import com.liferay.portal.kernel.json.JSONObject;
import com.liferay.portal.kernel.log.Log;
import com.liferay.portal.kernel.log.LogFactoryUtil;
import com.liferay.portal.kernel.mail.MailMessage;
import com.liferay.portal.kernel.util.ParamUtil;
import com.liferay.portal.kernel.util.Validator;
import com.liferay.util.bridges.mvc.MVCPortlet;
public class AJaxMailSenderPortlet extends MVCPortlet {
public void serveResource(ResourceRequest resourceRequest,ResourceResponse resourceResponse)throws  IOException, PortletException {

String receiverName=ParamUtil.getString(resourceRequest,"receiverName");
String receiverEmail=ParamUtil.getString(resourceRequest,"receiverEmail");
String senderName=ParamUtil.getString(resourceRequest,"senderName");
String senderMail=ParamUtil.getString(resourceRequest,"senderMail");
String mailSubject=ParamUtil.getString(resourceRequest,"mailSubject");
String mailBody=ParamUtil.getString(resourceRequest,"mailBody");"receiverName:"+receiverName);"receiverEmail:"+receiverEmail);"senderName:"+senderName);"senderMail:"+senderMail);"mailSubject:"+mailSubject);"mailBody:"+mailBody);
JSONObject responseOject=JSONFactoryUtil.createJSONObject();
boolean success=false;
try {
MailMessage mailMessage=new MailMessage();
mailMessage.setFrom(new InternetAddress(senderMail,senderName));
mailMessage.setTo(new InternetAddress(receiverEmail,receiverName));
}catch (Exception e) {

responseOject.put("errorMessage","One of Email Adresess is not valid");
responseOject.put("successMessage","Your mail has been send successfully");
PrintWriter out=resourceResponse.getWriter();;
private static final Log logger = LogFactoryUtil.getLog(AJaxMailSenderPortlet.class);

Important Points

 This is simple example portlet and we can develop like the way we wanted and you can also handle server side validation in the code.

The web content form is a simple form not much style and we can design with good look and feel with validations.

Web content I have hard coded the host name(localhost) if your host name is changed then please change the host name in the web content ajax URL.

To send email in the portal we must configure mail server in the Liferay portal and you can find mail configuration in the following post.


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