CK Developer Notes

Ubuntu 12.04 and mysql does not start

noreply@blogger.com (Karthikeyan Chockalingam) — Mon, 04 Jun 2012 04:41:00 +0000

Once you upgrade to Ubuntu 12.04 and if you had configured mysql to use UTF character set, the mysql server may not start.

This is due to the following deprecated parameters.

default-character-set=utf8
default-collation=utf8_unicode_ci

Replace the above parameters (they are normally in /etc/mysql/my.cnf)

character-set-server = utf8
collation-server = utf8_unicode_ci

Now restart mysql server using the command

sudo service mysql start

Good motivational video

noreply@blogger.com (Karthikeyan Chockalingam) — Fri, 06 Apr 2012 10:14:00 +0000

http://www.youtube.com/watch?feature=player_embedded&v=hV63DbQ_qSc

ProGuard - A case to disable shrink

noreply@blogger.com (Karthikeyan Chockalingam) — Fri, 02 Mar 2012 18:53:00 +0000

Assume you are obfuscating a jar in a web application (say you deploy it on machines where you want to protect from decompile+disassembling).

If you come across the error message "The output jar is empty. Did you specify the proper '-keep' options?" , disable shrinking (as you may not have a valid main method entry point in a web application.

How to find if Apache is running prefork or worker MPM

noreply@blogger.com (Karthikeyan Chockalingam) — Sun, 13 Nov 2011 09:31:00 +0000

Use the command

apache2 -l

It should list modules like

 Compiled in modules:
  core.c
  mod_log_config.c
  mod_logio.c
  worker.c
  http_core.c
  mod_so.c

As worker.c is displayed then it uses worker MPM.

Shortcut to show desktop in Ubuntu 11.10

noreply@blogger.com (Karthikeyan Chockalingam) — Sun, 23 Oct 2011 17:05:00 +0000

Upgraded to Ubuntu 11.10 today.

The default short cut to show desktop minimizing all windows is Alt+Ctrl+D

Install tint2 (sudo apt-get install tint2) for the taskbar to switch between applications. Also add it to startup so that it appears after logging in.

PrimeFaces Themes Dependencies

noreply@blogger.com (Karthikeyan Chockalingam) — Fri, 21 Oct 2011 06:49:00 +0000

       <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>aristo</artifactId>
            <version>${theme.version}</version>
        </dependency>

        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>black-tie</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>blitzer</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>bluesky</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>casablanca</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>cupertino</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>dark-hive</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>dot-luv</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>eggplant</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>excite-bike</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>flick</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>glass-x</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>hot-sneaks</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>humanity</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>le-frog</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>midnight</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>mint-choc</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>overcast</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>pepper-grinder</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>redmond</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>rocket</artifactId>
            <version>${theme.version}</version>
        </dependency>
          <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>sam</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>smoothness</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>south-street</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>start</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>sunny</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>swanky-purse</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>trontastic</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>ui-darkness</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>ui-lightness</artifactId>
            <version>${theme.version}</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>vader</artifactId>
            <version>${theme.version}</version>
        </dependency>

GlassFish 3.1 - Enabling mod_jk

noreply@blogger.com (Karthikeyan Chockalingam) — Sun, 16 Oct 2011 11:41:00 +0000

Ensure GlassFish server is up and running. (or use asadmin start-domain domain1 command)
Execute asadmin create-http-listener --listenerport 8009 --listeneraddress 0.0.0.0 --defaultvs server jk-connector
Execute asadmin set configs.config.server-config.network-config.network-listeners.network-listener.jk-connector.jk-enabled=true
Final step is to restart GlassFish server. Thats it enjoy.

Configuring JDBC Realm in GlassFish 3.1

noreply@blogger.com (Karthikeyan Chockalingam) — Fri, 14 Oct 2011 20:55:00 +0000

Use the following sample in domain.xml (under config folder) in GlassFish. Change the digest-algorithm and encoding accordingly.

<security-service>
<auth-realm classname="com.sun.enterprise.security.auth.realm.jdbc.JDBCRealm" name="jdbcRealm">
          <property name="jaas-context" value="jdbcRealm"></property>
          <property name="datasource-jndi" value="jdbc/srack"></property>
          <property name="user-table" value="users"></property>
          <property name="user-name-column" value="username"></property>
          <property name="password-column" value="password"></property>
          <property name="group-table" value="groups"></property>
          <property name="group-name-column" value="groupname"></property>
          <property name="digest-algorithm" value="MD5"></property>
          <property name="encoding" value="Base64"></property>
          <property name="assign-groups" value=""></property>
   </auth-realm>
............
More config here
.............

SEVERE: Exception while loading the app GlassFish error CDI JPA

noreply@blogger.com (Karthikeyan Chockalingam) — Fri, 14 Oct 2011 17:34:00 +0000

Verify if one of your @Named annotated backing bean which is ViewScoped or ConversationScoped is Serializable if you receive the error SEVERE: Exception while loading the app without any stacktrace in GlassFish 3.1

DataExporter dependent jars - iText and Apache POI version

noreply@blogger.com (Karthikeyan Chockalingam) — Thu, 13 Oct 2011 19:01:00 +0000

If you are using PrimeFaces 3.x and wish to use dataExporter for producing pdf and xls files, iText and Apache POI jars are required. If you are using Maven please include the following dependencies.

         <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>3.7</version>
        </dependency>

         <dependency>
            <groupId>com.lowagie</groupId>
            <artifactId>itext</artifactId>
            <version>2.1.7</version>
          </dependency>

Listing long running conversations in CDI based web application

noreply@blogger.com (Karthikeyan Chockalingam) — Thu, 13 Oct 2011 11:44:00 +0000

I am not sure if CDI provides APIs to list all long running conversations. So I came up with the below class.

Note: Time-out and eviction of conversations by the container when not in use for a long time to save resoruces is NOT considered in the code below.

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import javax.enterprise.context.SessionScoped;
import javax.inject.Named;

@Named
@SessionScoped
public class SRackWorkSpace implements Serializable{

    private List<String> cids=new ArrayList<String>();

    public void addConversation(String cid){
        cids.add(cid);
    }

    public void removeConversation(String cid){
        cids.remove(cid);
    }

    public boolean isConversationActive(String cid){
        return cids.contains(cid);
    }


}

Inject conversation and the above session scoped bean and invoke

- addConversation method when you begin a conversation like

conversation.begin("deliverexam");
sRackWorkSpace.addConversation("deliverexam");

- removeConversation when we end a conversation like

sRackWorkSpace.removeConversation(conversation.getId());
conversation.end();.

You can check of a long running conversation for a desired use case is already active like

if (sRackWorkSpace.isConversationActive("deliverexam")) {

return "/YOUR_PATH_TO_XHTML_VIEW?cid=deliverexam&faces-redirect=true";

}

Validating email field programmatically - Hibernate Validator

noreply@blogger.com (Karthikeyan Chockalingam) — Tue, 11 Oct 2011 15:19:00 +0000

First the Email.java class

public class Email {

    @org.hibernate.validator.constraints.Email(message = "Email is not valid")
    private String email;

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }
}

Let us say you have to validate a Collection of email values,

import javax.validation.ConstraintViolation;
import javax.validation.Validation;
import javax.validation.Validator;
import javax.validation.ValidatorFactory;

//More code here

Email emailClass = new Email();
        ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
        Validator validator = factory.getValidator();

        for (String e : emails) {
            emailClass.setEmail(e.trim());
            Set<ConstraintViolation<Email>> constraintViolations =validator.validate(emailClass);
            if (!constraintViolations.isEmpty()) {
               //Email is not valid. Perform the logic
            }
        }

I use Hibernate Validator implementation. Since I use Maven for build, the dependency is as below.

<dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>4.2.0.Final</version>
</dependency>

Injection of EntityManager or CDI Bean in FacesConverter

noreply@blogger.com (Karthikeyan Chockalingam) — Mon, 10 Oct 2011 18:54:00 +0000

Seam3 Persistence Module along with Faces Module helps in enabling CDI injection in FacesConverter belonging to JSF. Example below.

@FacesConverter(value = "questionTagConverter", forClass = QuestionTag.class)
public class QuestionTagConverter implements Converter{

   @Inject
   EntityManager entityManager;

    @Override
    public Object getAsObject(FacesContext fc, UIComponent uic, String string) {
        return entityManager.find(QuestionTag.class, Integer.parseInt(string));
    }

    @Override
    public String getAsString(FacesContext fc, UIComponent uic, Object o) {
        return ((QuestionTag)o).getId().toString();
    }

}

The Java class which produces the EntityManager is as below.

import javax.enterprise.context.ConversationScoped;
import javax.enterprise.inject.Produces;
import javax.persistence.EntityManagerFactory;
import javax.persistence.PersistenceUnit;
import org.jboss.seam.solder.core.ExtensionManaged;

public class EntityMgrProducer {

    @ExtensionManaged
    @Produces
    @PersistenceUnit(name = "PU_NAMEHERE")
    @ConversationScoped
    EntityManagerFactory entityManager;
}

The related jars should be added to your web application. If you use Maven use the dependencies below.

      <dependency>
            <groupId>org.jboss.seam.faces</groupId>
            <artifactId>seam-faces</artifactId>
            <version>3.0.2.Final</version>
        </dependency>
        <dependency>
            <groupId>org.jboss.seam.persistence</groupId>
            <artifactId>seam-persistence</artifactId>
            <version>3.0.0.Final</version>
        </dependency>

Example Usage - xhtml file

<h:panelGrid columns="2">
                     <p:selectOneMenu value="#{searchMultipleChoiceQuestionAction.questionDataModel.selTag}" converter="questionTagConverter">
                    <f:selectItems value="#{searchMultipleChoiceQuestionAction.tags}" var="qt" itemLabel="#{qt.qtag}" itemValue="#{qt}"/>
                </p:selectOneMenu>
                    <p:commandButton update="searchresult" action="#{searchMultipleChoiceQuestionAction.search()}" value="Search"/>
</h:panelGrid>

Signing a jar file

noreply@blogger.com (Karthikeyan Chockalingam) — Tue, 04 Oct 2011 18:47:00 +0000

As I had to sign the jar file (to provide it permissions), used the following command to sign the jar file.

jarsigner -keystore PATHTO\srack.keys -storepass password PATHTOYOURJAR\audiorecording-1.0.jar https://www.skillrack.com/

Note: The srack.keys was generated earlier using a command like (as I was lazy specified 10 years validity :))
keytool -genkey -keystore srack.keys -alias https://www.skillrack.com/ -validity 3650

GlassFish Error - javax.ejb.AccessLocalException: Client not authorized for this invocation

noreply@blogger.com (Karthikeyan Chockalingam) — Mon, 03 Oct 2011 05:47:00 +0000

If you are using GlassFish (along with NetBeans and facing this error when invoking an EJB from a Servlet or any web layer class using @EJB inject, clear the generated policy files and redeploy the application.

Ensure a line for the (newly added or renamed) method being accessed is present in the policy file. An example is provided below.

permission javax.security.jacc.EJBMethodPermission "ExamManagementEJB", "getQuestionTags,Local,com.packagename.entity.SomeEntity";

Configuring Hibernate as JPA implementation provider in GlassFish

noreply@blogger.com (Karthikeyan Chockalingam) — Sun, 02 Oct 2011 19:27:00 +0000

This post helps to configure Hibernate as JPA implementation provider replacing the bundled EclipseLink.

I am using Maven and mine is an EAR containing a WAR and an EJB module. Hence in the pom.xml of the EAR module, the following dependency is mentioned.

        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
            <version>3.6.7.Final</version>
         </dependency>

As this jar has to go into the lib folder directly under EAR ROOT, specify the value for defaultLibBundleDir (in pom.xml)

               <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-ear-plugin</artifactId>
                <version>2.4.2</version>
                <configuration>
                    <version>6</version>
                    <defaultLibBundleDir>lib</defaultLibBundleDir>

Finally your persistence unit in persistence.xml

<persistence-unit name="yourPU" transaction-type="JTA">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <jta-data-source>jdbc/yourDataSourceName</jta-data-source>
        <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
            <property name="hibernate.transaction.manager_lookup_class" value="org.hibernate.transaction.SunONETransactionManagerLookup" />
        </properties>
    </persistence-unit>

PrimeFaces in Action to build a Word Guess feature at SkillRack.com

noreply@blogger.com (Karthikeyan Chockalingam) — Fri, 30 Sep 2011 15:10:00 +0000

YouTube video showing PrimeFaces in Action to build a Word Guess feature at SkillRack.com

My personal opinion - Seam 3 not heading in the right direction

noreply@blogger.com (Karthikeyan Chockalingam) — Fri, 30 Sep 2011 14:32:00 +0000

After reading this , my personal opinion is

Seam 2 was good and but in future Seam will RIP

How to check ROLES in EL in JSF 2 and conditionally render components

noreply@blogger.com (Karthikeyan Chockalingam) — Wed, 28 Sep 2011 14:28:00 +0000

In the below code we are checking for role ADMIN
<h:outputText value="abcd" rendered="#{request.isUserInRole('ADMIN')}"/>

GlassFish 3 server - Enabling JPA for WAR module

noreply@blogger.com (Karthikeyan Chockalingam) — Wed, 28 Sep 2011 14:15:00 +0000

My first sample web application in GlassFish 3 server involving JPA 2.0 and GlassFish was spitting out the error "Unable to retrieve EntityManagerFactory for unitName XXX". Other settings were right.
Solution: Edit domain.xml to enable JPA as below. By default JPA is enabled for EJB modules.


 <module name="yourwebmodulename">
 <engine sniffer="jpa"></engine>

How to have WAR and JAR folders exploded in an EAR project built by Maven

noreply@blogger.com (Karthikeyan Chockalingam) — Wed, 28 Sep 2011 14:05:00 +0000

Add the attribute unpack=true (example below)

<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-ear-plugin</artifactId>
<version>2.4.2</version>
<configuration>
<version>6</version>
<defaultLibBundleDir>lib</defaultLibBundleDir>
<modules>
<webModule>
<groupId>com.urcompany</groupId>
<artifactId>xxx-web</artifactId>
<contextRoot>/</contextRoot>
<unpack>true</unpack>
</webModule>
<ejbModule>
<groupId>com.urcompany</groupId>
<artifactId>xxx-ejb</artifactId>
<unpack>true</unpack>
</ejbModule>
</modules>
</configuration>
</plugin>

How to debug the root cause for AssertionFailure: null id in entry (don't flush the Session after an exception occurs)

noreply@blogger.com (Karthikeyan Chockalingam) — Sun, 05 Jun 2011 09:49:00 +0000

To figure out the real (root) cause of the error, please use the following snippet

     ClassValidator cv = new ClassValidator(YourEntity.class);
                    InvalidValue[] validationMessages = cv.getInvalidValues(yourInstanceOfEntity);
                    if (validationMessages.length > 0) {
                        for (InvalidValue iv : validationMessages) {
                            System.out.println("Invalid value::" +iv.getMessage()+"::"+iv.getPropertyName()+"::"+iv.getValue());
                        }
                    }

Migration from Seam 2 to Seam 3

noreply@blogger.com (Karthikeyan Chockalingam) — Tue, 10 May 2011 19:16:00 +0000

I am migrating one of my application from Seam 2 to Seam 3 and hence posting my observations in this post. The post is not complete yet and i will be adding to it when ever i work on the migration.

To begin with configure the profile mentioned in this link either in your pom.xml or settings.xml. Else the build will fail to resolve parent pom.
Install Maven 3.0.3 or above. Certain Maven plugins will not work with 2.2.1 or any 2.x.x versions.

UPDATE: As Seam 3.0 is lacking many of the features in Seam 2.0 I have paused the migration as of now and waiting for Seam 3.1 release

Generating a self signed certificate specifying validity using keytool in JDK

noreply@blogger.com (Karthikeyan Chockalingam) — Thu, 07 Apr 2011 11:30:00 +0000

Sometimes you may wish to change the default validity of a JDK keytool generated self signed certificate in your development environment. Use the argument validity to control the validity period. In the below example the validity is 10 years.

keytool -genkey -keystore yourname.keys -alias somealias -validity 3650

http://www.psychometric-success.com/products.htm

noreply@blogger.com (Karthikeyan Chockalingam) — Sun, 10 Oct 2010 07:46:00 +0000

http://www.psychometric-success.com/products.htm

--
Regards,
Karthikeyan C