Weblogic and Oracle RAC

The suggested solution for high availability is using a Multi Data Source with load balancing.

It turns out that Oracle RAC is very sensitive to the version of JDBC driver you are using:

http://e-docs.bea.com/platform/suppconfigs/configs100/100_over/supported_db.html#1143800

Automatic database connection failover and load balancing with global transactions (XA) in a highly-available (HA) DBMS architecture is supported with the following Oracle RAC versions and drivers:

Oracle Thin/XA Driver 10g

(which is oracle.jdbc.xa.client.OracleXADataSource, versus weblogic.jdbcx.oracle.OracleDataSource which is the Weblogic Oracle driver)

If you try using the Weblogic Type 4 JDBC driver (weblogic.jdbcx.oracle.OracleDataSource) you will encounter deadlock problems:

"[ACTIVE] ExecuteThread: '398' for queue: 'weblogic.kernel.Default (self-tuning)'" waiting for lock weblogic.jdbcx.base.BaseXAConnection@2923410e BLOCKED

weblogic.jdbcx.base.BaseXAResource.end(Unknown Source)

weblogic.jdbc.jta.DataSource.end(DataSource.java:803)

weblogic.transaction.internal.XAServerResourceInfo.end(XAServerResourceInfo.java:1232)

weblogic.transaction.internal.XAServerResourceInfo.internalDelist(XAServerResourceInfo.java:404)

weblogic.transaction.internal.XAServerResourceInfo.delist(XAServerResourceInfo.java:326)

weblogic.transaction.internal.ServerTransactionImpl.delistAll(ServerTransactionImpl.java:1624)

weblogic.transaction.internal.ServerTransactionImpl.localRollback(ServerTransactionImpl.java:2012)

weblogic.transaction.internal.ServerTransactionImpl.globalRetryRollback(ServerTransactionImpl.java:3020)

weblogic.transaction.internal.ServerTransactionImpl.access$100(ServerTransactionImpl.java:66)

weblogic.transaction.internal.ServerTransactionImpl$1.run(ServerTransactionImpl.java:3252)

weblogic.work.ExecuteThread.execute(ExecuteThread.java:209)

weblogic.work.ExecuteThread.run(ExecuteThread.java:181)

Highly recommended is this:

http://e-docs.bea.com/wls/docs100/jdbc_admin/oracle_rac.html

More specifically for ALBPM:
http://edocs.bea.com/albsi/docs60/installguide/index.html?t=installation/c_Required_Databases.html

Java and Shutdown

you can add a shutdown handler:

Runtime.getRuntime().addShutdownHook(sh);

where sh is a Thread

Problem is, in Unix it works only with CTRL-C, not witk kill -9 or kill -8 (abort).

In Windows, if I terminate my JVM with Eclipse's "terminate" button, the hook is not executed.

Thread Dumps and WLST

you can read WLST output into a String, so instead of into a file you can redirect some commands into a String:

String connect = "connect('weblogic', 'weblogic', 't3://bcdev07:5210')";

WLST.ensureInterpreter();

WLSTInterpreter interpreter = WLST.getWLSTInterpreter();

interpreter.exec(connect);

while (true) {

OutputStream os = new ByteArrayOutputStream();

interpreter.setOut(os);

interpreter.exec("threadDump('false')");

System.out.println("buffer="  + os.toString());

TestingUtilities.sleep(100);

}

Network performance tools

nmon http://en.wikipedia.org/wiki/Nmon

download nmon at http://www.ibm.com/developerworks/wikis/display/WikiPtype/nmon

movie on nmon http://download.boulder.ibm.com/ibmdl/pub/systems/power/community/aix/AIX_Movies/nmon_Intro.wmv

Satan seems obsolete, and it's mostly for network security than for performance benchmarking.

http://en.wikipedia.org/wiki/Measuring_network_throughput

Good tutorial on networks:

http://iptables-tutorial.frozentux.net/iptables-tutorial.html#TCPMSSTARGET

Logging Return Value and Method Arguments with Spring AOP

as in the previous example, but use this:

<aop:after-returning method="logExitAfterReturn" ref="loggingPointcut" returning="retVal"></aop:after-returning>

and the method becomes:

public void logExitAfterReturn(final JoinPoint joinPoint, Object retVal)

{
log( "Exiting method (after return) " + joinPoint.getSignature().getName() + ", retValue = " + retVal + ".");
}

while the logEntry becomes:

public void logEntry(final JoinPoint joinPoint)

{

StringBuilder arguments = new StringBuilder();

arguments.append(" args= ");

for (Object arg : joinPoint.getArgs()) {

arguments.append(arg).append(", ");

}

log("Entering method " + joinPoint.getSignature().getName() + arguments.toString() + "...");

}

Logging with Spring AOP

The bean to intercept:

package com.pierre.aop;

public class ExampleBeanClass implements IExampleBeanClass {

public String getMessage() {

return "ciao";

}

}

and its interface:

package com.pierre.aop;

public interface IExampleBeanClass {

String getMessage();

}

The interceptor:

package com.pierre.aop;

import org.aspectj.lang.JoinPoint;

/**

 * Aspect class for the Spring/AspectJ Logging example shown in the blog

 * 

 * @author vernetto

 */

public class LoggingAspect

{

/**

* Log method entry.

* 

* @param joinPoint

*/

public void logEntry(final JoinPoint joinPoint)

{

log("Entering method " + joinPoint.getSignature().getName() + "...");

}

/**

* Log method exit.

* 

* @param joinPoint

*/

public void logExit(final JoinPoint joinPoint)

{

log("Exiting method " + joinPoint.getSignature().getName() + ".");

}

/**

* Log method exit after returning.

* 

* @param joinPoint

*/

public void logExitAfterReturn(final JoinPoint joinPoint)

{

log( "Exiting method (after return) "

+ joinPoint.getSignature().getName() + ".");

}

/**

* "Log" the provided String.

* 

* @param messageToLog String to be logged.

*/

public static void log(final String messageToLog)

{

System.err.println(messageToLog);

}

}

the Main:

package com.pierre.aop;

import org.springframework.context.ConfigurableApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Main {

public static void main(String[] args) {

final ConfigurableApplicationContext context =

new ClassPathXmlApplicationContext("spring-aop-logging-context.xml");

final IExampleBeanClass example =

(IExampleBeanClass) context.getBean("exampleBean");

System.out.println(example.getMessage());

context.close();

}

}

and, at last, the XML:

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xmlns:p="http://www.springframework.org/schema/p"

xmlns:aop="http://www.springframework.org/schema/aop"

xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd

http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd">

<!-- Normal Spring-exposed bean. -->

<bean id="exampleBean" class="com.pierre.aop.ExampleBeanClass">

</bean>

<!-- The Aspect itself. -->

<bean id="exampleLoggingAspect" class="com.pierre.aop.LoggingAspect" />

<aop:config>

<!-- The Pointcut(s). -->

<aop:pointcut id="loggingPointcut" expression="within(com.pierre.aop.ExampleBeanClass)" />

<!-- The Advice(s). -->

<aop:aspect id="loggingAspect" ref="exampleLoggingAspect">

<aop:before pointcut-ref="loggingPointcut" method="logEntry" />

<aop:after pointcut-ref="loggingPointcut" method="logExit" />

<aop:after-returning pointcut-ref="loggingPointcut" method="logExitAfterReturn" />

</aop:aspect>

</aop:config>

</beans>

JMS, quick example

before you run it, create a Queue ""scavazza_SAFImportedDestinationsscavazza_localSAFQueue_0"

(in my case, it was a SAF destination)

package com.pierre.jms;

import java.util.Date;

import javax.jms.*;

import javax.naming.InitialContext;

import javax.naming.NamingException;

/**

 * Add these jars:

 * javax.jms_1.1.jar

 * wls-api.jar

 * 

 * @author vernetto

 *

 */

public class JMSSender {

public static void main(String[] args) throws NamingException, JMSException {

send();

}

private static void send() throws NamingException, JMSException {

String url = "t3://localhost:7001";

InitialContext ctx = JNDIHelper.getInitialContext(url);

QueueConnectionFactory qConFactory = (QueueConnectionFactory)ctx.lookup("javax/jms/QueueConnectionFactory");

QueueConnection qConnection = qConFactory.createQueueConnection();

QueueSession qSession    = qConnection.createQueueSession(false, Session.AUTO_ACKNOWLEDGE);

Queue queue = (Queue)ctx.lookup("scavazza_SAFImportedDestinationsscavazza_localSAFQueue_0");

QueueSender qSender  = qSession.createSender(queue);

TextMessage msg = qSession.createTextMessage();

msg.setJMSCorrelationID("iamanidagains");

msg.setIntProperty("sonoscemo", 27);

msg.setJMSPriority(7);

qConnection.start();

msg.setText("Hello this is Pierre " + new Date());

qSender.send(msg);

qSender.setDeliveryMode(DeliveryMode.PERSISTENT);

qSender.close();

qSession.close();

qConnection.close();

System.out.println("done");

}

}

Weblogic and SOASuite Certification Exams

sample questions:

http://www.scribd.com/doc/12580321/1z0108-Oracle-WebLogic-Server-10g-System-Administration-Certification

the Mock Exams company: http://www.certinside.com/

Certification Guide:

http://education.oracle.com/pls/web_prod-plq-dad/db_pages.getpage?page_id=41&p_org_id=1080544〈=US&p_exam_id=1Z0_108

topics of training:

http://www.webagesolutions.com/training/weblogic/wa1409/outline.html


1Z0-599 Oracle WebLogic Server 12c Certified Implementation Specialist

https://education.oracle.com/pls/web_prod-plq-dad/db_pages.getpage?page_id=654&get_params=p_id:136

GLP https://competencycenter.oracle.com/opncc/full_glp.cc?group_id=22243

https://www.pass-guaranteed.com/1Z0-599.htm

http://1z0-599-practice-exam-questions.blogspot.it/

http://www.oracle.com/partners/en/knowledge-zone/middleware/wls12cexampage-1595582.html



1Z0-478 Oracle SOA Suite 11g Certified Implementation Specialist

http://education.oracle.com/pls/web_prod-plq-dad/db_pages.getpage?page_id=5001&get_params=p_exam_id:1Z0-478

http://www.oracle.com/partners/en/knowledge-zone/applications/soasuite11g-1877659.pdf priceless guide to all the topics in the exam, with links to study material

http://certifyguide.com/exam/1z0-478/ good question list with explanations, reasonably priced

http://www.test4actual.com/1z0-478.html same as above, a bit more costly

http://www.aiotestking.com/oracle/category/exam-1z0-478-oracle-soa-suite-11g-certified-implementation-specialist/ same as above, but FREE of charge!

http://www.free-online-exams.com/pages/exams/DumpsQA.aspx?d=1&c=1z0-478&q=1

Accessing resources in a WAR file

you can easily read the content of a directory in Java, even if this directory is in the classpath:

Here is a useful method to load only the resources:

public static List getDirContent(String dir, boolean throwExceptionIfNotFound) throws IOException {

ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();

URL configDir = contextClassLoader.getResource(dir);

if (configDir == null && throwExceptionIfNotFound) throw new IllegalArgumentException("Unable to locate directory " + dir);

List result = new ArrayList();

if (configDir != null) {

URLConnection openConnection = configDir.openConnection();

openConnection.connect();

InputStream is = openConnection.getInputStream();

String content = NuonFileUtils.convertStreamToString(is);

String[] resources = content.split("\n");

for (String resource : resources) {

URL resurl = Thread.currentThread().getContextClassLoader().getResource(resource);

result.add(resurl);

}

}

return result;

}

the content of the resource can be read with a URL using its InputStream.

This method doesn't work in a WAR file, since the classloader's resource locator can't introspect the WAR file. The solution is to use the ServletContext and ServletConfig pattern:

in a JSP, you can do:

String path = ""/WEB-INF/config";

java.net.URL url = config.getServletContext().getResource(path);

and it works beautyfully!

The more elegant way is to have a ServletContextListener intercepting your servlet's initialization, and loading the resources:

public void contextInitialized(ServletContextEvent sce) {

String path = "/WEB-INF/classes";

try {

sce.getServletContext().getResource(path);

} catch (MalformedURLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}