ActiveMQ messages database logging with Apache Camel

Hi, we had epayment system based on Fuse ActiveMQ and  we decided to log into DB all messages passed through ActiveMQ. I want to share my first experience with Apache Camel :)

I changed ActiveMQ configuration and used ActiveMQ feature: 'Mirrored Queues' to forward all messages to mirrored queues prefixed with qmirror. Here is ActiceMQ configuration:

<destinationInterceptors>
<mirroredQueue copyMessage = "true" postfix="" prefix="qmirror."/>
</destinationInterceptors>

So now when we have copied messages in queues with names: 'qmirror.*' and it is time to log them with Apache Camel. Thus I changed '$ACTIVEMQ_HOME/conf/camel.xml' config file in the following way:

<beans...>

    <context:component-scan base-package="info.sargis.dbloggger"/>

    <context:annotation-config/>

    <camelContext xmlns="http://camel.apache.org/schema/spring">

        <package>info.sargis.dbloggger</package>

    </camelContext>

    <bean id="lobHandler" class="org.springframework.jdbc.support.lob.DefaultLobHandler"/>

    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">

        <property name="driverClassName" value="oracle.jdbc.driver.OracleDriver"/>

        <property name="url" value="jdbc:oracle:thin:@localhost:1521:TWMDB"/>

        <property name="username" value="activemq"/>

        <property name="password" value="ee0thaXu"/>

        <property name="maxActive" value="5"/>

        <property name="maxIdle" value="2"/>

    </bean>

    <bean id="activemq" class="org.apache.activemq.camel.component.ActiveMQComponent">

        <property name="connectionFactory">

            <bean class="org.apache.activemq.ActiveMQConnectionFactory">

                <property name="brokerURL"

                          value="vm://localhost?create=false&amp;waitForStart=10000&amp;broker.populateJMSXUserID=true"/>

                <property name="userName" value="${activemq.username}"/>

                <property name="password" value="${activemq.password}"/>

            </bean>

        </property>

    </bean>

</beans>

and created project with structure:

|-- docs
|   `-- create_db.sql
|-- payment-dblogger.iml
|-- pom.xml
|-- README.txt
`-- src
    |-- data
    `-- main
        |-- java
        |   `-- info
        |       `-- sargis
        |           `-- dbloggger
        |               |-- DBLoggerRouteBuilder.java
        |               `-- logger
        |                   |-- DBLogger.java
        |                   |-- DBLoggerProcessor.java
        |                   `-- Logger.java
        `-- resources
            |-- log4j.properties
            `-- META-INF
                `-- spring
                    `-- camel-context.xml

note that project artifact payment-dblogger-*.jar should be deployed to '$ACTIVEMQ_HOME/webapps/camel/WEB-INF/lib'

Now its time for router :) here everything is simple as well:

package info.sargis.dbloggger;

import org.apache.camel.builder.RouteBuilder;

public class DBLoggerRouteBuilder extends RouteBuilder {
    @Override
    public void configure() {
        from("activemq:topic:qmirror.>").threads().processRef("dbLoggerProcessor");
    }
}

Fun with 'fluent interface' and Java

Here is my story about 'fluent interface' and Java. In one project I have to compare in many places BigDecimals and other Comparable objects. So if I have:

BigDecimal requestedAmount = ...

BigDecimal paymentAmount = ...

In Java to compare BigDecimals I should use

if(requestedAmount.compareTo(paymentAmount) == 0) {

}

For me its not natural to compare numbers in such way and I decided to try to write small technical DSL, and here how looks my code now:

import static com.webbfontaine.twm.accounting.epaylog.utils.CompareDSL.*;

if (eq(valueOf(paymentAmount).comparingWith(requestedAmount))) {
}

if (ne(valueOf(paymentAmount).comparingWith(requestedAmount))) {

}

if (gt(valueOf(paymentAmount).comparingWith(requestedAmount))) {

}

.... and etc.

and here is API/DSL code:

public class CompareDSL {

    public static <T extends Comparable<T>> PairToCompare<T> valueOf(T value) {

        return new PairToCompare<T>(value);

    }

    public static <T extends Comparable<T>> boolean eq(PairToCompare<T> pairToCompare) {

        return pairToCompare.firstValue.compareTo(pairToCompare.secondValue) == 0;

    }

    public static <T extends Comparable<T>> boolean ne(PairToCompare<T> pairToCompare) {

        return !eq(pairToCompare);

    }

    public static <T extends Comparable<T>> boolean gt(PairToCompare<T> pairToCompare) {

        return pairToCompare.firstValue.compareTo(pairToCompare.secondValue) > 0;

    }

    public static <T extends Comparable<T>> boolean ge(PairToCompare<T> pairToCompare) {

        return pairToCompare.firstValue.compareTo(pairToCompare.secondValue) >= 0;

    }

    public static <T extends Comparable<T>> boolean lt(PairToCompare<T> pairToCompare) {

        return pairToCompare.firstValue.compareTo(pairToCompare.secondValue) < 0;

    }

    public static <T extends Comparable<T>> boolean le(PairToCompare<T> pairToCompare) {

        return pairToCompare.firstValue.compareTo(pairToCompare.secondValue) <= 0;

    }

    public static class PairToCompare<T extends Comparable<T>> {

        private T firstValue;

        private T secondValue;

        public PairToCompare(T firstValue) {

            this.firstValue = firstValue;

        }

        public PairToCompare<T> comparingWith(T value) {

            this.secondValue = value;

            return this;

        }

    }

}

API of course not the best one, but for me it works fine and it was fun to write it :-)

How to configure Oracle/SUN JVM to send notification in case of JVM fatal error/crash

Recently we had JVM crash in production server and of course we had notified by some monitoring tools but not as fast as we could expect. So I configured our server with following JVM option:
-XX:OnError="sendjvmcrashsms". 'sendjvmcrashsms' is a Linux shell/bash file which is of course in user PATH, and here is example of the file

#! /bin/bash
echo "Production JVM crashed" | mail -s "+33000000000"

It will send mail to address with subject '+33000000000'. In our server we have configured SMS gateway which will send SMS to number(s) defined in subject, and here is docs:
-XX:OnError="<cmd args>;<cmd args>" - Run user-defined commands on fatal error

Experience with slf4j/logback markers

I want to share my experience with slf4j/logback markers, hope can be useful for others.

Problem: want to have possibility to mail for particular log messages regardless log level.

Solution: Using slf4j/logback markers to mark :) interested messages and logback Filter.

First I've defined simple class to keep like global registry for slf4j markers:

public class LOGMarkers {
      public static final Marker SEND_MAIL_MARKER = MarkerFactory.getMarker("SEND_MAIL");
}

and here is code example which is actually using marker:

LOGGER.info(LOGMarkers.SEND_MAIL_MARKER, "Cannot save document with id: {}", instanceId);

or

try {
  .................
} catch (SomeException e) {
     LOGGER.warn(LOGMarkers.SEND_MAIL_MARKER, "", e);
}

also I have to write logback filters and use it in logback configuration file:

package info.sargis.logging.filter;

import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.core.filter.AbstractMatcherFilter;
import ch.qos.logback.core.spi.FilterReply;
import org.slf4j.Marker;
import org.slf4j.MarkerFactory;

/**
* Created by IntelliJ IDEA.
* User: Sargis Harutyunyan
* Date: 10 oct. 2010
* Time: 20:12:12
*/
public class MarkerFilter extends AbstractMatcherFilter {

Marker markerToMatch;

public void start() {
     if (this.markerToMatch != null) {
          super.start();
     } else {
          addError(String.format("The marker property must be set for [%s]", getName()));
     }
}

public FilterReply decide(ILoggingEvent event) {
     Marker marker = event.getMarker();
     if (!isStarted()) {
          return FilterReply.NEUTRAL;
     }

     if (marker == null) {
          return onMismatch;
     }

     if (markerToMatch.contains(marker)) {
          return onMatch;
     }
     return onMismatch;
}

public void setMarker(String markerStr) {
     if (markerStr != null) {
          markerToMatch = MarkerFactory.getMarker(markerStr);
     }
}

}

 and finally logback config file example:


    <appender name="MARKER_EMAIL" class="ch.qos.logback.classic.net.SMTPAppender">
        <filter class="info.sargis.logging.filter.MarkerFilter">
            <marker>SEND_MAIL</marker>
            <onMatch>ACCEPT</onMatch>
            <onMismatch>DENY</onMismatch>
        </filter>
        <evaluator class="ch.qos.logback.classic.boolex.OnMarkerEvaluator">
            <marker>SEND_MAIL</marker>
        </evaluator>
        <SMTPHost>localhost</SMTPHost>
        <To>sargis@localhost</To>
        <From>twm@localhost</From>
        <Subject>EPAYMAIL: %date %-5level - %message</Subject>
        <layout class="ch.qos.logback.classic.PatternLayout">
            <Pattern>%date [%thread] %-5level U:%X{vaspId} - %message%n</Pattern>
        </layout>
    </appender>

    <logger name="info.sargis" level="INFO">
        <appender-ref ref="EPAYCONSOLE"/>
        <appender-ref ref="MARKER_EMAIL"/>
    </logger>

and voila :)

How to config Java WebStart to use logging subsystem

I am using for client side slf4j as facade framework but behind we decided to use jdk14 standard logging. SO to config jdk14 for webstart you need to
do following:

1) Define according your OS platform JAVAWS_VM_ARGS environment variable, for linux its like this:
 export JAVAWS_VM_ARGS="-Djava.util.logging.config.file=/home/sargis/<localpath>/logging.properties"
2) Here is logging.properties content:

handlers= java.util.logging.ConsoleHandler

java.util.logging.ConsoleHandler.level = ALL
java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter

.level= INFO

info.sargis.level = FINE
info.sargis.handlers = java.util.logging.ConsoleHandler