Distributed Processing Sample for WSO2 CEP

Today we released WSO2 Complex Event Processor 2.0.0 Milestone 2.
This is available at  https://svn.wso2.org/repos/wso2/people/suho/packs/cep/wso2cep-2.0.0-M2.zip

One of the key feature of this CEP is its support for distributed processing via Siddhi CEP Engine. To demonstrate its capability I came up with a sample on distributed Processing. This sample uses Siddhi CEP Engine for processing and JMS ActiveMQ Broker to publish and subscribe events.

To run the Distributed Processing Sample follow the steps give below;
 
Step 01: Configure and run ActiveMQ in your local machine

Download the ActiveMQ from "http://activemq.apache.org/activemq-543-release.html".
unzip the distribution and run the ActiveMQ server using the command “./activemq console” from apache-activemq-xxx/bin (in Linux)
Note: WSO2CEP has been tested with ActiveMQ 5.4.3

For each CEP node in the cluster follow the steps from 02 to 08.

Step 02: Deploy CEP server 

Unzip the CEP server (Do not start the server).

      
Step 03: Change the CEP server Offset.

If you are running multiple servers in the same machine change the offset
from file "wso2cep-2.0.0-2/repository/conf/carbon.xml" to different numbers. 

E.g.

<offset>1</offset>

This is to overcome server port conflicts.
E.g. If three WSO2 servers are going to be deployed in the same machine, they can have offsets as 1, 2, and 3.

Step 04: Copy paste ActiveMQ jars.

Copy paste activemq-all-xxx.jar from the ActiveMQ home directory to 

wso2cep-2.0.0/samples/lib directory.

Copy paste activemq-core-xxx.jar and geronimo-j2ee-management_1.1_spec-1.0.1.jar
from apache-activemq-xxx/lib to wso2cep-2.0.0/repository/components/lib directory

 
Step 06: Deploy required broker management configuration

This allows CEP to receive and send messages via JMS Broker.

To deploy run "ant deploy-broker-manager" from wso2cep-2.0.0/samples/cep-samples directory.

Step 07: Configure input, output and queries

For this sample, the configurations of input, output and queries are at wso2cep-2.0.0-1/samples/cep-samples/conf/buckets/purchase-analyser-bucket.xml
When running multiple server nodes each server need to receive the input events through different topics. To enable this behaviour, open the above file and change the input topics to have different names. The default input topic name is “PurchaseTopic”.

E.g changing the names to “PurchaseTopic1”.

<input brokername="activemqJmsBroker" topic="PurchaseTopic1" />

Note : To enable distributed processing (already enabled for this sample) the change we have to do is to make the "siddhi.enable.distributed.processing" property to "true".

<engineproviderconfiguration engineprovider="SiddhiCEPRuntime">
     <property name="siddhi.persistence.snapshot.time.interval.minutes">0</property>
     <property name="siddhi.enable.distributed.processing">true</property>
</engineproviderconfiguration>

Step 08: Deploy bucket configuration

Deploy the bucket by adding the configuration purchase-analyser-bucket.xml to the directory wso2cep-2.0.0/repository/deployment/server/cepbuckets/

Step 09: Start all the servers

Start CEP servers by running "./wso2server.sh" from wso2cep-2.0.0/bin directory 

Step 10:Subscribing to output topic

Start the subscriber of the output topic "PurchaseResults" by running "ant purchaseResultsSubscriber" in a separate terminal,
from wso2cep-2.0.0/samples/cep-samples directory

Step 11:Publishing events

To publish events to all the servers (to their input topics as we defined in Step 07 ) run the publisher from wso2cep-2.0.0/samples/cep-samples directory
with the command  "ant purchasePublisher -Dtopics=xxx,xxx,..."
The client will publish events to all the given topics in a round robin manner.

E.g If we we have configured the buckets to receive the inputs via the input topics as PurchaseTopic1, PurchaseTopic2 and PurchaseTopic3

"ant purchasePublisher -Dtopics=PurchaseTopic1,PurchaseTopic2,PurchaseTopic3."

Step 12: Observation

You will be able to observe how the counts in the results steadily increases when messages are sent to any of the servers, and how the results remain consistent even when some servers goes down and comes back.

Setting brightness at Ubuntu startup

In Ubuthu machines such as Thinkpad T520 every-time when we restart the computer the brightness level will be at its maximum and then we need to manually set the brightness to a comfortable level.

To solve this issue here I share a small script I have written.

First install xdotool

sudo apt-get install xdotool

This will allow you to change the brightness easily from the command line with out admin privileges.


Check whether the brightness is changing with the following command

xdotool key XF86MonBrightnessDown

Now we have to find the file where the brightness value is stored, try doing

cat /sys/class/backlight/acpi_video0/brightness

If you get an integer value then your good to proceed, else you have to find the appropriate file in your system. In that case check in /sys/class/


Adjust the brightness and find your desired brightness level using the above command E.g. 9


In this example I have used 9 as my brightness level change it according to you.

 
#!/bin/bash

myBrightness=9;
currentBrightness=`cat /sys/class/backlight/acpi_video0/brightness`;
count=$(( $currentBrightness - $myBrightness )) ;
while [ $count -gt 0 ]
do
     xdotool key XF86MonBrightnessDown
     let  count=$(($count-1));
done

Save this as brightness.sh


Then make this file to be an executable, by running

chmod +x brightness.sh

Finally open the "Startup Applications" click Add and add the following

Name :<appropriate name>
Command:/<path to file from root>/brightness.sh
Comment:<appropriate comment>

How to install Java Cryptography Extension (JCE) unlimited strength jurisdiction policy files

How to over come "org.apache.xml.security.encryption.XMLEncryptionException: Illegal key size or default parameters" or "java.security.InvalidKeyException:illegal Key Size" error when invoking secured services

These "org.apache.xml.security.encryption.XMLEncryptionException: Illegal key size or default parameters" or "java.security.InvalidKeyException:illegal Key Size" error usually occurs when we try to invoke a web services in a secured manner and your JVM is not provisioned for Java unlimited security jurisdiction.


To provision for the Java unlimited security jurisdiction we have to install Java Cryptography Extension (JCE) unlimited strength jurisdiction policy files.


How to Install JCE

1. Go to the Oracle Java SE download page http://www.oracle.com/technetwork/java/javase/downloads/index.html
2. Scroll down ... Under "Additional Resources" section you will find "Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy File"
3. Download the version that matches your installed JVM E.g. UnlimitedJCEPolicyJDK7.zip
4. Unzip the downloaded zip 
5. Copy local_policy.jar and US_export_policy.jar to the $JAVA_HOME/jre/lib/security (Note: these jars will be already there so you have to overwrite them)
6. Then restart your application to get rid of this exception.

Change the default Java installation used by Ubuntu

Though you have installed and using a particular Java installation (E.g. Oracle Java 7), sometimes when you install some other softwares they might change the default to other Java installations (E.g. OpenJDK)

In such situations to change the default version, run the following commands and chose the appropriate selection when prompted.

For Java :

update-alternatives --config java

For Java compiler :

update-alternatives --config javac

For Java web start :

update-alternatives --config javaws

How to instal Java in Ubuntu

This is replication of blog http://rootzwiki.com/topic/23008-howto-install-java-7-on-ubuntu-1204/

Here I give some brief note on how to Install Sun (Oracle) Java in Ubuntu and from How to set JAVA_HOME in Ubuntu post you can get to know how to set your JAVA_HOME appropriately.

For Ubuntu 12.04  for Java 7 ...
First in the terminal enter:

sudo add-apt-repository ppa:eugenesan/java
sudo apt-get update

and then install...

sudo apt-get install oracle-java7-installer 

This will give and error and stop...

Don't worry we can make this work :-)

Go to Oracle Java site [http://www.oracle.com/technetwork/java/javase/downloads/jdk-7u3-download-1501626.html] and download Java "jdk-7u3-linux-x64.tar.gz" directly from their site.

Now, move the downloaded file to /var/cache/oracle-java7-installer/

sudo mv Downloads/jdk-7u3-linux-x64.tar.gz /var/cache/oracle-java7-installer/

Then edit the oracle-java7-installer.postinst file:

sudo gedit /var/lib/dpkg/info/oracle-java7-installer.postinst

To edit scroll down and find the following:           

echo "Downloading..."
rm -f $FILENAME
WGETRC=wgetrc wget $PARTNER_URL
|| fp_exit_with_error "download failed"
rm -f wgetrc
echo "Download done."

And put a # in front of the lines between "echo "Downloading..."" and "echo "Download done."" as follows:

echo "Downloading..."
#rm -f $FILENAME 
#WGETRC=wgetrc wget $PARTNER_URL
#|| fp_exit_with_error "download failed"
#rm -f wgetrc 

echo "Download done."

Save the file and from your terminal run:

sudo apt-get install oracle-java7-installer

Now it works :-)

Check it by running:

java -version

For older versions of Ubuntu (11.10 and older)...
First in the terminal enter:

sudo add-apt-repository "deb http://archive.canonical.com/ lucid partner"
sudo apt-get update

and then install...

sudo apt-get install sun-java6-jdk
sudo apt-get install sun-java6-jre

Now, Java is installed and we need to set the JAVA_HOME.
Visit How to set JAVA_HOME in Ubuntu post to get to know how you can appropriately set JAVA_HOME and PATH.