Saturday, December 8, 2012

Single Sign On across Web Applications and Web Services

Here the requirement is to have a single sign on across Web application and Web Services. In more detail once the user is  authenticated to access a WepApp he should not only be able to access other WepApps but those WebApps also should be able to access a set of back-end services with the logged in user's access rights with no further authentication. Here the back-end services can also be configured to authorize the user based on different user claims (E.g. email).

In the situation we can assume:
•  trust relation between Identity Server and Resource Server (ESB Proxy),
•  trust relation between Identity Server and Resource Client (Web App)
The communications are:

  1. User connect to the Web App with is the “Resource Client”
  2. WebApp finds out user is not authenticated and redirects to the SAML2 IdP.
  3. SAML2 Idp checks whether the user has an authenticated session - if not will prompt for credentials, once authenticated there ,user will be redirected back to WebApp (Resource Client)  with a SAML token, with the set of claims requested by the WebApp.
  4. Now, the WebApp (Resource Client) needs to access a back-end web service with the logged in user's access rights. WebApp process the “SAML assertion token” and creates the STSToken from which it calls the Proxy Service (Resource server).
  5. Proxy Service (Resource server) checks the “SAML assertion token” and allows access to the backend Web Service.
This is tested with;
•  WSO2 Identity Server 4.0.0
•  WSO2 Enterprise Service Bus 4.5.1
•  Apache Tomcat 7.0.25
•  Apache Subversion 1.6.12
•  Apache Maven 3.2.3
•  Java 1.6.0_26

Step 1,

Download and deploy WSO2 IS 4.0.0 from

Step 2
Download WSO2 ESB 4.5.1 from
When deploying ESB change the port offsets by 1, by editing

<ESB_HOME>/repository/conf/carbon.xml file, and change the Offset element as follows

Step 3,

Download and deploy Apache Tomcat

Step 4,
Checkout sso-webapp-ws
This contains all the artifacts needed for this sample

Step 5,
Setup WSO2 IS for SSO for Web Apps
  1. Login to IS
  2. Click SAML SSO from the management console
  3. Add SSO details

    For the WebApp
    Issuer: http://localhost:8081/
    Assertion Consumer URL: http://localhost:8081/
    Check “Enable Attribute Profile” and add the following claims
    For the WebApp
    Issuer: http://localhost:8081/
    Assertion Consumer URL: http://localhost:8081/
    Check “Enable Attribute Profile” and add the following claims
    When successfully added you will get Consumer Index for each entry

    Now the SSO setup in the WSO2 IS is done.

Step 6,
Configuring the WebApps
  1. You can add these by editing the war file or edit in the src-dist and build that.
  2. Edit the WEB-INF/web.xml of each WebApp and add the appropriate “Consumer Index” returned by the WSO2IS as the param-value for AttributeConsumingServiceIndex.
  3. Edit the WEB-INF/classes/ of each WebApp and add the appropriate
    properties. You can find all the necessary files in the resources directory.

Step 7,
Add the proxy service
  1. Login to ESB
  2. Click on Add Proxy Service from the management console
  3. Create a Pass Through Proxy
  4. Add the proxy name and endpoint
    Proxy Service Name: echoProxy
    Target Endpoint: “Enter URL”
    Target URL: http://localhost:8281/services/echo
    And click “Create”

    Here the echo service (Endpoint service) is deployed on ESB by default

Step 8,
Add the policy to the registry to secure the Proxy Service

  1. Click on Registry from the ESB management console
  2. Navigate to /_system/config/repository and click on the repository
  3. Under “Entries” click on the add recourses to add policy file
  4. Now browse and add the bearer-policy.xml. This will be in the resources folder you
    checked out. Click “Add” to add the file.

Step 9,
Securing the proxy service
  1. Click on List under services from the ESB management console, and click on “Unsecured” link next to the echoProxy service entry.
  2. Select “yes”
  3. From the “Policy From Registry” section, click in Configuration registry to add policy from the cofig registry.
  4. Browse for the added “bearer-policy.xml” and click “OK”
  5. Click “Next”, then click on the “admin” and “wso2carbon.jks” checkboxes, select the private key store as “wso2carbon.jks” and click on “Finish” to Activate Security.
Step 10,
Deploy the webapps in Tomcat

Step 11,
  1. Enter following in the redirected page
    User Name: admin
    Password: admin

    With successful login you will be redirected to the home page, where the Web App will be call the proxy using the “SAML assertion token” received at the SSO login.
  2. With successful login at the Proxy Service you will get the following page
    Note: Here the Web Service Response will be as “Hi WSO2”
  3. If the login at the Proxy Service fails you will get the following page
    Note: Here the Web Service Response will be as “’Hi WSO2’ expected but, no response from the web service”

I would like to thank the WSO2 forks; Suresh AttanayakePrabath Siriwardena, & Balachandiran Ajanthan for helping me on this.

Wednesday, November 21, 2012

Enabling WSO2 ESB APIs to Pass-Through response Content-Types

This post explains how to configure WSO2ESB 4.5.x to Pass-Through response Content-Types.

WSO2 ESB is build to work on soap environments therefore WSO2 ESB (proxy service) always sends the response message in the same Content Type of the request, which is the expected behaviour.
This works fine for SOAP, because the incoming message to the proxy service and the outgoing  messages from the proxy service are both SOAP messages.

But this is not the case for REST calls, there can be cases where the proxy service need to mimic the actual service as it is.
E.g. Client sends the request in the Content-Type to be "application/json" and the Actual service receives the request in the same "application/json"  Content-Type and responds in the Content-Type of "text/plain" which the client can Accept.

This can be achieved using Message Relays, but in any case if you need to achieve this for your custom formatters you have to manually set these Content-Type as below.

<api name="api_content_type_passthrough" context="/esbsanitycheck">
  <resource methods="POST GET DELETE PUT">
           <endpoint key="ep_esb_sanity_check"/>
        <property name="messageType" expression="$trp:Content-Type" scope="axis2"/>
        <property name="ContentType" expression="$trp:Content-Type" scope="axis2"/>

Tuesday, August 28, 2012

Distributed Processing Sample for WSO2 CEP

Today we released WSO2 Complex Event Processor 2.0.0 Milestone 2.
This is available at

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 "".
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. 

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>

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 "./" 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.

Tuesday, May 8, 2012

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.


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

Then make this file to be an executable, by running
chmod +x

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

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

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

How to over come " Illegal key size or default parameters" or " Key Size" error when invoking secured services

These " Illegal key size or default parameters" or " 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
  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.
  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.

Monday, April 30, 2012

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

Sunday, April 29, 2012

How to instal Java in Ubuntu

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.

Saturday, April 28, 2012

Apache MeetUp held in Hill Country

The students of University of Peradeniya did a great job organizing an amazing Apache meet up at Kandy, Sri Lanka. This was the second major event in Sri Lanka next to the Apache Bar Camp Colombo that was held this year.

Here the first talk was on "FOSS in Kandy" by Dr. Nimal Rathnayaka, followed by Dr. Srinath Perera explaining "The Apache Way" of managing projects, how the communities work together and how they resolve conflicts using the voting system with the -1 veto. 

After the introduction of open source and Apache, Nandika Jayawardrdana gave an inspiring speech on "Open source and your career" giving out some valuable informations to the audience how one can use open source to become much better at his career. Here he explained how open source can improve your communication skills, writing skills - where you have to convince and argue on your ideas via the mailing list, and how your participation on open source makes you famous - which indeed will be eye catching even at the selection phase for a grad school, and most importantly he also expressed how we get a self satisfaction when so many people are using the product that you have build. This also falls according to the famous saying "A project without users (means, it) does not exist".  

Following this, Sagara Gunathunga gave a good briefing on how you can "Find your way to Apache Contribution", Here he not only stressed on coding but also mentions some other great ways of contributing, like writing technical blogs on the project, helping with documentation and testing the project. He continued explaining how these are extremely valuable to do when you are a newbie and gain recognition from your project community. 

After lunch, we had two practical sessions, the first one is on how to configure and use Apache Web Server in an efficient manner - by Anuradha Ratnaweera, and the second was on "Apache build projects" - by Prabath Abeysekara and myself, where we demonstrated Apache Subversion, Maven and Ant. 

Finally the session was concluded with Pradeeban's lighting talk on how to build a community for your project.

Sunday, February 26, 2012

Apache BarCamp Colombo

We just had a wonderful Apache BarCamp here in Colombo at the UCSC Auditorium. The main motivation behind this activity is to promote open source contribution and give an inside into "Apache Way" of software development. Here I'm sharing some bits and pieces that stick to my mind.

The session kicked off with an excellent keynote by Dr. Sanjiva Weerawarana, where he was talking on the interesting point on how Sri lanka eventually became the third largest contributor to Apache Software Foundation (ASF). There he mentioned how they initiated the first ever Sri Lankan open source development at a UCSC lab with four C++ programmers and how they were able to come up with AxisC++ which was then been shipped by IBM.

Following Sanjiva, Ross Gardler took the floor and went on explaining “The Apache Way”, from what ASF is and how we could start and become a long term contributor. He clarified all important small words thats binds ASF like, Meritocracy where the action should speak louder than words, Lazy Consensus where “when you are convinced that you know what the community would like to see happening you can simply assume that you already have its support unless someone says otherwise” and the use of -1's where one should be opposing the arguments with valid points.

The final key note was by Nick Burch, who did a wonderful job sharing his experience on what a pain he went through to apply his first patch, explaining how open source communities work and why we should not take things personally when they did not apply your patch or response to your queries. He gave a strong point on how developers might be busy on some other projects and in open source if you want things to happen the way you want you have to "Just F****** Do It" (JFDI). He ended up his great talk with the final touch by saying how open source development could be very fun and how it might even end up as an addiction.

With all these three key notes we too had two other sessions where in one, Sagara Gunathunga was presenting they key steps that you will need when you "Find your way to Apache contribution" by giving some clear idea for all newbies to get a kickoff start.

Finally we had an interesting session on  "How to prepare to Google Summer of Code 2012 with Apache projects" motivating young undergraduates to take off the fear of open source and accept the challenge on doing GSOC 2012! Thanks Pradeeban for presiding the sessions and Nirmal and Eranda for sharing your experience with me to all the enthusiastic ordinance.

We thank WSO2, Vertusa, ASF and UCSC for your help in sponsoring this great event.

Monday, February 20, 2012

Installing Apache Thrift in Ubuntu

Apache Thrift is a RPC framework for scalable cross-language services development which in simpler words allows easy exchange of data such as variables, objects between applications written in different languages. Thrift offers seamless cross language serialization between languages like C++, Java, Python, PHP, Ruby, Erlang, Perl, Haskell, C#, Cocoa, Smalltalk and OCaml, through Code generation. The advantage of Thrift is that it’s faster than using SOAP since it’s using a binary protocol.

For better understanding of Thrift's architecture which consists of Transports, Protocols and Processors I recommend you to go through the paper I found [1].
Thrift was initially developed at Facebook, and now open sourced as an Apache project. Since I found Thrift is less documented, in this post I'll try to walk through the installation steps in Ubuntu.

I have tested this on Ubuntu 11.11 and 12.04

To install Thrift

Step 1.
First install
sudo apt-get install libboost-dev libboost-test-dev libboost-program-options-dev libevent-dev automake libtool flex bison pkg-config g++ libssl-dev

Step 2.
Then Download tar.gz archive from the download site, decompress archive in your home directory:
tar -xvzf thrift-0.8.0.tar.gz

Step 3.
Go to the installation root directory  and run
$ ./configure

Step 4.
A the end of the output you will find something like this

thrift 0.8.0
Building code generators ..... :
Building C++ Library ......... : yes
Building C (GLib) Library .... : no
Building Java Library ........ : yes
Building C# Library .......... : no
Building Python Library ...... : yes
Building Ruby Library ........ : no
Building Haskell Library ..... : no
Building Perl Library ........ : no
Building PHP Library ......... : no
Building Erlang Library ...... : no
Building Go Library .......... : no
Building TZlibTransport ...... : yes
Building TNonblockingServer .. : yes
Using javac .................. : javac
Using java ................... : java
Using ant .................... : /usr/bin/ant
Using Python ................. : /usr/bin/python

Check whether the libraries for your development environment have been code generated. If something is missing skim through the output of configure to find the missing component and install that, and then again run step 3.

Step 5.
Finally from the same directory run
$ make

Step 6.
Now run
$ sudo make install

Now your done

To check whether Thrift is working, run;
$ thrift -version


Hot deployment of CEP query configuration in WSO2 CEP

WSO2 CEP is an open source CEP server released under Apache License v2.0

WSO2 CEP has an added advantage of flexible integration, such as enabling it to integration with Enterprise Service Buses like WSO2 ESB which can send events across transports into various streams. WSO2 CEP can also be used with Message Brokers (E.g. WSO2 MB) to process messages of the topics CEP has subscribed and publishing back the matching occurrences in MB. Further this can also be used with WSO2 Business Activity Monitor to monitor actionable events on the fly and report them.

WSO2 CEP is designed to support multiple open source CEP engines, with out-of-the-box support for Drools Fusion and EsperTM.

WSO2 CEP's back-end CEP engine, query configuration, and all input and output mappings are represented as buckets. Here we create buckets for each of our use-cases.

In earlier versions of WSO2 CEP cep-config.xml file is the only mean of deploying cep buckets via configuration. Here the configurations will be added only at server start up. From WSO2 CEP 4.0.0 release writing buckets and deploying them in the Server has become very easy via the Axis2 hot deployment.

For hot deployment we just need to write an xml containing the bucket configuration and drop that in the CARBON_HOME/repository/deployment/server/cepbuckets/

Here each bucket configuration file can contain configuration of a single CEP bucket.
This file need to have a .xml extension and follow the cep-config.xsd.


<bucket xmlns="" .... >
         .... configuration....
</bucket >