Dashboard - Gadget communication using pub/sub within WSO2 UES

What is pub/sub?

This is a messaging pattern where message senders named publishers and consumers named subscribers. In this architecture publishers are not directly sending messages to consumers but sending to a channel where interesting parties(subscribers) subscribe to this channel and consume messages.

In this blog-post, portal or my dashboard acts as the publisher where user triggers any event to publish and simple gadget acts as the subscriber.

My requirement is to have something similar to the following, When user triggers "Publish a random number" button, dashboard should publish a random number to a predefined channel.Subscriber gadget subscribes to this channel and print the published random number.

How can we create this type of a dashboard?

Refer WSO2-UES documentation on how to create a gadget and how to add gadgets to dashboards.

Note :- 
If you browse <UES_HOME>/repository/deployment/server/jaggeryapps/portal/dashboard-template/files/ directory this is where we store template files for your dashboards. You may update index.jag.hbs file according to your preference, but keep in mind hereafter every time you create a dashboard, these changes will reflect on the dashboard.

Since our requirement is to have this template for all my dashboards, lets update the index.jag.hbs file.

You can find the full updated source gist here[1].
Note I have added the following HTML snippet to get the user input and display the published value.

<input type="button" value="Publish a random number" onclick="publish()"/>
<div id="output"> </div>

Also I have introduced following script, in order to publish a random number to the defined channel.

<script>
function publish() {
               var message = Math.random();
               UESContainer.inlineClient.publish('my-channel', message);
               document.getElementById("output").innerHTML = "Number that is published to the channel : " + message;
        }
</script>

Lets move to the gadget, you may find the source for this sample subscriber gadget here[2] and refer "Subscriber Gadget" section from this blog post[3] if you need to build the subscriber gadget from the scratch.

Interested about inter-gadget communication within WSO2-UES? you may refer the same blog post[3] done by tanya.

[1]. https://gist.github.com/udarakr/d9ebe3c32b64ec4e1ba0
[2]. https://svn.wso2.org/repos/wso2/people/tanya/pub-sub/subscriber/
[3] http://tanyamadurapperuma.blogspot.com/2013/12/inter-gadget-communication-with-wso2-ues.html

Simple web-app with SSO capability which showcase CarbonContext usage

I'm going to use WSO2 Application Server 5.2.1[1] and WSO2 Identity Server 4.5.0[2] to deploy simple web-app with SSO capability to showcase CarbonContext[3] usage.

Without writing this webapp from the scratch I will use/modify the SSOAgentSample which can find here[4].

First let's checkout the source from this location[4] and modify it for our purpose.

a) Open travelocity.properties which can find under SSOAgentSample/src/main/resources/ directory,

vi src/main/resources/travelocity.properties

b) Update following properties, update the port from 8080 to 9764 and comment out AttributeConsumingServiceIndex property.

#The URL of the SAML 2.0 Assertion Consumer
SAML.ConsumerUrl=http://localhost:9764/travelocity.com/samlsso-home.jsp

#Identifier given for the Service Provider for SAML 2.0 attributes
#exchange
#SAML.AttributeConsumingServiceIndex=1701087467

 c) Run following command within SSOAgentSample directory to build the webapp.

mvn clean install

 We are done with the sample webapp for now, but I will update this to showcase CarbonContext usage and provide source in github.

d) Start WSO2 Identity Server, run following within Identity Server home.

sh bin/wso2server.sh

e) Lets register a new service provider in IS, browse Home> Manage> SAML SSO
and press  Register New Service Provider link.Provide following details and press Register.

Issuer : travelocity.com
Assertion Consumer URL:http://localhost:9764/travelocity.com/samlsso-home.jsp

Select other stuff according to your requirements, I'm going to select
Enable Response Signing, Enable Assertion Signing, Enable Single Logout and Enable Attribute Profile. 

Since I'm going to display roles, email address and given name of the logged in user within webapp I will select and add following three claims.

http://wso2.org/claims/role
http://wso2.org/claims/emailaddress
http://wso2.org/claims/givenname

f) Lets upload our webapp to AS and start using a port offset. Copy travelocity.com.war from SSOAgentSample/target to <AS_HOME>/repository/deployment/server/webapps/ directory.

In my local setup,

cp target/travelocity.com.war /home/udara/wso2/workspace/wso2as-5.2.1/repository/deployment/server/webapps

Since I'm starting Application Server in the same local machine which Identity Server instance resides, In-order to avoid port conflicts lets update port-offset within <AS_HOME>repository/conf/carbon.xml.

 <Offset>1</Offset>

g) Start WSO2 Application Server, run following within Application Server home.

sh bin/wso2server.sh

h) Browse http://localhost:9764/travelocity.com/ and select login with SAML from Identity Server and it will automatically redirects to the Identity Server login page.

 



Provide your username/password and Identity Server will automatically redirects you back to the http://localhost:9764/travelocity.com/samlsso-home.jsp with claims that we select in step e.

CarbonContext[3] usage

Lets update our webapp to list down all users within same tenant.

Add following import statements to the src/main/webapp/samlsso-home.jsp file along with current import statements.

<%@page import="org.wso2.carbon.context.CarbonContext" %>
<%@page import="org.wso2.carbon.user.api.UserRealm" %>
Add following highlighted snippet to obtain the reference to the user-realm from the CarbonContext and print user list.

        </table>
        <a href="index.jsp">Go to Login page</a>
        <hr/>
        <!--Start of The user list-->
        <p><b>The user list</b></p>
            <%
                CarbonContext context = CarbonContext.getCurrentContext();
                UserRealm realm = context.getUserRealm();
                String[] names = realm.getUserStoreManager().listUsers("*", 100);
                    for (String name : names) {
                       %><%=name%><br/><%
                    }
            %>
            <!--End of The user list-->
        <form action="logout">
        <input type="submit" value="Logout">

i) Build(Step c) and re-deploy your webapp.
j) Browse http://localhost:9764/travelocity.com/samlsso-home.jsp and you will get,

I have created a repo to provide the updated source, you can find related repo here[5].


[1]. http://wso2.com/products/application-server/
[2]. http://wso2.com/products/identity-server/
[3]. http://docs.wso2.org/display/Carbon420/CarbonContext+API
[4]. https://svn.wso2.org/repos/wso2/carbon/platform/branches/turing/products/is/4.5.0/modules/samples/sso/SSOAgentSample/
[5]. https://github.com/udarakr/SSOAgentSample-1.0

Creating RabbitMQ Proxy Service in WSO2 ESB with different exchange types

You can follow documentation for RabbitMQ AMQP Transport here[1] if you wish to use exchange type as direct.According to the following implementation

if you don't specify the exchange type it will set to direct by default.

String exchangerType = properties.get(RabbitMQConstants.EXCHANGE_TYPE);
if (exchangerType != null) {
     String durable = properties.get(RabbitMQConstants.EXCHANGE_DURABLE);
         if (durable != null) {
              channel.exchangeDeclare(exchangeName, exchangerType, Boolean.parseBoolean(durable));
         } else {
              channel.exchangeDeclare(exchangeName, exchangerType, true);
         }
 } else {
      channel.exchangeDeclare(exchangeName, "direct", true);
 }

So how to use other exchange types such as topic, headers, x-consistent-hash etc...

Simple solution is to introduce the property "rabbitmq.exchange.type" to your proxy end-point URI.

Default sample proxy,

<proxy xmlns="http://ws.apache.org/ns/synapse" name="AMQPProxy" transports="rabbitmq" statistics="disable" trace="disable" startOnLoad="true">

   <target>

      <inSequence>

         <log level="full"/>

         <property name="OUT_ONLY" value="true"/>

         <property name="FORCE_SC_ACCEPTED" value="true" scope="axis2"/>

      </inSequence>

      <endpoint>

         <address

         uri="rabbitmq:/AMQPProxy?rabbitmq.server.host.name=localhost&rabbitmq.server.port=5672&rabbitmq.server.user.name=guest&rabbitmq.server.password=guest&rabbitmq.queue.name=queue2&rabbitmq.exchange.name=exchange2"/>

      </endpoint>

   </target>

   <parameter name="rabbitmq.queue.name">queue1</parameter>

   <parameter name="rabbitmq.exchange.name">exchange1</parameter>

   <parameter name="rabbitmq.connection.factory">AMQPConnectionFactory</parameter>

   <description></description>

</proxy>

Following is my updated end-point, which is going to use x-consistent-hash as the exchange type.

<endpoint>

         <address

         uri="rabbitmq:/AMQPProxy?rabbitmq.server.host.name=localhost&rabbitmq.server.port=5672&rabbitmq.server.user.name=guest&rabbitmq.server.password=guest&rabbitmq.queue.name=queue2&rabbitmq.exchange.type=x-consistent-hash&rabbitmq.exchange.name=exchange2"/>

      </endpoint>

[1]. http://docs.wso2.org/display/ESB460/RabbitMQ+AMQP+Transport

RabbitMQ Management and Configuration

While creating a RabbitMQ proxy service with WSO2 ESB, I googled a bit about management aspects of RabbitMQ and complied this post as a future reference.

I took the easiest way to install RabbitMQ by using a .deb downloaded from here[1]. Found that there are two main configuration files in RabbitMQ, rabbitmq-env.conf is to set up environment related details and rabbitmq.config to configure RabbitMQ core application, Erlang services and RabbitMQ plug-ins.But the most important fact to keep in mind is that these configuration files are not created by default.

For my purpose of moving from default port 5672 to 8080, I have created /etc/rabbitmq/rabbitmq.config file with the following content.

[ {rabbit, [{tcp_listeners, [8080]}]} ].

Then start/restart RabbitMQ server with the following command.

sudo service rabbitmq-server start

Since I haven't change any environment specific configurations yet, I can use the default RabbitMQ startup log to monitor startup process with following command.

tail -f /var/log/rabbitmq/startup_log

For easy management and configuration RabbitMQ do have a nice web UI. But you have to activate rabbitmq_management plugin in-order-to access it.

rabbitmq-plugins enable rabbitmq_management

Then,browse http://localhost:15672/#/ or if you have already changed the port same as me http://localhost:18080/#/.

For more information you can find out official documentation here[2].
 
[1]. http://www.rabbitmq.com/releases/rabbitmq-server/v3.0.2/
[2]. https://www.rabbitmq.com/

Use cqlsh terminal to browse cassandra | WSO2 ES 1.0.0

We have used WSO2-BAM’s event stream architecture to store data on Cassandra for social aspects of the WSO2 Enterprise Store.

I have to do few direct Cassandra querying while adding a new feature to the social application within ES distribution. Find following steps I followed in this activity.

1. Download Apache Cassandra 1.1.3 from here[1].
2. Unzip and browse apache-cassandra-1.1.3/bin directory using terminal.
3. Give following command to get the cqlsh terminal. Since I'm using default configuration in my local deployment I'm using admin as the both username and password, localhost as the hostname and 9160 as the port.

./cqlsh localhost 9160 -u admin -p admin

udara@thinkPad:~/Downloads/apache-cassandra-1.1.3/bin$ ./cqlsh localhost 9160 -u admin -p admin
Connected to Test Cluster at localhost:9160.
[cqlsh 2.2.0 | Cassandra 1.1.3 | CQL spec 2.0.0 | Thrift protocol 19.32.0]
Use HELP for help.
cqlsh>

4. Select key-space, in my deployment "EVENT_KS".

cqlsh> use EVENT_KS;

5. Select data from the column family "org_wso2_social_activity".

cqlsh:EVENT_KS> SELECT * FROM org_wso2_social_activity;

To learn more CQL follow this official document[2].

[1]. http://archive.apache.org/dist/cassandra/1.1.3/
[2]. http://cassandra.apache.org/doc/cql/CQL.html

PostgreSQL- Basics

I'm compiling this post to create a reference which any postgreSQL-newbie (like myself) can use to get the basic things right !

You need a postgreSQL server up and running before moving further.

sudo apt-get install postgresql

1. Update postgres user password.In a terminal run following and give the password when prompted.

sudo -u postgres psql postgres
\password postgres

2.  Create Database with the name wso2bam. In a terminal run,

sudo -u postgres createdb wso2bam

3.  Connect to psql- the terminal based frontend,

sudo -u postgres psql postgres

 after you run the above command you will get a terminal with postgres=#.

root@thinkPad:~# sudo -u postgres psql postgres
psql (8.4.19)
Type "help" for help.

postgres=#

Note -: Here onwards I'm going to execute all commands within this psql terminal.

4. List down databases(similar to MySQL show databases.

\list

5. Select database wso2bam.

\c wso2bam

6. List tables within wso2bam current database.

\dt

If you are not interested in remembering and typing all these commands, pgAdmin3 might make your life easy. You can install this tool by running,

sudo apt-get install pgadmin3

You can use following official documentation to try out basic queries[1].

Please note that I have tested and verified above steps on a Ubuntu 12.10 machine, using  both PostgreSQL 8.4 and 9.1 servers.

[1]. http://www.postgresql.org/docs/8.4/static/tutorial-select.html

Install PostgreSQL 8.X on Ubuntu 12.10

If you try to install PostgreSQL on ubuntu using apt-get install postgresql command it will automatically fetch and setup PostgreSQL 9.X.

If following methods are not any option to install PostgreSQL you may continue this blog post.

1. Build using the source code.
2. Downloading deb package and install.

Lets configure our system by updating source list so we can simply install  PostgreSQL using apt-get install postgresql-8.X :)

First create pgdg.list file inside /etc/apt/sources.list.d/ directory with the following content.

deb http://apt.postgresql.org/pub/repos/apt/ precise-pgdg main

Next import sigining key for this repository by executing following command in terminal.

wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add -

You are done, simply run "sudo apt-get update" before installing
PostgreSQL 8.X.