Eventing using WSO2 DSS - Send data to a JMS Queue for a given event trigger

If you want to trigger an event depend on an SQL related service call this is a great example on how you can do it using WSO2 Data Service Server.

In this sample I am going to explain how you can handle event triggers in WSO2 Data service server.  In WSO2 DSS, you have two types of event triggers.

1. Input event triggers - which trigger's an event looking at the request.
2. Output event triggers - which trigger's an event looking at the response.

For both of these trigger's you can specify an ex-path expression to trigger the event.

To demonstrate this functionality I  am going to write a small data service which insert Student information. And every time an insertion happen, primary key of the inserted record will be send to a JMS Queue.

Prerequisites

In order to try out this sample you need to have
  -> WSO2 Data Services Server Downloaded
  -> You need to have a database of your choice
  -> Add related drivers to DSS_HOME/repository/component/lib folder
  -> ActiveMQ downloaded and started

Step 1 - Enable JMS senders in WSO2 DSS.

In order to send JMS messages from data services, you need to enable the JMS sender in data services server.
To enable JMSSender -> Go to DSS_HOME/repository/conf/axis2/axis2.xml and un-comment the following line.

<transportSender name="jms" class="org.apache.axis2.transport.jms.JMSSender"/>

and then start the data services instance.

Step 2 - Create data Service.

If you are new on creating data services, please refer the following post on how to create a data service using WSO2 Data Service Server.

I have a small table called Student. Lets create a simple data service for the table student.

describe Student;
+---------+-------------+------+-----+---------+----------------+
| Field   | Type        | Null | Key | Default | Extra          |
+---------+-------------+------+-----+---------+----------------+
| sid     | int(11)     | NO   | PRI | NULL    | auto_increment |
| name    | varchar(90) | YES  |     | NULL    |                |
| address | varchar(75) | YES  |     | NULL    |                |
| country | varchar(75) | YES  |     | NULL    |                |
| phone   | varchar(20) | YES  |     | NULL    |                |
| major   | varchar(50) | YES  |     | NULL    |                |
| gpa     | float       | YES  |     | NULL    |                |
| tutorid | int(11)     | YES  |     | NULL    |                |
+---------+-------------+------+-----+---------+----------------+
8 rows in set (0.00 sec)

Log in to DSS management console -> Create New Data Service. Give the data service name appropriately and click on next.

Click on Add Data Source and give database configuration appropriately and click on next.

Next section we will discuss how we can write a data service Query which can invoke a trigger according to the query result.

In this Query my SQL is simple insert

INSERT INTO Student(name,address,country,phone,major,gpa,tutorid) VALUES(:name,:address,:country,:phone,:major,:gpa,:tutorid)

Click on "Generate Input Mappings", and this will generate the input mappings for the input parameters.

Since we need a response back (ideally it will be the primary key of the newly inserted record) we can click  Return generated key which will auto generate the response.

To add the event trigger, scroll down a little bit. Under Events, click on Manage Events. There, we give the eventing configurations.

Event ID - student_addition_trigger

Xpath - //*[local-name()='ID' and namespace-uri()='http://ws.wso2.org/dataservice']>0

Target Topic - student_insertion_topic

Event Sink URL ( JMS URL according to your activeMQ)

jms:/student_insertion_topic?transport.jms.DestinationType=queue&transport.jms.ContentTypeProperty=Content-Type&java.naming.provider.url=tcp://localhost:61616&java.naming.factory.initial=org.apache.activemq.jndi.ActiveMQInitialContextFactory&transport.jms.ConnectionFactoryType=queue&transport.jms.ConnectionFactoryJNDIName=QueueConnectionFactory

Go to Main Configuration and add the Output trigger as shown below.

Now we have done with our Query Section. Click on Save to save the Query and Click next to add the  operation.
Add New Opperation ->
Operation Name* - InsertStudent
Query ID* - insertQ

Save and finish.

Now we can test this functionality by using the try it function provided by Data Service Server

My Request

   <body> <p:InsertStudent xmlns:p="http://ws.wso2.org/dataservice">
      <p:name>Amani</p:name>
      <p:address>Soysa</p:address>
      <p:country>SL</p:country>
      <p:phone>1923123111</p:phone>
      <p:major>SE</p:major>
      <p:gpa>4.2</p:gpa>
      <p:tutorid>12</p:tutorid>
   </p:InsertStudent>
</body>

My Response

   <GeneratedKeys xmlns="http://ws.wso2.org/dataservice"> <Entry>
      <ID>5</ID>
   </Entry>
</GeneratedKeys>

If you go to your active MQ console, You would see number of pending messages as shown below. You can go inside your Queue and explore more!!!!