WSO2 Data Services Server (DSS) not consuming messages from JMS Queues

As we know , we can integrate wso2 data services server with wso2 message broker , in a way that Data services server consumes messages from the queues of the Message  broker.

When it comes to large scale like, more than 100 data services consume messages from Message broker, it will throw following exception and will not start to consume messages from queues.

WARN {org.apache.axis2.transport.jms.JMSListener} -  Polling tasks on destination : xxx of type queue for service xxx have not yet started after 3 seconds ..


The reason behind this warning and the situation is, controlled limitation of the system. In Data Services   server, it has been limited the number of threads which consume messages from jms queues from the implementation to 100.

It has been done by adding a configurable parameter to the start up script ( wso2server.sh) of the server. By default the value of the parameter snd_t_core=100. If any one getting above exception in a situation like more than 100 consumers, he can increase this parameter to overcome that situation as highlighted bellow;



    -Dcom.sun.jndi.ldap.connect.pool.authentication=simple  \
    -Dcom.sun.jndi.ldap.connect.pool.timeout=3000  \
    -Dorg.terracotta.quartz.skipUpdateCheck=true \
    -Dsnd_t_core=200 \
    -Dsnd_t_max=250 \
    -Djava.security.egd=file:/dev/./urandom \

How to start SimpleAxis2Server in debug mode..

In most of the wso2 products , we could find the simple axis2 server shipped in it's samples directory. I had a situation which i wanted to debug an axis2 service deployed in this simple axis2 server.


Yes, It is very simple thing to start the simple axis2 server in debug mode..... But i had to dig in to the start up script to find out how to do that.

we can start the simple axis2 server in debug  mode with following:

sh axis2server.sh  -xdebug

it will start the server in debug mode with listening to the port 8000