Pega deploys MDB through native application servers: https://community.pega.com/knowledgebase/articles/deploying-jms-message-driven-bean-mdb-represents-jms-mdb-listener-pega-7. For example, if you deploy an MDB in a Websphere cluster then all servers within the cluster will process messages. The onMessage is triggered by container listening to a JMS resources (e.g., queue or topic) defined by a JNDI name that the application server container can connect. In theory, you can hide all the JMS servers behind a logic JNDI resource. You only have to define one JMS MDB Listener instance, which is persisted in Pega database and available for all Pega nodes. Consult the documentation of your specific app server (We support Websphere/Weblogic/JBoss).