Messaging
Enterprise Java Bean (EJB) Message Driven Bean (MDB) that consumes from MQ and passes the contents of the message to a notification service.
This MDB responds to the JMS TextMessages that the portfolio microservice delivers to MQ whenever a portfolio changes levels, such as from Silver to Gold.
Note that this is the only microservice in the Stock Trader sample that uses the traditional Java EE programming model (EJBs, JMS, JNDI, etc.). Due to this, it is also the only one that depends on the full open-liberty:javaee8 Docker image (as opposed to the others that just need open-liberty:microProfile3).
This MDB expects to receive a TextMessage containing a JSON object with four fields: id, owner, old, and new. For example, you could post a message like {"id": "jalcorn@us.ibm.com", "owner": "John", "old": "Silver", "new": "Gold"} to its MQ queue, and it will pass that JSON object to the notification microservice. There are multiple versions of the notification service; one posts a message to Slack (the #stock-trader-messages channel on ibm-cloud.slack.com), and another sends a tweet to Twitter (the @IBMStockTrader account).
Deploy
Use WebSphere Liberty helm chart to deploy Messaging microservice:
helm repo add ibm-charts https://raw.githubusercontent.com/IBM/charts/master/repo/stable/
helm install ibm-charts/ibm-websphere-liberty -f <VALUES_YAML> -n <RELEASE_NAME> --tlsIn practice this means you'll run something like:
helm repo add ibm-charts https://raw.githubusercontent.com/IBM/charts/master/repo/stable/
helm install ibm-charts/ibm-websphere-liberty -f manifests/messaging-values.yaml -n messaging --namespace stock-trader --tls