A Java Message Service (JMS) developer designs, builds, and maintains applications using the Java-based JMS API for two-way, server-to-server communication. They create point-to-point and publish-subscribe messaging models for real-time, asynchronous data exchange. They work on message queue management, topic (publish/subscribe) handling, and message-driven beans. They ensure reliable data transfer and handle exceptions, transaction management, and messaging security. They also perform system integration, troubleshooting, and collaborate with other team members to optimize system efficiency and performance. These professionals usually have strong knowledge of Java, JMS, and other related technologies like Spring and middleware solutions.