A JAX-WS developer is responsible for designing, developing, and deploying web services using Java API for XML Web Services (JAX-WS). They utilize this technology to create SOAP-based web services and clients that communicate via XML. Their tasks involve writing server-side components, handling XML requests and responses, managing SOAP message processing, and ensuring secure data transmission. Additionally, they focus on web services interoperability and standards, including WSDL and UDDI. They are also involved in debugging, testing, and optimizing the application for performance. They work closely with other developers, ensuring seamless integration of JAX-WS services with other parts of the application.