Connector is an important concept in software architecture design, but it doesn’t get explicit support from runtime. This paper describes the work on supporting user-defined connector in J2EE application server PKUAS. The PKUAS connector model takes advantage of the Aspect technology. A construct named Advice is used to model crosscutting concerns related to interaction behaviours. These advices are organized into connector and are invoked dynamically at runtime. At deployment time, PKUAS will generate a client-side connector object and publish it to a naming service. Application clients download the connector object to a local machine to manage the component interactions. Runtime connectors correspond well to those in the design time, thus narrowing the concept gap greatly. This flexible and modular approach effectively facilitates the separation of concerns.