IOException in Cases When Client Closes Connection 

The SAP J2EE Engine Web Container provides the runtime IOException to determine the behavior of the servlet output stream when the client connection has been lost. The purpose of the exception is to notify servlets that the client connection has been closed so they can stop processing the request and writing content to the output stream.

When the physical connection to the client is lost for some reason, the event is known only to the Java dispatcher that handles client connections. To inform server processes in the cluster where servlets or JSP pages are running about the client connection loss, the Java dispatcher sends an event to them. The SAP implementation of the ServletOutputStream checks in its flush() method whether such an event has been received. In cases when the client connection has been closed, the IOException is thrown with an error message of Connection is closed. This interrupts the flushing of the content of the output stream.