7.12.3. Using annotations for exception handling

The following exception results in a HTTP 404 error whenever it propagates outside the Seam component layer. It does not roll back the current transaction immediately when thrown, but the transaction will be rolled back if it the exception is not caught by another Seam component. 
@HttpError(errorCode=404) 
public class ApplicationException extends Exception { 
    ... 
}
This exception results in a browser redirect whenever it propagates outside the Seam component layer. It also ends the current conversation. It causes an immediate rollback of the current transaction. 
@Redirect(viewId="/failure.xhtml", end=true) 
@ApplicationException(rollback=true) 
public class UnrecoverableApplicationException extends RuntimeException { 
    ... 
}

Note

Seam cannot handle exceptions that occur during JSF's RENDER_RESPONSE phase, as it is not possible to perform a redirect once writing to the response has begun.
You can also use EL to specify the viewId to redirect to.
When this exception propagates outside the Seam component layer, it results in a redirect and a message to the user. It also immediately rolls back the current transaction. 
@Redirect(viewId="/error.xhtml", message="Unexpected error") 
public class SystemException extends RuntimeException { 
    ... 
}