Sending an error response with com.sun.net.httpserver.HttpServer

Question

I'm an experienced Java programmer but a newbie web developer. I'm trying to put together a simple web service using the HttpServer class that ships with JDK 1.6. From the examples I've viewed, some typical code from an HttpHandler's handle method would look something like this:

Headers responseHeaders = exchange.getResponseHeaders();
responseHeaders.set("Content-Type", "text/plain");
exchange.sendResponseHeaders(200, 0);

OutputStream responseBody = exchange.getResponseBody();
responseBody.write(createMyResponseAsBytes());
responseBody.close();

My question: What happens if I send a response header to indicate success (i.e. response code 200) and perhaps begin to stream back data and then encounter an exception, which would necessitate sending an "internal server error" response code along with some error content? In other words, what action should I take given that I've already sent a partial "success" response back to the client at the point where I encounter the exception?

Answer 1

200 is not sent until you either flush the stream or close it. But once it is sent, there is nothing you can do about it.
Usually it may happen only when you have a really large amount of data and you use chunking.