Hi,
On Wed, Jul 9, 2014 at 1:18 AM, Marko Asplund <[email protected]>
wrote:
> Hi,
>
> I'm just starting out with using the Servlet 3.1 asynchronous processing
> API.
> I use the API for generating response content, that can potentially be a
> slow process, in another thread.
> The code appears to be working, but since the specification contains many
caveats, I'd like to try and verify correctness.
>
> There's a couple of parts in particular that I'm wondering about:
> - what's the correct way to deliver error response to client? Can I just
> cast the response acquired from AsyncContext to HttpServletResponse and use
> the normal Servlet API mechanisms?
> - does the code contain thread-safety issues in particular related to the
> response object and OutputStream?
>
> Here's a simplified version of my code:
>
> @Override
> protected void doGet(HttpServletRequest req, HttpServletResponse resp)
> throws ServletException, IOException {
> final AsyncContext asyncContext = req.startAsync();
> asyncContext.start(new Runnable() {
> @Override
> public void run() {
> HttpServletResponse response = null;
> try {
> response = (HttpServletResponse)asyncContext;
>
Maybe it is implementation detail that this cast works but usually you have
to use
http://docs.oracle.com/javaee/6/api/javax/servlet/AsyncContext.html#getResponse()
to get the response
> if(hasOperationFailed()) {
>
> response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
> } else {
>
> response.getOutputStream().write(generateResponseContent().getBytes());
> }
> } catch (IOException e) {
> try {
>
> response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
> } catch (IOException e1) {
> e1.printStackTrace();
> }
> }
> asyncContext.complete();
> }
> });
> }
>
> Any feedback and pointers would be welcome.
>
>
> marko
>
