At a first glance, I'd say your while{} block never returns. Is ServletInputStream.isFinished() what you've been looking for, instead of isReady() On 28 Mar 2014, at 16:26, PB <pbielicki(a)gmail.com&gt; wrote: while (in.isReady()) { -- http://about.me/hbraun

So here's what I'm getting (my source code is attached) ... __Telnet__ dador-iMac:~ dador$ telnet 10.0.1.14 8080 Trying 10.0.1.14... Connected to 10.0.1.14. Escape character is '^]'. GET /wildfly-debug/upgrade HTTP/1.1 Connection: upgrade HTTP/1.1 101 Switching Protocols Connection: Upgrade X-Powered-By: Undertow 1 Server: Wildfly 8 Content-Length: 0 Date: Fri, 28 Mar 2014 20:22:36 GMT the quick brown fox blah, blah, blah ^] telnet> quit Connection closed. dador-iMac:~ dador$ __console___ 15:22:36,825 INFO [stdout] (default task-15) servlet doGet() received 'upgrade' 15:22:46,488 INFO [stdout] (default I/O-3) listener onDataAvailable() called 15:22:46,488 INFO [stdout] (default I/O-3) listener read 'the quick brown fox blah, blah, blah'; successfully offered to queue 15:22:46,489 INFO [stdout] (default I/O-3) listener read ''; successfully offered to queue 15:22:56,824 INFO [stdout] (default I/O-3) listener onDataAvailable() called 15:22:56,824 INFO [stdout] (default I/O-3) listener onAllDataRead() called 15:22:56,824 INFO [stdout] (default I/O-3) here is data queued ... 15:22:56,825 INFO [stdout] (default I/O-3) the quick brown fox blah, blah, blah 15:22:56,825 INFO [stdout] (default I/O-3) 15:22:56,825 INFO [stdout] (default I/O-3) 15:22:56,825 INFO [stdout] (default I/O-3) now do something So the queue is getting the data as it's being piped in (the blanks in the queued data are telnet line feeds). But I have to send a signal to the servlet that all of the data has been sent (I simply close the telnet connection). Then the listener's onAllDataRead() method gets called. So maybe this is a configuration issue. By the way, it made a difference for me in the telnet session when I specified the Connection as "upgrade" versus "Upgrade". Just a suggestion, but you may also want to take a look at the non-blocking I/O if you input stream is a long one. Good luck, --Jim. On Fri, Mar 28, 2014 at 3:05 PM, PB <pbielicki(a)gmail.com&gt; wrote: > Hi, > > I dare to say that my code is correct ;) The problem is that it is NEVER > called - this condition (even if it's wrong, however it's not) is never > checked. When I remove this line: > > out.setWriteListener(new EchoWriteListener(queue, out)); > > it seems to work. However, I have no writer, so it should be rather > called SwallowListener... It's not my goal. > > Maybe I should initialize WriteListener from the ReadListener after the > first read? Or maybe, when I want to send back the response I should do > this directly from the read listener? e.g. > https://java.net/projects/tyrus/sources/source-code-repository/content/tr... > > Thanks, > Przemyslaw > > > On Fri, Mar 28, 2014 at 5:14 PM, Heiko Braun <hbraun(a)redhat.com&gt; wrote: > >> At a first glance, I'd say your while{} block never returns. Is >> ServletInputStream.isFinished() what you've been looking for, instead of >> isReady() >> >> On 28 Mar 2014, at 16:26, PB <pbielicki(a)gmail.com&gt; wrote: >> >> while (in.isReady()) { >> >> >> -- >> >> http://about.me/hbraun >> >> >> >> >> >> >> >> > > _______________________________________________ > wildfly-dev mailing list > wildfly-dev(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/wildfly-dev >

Can you try with the latest development build of Wildfly (from https://ci.jboss.org/hudson/job/WildFly-latest-master/). There have been some fixes in this area, so your problem may have already been fixed. Stuart PB wrote: > Hi, > > I'm testing the HTTP Upgrade feature of WF 8.0 and I'm facing some banal > problem. Basically my ReadListener is NEVER called. > Here's the code: > > @WebServlet(urlPatterns = "/upgrade") > public class UpgradeServlet extends HttpServlet { > @Override > protected void doGet(HttpServletRequest req, HttpServletResponse > resp) throws ServletException, IOException { > if ("upgrade".equalsIgnoreCase(req.getHeader("Connection"))) { > req.upgrade(EchoHandler.class); > } > } > } > > public class EchoHandler implements HttpUpgradeHandler { > @Override > public void init(WebConnection wc) { > try { > ServletInputStream in = wc.getInputStream(); > ServletOutputStream out = wc.getOutputStream(); > > BlockingQueue<String> queue = new LinkedBlockingQueue<String>(); > in.setReadListener(new EchoReadListener(queue, in)); > out.setWriteListener(new EchoWriteListener(queue, out)); > } catch (IOException e) { > throw new IllegalStateException(e); > } > } > > public class EchoReadListener implements ReadListener { > @Override > public void onDataAvailable() throws IOException { > while (in.isReady()) { > int length = in.read(buffer); > String input = new String(buffer, 0, length); > if (false == queue.offer(input)) { > System.err.println("'" + input + "' input was ignored"); > } > } > } > > I'm connecting to WF using telnet and sending the upgrade request: > GET /example-webapp/upgrade HTTP/1.1 > Host: localhost > Connection: upgrade > Upgrade: echo > > and I'm getting correct response: > > HTTP/1.1 101 Switching Protocols > Connection: Upgrade > X-Powered-By: Undertow 1 > Server: Wildfly 8 > Content-Length: 0 > > which means that from now on the protocol between my telnet client and > WF is pure TCP. > So, I start typing some text, hit Enter and.... nothing happens. > onDataAvailable() is NEVER called. More so, this makes WF totally > irresponsive - my whole webapp is dead. > > I believe, I'm doing something wrong - any ideas what exactly? There is > also a slight chance that Upgrade feature in WF is f****d :) > Anyway, WF should not block even in case my upgraded protocol is not > working correctly? > > Many thanks, > Przemyslaw > > _______________________________________________ > wildfly-dev mailing list > wildfly-dev(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/wildfly-dev >

On 03/04/2014 15:21, Przemyslaw Bielicki wrote: > I tried - exactly the same results. > > Another weird observation is that ServletOutputStream.isReady() is > returning true even after the connection is closed > (ServletInputStream.isFinished() is correctly returning true). > > Here's the scenario that works but I can write back the data only once: > 1. In HttpUpgradeHandler I set only the ReadListener > 2. I switch the protocol and send some data > 3. ReadListener gets activated i.e. onDataAvailable() is called. > 4. I process the input data, read as much as possible and put the > input into the queue > 5. From within ReadListener I set the WriteListener > 6. WriteListener.onWritePossible() gets called and I process the data > - I clean the queue > 7. As long as I'm in WriteListener.onWritePossible() > (while.out.isReady() is constantly returning true, which is a correct > bahavior) the ReadListener is on-hold. I can send as much data as I > like but onDataAvailable() is not called > 8. Only when I leave WriteListener.onWritePossible() method the > ReadListener.onDataAvailable() is called again and I can consume the > input data again. > 9. I can process the input data again i.e. put it into the queue but > WriteListener.onWritePossible() is never called again. When I try to > reset it I get IllegalStateException > > Either the specification or implementation seem not very mature.... > Wildfly behavior is consistent with the one of Tomcat. > > At the moment I conclude that the non-blocking write is not possible > in Servlet 3.1. > > I would appreciate if someone can provide an example that actually > works or explain why the weird behavior I observe is correct (is it?) This looks as expected (although Tomcat 8 should concurrently call read/write in upgraded mode, as a proprietary extension to be able to implement Websockets on top of Servlets 3.1, besides that Servlet 3.1 is still not concurrent, so at most one thread processing a request a given time). Non blocking IO means it allows avoiding to block on IO, it doesn't imply anything else. Servlets 3.1 is actually async IO (similar to NIO2, rather than NIO1), since non blocking IO is unusable as is. Rémy _______________________________________________ wildfly-dev mailing list wildfly-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/wildfly-dev

Let me play with your use case, although it will be a few hours before I can get to it. There are some limitations to the spec, but they are manageable. As an example the write is actually written for you in a non blocking fashion. It's basically an async deferred write. The undertow http handler API is, in my opinion a much better fit for pure non-blocking / reactive applications. On Apr 3, 2014, at 9:52 AM, Przemyslaw Bielicki <pbielicki(a)gmail.com&gt; wrote: As I showed I'm not able to read and write at the same time using non-blocking IO, as promised by Servlet 3.1. I'm able to read using non-blocking IO but my writes are blocking and I'm looking for the solution. Regarding concurrent access, HTTP Upgrade promises that the upgraded protocol will be full-duplex, so I should be able to read and write concurrently but I'm not. Another comment is that Servlets 3.1 is actually async ONLY from the server point of view - the client is still blocked because HTTP 1.1 is synchronous (we have to wait for HTTP 2.0 to solve this). Here Upgrade should help as it is a pure TCP, so I'm the master of my protocol and I'm no longer bound to HTTP - I can be as asynchronous as I want. Unfortunately Servlet 3.1 API does not respect this. It looks like the specification is not meeting the promises given.... On Thu, Apr 3, 2014 at 4:41 PM, Rémy Maucherat <rmaucher(a)redhat.com&gt;wrote: > On 03/04/2014 15:21, Przemyslaw Bielicki wrote: > > I tried - exactly the same results. > > > > Another weird observation is that ServletOutputStream.isReady() is > > returning true even after the connection is closed > > (ServletInputStream.isFinished() is correctly returning true). > > > > Here's the scenario that works but I can write back the data only once: > > 1. In HttpUpgradeHandler I set only the ReadListener > > 2. I switch the protocol and send some data > > 3. ReadListener gets activated i.e. onDataAvailable() is called. > > 4. I process the input data, read as much as possible and put the > > input into the queue > > 5. From within ReadListener I set the WriteListener > > 6. WriteListener.onWritePossible() gets called and I process the data > > - I clean the queue > > 7. As long as I'm in WriteListener.onWritePossible() > > (while.out.isReady() is constantly returning true, which is a correct > > bahavior) the ReadListener is on-hold. I can send as much data as I > > like but onDataAvailable() is not called > > 8. Only when I leave WriteListener.onWritePossible() method the > > ReadListener.onDataAvailable() is called again and I can consume the > > input data again. > > 9. I can process the input data again i.e. put it into the queue but > > WriteListener.onWritePossible() is never called again. When I try to > > reset it I get IllegalStateException > > > > Either the specification or implementation seem not very mature.... > > Wildfly behavior is consistent with the one of Tomcat. > > > > At the moment I conclude that the non-blocking write is not possible > > in Servlet 3.1. > > > > I would appreciate if someone can provide an example that actually > > works or explain why the weird behavior I observe is correct (is it?) > This looks as expected (although Tomcat 8 should concurrently call > read/write in upgraded mode, as a proprietary extension to be able to > implement Websockets on top of Servlets 3.1, besides that Servlet 3.1 is > still not concurrent, so at most one thread processing a request a given > time). > > Non blocking IO means it allows avoiding to block on IO, it doesn't > imply anything else. Servlets 3.1 is actually async IO (similar to NIO2, > rather than NIO1), since non blocking IO is unusable as is. > > Rémy > > _______________________________________________ > wildfly-dev mailing list > wildfly-dev(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/wildfly-dev > _______________________________________________ wildfly-dev mailing list wildfly-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/wildfly-dev

Przemyslaw Bielicki wrote: > I tried - exactly the same results. > > Another weird observation is that ServletOutputStream.isReady() is > returning true even after the connection is closed > (ServletInputStream.isFinished() is correctly returning true). > > Here's the scenario that works but I can write back the data only once: > 1. In HttpUpgradeHandler I set only the ReadListener > 2. I switch the protocol and send some data > 3. ReadListener gets activated i.e. onDataAvailable() is called. > 4. I process the input data, read as much as possible and put the input > into the queue > 5. From within ReadListener I set the WriteListener > 6. WriteListener.onWritePossible() gets called and I process the data - > I clean the queue > 7. As long as I'm in WriteListener.onWritePossible() > (while.out.isReady() is constantly returning true, which is a correct > bahavior) the ReadListener is on-hold. I can send as much data as I like > but onDataAvailable() is not called > 8. Only when I leave WriteListener.onWritePossible() method the > ReadListener.onDataAvailable() is called again and I can consume the > input data again. > 9. I can process the input data again i.e. put it into the queue but > WriteListener.onWritePossible() is never called again. When I try to > reset it I get IllegalStateException > > Either the specification or implementation seem not very mature.... > Wildfly behavior is consistent with the one of Tomcat. > As Remy said this is expected. Basically there is only ever one IO thread per connection, so only one method will be active at a time. The reason why your listener method is not being called again would become apparent if you look at the javadoc for the read/write listeners: Subsequently the container will invoke this method if and only if {@link javax.servlet.ServletOutputStream#isReady()} method has been called and has returned <code>false</code>. Basically what this means is that the listener is only invoked if isReady() returns false at some point. If you have read some data and then you want to echo it you should call the onWritePossible method yourself, after you have received the data. Stuart > At the moment I conclude that the non-blocking write is not possible in > Servlet 3.1. > > I would appreciate if someone can provide an example that actually works > or explain why the weird behavior I observe is correct (is it?) > > Cheers, > Przemyslaw > > > > > On Thu, Apr 3, 2014 at 6:18 AM, Stuart Douglas > <stuart.w.douglas(a)gmail.com <mailto:stuart.w.douglas@gmail.com>> wrote: > > Can you try with the latest development build of Wildfly (from > https://ci.jboss.org/hudson/__job/WildFly-latest-master/ > <https://ci.jboss.org/hudson/job/WildFly-latest-master/>). > > > There have been some fixes in this area, so your problem may have > already been fixed. > > Stuart > > > PB wrote: > > Hi, > > I'm testing the HTTP Upgrade feature of WF 8.0 and I'm facing > some banal > problem. Basically my ReadListener is NEVER called. > Here's the code: > > @WebServlet(urlPatterns = "/upgrade") > public class UpgradeServlet extends HttpServlet { > @Override > protected void doGet(HttpServletRequest req, > HttpServletResponse > resp) throws ServletException, IOException { > if > ("upgrade".equalsIgnoreCase(__req.getHeader("Connection"))) { > req.upgrade(EchoHandler.class)__; > > } > } > } > > public class EchoHandler implements HttpUpgradeHandler { > @Override > public void init(WebConnection wc) { > try { > ServletInputStream in = wc.getInputStream(); > ServletOutputStream out = wc.getOutputStream(); > > BlockingQueue<String> queue = new > LinkedBlockingQueue<String>(); > in.setReadListener(new EchoReadListener(queue, in)); > out.setWriteListener(new EchoWriteListener(queue, out)); > } catch (IOException e) { > throw new IllegalStateException(e); > } > } > > public class EchoReadListener implements ReadListener { > @Override > public void onDataAvailable() throws IOException { > while (in.isReady()) { > int length = in.read(buffer); > String input = new String(buffer, 0, length); > if (false == queue.offer(input)) { > System.err.println("'" + input + "' input was ignored"); > } > } > } > > I'm connecting to WF using telnet and sending the upgrade request: > GET /example-webapp/upgrade HTTP/1.1 > Host: localhost > Connection: upgrade > Upgrade: echo > > and I'm getting correct response: > > HTTP/1.1 101 Switching Protocols > Connection: Upgrade > X-Powered-By: Undertow 1 > Server: Wildfly 8 > Content-Length: 0 > > which means that from now on the protocol between my telnet > client and > WF is pure TCP. > So, I start typing some text, hit Enter and.... nothing happens. > onDataAvailable() is NEVER called. More so, this makes WF totally > irresponsive - my whole webapp is dead. > > I believe, I'm doing something wrong - any ideas what exactly? > There is > also a slight chance that Upgrade feature in WF is f****d :) > Anyway, WF should not block even in case my upgraded protocol is > not > working correctly? > > Many thanks, > Przemyslaw > > _________________________________________________ > wildfly-dev mailing list > wildfly-dev(a)lists.jboss.org <mailto:wildfly-dev@lists.jboss.org> > https://lists.jboss.org/__mailman/listinfo/wildfly-dev > <https://lists.jboss.org/mailman/listinfo/wildfly-dev> > > >

Try something like the code below: public class AsyncEchoUpgradeServlet extends HttpServlet { @Override protected void doGet(final HttpServletRequest req, final HttpServletResponse resp) throws ServletException, IOException { req.upgrade(Handler.class); } public static class Handler implements HttpUpgradeHandler { @Override public void init(final WebConnection wc) { Listener listener = new Listener(wc); try { //we have to set the write listener before the read listener //otherwise the output stream could be written to before it is //in async mode wc.getOutputStream().setWriteListener(listener); wc.getInputStream().setReadListener(listener); } catch (IOException e) { UndertowLogger.REQUEST_IO_LOGGER.ioException(e); } } @Override public void destroy() { } } private static class Listener implements WriteListener, ReadListener { private final WebConnection connection; private final Queue<String> queue = new ArrayDeque<String>(); private Listener(final WebConnection connection) { this.connection = connection; } @Override public synchronized void onDataAvailable() throws IOException { byte[] data = new byte[100]; while (connection.getInputStream().isReady()) { int read; if ((read = connection.getInputStream().read(data)) != -1) { queue.add(new String(data, 0, read)); } onWritePossible(); } } @Override public void onAllDataRead() throws IOException { } @Override public synchronized void onWritePossible() throws IOException { while (!queue.isEmpty() && connection.getOutputStream().isReady()) { String data = queue.poll(); connection.getOutputStream().write(data.getBytes()); } } @Override public void onError(final Throwable t) { } } } Przemyslaw Bielicki wrote: > Hi Stuart, > > thx for the explanations. There is a problem anyway - if you set both > read and write listeners from the handler it won't work at all as in the > write listener ServletOutputStream.isReady() will be returning true all > the time (why not? the output is ready to send some data at the same > time in is ready to read some data), and the read listener will be > ignored (as the tread is focused on the writer). The solution here is > not to have while (out.isReady()) loop in the writer but a simple check > if (out.isReady()), but then you have to call onWritePossible yourself. > It means you need to pass a write listener reference to the read > listener - it's smells more than a bit. > > I think I have my conclusion, that is: it is impossible to achieve > full-duplex (thus multiplexing) in an upgraded protocol using Servlet > 3.1 API as there is "only ever one IO thread per connection" (I didn't > find such limitation in the specification - can you point out the > section in which it is said there should be on thread per connection?). > In order to achieve multiplexing one have to explicitly create a > separate thread dealing with either reading or writing the data. > Also, using Servlet 3.1 it is impossible to achieve non-blocking read > and write and multiplexing on the same connection, even using a separate > thread. > > I will contact the specification owners to see their opinion. > > Many thanks, > Przemyslaw > > > On Fri, Apr 4, 2014 at 12:33 AM, Stuart Douglas > <stuart.w.douglas(a)gmail.com <mailto:stuart.w.douglas@gmail.com>> wrote: > > > > Przemyslaw Bielicki wrote: > > I tried - exactly the same results. > > Another weird observation is that ServletOutputStream.isReady() is > returning true even after the connection is closed > (ServletInputStream.__isFinished() is correctly returning true). > > > Here's the scenario that works but I can write back the data > only once: > 1. In HttpUpgradeHandler I set only the ReadListener > 2. I switch the protocol and send some data > 3. ReadListener gets activated i.e. onDataAvailable() is called. > 4. I process the input data, read as much as possible and put > the input > into the queue > 5. From within ReadListener I set the WriteListener > 6. WriteListener.onWritePossible(__) gets called and I process > > the data - > I clean the queue > 7. As long as I'm in WriteListener.onWritePossible(__) > > (while.out.isReady() is constantly returning true, which is a > correct > bahavior) the ReadListener is on-hold. I can send as much data > as I like > but onDataAvailable() is not called > 8. Only when I leave WriteListener.onWritePossible(__) method the > > ReadListener.onDataAvailable() is called again and I can consume > the > input data again. > 9. I can process the input data again i.e. put it into the queue > but > WriteListener.onWritePossible(__) is never called again. When I > > try to > reset it I get IllegalStateException > > Either the specification or implementation seem not very > mature.... > Wildfly behavior is consistent with the one of Tomcat. > > > As Remy said this is expected. > Basically there is only ever one IO thread per connection, so only > one method will be active at a time. > > The reason why your listener method is not being called again would > become apparent if you look at the javadoc for the read/write > listeners: > > Subsequently the container will invoke this method if and only > if {@link javax.servlet.__ServletOutputStream#isReady()} method > > has been called and has returned <code>false</code>. > > Basically what this means is that the listener is only invoked if > isReady() returns false at some point. If you have read some data > and then you want to echo it you should call the onWritePossible > method yourself, after you have received the data. > > Stuart > > > > > At the moment I conclude that the non-blocking write is not > possible in > Servlet 3.1. > > I would appreciate if someone can provide an example that > actually works > or explain why the weird behavior I observe is correct (is it?) > > Cheers, > Przemyslaw > > > > > On Thu, Apr 3, 2014 at 6:18 AM, Stuart Douglas > <stuart.w.douglas(a)gmail.com <mailto:stuart.w.douglas@gmail.com> > <mailto:stuart.w.douglas@__gmail.com > > <mailto:stuart.w.douglas@gmail.com>>> wrote: > > Can you try with the latest development build of Wildfly > (from > https://ci.jboss.org/hudson/____job/WildFly-latest-master/ > <https://ci.jboss.org/hudson/__job/WildFly-latest-master/> > > <https://ci.jboss.org/hudson/__job/WildFly-latest-master/ > <https://ci.jboss.org/hudson/job/WildFly-latest-master/>>). > > > There have been some fixes in this area, so your problem > may have > already been fixed. > > Stuart > > > PB wrote: > > Hi, > > I'm testing the HTTP Upgrade feature of WF 8.0 and I'm > facing > some banal > problem. Basically my ReadListener is NEVER called. > Here's the code: > > @WebServlet(urlPatterns = "/upgrade") > public class UpgradeServlet extends HttpServlet { > @Override > protected void doGet(HttpServletRequest req, > HttpServletResponse > resp) throws ServletException, IOException { > if > > ("upgrade".equalsIgnoreCase(____req.getHeader("Connection"))) { > req.upgrade(EchoHandler.class)____; > > > } > } > } > > public class EchoHandler implements HttpUpgradeHandler { > @Override > public void init(WebConnection wc) { > try { > ServletInputStream in = wc.getInputStream(); > ServletOutputStream out = wc.getOutputStream(); > > BlockingQueue<String> queue = new > LinkedBlockingQueue<String>(); > in.setReadListener(new EchoReadListener(queue, > in)); > out.setWriteListener(new > EchoWriteListener(queue, out)); > } catch (IOException e) { > throw new IllegalStateException(e); > } > } > > public class EchoReadListener implements ReadListener { > @Override > public void onDataAvailable() throws IOException { > while (in.isReady()) { > int length = in.read(buffer); > String input = new String(buffer, 0, length); > if (false == queue.offer(input)) { > System.err.println("'" + input + "' input was > ignored"); > } > } > } > > I'm connecting to WF using telnet and sending the > upgrade request: > GET /example-webapp/upgrade HTTP/1.1 > Host: localhost > Connection: upgrade > Upgrade: echo > > and I'm getting correct response: > > HTTP/1.1 101 Switching Protocols > Connection: Upgrade > X-Powered-By: Undertow 1 > Server: Wildfly 8 > Content-Length: 0 > > which means that from now on the protocol between my > telnet > client and > WF is pure TCP. > So, I start typing some text, hit Enter and.... nothing > happens. > onDataAvailable() is NEVER called. More so, this makes > WF totally > irresponsive - my whole webapp is dead. > > I believe, I'm doing something wrong - any ideas what > exactly? > There is > also a slight chance that Upgrade feature in WF is > f****d :) > Anyway, WF should not block even in case my upgraded > protocol is not > working correctly? > > Many thanks, > Przemyslaw > > ___________________________________________________ > > wildfly-dev mailing list > wildfly-dev(a)lists.jboss.org <mailto:wildfly-dev@lists.jboss.org> > <mailto:wildfly-dev@lists.__jboss.org > <mailto:wildfly-dev@lists.jboss.org>> > https://lists.jboss.org/____mailman/listinfo/wildfly-dev > <https://lists.jboss.org/__mailman/listinfo/wildfly-dev> > <https://lists.jboss.org/__mailman/listinfo/wildfly-dev > <https://lists.jboss.org/mailman/listinfo/wildfly-dev>> > > > > > _______________________________________________ > wildfly-dev mailing list > wildfly-dev(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/wildfly-dev >

On Fri, Apr 4, 2014 at 6:19 PM, Przemyslaw Bielicki <pbielicki(a)gmail.com&gt;wrote: > thanks a lot - it seems to work but: > > 1. Synchronized is bad :) anyway, you wrote that there is only one thread > so synchronization is not needed > oops, that was a copy paste error, it is not needed. > 2. Main issue: it's not bi-directional full-duplex (like WebSockets) i.e. > you are not able to receive and send data at the same time, it's still > synchronous > Web sockets is exactly the same. There is generally only one thread, and it handles both read and write notifications. If you are worried about the read thread just reading constantly and the write thread never getting a go then just put a limit on how much data can be queued before it is written out. At one point XNIO did have separate read and write threads, however it ended up being much slower as you end up needing to synchronise. A single IO thread is faster, you just have to be careful of how much you buffer on the read side before writing. Stuart > > many thanks anyway - nice try :) > > > On Fri, Apr 4, 2014 at 9:02 AM, Stuart Douglas < > stuart.w.douglas(a)gmail.com&gt; wrote: > >> Try something like the code below: >> >> >> public class AsyncEchoUpgradeServlet extends HttpServlet { >> >> @Override >> protected void doGet(final HttpServletRequest req, final >> HttpServletResponse resp) throws ServletException, IOException { >> req.upgrade(Handler.class); >> } >> >> public static class Handler implements HttpUpgradeHandler { >> >> @Override >> public void init(final WebConnection wc) { >> Listener listener = new Listener(wc); >> try { >> //we have to set the write listener before the read >> listener >> //otherwise the output stream could be written to before >> it is >> //in async mode >> wc.getOutputStream().setWriteListener(listener); >> wc.getInputStream().setReadListener(listener); >> } catch (IOException e) { >> UndertowLogger.REQUEST_IO_LOGGER.ioException(e); >> } >> } >> >> @Override >> public void destroy() { >> >> } >> } >> >> >> private static class Listener implements WriteListener, ReadListener >> { >> >> private final WebConnection connection; >> private final Queue<String> queue = new ArrayDeque<String>(); >> >> private Listener(final WebConnection connection) { >> this.connection = connection; >> } >> >> @Override >> public synchronized void onDataAvailable() throws IOException { >> byte[] data = new byte[100]; >> while (connection.getInputStream().isReady()) { >> int read; >> if ((read = connection.getInputStream().read(data)) != >> -1) { >> queue.add(new String(data, 0, read)); >> } >> onWritePossible(); >> } >> } >> >> @Override >> public void onAllDataRead() throws IOException { >> >> } >> >> @Override >> public synchronized void onWritePossible() throws IOException { >> >> while (!queue.isEmpty() && connection.getOutputStream().isReady()) >> { >> String data = queue.poll(); >> connection.getOutputStream().write(data.getBytes()); >> } >> } >> >> @Override >> public void onError(final Throwable t) { >> >> } >> } >> } >> >> >> >> Przemyslaw Bielicki wrote: >> >>> Hi Stuart, >>> >>> thx for the explanations. There is a problem anyway - if you set both >>> read and write listeners from the handler it won't work at all as in the >>> write listener ServletOutputStream.isReady() will be returning true all >>> the time (why not? the output is ready to send some data at the same >>> time in is ready to read some data), and the read listener will be >>> ignored (as the tread is focused on the writer). The solution here is >>> not to have while (out.isReady()) loop in the writer but a simple check >>> if (out.isReady()), but then you have to call onWritePossible yourself. >>> It means you need to pass a write listener reference to the read >>> listener - it's smells more than a bit. >>> >>> I think I have my conclusion, that is: it is impossible to achieve >>> full-duplex (thus multiplexing) in an upgraded protocol using Servlet >>> 3.1 API as there is "only ever one IO thread per connection" (I didn't >>> find such limitation in the specification - can you point out the >>> section in which it is said there should be on thread per connection?). >>> In order to achieve multiplexing one have to explicitly create a >>> separate thread dealing with either reading or writing the data. >>> Also, using Servlet 3.1 it is impossible to achieve non-blocking read >>> and write and multiplexing on the same connection, even using a separate >>> thread. >>> >>> I will contact the specification owners to see their opinion. >>> >>> Many thanks, >>> Przemyslaw >>> >>> >>> On Fri, Apr 4, 2014 at 12:33 AM, Stuart Douglas >>> <stuart.w.douglas(a)gmail.com <mailto:stuart.w.douglas@gmail.com>> wrote: >>> >>> >>> >>> Przemyslaw Bielicki wrote: >>> >>> I tried - exactly the same results. >>> >>> Another weird observation is that ServletOutputStream.isReady() >>> is >>> returning true even after the connection is closed >>> (ServletInputStream.__isFinished() is correctly returning >>> true). >>> >>> >>> Here's the scenario that works but I can write back the data >>> only once: >>> 1. In HttpUpgradeHandler I set only the ReadListener >>> 2. I switch the protocol and send some data >>> 3. ReadListener gets activated i.e. onDataAvailable() is called. >>> 4. I process the input data, read as much as possible and put >>> the input >>> into the queue >>> 5. From within ReadListener I set the WriteListener >>> 6. WriteListener.onWritePossible(__) gets called and I process >>> >>> the data - >>> I clean the queue >>> 7. As long as I'm in WriteListener.onWritePossible(__) >>> >>> (while.out.isReady() is constantly returning true, which is a >>> correct >>> bahavior) the ReadListener is on-hold. I can send as much data >>> as I like >>> but onDataAvailable() is not called >>> 8. Only when I leave WriteListener.onWritePossible(__) method >>> the >>> >>> ReadListener.onDataAvailable() is called again and I can >>> consume the >>> input data again. >>> 9. I can process the input data again i.e. put it into the >>> queue but >>> WriteListener.onWritePossible(__) is never called again. When I >>> >>> try to >>> reset it I get IllegalStateException >>> >>> Either the specification or implementation seem not very >>> mature.... >>> Wildfly behavior is consistent with the one of Tomcat. >>> >>> >>> As Remy said this is expected. >>> Basically there is only ever one IO thread per connection, so only >>> one method will be active at a time. >>> >>> The reason why your listener method is not being called again would >>> become apparent if you look at the javadoc for the read/write >>> listeners: >>> >>> Subsequently the container will invoke this method if and only >>> if {@link javax.servlet.__ServletOutputStream#isReady()} method >>> >>> has been called and has returned <code>false</code>. >>> >>> Basically what this means is that the listener is only invoked if >>> isReady() returns false at some point. If you have read some data >>> and then you want to echo it you should call the onWritePossible >>> method yourself, after you have received the data. >>> >>> Stuart >>> >>> >>> >>> >>> At the moment I conclude that the non-blocking write is not >>> possible in >>> Servlet 3.1. >>> >>> I would appreciate if someone can provide an example that >>> actually works >>> or explain why the weird behavior I observe is correct (is it?) >>> >>> Cheers, >>> Przemyslaw >>> >>> >>> >>> >>> On Thu, Apr 3, 2014 at 6:18 AM, Stuart Douglas >>> <stuart.w.douglas(a)gmail.com <mailto:stuart.w.douglas@gmail.com> >>> <mailto:stuart.w.douglas@__gmail.com >>> >>> <mailto:stuart.w.douglas@gmail.com>>> wrote: >>> >>> Can you try with the latest development build of Wildfly >>> (from >>> https://ci.jboss.org/hudson/____job/WildFly-latest-master/ >>> <https://ci.jboss.org/hudson/__job/WildFly-latest-master/> >>> >>> <https://ci.jboss.org/hudson/__job/WildFly-latest-master/ >>> <https://ci.jboss.org/hudson/job/WildFly-latest-master/>>). >>> >>> >>> There have been some fixes in this area, so your problem >>> may have >>> already been fixed. >>> >>> Stuart >>> >>> >>> PB wrote: >>> >>> Hi, >>> >>> I'm testing the HTTP Upgrade feature of WF 8.0 and I'm >>> facing >>> some banal >>> problem. Basically my ReadListener is NEVER called. >>> Here's the code: >>> >>> @WebServlet(urlPatterns = "/upgrade") >>> public class UpgradeServlet extends HttpServlet { >>> @Override >>> protected void doGet(HttpServletRequest req, >>> HttpServletResponse >>> resp) throws ServletException, IOException { >>> if >>> >>> ("upgrade".equalsIgnoreCase(____req.getHeader("Connection"))) { >>> req.upgrade(EchoHandler.class)____; >>> >>> >>> } >>> } >>> } >>> >>> public class EchoHandler implements HttpUpgradeHandler >>> { >>> @Override >>> public void init(WebConnection wc) { >>> try { >>> ServletInputStream in = wc.getInputStream(); >>> ServletOutputStream out = wc.getOutputStream(); >>> >>> BlockingQueue<String> queue = new >>> LinkedBlockingQueue<String>(); >>> in.setReadListener(new EchoReadListener(queue, >>> in)); >>> out.setWriteListener(new >>> EchoWriteListener(queue, out)); >>> } catch (IOException e) { >>> throw new IllegalStateException(e); >>> } >>> } >>> >>> public class EchoReadListener implements ReadListener { >>> @Override >>> public void onDataAvailable() throws IOException { >>> while (in.isReady()) { >>> int length = in.read(buffer); >>> String input = new String(buffer, 0, length); >>> if (false == queue.offer(input)) { >>> System.err.println("'" + input + "' input was >>> ignored"); >>> } >>> } >>> } >>> >>> I'm connecting to WF using telnet and sending the >>> upgrade request: >>> GET /example-webapp/upgrade HTTP/1.1 >>> Host: localhost >>> Connection: upgrade >>> Upgrade: echo >>> >>> and I'm getting correct response: >>> >>> HTTP/1.1 101 Switching Protocols >>> Connection: Upgrade >>> X-Powered-By: Undertow 1 >>> Server: Wildfly 8 >>> Content-Length: 0 >>> >>> which means that from now on the protocol between my >>> telnet >>> client and >>> WF is pure TCP. >>> So, I start typing some text, hit Enter and.... nothing >>> happens. >>> onDataAvailable() is NEVER called. More so, this makes >>> WF totally >>> irresponsive - my whole webapp is dead. >>> >>> I believe, I'm doing something wrong - any ideas what >>> exactly? >>> There is >>> also a slight chance that Upgrade feature in WF is >>> f****d :) >>> Anyway, WF should not block even in case my upgraded >>> protocol is not >>> working correctly? >>> >>> Many thanks, >>> Przemyslaw >>> >>> ___________________________________________________ >>> >>> wildfly-dev mailing list >>> wildfly-dev(a)lists.jboss.org <mailto:wildfly-dev@lists.jboss.org >>> > >>> <mailto:wildfly-dev@lists.__jboss.org >>> <mailto:wildfly-dev@lists.jboss.org>> >>> https://lists.jboss.org/____mailman/listinfo/wildfly-dev >>> <https://lists.jboss.org/__mailman/listinfo/wildfly-dev> >>> <https://lists.jboss.org/__mailman/listinfo/wildfly-dev >>> <https://lists.jboss.org/mailman/listinfo/wildfly-dev>> >>> >>> >>> >>> >>> _______________________________________________ >>> wildfly-dev mailing list >>> wildfly-dev(a)lists.jboss.org >>> https://lists.jboss.org/mailman/listinfo/wildfly-dev >>> >> >