Hi Jason,
that would be great. I appreciate.
Take your time, it's not super urgent but I would like to have a complete
example of the full-duplex upgrade mechanism using standard API. Then I
would be more than interested in seeing how I can employ undertow to do the
job :)
Cheers,
Przemyslaw
3 kwi 2014 20:31 "Jason T. Greene" <jgreene(a)redhat.com> napisał(a):
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>
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>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
>
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