Hi,
I am writing a Grizzly Adapter that compute asynchronously several requests and return the results as they are computed in the server. It means that my UI make a single GET and just have, in a streaming way, each request result as they are computed on the server side.
To implement this I use grizzly 1.8.6.1 and the CometEngine. On each service() call a CometContext and a CometHandler are created in order to send back the results as they are computed.
My first question is that I am not sure that it's a good design to create a CometContext and a CometHandler on each service() call. Of course, on each service() call different requests are computed. So I use different CometContext to ensure that the right UI will get the right results.
The problem that I have is to understand how to manage correctly the case when all the asynchronous requests are completed. What I want to do is to send back an end notification to my UI and to finish the request.
I tried many different ways and each of them falls into issues.
What about simply resuming the request and finishing it?
If I try to use the CometEngine in a normal way (as I can read in the documentation) I fall also into issues. On the last message at the end of all the requests, I send a cometContext.notify(message, CometEvent.TERMINATE) and in the onTerminate() handler of my CometHandler I call the cometContext.removeCometHandler(). This way everything works fine but the CometContext instances are not removed from the CometEngine.
So after a while, I have many CometContext instances registered into the CometEngine and I have issues.
I tried to call the unregister() method of the CometEngine but it cause many issues.
Could you tell me if there is an automatic unregistration mechanism or what is the good way to do that?
PS: In my case, when I speak about issues it means that I have error stack trace on my java console. Something like:
---------------------------------------------------------------------------
com.sun.grizzly.DefaultProtocolChain executeProtocolFilter
GRAVE: ProtocolChain exception
java.lang.NullPointerException
at com.sun.grizzly.Context.getProtocol(Context.java:601)
at com.sun.grizzly.filter.ReadFilter.execute(ReadFilter.java:133)
at com.sun.grizzly.filter.ReadFilter.execute(ReadFilter.java:98)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:136)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:103)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:89)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:76)
at com.sun.grizzly.comet.CometTask.doTask(CometTask.java:248)
at com.sun.grizzly.http.TaskBase.call(TaskBase.java:359)
at com.sun.grizzly.util.WorkerThreadImpl.processTask(WorkerThreadImpl.java:325)
at com.sun.grizzly.util.WorkerThreadImpl.run(WorkerThreadImpl.java:184)
---------------------------------------------------------------------------
com.sun.grizzly.http.DefaultProcessorTask invokeAdapter
GRAVE: HTTP Processing error
java.nio.channels.ClosedChannelException
at sun.nio.ch.SocketChannelImpl.ensureWriteOpen(SocketChannelImpl.java:126)
at sun.nio.ch.SocketChannelImpl.write(SocketChannelImpl.java:324)
at com.sun.grizzly.util.OutputWriter.flushChannel(OutputWriter.java:105)
at com.sun.grizzly.util.OutputWriter.flushChannel(OutputWriter.java:73)
at com.sun.grizzly.http.SocketChannelOutputBuffer.flushChannel(SocketChannelOutputBuffer.java:175)
at com.sun.grizzly.http.SocketChannelOutputBuffer.flushBuffer(SocketChannelOutputBuffer.java:208)
at com.sun.grizzly.http.SocketChannelOutputBuffer.flush(SocketChannelOutputBuffer.java:186)
at com.sun.grizzly.http.SocketChannelOutputBuffer.realWriteBytes(SocketChannelOutputBuffer.java:150)
at com.sun.grizzly.tcp.http11.InternalOutputBuffer$OutputStreamOutputBuffer.doWrite(InternalOutputBuffer.java:864)
at com.sun.grizzly.tcp.http11.filters.IdentityOutputFilter.doWrite(IdentityOutputFilter.java:155)
at com.sun.grizzly.tcp.http11.InternalOutputBuffer.doWrite(InternalOutputBuffer.java:620)
at com.sun.grizzly.tcp.Response.doWrite(Response.java:623)
---------------------------------------------------------------------------
Thanks for your help.
Don't hesitate if you want more details.
Regards,
Etienne VRIGNAUD