You are viewing a plain text version of this content. The canonical link for it is here.
Posted to dev@mina.apache.org by Pat Chang - 1973 <pa...@gmail.com> on 2007/09/04 08:15:45 UTC
Synchronous communication without dropping connection
Hi,
We want to implement synchronous communication.
After session.write(ProtocolObj); and session.join();, the thread waits
until session is closed.
I would prefer the session to be open, because on the server side, I am
maintaining the data in the server session to accept further data. Secondly,
I think it may not be the optimal way to close and open connections
everytime either.
Is there a way to achieve synchronized communication which does not involve
reconnecting for every request so that we can reuse the data saved int he
server session as well?
Regards
Pat
--
View this message in context: http://www.nabble.com/Synchronous-communication-without-dropping-connection-tf4375713s16868.html#a12472427
Sent from the Apache MINA Support Forum mailing list archive at Nabble.com.
Re: Synchronous communication without dropping connection
Posted by Pat Chang - 1973 <pa...@gmail.com>.
Thanks Michael for your response. I would agree on your approach and we will
explore the implementation that way.
I thought I read somewhere that Mina supports Synchronized communications as
well. I think it was at the serverside portal. I guess when Trustin said
that, he probably meant that the synchronization could be met over a
combination of a session.join() and closing a session in receiving a
response from server.
Thanks again for your reply.
Michael Link wrote:
>
> Hi Pat,
>
> here a little explanation of the MINA mechanisms. When you close a
> client-side connection the underlying socket connection is closed, too.
> Therefore you will also lose all the session data that is stored on the
> server. So it isn't the right way to close and re-open the session to
> implement a request/reponse protocol.
>
> Basically MINA is asynchronous so the outgoing and incoming bytes are
> independent in their socket stream. To implement request/response you must
> do this by yourself. For my project I implemented such a simple protocol.
> After the request is written to the session the calling thread enters a
> wait-Loop based on a synchronized request object and the request object is
> put into a hashmap where the key is a sequence number. After a response
> arrives the sequence id is read from the response and the originating
> request is looked up from the hashmap. Then the waiting thread is woken up
> with requestObj.notify(). Quite simple in the whole but it works fine and
> you can easily support parallel requests from different threads.
>
> Regards,
>
> Michael
>
>
> Pat Chang - 1973 wrote:
>>
>> Dear Maarten,
>>
>> Firstly, thanks for your response. I hope you dont mind my basic
>> questions.
>>
>> In our application we are sending a sequence of files one after the other
>> often through a sequence of session.write() operations. Completion of one
>> write() operation will then invoke the next operation to send the next
>> sequence. So this has to be synchronous so that we identify the closure
>> of the last write() before sending the next one.
>>
>> Now, yes, you are right, at the client thread is blocked until the
>> session is closed. This works.
>>
>> But my doubts / questions are:
>>
>> Question 1: Does closing of session mean closing of actual connection
>> pipe from client to server? So when I sent the next sequence, do I have
>> to reconnect? If yes, then this may not be the optimal way of sending
>> data, as we would need to reconnect every time we send the next set of
>> sequences.
>>
>> Question 2: I use session at the server to store additional data such as
>> user who has logged in and all the files that were transfered in the
>> past. When we close the session at the client, and reconnect, will all
>> this data saved in the server session be lost?
>>
>> A few "simple" code snippets on various aspects of Mina Wiki would help
>> the new "learning" developers like us in quickly learning to use this
>> great library.
>>
>> Thanks again in advance,
>> Pat
>>
>>
>> Maarten Bosteels-4 wrote:
>>>
>>> Hello Pat,
>>>
>>> On 9/4/07, Pat Chang - 1973 <pa...@gmail.com> wrote:
>>>>
>>>>
>>>> Can someone please answer my simple question. Would be much
>>>> appreciated.
>>>>
>>>>
>>>> Pat Chang - 1973 wrote:
>>>> >
>>>> > Hi,
>>>> >
>>>> > We want to implement synchronous communication.
>>>> >
>>>> > After session.write(ProtocolObj); and session.join();, the thread
>>>> waits
>>>> > until session is closed.
>>>
>>>
>>> I guess you session.write(obj).join() since IoSession itself has no
>>> join()
>>> method ?
>>> The thread will wait until the message is written, not until session is
>>> closed.
>>>
>>>>
>>>> > I would prefer the session to be open, because on the server side, I
>>>> am
>>>> > maintaining the data in the server session to accept further data.
>>>> > Secondly, I think it may not be the optimal way to close and open
>>>> > connections everytime either.
>>>
>>>
>>> session stays open after writing to it, until you close it (unless
>>> remote
>>> peer closes it)
>>>
>>> Maarten
>>>
>>>>
>>>> > Is there a way to achieve synchronized communication which does not
>>>> > involve reconnecting for every request so that we can reuse the data
>>>> saved
>>>> > int he server session as well?
>>>> >
>>>> > Regards
>>>
>>>
>>>
>>>
>>>
>>>> Pat
>>>> >
>>>>
>>>> --
>>>> View this message in context:
>>>> http://www.nabble.com/Synchronous-communication-without-dropping-connection-tf4375713s16868.html#a12479878
>>>> Sent from the Apache MINA Support Forum mailing list archive at
>>>> Nabble.com
>>>> .
>>>>
>>>>
>>>
>>>
>>
>>
>
>
--
View this message in context: http://www.nabble.com/Synchronous-communication-without-dropping-connection-tf4375713s16868.html#a12482542
Sent from the Apache MINA Support Forum mailing list archive at Nabble.com.
Re: Synchronous communication without dropping connection
Posted by Michael Link <vj...@gmx.net>.
Hi Pat,
here a little explanation of the MINA mechanisms. When you close a
client-side connection the underlying socket connection is closed, too.
Therefore you will also lose all the session data that is stored on the
server. So it isn't the right way to close and re-open the session to
implement a request/reponse protocol.
Basically MINA is asynchronous so the outgoing and incoming bytes are
independent in their socket stream. To implement request/response you must
do this by yourself. For my project I implemented such a simple protocol.
After the request is written to the session the calling thread enters a
wait-Loop based on a synchronized request object and the request object is
put into a hashmap where the key is a sequence number. After a response
arrives the sequence id is read from the response and the originating
request is looked up from the hashmap. Then the waiting thread is woken up
with requestObj.notify(). Quite simple in the whole but it works fine and
you can easily support parallel requests from different threads.
Regards,
Michael
Pat Chang - 1973 wrote:
>
> Dear Maarten,
>
> Firstly, thanks for your response. I hope you dont mind my basic
> questions.
>
> In our application we are sending a sequence of files one after the other
> often through a sequence of session.write() operations. Completion of one
> write() operation will then invoke the next operation to send the next
> sequence. So this has to be synchronous so that we identify the closure of
> the last write() before sending the next one.
>
> Now, yes, you are right, at the client thread is blocked until the session
> is closed. This works.
>
> But my doubts / questions are:
>
> Question 1: Does closing of session mean closing of actual connection pipe
> from client to server? So when I sent the next sequence, do I have to
> reconnect? If yes, then this may not be the optimal way of sending data,
> as we would need to reconnect every time we send the next set of
> sequences.
>
> Question 2: I use session at the server to store additional data such as
> user who has logged in and all the files that were transfered in the past.
> When we close the session at the client, and reconnect, will all this data
> saved in the server session be lost?
>
> A few "simple" code snippets on various aspects of Mina Wiki would help
> the new "learning" developers like us in quickly learning to use this
> great library.
>
> Thanks again in advance,
> Pat
>
>
> Maarten Bosteels-4 wrote:
>>
>> Hello Pat,
>>
>> On 9/4/07, Pat Chang - 1973 <pa...@gmail.com> wrote:
>>>
>>>
>>> Can someone please answer my simple question. Would be much appreciated.
>>>
>>>
>>> Pat Chang - 1973 wrote:
>>> >
>>> > Hi,
>>> >
>>> > We want to implement synchronous communication.
>>> >
>>> > After session.write(ProtocolObj); and session.join();, the thread
>>> waits
>>> > until session is closed.
>>
>>
>> I guess you session.write(obj).join() since IoSession itself has no
>> join()
>> method ?
>> The thread will wait until the message is written, not until session is
>> closed.
>>
>>>
>>> > I would prefer the session to be open, because on the server side, I
>>> am
>>> > maintaining the data in the server session to accept further data.
>>> > Secondly, I think it may not be the optimal way to close and open
>>> > connections everytime either.
>>
>>
>> session stays open after writing to it, until you close it (unless remote
>> peer closes it)
>>
>> Maarten
>>
>>>
>>> > Is there a way to achieve synchronized communication which does not
>>> > involve reconnecting for every request so that we can reuse the data
>>> saved
>>> > int he server session as well?
>>> >
>>> > Regards
>>
>>
>>
>>
>>
>>> Pat
>>> >
>>>
>>> --
>>> View this message in context:
>>> http://www.nabble.com/Synchronous-communication-without-dropping-connection-tf4375713s16868.html#a12479878
>>> Sent from the Apache MINA Support Forum mailing list archive at
>>> Nabble.com
>>> .
>>>
>>>
>>
>>
>
>
--
View this message in context: http://www.nabble.com/Synchronous-communication-without-dropping-connection-tf4375713s16868.html#a12481979
Sent from the Apache MINA Support Forum mailing list archive at Nabble.com.
Re: Synchronous communication without dropping connection
Posted by Pat Chang - 1973 <pa...@gmail.com>.
Dear Maarten,
Firstly, thanks for your response. I hope you dont mind my basic questions.
In our application we are sending a sequence of files one after the other
often through a sequence of session.write() operations. Completion of one
write() operation will then invoke the next operation to send the next
sequence. So this has to be synchronous so that we identify the closure of
the last write() before sending the next one.
Now, yes, you are right, at the client thread is blocked until the session
is closed. This works.
But my doubts / questions are:
Question 1: Does closing of session mean closing of actual connection pipe
from client to server? So when I sent the next sequence, do I have to
reconnect? If yes, then this may not be the optimal way of sending data, as
we would need to reconnect every time we send the next set of sequences.
Question 2: I use session at the server to store additional data such as
user who has logged in and all the files that were transfered in the past.
When we close the session at the client, and reconnect, will all this data
saved in the server session be lost?
A few "simple" code snippets on various aspects of Mina Wiki would help the
new "learning" developers like us in quickly learning to use this great
library.
Thanks again in advance,
Pat
Maarten Bosteels-4 wrote:
>
> Hello Pat,
>
> On 9/4/07, Pat Chang - 1973 <pa...@gmail.com> wrote:
>>
>>
>> Can someone please answer my simple question. Would be much appreciated.
>>
>>
>> Pat Chang - 1973 wrote:
>> >
>> > Hi,
>> >
>> > We want to implement synchronous communication.
>> >
>> > After session.write(ProtocolObj); and session.join();, the thread
>> waits
>> > until session is closed.
>
>
> I guess you session.write(obj).join() since IoSession itself has no
> join()
> method ?
> The thread will wait until the message is written, not until session is
> closed.
>
>>
>> > I would prefer the session to be open, because on the server side, I am
>> > maintaining the data in the server session to accept further data.
>> > Secondly, I think it may not be the optimal way to close and open
>> > connections everytime either.
>
>
> session stays open after writing to it, until you close it (unless remote
> peer closes it)
>
> Maarten
>
>>
>> > Is there a way to achieve synchronized communication which does not
>> > involve reconnecting for every request so that we can reuse the data
>> saved
>> > int he server session as well?
>> >
>> > Regards
>
>
>
>
>
>> Pat
>> >
>>
>> --
>> View this message in context:
>> http://www.nabble.com/Synchronous-communication-without-dropping-connection-tf4375713s16868.html#a12479878
>> Sent from the Apache MINA Support Forum mailing list archive at
>> Nabble.com
>> .
>>
>>
>
>
--
View this message in context: http://www.nabble.com/Synchronous-communication-without-dropping-connection-tf4375713s16868.html#a12480338
Sent from the Apache MINA Support Forum mailing list archive at Nabble.com.
Re: Synchronous communication without dropping connection
Posted by Maarten Bosteels <mb...@gmail.com>.
Hello Pat,
On 9/4/07, Pat Chang - 1973 <pa...@gmail.com> wrote:
>
>
> Can someone please answer my simple question. Would be much appreciated.
>
>
> Pat Chang - 1973 wrote:
> >
> > Hi,
> >
> > We want to implement synchronous communication.
> >
> > After session.write(ProtocolObj); and session.join();, the thread waits
> > until session is closed.
I guess you session.write(obj).join() since IoSession itself has no join()
method ?
The thread will wait until the message is written, not until session is
closed.
>
> > I would prefer the session to be open, because on the server side, I am
> > maintaining the data in the server session to accept further data.
> > Secondly, I think it may not be the optimal way to close and open
> > connections everytime either.
session stays open after writing to it, until you close it (unless remote
peer closes it)
Maarten
>
> > Is there a way to achieve synchronized communication which does not
> > involve reconnecting for every request so that we can reuse the data
> saved
> > int he server session as well?
> >
> > Regards
> Pat
> >
>
> --
> View this message in context:
> http://www.nabble.com/Synchronous-communication-without-dropping-connection-tf4375713s16868.html#a12479878
> Sent from the Apache MINA Support Forum mailing list archive at Nabble.com
> .
>
>
Re: Synchronous communication without dropping connection
Posted by Pat Chang - 1973 <pa...@gmail.com>.
Can someone please answer my simple question. Would be much appreciated.
Pat Chang - 1973 wrote:
>
> Hi,
>
> We want to implement synchronous communication.
>
> After session.write(ProtocolObj); and session.join();, the thread waits
> until session is closed.
>
> I would prefer the session to be open, because on the server side, I am
> maintaining the data in the server session to accept further data.
> Secondly, I think it may not be the optimal way to close and open
> connections everytime either.
>
> Is there a way to achieve synchronized communication which does not
> involve reconnecting for every request so that we can reuse the data saved
> int he server session as well?
>
> Regards
> Pat
>
--
View this message in context: http://www.nabble.com/Synchronous-communication-without-dropping-connection-tf4375713s16868.html#a12479878
Sent from the Apache MINA Support Forum mailing list archive at Nabble.com.