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Posted to users@mina.apache.org by vanja ozegovic <va...@gmail.com> on 2011/09/02 14:23:13 UTC
Proxy HTTP-Serial
Hello everyone,
I'm new in this mailing list; my name is Vanja Ozegovic and I'm currently
getting to know Apache Mina. I have read the tutorials, documentation and
the code, and have been working with the framework for couple of months.
The problem I am facing is as follows. I created a proxy server in Apache
Mina, following the logic in Proxy Example. On the server side I have an
HTTP server (also following modified HTTP server logic) and on the client
side I have a Serial Port Connector.
The main requirement is to be able to process petitions from thousands HTTP
clients simultaneously. I am aware that this is not possible on the serial
port side since the access to the serial port is exclusive (one client at a
moment). My question is what would be the correct approach for
synchronization in this case?
I was considering to create a request queue on the server side, to allow
only one petition to be forwarded to the Serial Port Connector at a given
moment but this doesn't seem quite correct. I also though about using
semaphores but this doesn't seem to be right neither since I need to
restrict access for obtaining the serial port session and also to restrict
the writing the messages to the serial port session (in sessionOpened and
messageReceived methods respectively). Is there any other approach?
I haven't work that deeply with event driven approach, so if anyone can
provide my a hint on this problem, I would be very grateful.
Best Regards,
V. Ozegovic
RE: Proxy HTTP-Serial
Posted by Vanja Ozegovic <va...@gmail.com>.
Hello,
I agree, but in that case I will be able to have a reference to who to send
back the request but it still doesn't solve the issue of synchronization.
The issue as I stated is that only one client can access the serial port
channel (serial connector) but many petitions can come to HTTP server side.
I need to make those requests wait somehow and execute on the serial client
side one by one.
Hu, Mei Mei wrote:
>
> I'm not quite understand the detail. However, if you put a message into
> some queue after receiving a message, you can wrap the message along with
> the session into 1 object and put that obj in the queue.
>
>
>
>
>
> -----Original Message-----
> From: Vanja Ozegovic [mailto:vanja.ozegovic@gmail.com]
> Sent: Thursday, September 08, 2011 10:37 AM
> To: users@mina.apache.org
> Subject: Re: Proxy HTTP-Serial
>
>
> Hello everyone,
>
> I worked out this problem so I will post my experience in case someone
> else
> has a similar issue.
>
> As I stated before, I thought first about using queues for incoming
> requests. This wouldn't solve my synchronization issues, because at the
> end,
> I needed to simulate synchronous communication through all the layers (the
> same request received on HTTP server side has to be forwarded to Serial
> port
> client and vice-versa with the response). That meant that if I put a
> message
> into some queue I wouldn't know to who to send the response (or at least
> it
> would be quite more complicated).
>
> The other approach of using semaphores/critical sections worked but not as
> I
> imagined in the beginning.
>
> To be able to provide a "real" synchronization on both events
> (messageReceived and sessionOpened), I needed to "group" these somehow.
> What
> I ended up using is customized approach. I took the idea from HTTP Server
> implementation example (streaming case) and created my own thread which
> will
> start every time a message is received on HTTP Server side.
>
> In this thread the connection to serial port is established and listener
> for
> "connect" method is created. Only when OperationComplete is invoked
> (connection is established), the message is sent from HTTP Server side to
> the Serial port side (serial port session). I tried using synchronizing
> run() method but this approach always blocked the second thread (second
> client) and didn't work well. In stead of that at the end, inside the
> run()
> method, I used semaphores (semaph.acquireUninterruptibly();) which solves
> the problem correctly. Semaphore is released on the serial port handler
> side
> when the response is sent back.
>
> The downside is that all the incoming requests for the HTTP server side
> are
> mapped to threads and these are maintained in the memory until their
> execution is finished (few seconds per thread in my testing environment).
> This is the only solution I found without denegating the service to the
> clients.
>
> Best Regards,
> Vanja Ozegovic
>
>
> Vanja Ozegovic wrote:
>>
>> Hello everyone,
>>
>> I'm new in this mailing list; my name is Vanja Ozegovic and I'm currently
>> getting to know Apache Mina. I have read the tutorials, documentation and
>> the code, and have been working with the framework for couple of months.
>>
>> The problem I am facing is as follows. I created a proxy server in Apache
>> Mina, following the logic in Proxy Example. On the server side I have an
>> HTTP server (also following modified HTTP server logic) and on the client
>> side I have a Serial Port Connector.
>>
>> The main requirement is to be able to process petitions from thousands
>> HTTP
>> clients simultaneously. I am aware that this is not possible on the
>> serial
>> port side since the access to the serial port is exclusive (one client at
>> a
>> moment). My question is what would be the correct approach for
>> synchronization in this case?
>>
>> I was considering to create a request queue on the server side, to allow
>> only one petition to be forwarded to the Serial Port Connector at a given
>> moment but this doesn't seem quite correct. I also though about using
>> semaphores but this doesn't seem to be right neither since I need to
>> restrict access for obtaining the serial port session and also to
>> restrict
>> the writing the messages to the serial port session (in sessionOpened and
>> messageReceived methods respectively). Is there any other approach?
>>
>> I haven't work that deeply with event driven approach, so if anyone can
>> provide my a hint on this problem, I would be very grateful.
>>
>> Best Regards,
>> V. Ozegovic
>>
>>
>
> --
> View this message in context:
> http://old.nabble.com/Proxy-HTTP-Serial-tp32386348p32424100.html
> Sent from the Apache MINA User Forum mailing list archive at Nabble.com.
>
>
>
-----
Best Regards,
Vanja Ozegovic
--
View this message in context: http://old.nabble.com/Proxy-HTTP-Serial-tp32386348p32426020.html
Sent from the Apache MINA User Forum mailing list archive at Nabble.com.
RE: Proxy HTTP-Serial
Posted by "Hu, Mei Mei " <me...@citi.com>.
I'm not quite understand the detail. However, if you put a message into some queue after receiving a message, you can wrap the message along with the session into 1 object and put that obj in the queue.
-----Original Message-----
From: Vanja Ozegovic [mailto:vanja.ozegovic@gmail.com]
Sent: Thursday, September 08, 2011 10:37 AM
To: users@mina.apache.org
Subject: Re: Proxy HTTP-Serial
Hello everyone,
I worked out this problem so I will post my experience in case someone else
has a similar issue.
As I stated before, I thought first about using queues for incoming
requests. This wouldn't solve my synchronization issues, because at the end,
I needed to simulate synchronous communication through all the layers (the
same request received on HTTP server side has to be forwarded to Serial port
client and vice-versa with the response). That meant that if I put a message
into some queue I wouldn't know to who to send the response (or at least it
would be quite more complicated).
The other approach of using semaphores/critical sections worked but not as I
imagined in the beginning.
To be able to provide a "real" synchronization on both events
(messageReceived and sessionOpened), I needed to "group" these somehow. What
I ended up using is customized approach. I took the idea from HTTP Server
implementation example (streaming case) and created my own thread which will
start every time a message is received on HTTP Server side.
In this thread the connection to serial port is established and listener for
"connect" method is created. Only when OperationComplete is invoked
(connection is established), the message is sent from HTTP Server side to
the Serial port side (serial port session). I tried using synchronizing
run() method but this approach always blocked the second thread (second
client) and didn't work well. In stead of that at the end, inside the run()
method, I used semaphores (semaph.acquireUninterruptibly();) which solves
the problem correctly. Semaphore is released on the serial port handler side
when the response is sent back.
The downside is that all the incoming requests for the HTTP server side are
mapped to threads and these are maintained in the memory until their
execution is finished (few seconds per thread in my testing environment).
This is the only solution I found without denegating the service to the
clients.
Best Regards,
Vanja Ozegovic
Vanja Ozegovic wrote:
>
> Hello everyone,
>
> I'm new in this mailing list; my name is Vanja Ozegovic and I'm currently
> getting to know Apache Mina. I have read the tutorials, documentation and
> the code, and have been working with the framework for couple of months.
>
> The problem I am facing is as follows. I created a proxy server in Apache
> Mina, following the logic in Proxy Example. On the server side I have an
> HTTP server (also following modified HTTP server logic) and on the client
> side I have a Serial Port Connector.
>
> The main requirement is to be able to process petitions from thousands
> HTTP
> clients simultaneously. I am aware that this is not possible on the serial
> port side since the access to the serial port is exclusive (one client at
> a
> moment). My question is what would be the correct approach for
> synchronization in this case?
>
> I was considering to create a request queue on the server side, to allow
> only one petition to be forwarded to the Serial Port Connector at a given
> moment but this doesn't seem quite correct. I also though about using
> semaphores but this doesn't seem to be right neither since I need to
> restrict access for obtaining the serial port session and also to restrict
> the writing the messages to the serial port session (in sessionOpened and
> messageReceived methods respectively). Is there any other approach?
>
> I haven't work that deeply with event driven approach, so if anyone can
> provide my a hint on this problem, I would be very grateful.
>
> Best Regards,
> V. Ozegovic
>
>
--
View this message in context: http://old.nabble.com/Proxy-HTTP-Serial-tp32386348p32424100.html
Sent from the Apache MINA User Forum mailing list archive at Nabble.com.
Re: Proxy HTTP-Serial
Posted by Vanja Ozegovic <va...@gmail.com>.
Hello everyone,
I worked out this problem so I will post my experience in case someone else
has a similar issue.
As I stated before, I thought first about using queues for incoming
requests. This wouldn't solve my synchronization issues, because at the end,
I needed to simulate synchronous communication through all the layers (the
same request received on HTTP server side has to be forwarded to Serial port
client and vice-versa with the response). That meant that if I put a message
into some queue I wouldn't know to who to send the response (or at least it
would be quite more complicated).
The other approach of using semaphores/critical sections worked but not as I
imagined in the beginning.
To be able to provide a "real" synchronization on both events
(messageReceived and sessionOpened), I needed to "group" these somehow. What
I ended up using is customized approach. I took the idea from HTTP Server
implementation example (streaming case) and created my own thread which will
start every time a message is received on HTTP Server side.
In this thread the connection to serial port is established and listener for
"connect" method is created. Only when OperationComplete is invoked
(connection is established), the message is sent from HTTP Server side to
the Serial port side (serial port session). I tried using synchronizing
run() method but this approach always blocked the second thread (second
client) and didn't work well. In stead of that at the end, inside the run()
method, I used semaphores (semaph.acquireUninterruptibly();) which solves
the problem correctly. Semaphore is released on the serial port handler side
when the response is sent back.
The downside is that all the incoming requests for the HTTP server side are
mapped to threads and these are maintained in the memory until their
execution is finished (few seconds per thread in my testing environment).
This is the only solution I found without denegating the service to the
clients.
Best Regards,
Vanja Ozegovic
Vanja Ozegovic wrote:
>
> Hello everyone,
>
> I'm new in this mailing list; my name is Vanja Ozegovic and I'm currently
> getting to know Apache Mina. I have read the tutorials, documentation and
> the code, and have been working with the framework for couple of months.
>
> The problem I am facing is as follows. I created a proxy server in Apache
> Mina, following the logic in Proxy Example. On the server side I have an
> HTTP server (also following modified HTTP server logic) and on the client
> side I have a Serial Port Connector.
>
> The main requirement is to be able to process petitions from thousands
> HTTP
> clients simultaneously. I am aware that this is not possible on the serial
> port side since the access to the serial port is exclusive (one client at
> a
> moment). My question is what would be the correct approach for
> synchronization in this case?
>
> I was considering to create a request queue on the server side, to allow
> only one petition to be forwarded to the Serial Port Connector at a given
> moment but this doesn't seem quite correct. I also though about using
> semaphores but this doesn't seem to be right neither since I need to
> restrict access for obtaining the serial port session and also to restrict
> the writing the messages to the serial port session (in sessionOpened and
> messageReceived methods respectively). Is there any other approach?
>
> I haven't work that deeply with event driven approach, so if anyone can
> provide my a hint on this problem, I would be very grateful.
>
> Best Regards,
> V. Ozegovic
>
>
--
View this message in context: http://old.nabble.com/Proxy-HTTP-Serial-tp32386348p32424100.html
Sent from the Apache MINA User Forum mailing list archive at Nabble.com.