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Posted to users@tomcat.apache.org by uprooter <up...@gmail.com> on 2008/10/06 16:29:20 UTC
Using tomcat to hold many open connections.
Hi.
I'm looking for a server that has to hold many (web services) remote clients
for controlling them.
I want to do things like sending power off command to a bunch of machines
remotely.
The clients are usually windows machines behind firewalls NAT or web
proxies that only allow HTTP (this is why I thought of webservices)
The regular request-response fashion that servlet follows is not suitable
here since the initiator of the operation is the server.
What can I do in order to solve this and still use web services?
--
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RE: Using tomcat to hold many open connections.
Posted by "Caldarale, Charles R" <Ch...@unisys.com>.
> From: ayden@gera.co.nz [mailto:ayden@gera.co.nz]
> Subject: Re: Using tomcat to hold many open connections.
>
> Does CometProcessor and/or NIO come pre-installed &
> pre-configured as part of Tomcat 6?
All part of the basic package:
http://tomcat.apache.org/tomcat-6.0-doc/aio.html
- Chuck
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Re: Using tomcat to hold many open connections.
Posted by ay...@gera.co.nz.
Does CometProcessor and/or NIO come pre-installed & pre-configured as part
of Tomcat 6?
or do you have to download/install additional things?
> tomcat has one too, it's called the CometProcessor
>
> Filip
>
> Clemens Eisserer wrote:
>> Jetty has a special api to allow exactly this kind of request
>> efficiently.
>> The thread is not kept assignd to the "sleeping" connection, but is
>> re-used.
>>
>> lg Clemens
>>
>> 2008/10/6 Kees Jan Koster <kj...@kjkoster.org>:
>>
>>> Dear Uprooter,
>>>
>>>
>>>> I'm looking for a server that has to hold many (web services) remote
>>>> clients
>>>> for controlling them.
>>>> I want to do things like sending power off command to a bunch of
>>>> machines
>>>> remotely.
>>>>
>>> Building a botnet? :-)
>>>
>>>
>>>> The clients are usually windows machines behind firewalls NAT or web
>>>> proxies that only allow HTTP (this is why I thought of webservices)
>>>>
>>>> The regular request-response fashion that servlet follows is not
>>>> suitable
>>>> here since the initiator of the operation is the server.
>>>> What can I do in order to solve this and still use web services?
>>>>
>>> If you have the resources, you can just block in the servlet on your
>>> server.
>>> It's pretty expensive since Tomcat uses a thread per request I believe.
>>> Java
>>> threads are expensive (256kB each?), so that adds up quickly. You could
>>> spend some time tuning your thread stacks, though. Depending on your
>>> actual
>>> number of clients, you should be able to get this to work with a few GB
>>> of
>>> RAM.
>>>
>>> But then, 20K client polling once an hour might be cheaper. You may
>>> want to
>>> find a way to stagger the requests though.
>>>
>>> --
>>> Kees Jan
>>>
>>> http://java-monitor.com/forum/
>>> kjkoster@kjkoster.org
>>> 06-51838192
>>>
>>> The secret of success lies in the stability of the goal. -- Benjamin
>>> Disraeli
>>>
>>>
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>>>
>>>
>>>
>>
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>>
>
>
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RE: Using tomcat to hold many open connections.
Posted by Martin Gainty <mg...@hotmail.com>.
Jan-
BB software has the potential to cause a considerable amount of havoc and heartache
you could be damaging the disks if you dont quiesce all of your DB,mail,ftp, tc servers first
I can see the utility to either turn on or turn off smart appliances though..
Martin
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> Date: Mon, 6 Oct 2008 15:22:38 -0600
> From: devlists@hanik.com
> To: users@tomcat.apache.org
> Subject: Re: Using tomcat to hold many open connections.
>
> tomcat has one too, it's called the CometProcessor
>
> Filip
>
> Clemens Eisserer wrote:
> > Jetty has a special api to allow exactly this kind of request efficiently.
> > The thread is not kept assignd to the "sleeping" connection, but is re-used.
> >
> > lg Clemens
> >
> > 2008/10/6 Kees Jan Koster <kj...@kjkoster.org>:
> >
> >> Dear Uprooter,
> >>
> >>
> >>> I'm looking for a server that has to hold many (web services) remote
> >>> clients
> >>> for controlling them.
> >>> I want to do things like sending power off command to a bunch of machines
> >>> remotely.
> >>>
> >> Building a botnet? :-)
> >>
> >>
> >>> The clients are usually windows machines behind firewalls NAT or web
> >>> proxies that only allow HTTP (this is why I thought of webservices)
> >>>
> >>> The regular request-response fashion that servlet follows is not suitable
> >>> here since the initiator of the operation is the server.
> >>> What can I do in order to solve this and still use web services?
> >>>
> >> If you have the resources, you can just block in the servlet on your server.
> >> It's pretty expensive since Tomcat uses a thread per request I believe. Java
> >> threads are expensive (256kB each?), so that adds up quickly. You could
> >> spend some time tuning your thread stacks, though. Depending on your actual
> >> number of clients, you should be able to get this to work with a few GB of
> >> RAM.
> >>
> >> But then, 20K client polling once an hour might be cheaper. You may want to
> >> find a way to stagger the requests though.
> >>
> >> --
> >> Kees Jan
> >>
> >> http://java-monitor.com/forum/
> >> kjkoster@kjkoster.org
> >> 06-51838192
> >>
> >> The secret of success lies in the stability of the goal. -- Benjamin
> >> Disraeli
> >>
> >>
> >> ---------------------------------------------------------------------
> >> To start a new topic, e-mail: users@tomcat.apache.org
> >> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
> >> For additional commands, e-mail: users-help@tomcat.apache.org
> >>
> >>
> >>
> >
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> >
> >
> >
>
>
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Re: Using tomcat to hold many open connections.
Posted by Filip Hanik - Dev Lists <de...@hanik.com>.
tomcat has one too, it's called the CometProcessor
Filip
Clemens Eisserer wrote:
> Jetty has a special api to allow exactly this kind of request efficiently.
> The thread is not kept assignd to the "sleeping" connection, but is re-used.
>
> lg Clemens
>
> 2008/10/6 Kees Jan Koster <kj...@kjkoster.org>:
>
>> Dear Uprooter,
>>
>>
>>> I'm looking for a server that has to hold many (web services) remote
>>> clients
>>> for controlling them.
>>> I want to do things like sending power off command to a bunch of machines
>>> remotely.
>>>
>> Building a botnet? :-)
>>
>>
>>> The clients are usually windows machines behind firewalls NAT or web
>>> proxies that only allow HTTP (this is why I thought of webservices)
>>>
>>> The regular request-response fashion that servlet follows is not suitable
>>> here since the initiator of the operation is the server.
>>> What can I do in order to solve this and still use web services?
>>>
>> If you have the resources, you can just block in the servlet on your server.
>> It's pretty expensive since Tomcat uses a thread per request I believe. Java
>> threads are expensive (256kB each?), so that adds up quickly. You could
>> spend some time tuning your thread stacks, though. Depending on your actual
>> number of clients, you should be able to get this to work with a few GB of
>> RAM.
>>
>> But then, 20K client polling once an hour might be cheaper. You may want to
>> find a way to stagger the requests though.
>>
>> --
>> Kees Jan
>>
>> http://java-monitor.com/forum/
>> kjkoster@kjkoster.org
>> 06-51838192
>>
>> The secret of success lies in the stability of the goal. -- Benjamin
>> Disraeli
>>
>>
>> ---------------------------------------------------------------------
>> To start a new topic, e-mail: users@tomcat.apache.org
>> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
>> For additional commands, e-mail: users-help@tomcat.apache.org
>>
>>
>>
>
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>
>
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Re: Using tomcat to hold many open connections.
Posted by Clemens Eisserer <li...@gmail.com>.
Jetty has a special api to allow exactly this kind of request efficiently.
The thread is not kept assignd to the "sleeping" connection, but is re-used.
lg Clemens
2008/10/6 Kees Jan Koster <kj...@kjkoster.org>:
> Dear Uprooter,
>
>> I'm looking for a server that has to hold many (web services) remote
>> clients
>> for controlling them.
>> I want to do things like sending power off command to a bunch of machines
>> remotely.
>
> Building a botnet? :-)
>
>> The clients are usually windows machines behind firewalls NAT or web
>> proxies that only allow HTTP (this is why I thought of webservices)
>>
>> The regular request-response fashion that servlet follows is not suitable
>> here since the initiator of the operation is the server.
>> What can I do in order to solve this and still use web services?
>
> If you have the resources, you can just block in the servlet on your server.
> It's pretty expensive since Tomcat uses a thread per request I believe. Java
> threads are expensive (256kB each?), so that adds up quickly. You could
> spend some time tuning your thread stacks, though. Depending on your actual
> number of clients, you should be able to get this to work with a few GB of
> RAM.
>
> But then, 20K client polling once an hour might be cheaper. You may want to
> find a way to stagger the requests though.
>
> --
> Kees Jan
>
> http://java-monitor.com/forum/
> kjkoster@kjkoster.org
> 06-51838192
>
> The secret of success lies in the stability of the goal. -- Benjamin
> Disraeli
>
>
> ---------------------------------------------------------------------
> To start a new topic, e-mail: users@tomcat.apache.org
> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
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>
>
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Re: Using tomcat to hold many open connections.
Posted by André Warnier <aw...@ice-sa.com>.
Original post :
quote
Hi.
I'm looking for a server that has to hold many (web services) remote clients
for controlling them.
I want to do things like sending power off command to a bunch of machines
remotely.
The clients are usually windows machines behind firewalls NAT or web
proxies that only allow HTTP (this is why I thought of webservices)
The regular request-response fashion that servlet follows is not suitable
here since the initiator of the operation is the server.
What can I do in order to solve this and still use web services?
unquote
I'm not really competent to opinionate on whether Tomcat can do this or
not, but going back to the original description of the problem, apart
from the fact (maybe) that the "clients" are only accessible via port
80, I must say that I don't really see what this has to do with Tomcat,
or any standard HTTP server for that matter.
On the "client" side (the machines to stop), it looks like you would
need some process listening on port 80, able to interpret a limited set
of commands and do something local (stop/start a motor ?).
On the "server" side, you probably want some easy interface allowing you
to send such commands to the many "clients", efficiently and fast.
(I quote the "client" and "server" terms because I'm not quite sure
which is which here).
So I guess yes, to stop yourself from re-inventing the wheel, you could
use webservers on both sides as "containers" for this application, and
you could implement some kind of Web Service to do this, but isn't this
a bit heavy ? I mean that if you have a Tomcat on the client side, most
of the time sitting idle and just wating for the occasional request for
doing something, it is going to take quite a while for it to "wake up"
when it receives this single request, and to process it if it comes in a
SOAP envelope. And if your "server" each time has to wait for each
client to acknowledge the request before going on to the next one, it
will take it a while to loop through all clients.
But then, maybe speed is not the issue here. It's just that you were
talking about powering off a bunch of machines. I hope this has nothing
to do with preventing a nuclear war or so.
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Re: Using tomcat to hold many open connections.
Posted by ay...@gera.co.nz.
Im no techo but I think this is might help
Have a look at icefaces.org
if you can work out how to do it and whats required from tomcat side (NIO
etc) please let me know :)
>
> ----- Original Message -----
> From: "Kees Jan Koster" <kj...@kjkoster.org>
> To: "Tomcat Users List" <us...@tomcat.apache.org>
> Sent: Monday, October 06, 2008 9:22 PM
> Subject: Re: Using tomcat to hold many open connections.
>
>
>> Dear Uprooter,
>>
>>> I'm looking for a server that has to hold many (web services) remote
>>> clients
>>> for controlling them.
>>> I want to do things like sending power off command to a bunch of
>>> machines
>>> remotely.
>>
>> Building a botnet? :-)
>>
>>> The clients are usually windows machines behind firewalls NAT or web
>>> proxies that only allow HTTP (this is why I thought of webservices)
>>>
>>> The regular request-response fashion that servlet follows is not
>>> suitable
>>> here since the initiator of the operation is the server.
>>> What can I do in order to solve this and still use web services?
>>
>> If you have the resources, you can just block in the servlet on your
>> server. It's pretty expensive since Tomcat uses a thread per request I
>> believe. Java threads are expensive (256kB each?), so that adds up
>> quickly. You could spend some time tuning your thread stacks, though.
>> Depending on your actual number of clients, you should be able to get
>> this to work with a few GB of RAM.
>>
>> But then, 20K client polling once an hour might be cheaper. You may
>> want
>> to find a way to stagger the requests though.
>>
>> --
>> Kees Jan
>
> Yes Kees exactly... this is why I say "engineer it"... these guys find a
> hammer, and then everything look like a nail... ha ha
> Without more details we cant engineer it... but I do think, web services
> are
> not the right tool, at most an addendum, not the core... and that there
> are
> two distinct processes at work, web side and machine side... they
> interface
> but cant be combined... to do this right, you got to be a good general
> coder...
>
> ---------------------------------------------------------------------------
> HARBOR : http://www.kewlstuff.co.za/index.htm
> The most powerful application server on earth.
> The only real POJO Application Server.
> See it in Action : http://www.kewlstuff.co.za/cd_tut_swf/whatisejb1.htm
> ---------------------------------------------------------------------------
>
>
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Re: Using tomcat to hold many open connections.
Posted by Johnny Kewl <jo...@kewlstuff.co.za>.
----- Original Message -----
From: "Kees Jan Koster" <kj...@kjkoster.org>
To: "Tomcat Users List" <us...@tomcat.apache.org>
Sent: Monday, October 06, 2008 9:22 PM
Subject: Re: Using tomcat to hold many open connections.
> Dear Uprooter,
>
>> I'm looking for a server that has to hold many (web services) remote
>> clients
>> for controlling them.
>> I want to do things like sending power off command to a bunch of
>> machines
>> remotely.
>
> Building a botnet? :-)
>
>> The clients are usually windows machines behind firewalls NAT or web
>> proxies that only allow HTTP (this is why I thought of webservices)
>>
>> The regular request-response fashion that servlet follows is not
>> suitable
>> here since the initiator of the operation is the server.
>> What can I do in order to solve this and still use web services?
>
> If you have the resources, you can just block in the servlet on your
> server. It's pretty expensive since Tomcat uses a thread per request I
> believe. Java threads are expensive (256kB each?), so that adds up
> quickly. You could spend some time tuning your thread stacks, though.
> Depending on your actual number of clients, you should be able to get
> this to work with a few GB of RAM.
>
> But then, 20K client polling once an hour might be cheaper. You may want
> to find a way to stagger the requests though.
>
> --
> Kees Jan
Yes Kees exactly... this is why I say "engineer it"... these guys find a
hammer, and then everything look like a nail... ha ha
Without more details we cant engineer it... but I do think, web services are
not the right tool, at most an addendum, not the core... and that there are
two distinct processes at work, web side and machine side... they interface
but cant be combined... to do this right, you got to be a good general
coder...
---------------------------------------------------------------------------
HARBOR : http://www.kewlstuff.co.za/index.htm
The most powerful application server on earth.
The only real POJO Application Server.
See it in Action : http://www.kewlstuff.co.za/cd_tut_swf/whatisejb1.htm
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Re: Using tomcat to hold many open connections.
Posted by Kees Jan Koster <kj...@kjkoster.org>.
Dear Uprooter,
> I'm looking for a server that has to hold many (web services) remote
> clients
> for controlling them.
> I want to do things like sending power off command to a bunch of
> machines
> remotely.
Building a botnet? :-)
> The clients are usually windows machines behind firewalls NAT or web
> proxies that only allow HTTP (this is why I thought of webservices)
>
> The regular request-response fashion that servlet follows is not
> suitable
> here since the initiator of the operation is the server.
> What can I do in order to solve this and still use web services?
If you have the resources, you can just block in the servlet on your
server. It's pretty expensive since Tomcat uses a thread per request I
believe. Java threads are expensive (256kB each?), so that adds up
quickly. You could spend some time tuning your thread stacks, though.
Depending on your actual number of clients, you should be able to get
this to work with a few GB of RAM.
But then, 20K client polling once an hour might be cheaper. You may
want to find a way to stagger the requests though.
--
Kees Jan
http://java-monitor.com/forum/
kjkoster@kjkoster.org
06-51838192
The secret of success lies in the stability of the goal. -- Benjamin
Disraeli
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Re: Using tomcat to hold many open connections.
Posted by Johnny Kewl <jo...@kewlstuff.co.za>.
----- Original Message -----
From: "uprooter" <up...@gmail.com>
To: <us...@tomcat.apache.org>
Sent: Monday, October 06, 2008 6:48 PM
Subject: Re: Using tomcat to hold many open connections.
>
> Thanks johnny.
> Will TC can survive 20k polling clients ?
How much pipe do you have?
How "real time" do you want it?
Are you images displayed on google earth, or just 1 byte that represent on
or off?
This is the design you have to do, this is the engineering you have to do...
that will tell you how much pipe you need, TC is very likely not the
restiriction, and if it was, you would use more than one.
Clients only poll for a specific item, if they open, if the user is on that
view, and that in itself is no the issue normally... its a small question...
.... have you got data for me? ... a few bytes... but then if you deliver
google earth... thats the issue and there are other technologies here like
ETAGS as work... ie if data has not changed... nothing is sent.
Thats the way it is... you are never going to be able to push to a client on
a dail up for example... its the only way.
Server watches the machines close to perfect real time.... the web gets that
as fast as the web allows... just think about your browser displaying
video... theres a pragmatic limits, and thats what makes one solution well
engineered and another a blindly applied technology, thats a disaster... you
can make it good or you can make a terrible solution....
Can you calculate the byte traffic?... that will tell you which way to go ;)
You got to engineer it... and becareful of all the IT spam out there, make
sure you understand it...
Good Luck...
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HARBOR : http://www.kewlstuff.co.za/index.htm
The most powerful application server on earth.
The only real POJO Application Server.
See it in Action : http://www.kewlstuff.co.za/cd_tut_swf/whatisejb1.htm
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Re: Using tomcat to hold many open connections.
Posted by uprooter <up...@gmail.com>.
Thanks johnny.
Will TC can survive 20k polling clients ?
Johnny Kewl wrote:
>
>
> ----- Original Message -----
> From: "uprooter" <up...@gmail.com>
> To: <us...@tomcat.apache.org>
> Sent: Monday, October 06, 2008 4:29 PM
> Subject: Using tomcat to hold many open connections.
>
>
>>
>> Hi.
>> I'm looking for a server that has to hold many (web services) remote
>> clients
>> for controlling them.
>> I want to do things like sending power off command to a bunch of machines
>> remotely.
>> The clients are usually windows machines behind firewalls NAT or web
>> proxies that only allow HTTP (this is why I thought of webservices)
>>
>> The regular request-response fashion that servlet follows is not
>> suitable
>> here since the initiator of the operation is the server.
>> What can I do in order to solve this and still use web services?
>
> HTTP is pull only.... Browser asked a question, server answers
> But technologies like Ajax (javascript with a fancy name) simulate real
> time
> display... they can poll.
> So thats how you get your charts...
>
> (talks to server)
>
> TC will service those requests but inside TC you can do anything... and in
> your case beside the monitoring stuff you going to have a machine client.
> ie either the machines are "mini webservers" and or they using a serial
> protocol... so you have a "machine service" that talks to them, and
> monitors
> them.
> The design may even include talking to a PLC or some some other
> controller,
> possibly even relay logic if the there are safety aspects... ie cant have
> the factory shutdown just because a web server crashed, so got to think
> about that.
>
> For cool charting and that sort of thing, you looking at rich clients...
> TC
> has GWT, and Flex and our Pojo Application Server which allows you to run
> normal Java at the client as well for cool real time graphs and that sort
> of
> thing. What the PAS can also do is run mixed native and you going to need
> it
> because java is not hot on serial/usb parellel etc... which you will need
> for the machine interface... typically the drivers and the interface are
> not
> done in Java.
>
> Really cool project you got there... there are lots of skills needed but I
> would definitely use TC.
> You outside the box, crossing over between engineering, electronics and IT
> so you not going to get too much help in any one mailing list... but it
> can
> be done if you know the protocol on the machines, and you good... in the
> end
> you'll watch and control those machines from anywhere... lucky devil, its
> a
> technical orgasm.. ha ha
>
> ---------------------------------------------------------------------------
> HARBOR : http://www.kewlstuff.co.za/index.htm
> The most powerful application server on earth.
> The only real POJO Application Server.
> See it in Action : http://www.kewlstuff.co.za/cd_tut_swf/whatisejb1.htm
> ---------------------------------------------------------------------------
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Re: Using tomcat to hold many open connections.
Posted by Johnny Kewl <jo...@kewlstuff.co.za>.
----- Original Message -----
From: "uprooter" <up...@gmail.com>
To: <us...@tomcat.apache.org>
Sent: Monday, October 06, 2008 4:29 PM
Subject: Using tomcat to hold many open connections.
>
> Hi.
> I'm looking for a server that has to hold many (web services) remote
> clients
> for controlling them.
> I want to do things like sending power off command to a bunch of machines
> remotely.
> The clients are usually windows machines behind firewalls NAT or web
> proxies that only allow HTTP (this is why I thought of webservices)
>
> The regular request-response fashion that servlet follows is not suitable
> here since the initiator of the operation is the server.
> What can I do in order to solve this and still use web services?
HTTP is pull only.... Browser asked a question, server answers
But technologies like Ajax (javascript with a fancy name) simulate real time
display... they can poll.
So thats how you get your charts...
(talks to server)
TC will service those requests but inside TC you can do anything... and in
your case beside the monitoring stuff you going to have a machine client.
ie either the machines are "mini webservers" and or they using a serial
protocol... so you have a "machine service" that talks to them, and monitors
them.
The design may even include talking to a PLC or some some other controller,
possibly even relay logic if the there are safety aspects... ie cant have
the factory shutdown just because a web server crashed, so got to think
about that.
For cool charting and that sort of thing, you looking at rich clients... TC
has GWT, and Flex and our Pojo Application Server which allows you to run
normal Java at the client as well for cool real time graphs and that sort of
thing. What the PAS can also do is run mixed native and you going to need it
because java is not hot on serial/usb parellel etc... which you will need
for the machine interface... typically the drivers and the interface are not
done in Java.
Really cool project you got there... there are lots of skills needed but I
would definitely use TC.
You outside the box, crossing over between engineering, electronics and IT
so you not going to get too much help in any one mailing list... but it can
be done if you know the protocol on the machines, and you good... in the end
you'll watch and control those machines from anywhere... lucky devil, its a
technical orgasm.. ha ha
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