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Posted to dev@hc.apache.org by Sven Köhler <sk...@upb.de> on 2003/11/12 01:55:23 UTC
Cookies, Chunked-Post & Threads
Hi,
i'm working on a so called ProxyServlet which uses the Information
provided by the ServletContainer to deliver the Requests to another
Web-Server.
At present, i'm using the HttpMethod-Objects (GetMethod, PutMethod, ...)
and HttpClient.execute() to deliver the Requests to the other Web-Server.
I hope you can provide me with some sollutions to the following Problems:
- I like to maintain one "Cookie-Container" for each Session (Session =
Session-Object offered by the Servlet-Container)
- I like my Servlet to be Thread-safe and be abled to deliver many
(unlimited) requests at a time
- I tried to avoid the Content-Length Header in POST requests by using
Chunked Transfer-Encoding, but the Apache-Server i'm using for testing
seems to deny chunked POST-requests.
Well, how's cookie-management done in Commons-HttpClient? Does each
HttpClient-Object maintain it's own "Cookie-Container"?
HttpClient.execute() doesn't seem to be thread-safe.
I like chunked Transfer-Encoding since is more like a stream and not
like that huge block of data that's usually used (content-length header
etc.) Are chunked POST-Requests not allowed? Well, i'm setting the
content-length header right now if it is provided to the servlet. So
that's a big proble, but i'm just curious.
Thx
Sven
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Re: Cookies, Chunked-Post & Threads
Posted by Sven Köhler <sk...@upb.de>.
> browsers make requests in parallel for *one* user!
> Meaning that all the cookies returned end up in the
> same cookie store, as they do here.
> A proxy servlet will make requests for different users
> (browsers) and therefore has to maintain a different
> state for each user. That state is typically associated
> with the session between the browser and servlet.
I maintain a HttpState-Object for each Session the Servlet sees.
> It's either that, or different state objects for each
> session. But you can't just throw all cookies returned
> for all users into a single state and expect the HTTP
> client to figure out which cookie belongs to which
> user.
Sorry, it seems we missunderstood each other. I never wanted to put all
in one HttpState-Object. My intention was to maintain one "CookieBox"
per Session and that's what i do with the HttpState-Objects at the moment.
Everything works fine now.
Thanks for your help.
Sven
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Re: Cookies, Chunked-Post & Threads
Posted by Roland Weber <RO...@de.ibm.com>.
Hello Sven,
browsers make requests in parallel for *one* user!
Meaning that all the cookies returned end up in the
same cookie store, as they do here.
A proxy servlet will make requests for different users
(browsers) and therefore has to maintain a different
state for each user. That state is typically associated
with the session between the browser and servlet.
I have rewritten our own proxy servlet to optionally use
the HTTP Client instead of the HttpURLConnection,
and I didn't encounter problems with parallel requests
by now. Which could also indicate that I didn't have
enough time to test it thoroughly yet :-)
Anyway, I handle "cookie" and "set-cookie" headers
manually and use a single state object that does
never store any cookies. And when manually handling
the cookies, I use a "CookieBox" class that gets
instantiated once for each session.
It's either that, or different state objects for each
session. But you can't just throw all cookies returned
for all users into a single state and expect the HTTP
client to figure out which cookie belongs to which
user.
regards,
Roland
Sven Köhler <sk...@upb.de>
12.11.2003 15:40
Please respond to "Commons HttpClient Project"
To: Commons HttpClient Project
<co...@jakarta.apache.org>
cc:
Subject: Re: Cookies, Chunked-Post & Threads
> unless you have taken special precautions, the state object
> is used to store cookies. Using the same state from different
> threads can mix up the cookies from different clients pretty
> badly.
> Once you have the cookie problem solved, there is no issue
> with using the same state object. I dimly remember seeing
> some synchronized statements in there. Anyway, except for
> storing cookies, it is accessed read-only.
Well, it's a that odd application of the HttpState-Object since every
browser makes multiple requests to a server in parrallel. So this would
be a feature i would request.
Well, most methods of HttpState seem to be synchronized, but as i
already mentioned, it's pretty easy to easy to solve any "bad mix-up".
What i don't want is to serialize (meaning executing one after another)
the HTTP-Requests. I want them to execute in parralel.
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Re: Cookies, Chunked-Post & Threads
Posted by Sven Köhler <sk...@upb.de>.
> unless you have taken special precautions, the state object
> is used to store cookies. Using the same state from different
> threads can mix up the cookies from different clients pretty
> badly.
> Once you have the cookie problem solved, there is no issue
> with using the same state object. I dimly remember seeing
> some synchronized statements in there. Anyway, except for
> storing cookies, it is accessed read-only.
Well, it's a that odd application of the HttpState-Object since every
browser makes multiple requests to a server in parrallel. So this would
be a feature i would request.
Well, most methods of HttpState seem to be synchronized, but as i
already mentioned, it's pretty easy to easy to solve any "bad mix-up".
What i don't want is to serialize (meaning executing one after another)
the HTTP-Requests. I want them to execute in parralel.
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Re: Cookies, Chunked-Post & Threads
Posted by Roland Weber <RO...@de.ibm.com>.
Hello Sven,
unless you have taken special precautions, the state object
is used to store cookies. Using the same state from different
threads can mix up the cookies from different clients pretty
badly.
Once you have the cookie problem solved, there is no issue
with using the same state object. I dimly remember seeing
some synchronized statements in there. Anyway, except for
storing cookies, it is accessed read-only.
regards,
Roland
Sven Köhler <sk...@upb.de>
12.11.2003 15:02
Please respond to "Commons HttpClient Project"
To: Commons HttpClient Project
<co...@jakarta.apache.org>
cc:
Subject: Re: Cookies, Chunked-Post & Threads
> HttpClient.executeMethod
> (HostConfiguration, HttpMethod, HttpState)
>
> If you have used the same client from different
> threads without specifying different states, that
> might be a problem.
Well, i use this method now from different thread with different
HttpStates. I'd like to use even one HttpState-Object from different
threads! Is that possible. I'm doing that right now, but i'm not sure if
the HttpClient-APIs cares about that case.
If not, that would be very easy:
synchronized (state)
{
//get cookie headers
}
//execute HTTP-request
synchronized (state)
{
//put cookie header
}
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Re: Cookies, Chunked-Post & Threads
Posted by Sven Köhler <sk...@upb.de>.
> HttpClient.executeMethod
> (HostConfiguration, HttpMethod, HttpState)
>
> If you have used the same client from different
> threads without specifying different states, that
> might be a problem.
Well, i use this method now from different thread with different
HttpStates. I'd like to use even one HttpState-Object from different
threads! Is that possible. I'm doing that right now, but i'm not sure if
the HttpClient-APIs cares about that case.
If not, that would be very easy:
synchronized (state)
{
//get cookie headers
}
//execute HTTP-request
synchronized (state)
{
//put cookie header
}
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Re: Cookies, Chunked-Post & Threads
Posted by Roland Weber <RO...@de.ibm.com>.
Hello Sven
you don't specify the HttpState for a connection.
You specify it for each method execution:
HttpClient.executeMethod
(HostConfiguration, HttpMethod, HttpState)
If you have used the same client from different
threads without specifying different states, that
might be a problem.
regards,
Roland
Sven Köhler <sk...@upb.de>
12.11.2003 14:27
Please respond to "Commons HttpClient Project"
To: Commons HttpClient Project
<co...@jakarta.apache.org>
cc:
Subject: Re: Cookies, Chunked-Post & Threads
> 1. Cookie Container:
> Let every session use it's own HttpState object. That's where
> HTTP Client stores it's cookies. The only problem is that it's
> not serializable, so it won't work with persistent sessions.
That's OK, but how do i say which HttpState to use for which connection?
> 2. Thread Safety:
> HTTP Client is thread safe as long as you use a thread safe
> connection manager.
Perhaps that's a bug or just intended behaviour, but multiple
HttpClient-Object used from different threads using one
MultiThreadHttpConnectionManager doesn't seems to work properly.
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Re: Cookies, Chunked-Post & Threads
Posted by Sven Köhler <sk...@upb.de>.
> 1. Cookie Container:
> Let every session use it's own HttpState object. That's where
> HTTP Client stores it's cookies. The only problem is that it's
> not serializable, so it won't work with persistent sessions.
That's OK, but how do i say which HttpState to use for which connection?
> 2. Thread Safety:
> HTTP Client is thread safe as long as you use a thread safe
> connection manager.
Perhaps that's a bug or just intended behaviour, but multiple
HttpClient-Object used from different threads using one
MultiThreadHttpConnectionManager doesn't seems to work properly.
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Re: Cookies, Chunked-Post & Threads
Posted by Roland Weber <RO...@de.ibm.com>.
Hello Sven,
1. Cookie Container:
Let every session use it's own HttpState object. That's where
HTTP Client stores it's cookies. The only problem is that it's
not serializable, so it won't work with persistent sessions.
2. Thread Safety:
HTTP Client is thread safe as long as you use a thread safe
connection manager.
3. Unlimited Requests:
Adjust the parameters of the MultiThreadedConnectionManager
to change the maximum number of simultaneous requests. Your
servlet container most likely has some load limitation policy, so
you don't have to allow much more connections than there are
threads to execute servlets.
(no clue about content length in POST requests)
regards,
Roland
Sven Köhler <sk...@upb.de>
12.11.2003 01:55
Please respond to "Commons HttpClient Project"
To: Commons HttpClient Project
<co...@jakarta.apache.org>
cc:
Subject: Cookies, Chunked-Post & Threads
Hi,
i'm working on a so called ProxyServlet which uses the Information
provided by the ServletContainer to deliver the Requests to another
Web-Server.
At present, i'm using the HttpMethod-Objects (GetMethod, PutMethod, ...)
and HttpClient.execute() to deliver the Requests to the other Web-Server.
I hope you can provide me with some sollutions to the following Problems:
- I like to maintain one "Cookie-Container" for each Session (Session =
Session-Object offered by the Servlet-Container)
- I like my Servlet to be Thread-safe and be abled to deliver many
(unlimited) requests at a time
- I tried to avoid the Content-Length Header in POST requests by using
Chunked Transfer-Encoding, but the Apache-Server i'm using for testing
seems to deny chunked POST-requests.
Well, how's cookie-management done in Commons-HttpClient? Does each
HttpClient-Object maintain it's own "Cookie-Container"?
HttpClient.execute() doesn't seem to be thread-safe.
I like chunked Transfer-Encoding since is more like a stream and not
like that huge block of data that's usually used (content-length header
etc.) Are chunked POST-Requests not allowed? Well, i'm setting the
content-length header right now if it is provided to the servlet. So
that's a big proble, but i'm just curious.
Thx
Sven
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Re: Cookies, Chunked-Post & Threads
Posted by Andreas Probst <an...@gmx.net>.
Hi Sven,
Regarding the thread safeness, I suggest try using
MultiThreadedHttpConnectionManager. Instance it and put into
HttpClient's constructor.
Regards.
Andreas
On 12 Nov 2003 at 1:55, Sven Köhler wrote:
> Hi,
>
> i'm working on a so called ProxyServlet which uses the Information
> provided by the ServletContainer to deliver the Requests to another
> Web-Server.
> At present, i'm using the HttpMethod-Objects (GetMethod, PutMethod, ...)
> and HttpClient.execute() to deliver the Requests to the other Web-Server.
>
> I hope you can provide me with some sollutions to the following Problems:
>
> - I like to maintain one "Cookie-Container" for each Session (Session =
> Session-Object offered by the Servlet-Container)
> - I like my Servlet to be Thread-safe and be abled to deliver many
> (unlimited) requests at a time
> - I tried to avoid the Content-Length Header in POST requests by using
> Chunked Transfer-Encoding, but the Apache-Server i'm using for testing
> seems to deny chunked POST-requests.
>
> Well, how's cookie-management done in Commons-HttpClient? Does each
> HttpClient-Object maintain it's own "Cookie-Container"?
> HttpClient.execute() doesn't seem to be thread-safe.
> I like chunked Transfer-Encoding since is more like a stream and not
> like that huge block of data that's usually used (content-length header
> etc.) Are chunked POST-Requests not allowed? Well, i'm setting the
> content-length header right now if it is provided to the servlet. So
> that's a big proble, but i'm just curious.
>
> Thx
> Sven
>
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