Hi Mike,
Thanks for the help -
I've modified my code to use a MultiThreadedHttpConnectionManager and
I'm using the method
you suggested - HttpClient.executeMethod(HostConfiguration,
HttpMethod, HttpState).
To maintain persistence - I assume I still need to set/get Cookies
from the user session.
The following code works until the last bit where I try to retrieve
the cookie after the GET method was executed. (Cookie[] cookieAfter =
client.getState().getCookies();)
The cookies have a null value and so I lose persistence.
// Create a GET method instance.
GetMethod method = new GetMethod(BASE_LOCKWOOD_POST_URL +
duiUrl);
// set the query string passed in from CC
method.setQueryString(queryString);
// Provide custom retry handler if necessary
method.getParams().setParameter(HttpMethodParams.RETRY_HANDLER,
new DefaultHttpMethodRetryHandler(3, false));
// get cookies from this user's session
Cookie[] cookie = (Cookie[]) request.getSession().getAttribute(
"cookie");
// get a new Host configuration and set the Host and port
HostConfiguration config = new HostConfiguration();
config.setHost("24.167.26.100",8083);
// instantiate a new HttpState and set the cookies from the
session
HttpState state = new HttpState();
state.addCookies(cookie);
// execute the GET method
try {
int statusCode = client.executeMethod(config, method,
state);
if (statusCode != HttpStatus.SC_OK) {
System.out.print("Method failed: " +
method.getStatusLine());
} else {
// get the response as a String
xml = method.getResponseBodyAsString();
}
} catch (HttpException he) {
System.out.print("Fatal protocol violation: " +
he.getMessage());
he.printStackTrace();
} catch (IOException ioe) {
System.out.print("Fatal transport error: " +
ioe.getMessage());
ioe.printStackTrace();
} finally {
method.releaseConnection(); // Release the connection.
}
Cookie[] cookieAfter = client.getState().getCookies();
request.getSession().setAttribute("cookie",cookieAfter);
On Aug 18, 2005, at 11:33 PM, Michael Becke wrote:
Hi Keith,
You don't want to share HttpState among different users. You should
use HttpClient.executeMethod(HostConfiguration, HttpMethod, HttpState)
and pass in an instance of HttpState unique to each user. Also make
sure you're using a http connection manager that support multiple
threads.
Mike
On 8/18/05, Keith Campbell <[EMAIL PROTECTED]> wrote:
Yes -- that worked. One last question if somebody could answer:
Because of implementing it this way -- I think I need to create a
synchronized block
where I clear and set cookies from the HttpClient. But I'm concerned
that this might
be too big of a performance hit if I have many concurrent users.
Could somebody quickly take a look at my code and let me know if
there's some way to possibly speed this up or is this the best I can
hope for?
package com.paperloop.bus;
import java.io.IOException;
import javax.servlet.http.HttpServletRequest;
import org.apache.commons.httpclient.DefaultHttpMethodRetryHandler;
import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.Cookie;
import org.apache.commons.httpclient.HttpState;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.params.HttpMethodParams;
public class DUIHtmlProvider implements HTMLProvider {
private String xml;
private static String BASE_LOCKWOOD_POST_URL = "http://
xxx.xxx.xxx.xxx:8083/pl_dui/";
public DUIHtmlProvider(HttpServletRequest request, HttpClient
client) {
String duiUrl = request.getParameter("url"), queryString;
// has this user logged in to DUI yet?
if (duiUrl == null) {
// no url within DUI yet -- must be new user
duiUrl = "index.php";
// set GET query string to login query string
queryString = "pcd=NS&uid="+request.getParameter("uid");
} else {
// user has a url -- already logged in
queryString = request.getQueryString();
}
// Create a GET method instance.
GetMethod method = new GetMethod(BASE_LOCKWOOD_POST_URL +
duiUrl);
// set the query string passed in from CC
method.setQueryString(queryString);
// Provide custom retry handler is necessary
method.getParams().setParameter
(HttpMethodParams.RETRY_HANDLER,
new DefaultHttpMethodRetryHandler(3, false));
// get cookies from this user's session
Cookie[] cookie = (Cookie[]) request.getSession
().getAttribute(
"cookie");
// we don't want users' to execute a GET or POST
// while somebody else's cookies are set in the HTTP
// client, so this block is synchronized (Performance
// hit should be negligible but maybe should be tested??)
synchronized (client) {
// get the client HTTP state
HttpState state = client.getState();
// clear cookies from the HTTP client
state.clearCookies();
// restore this user's cookies to the HTTP client state
state.addCookies(cookie);
// add the HttpState back to the client
client.setState(state);
// execute the GET method
try {
int statusCode = client.executeMethod(method);
if (statusCode != HttpStatus.SC_OK) {
System.out.print("Method failed: " +
method.getStatusLine());
} else {
// get the response as a String
xml = method.getResponseBodyAsString();
}
} catch (HttpException he) {
System.out.print("Fatal protocol violation: " +
he.getMessage());
he.printStackTrace();
} catch (IOException ioe) {
System.out.print("Fatal transport error: " +
ioe.getMessage());
ioe.printStackTrace();
} finally {
method.releaseConnection(); // Release the
connection.
}
// get the Cookies from the HTTP client
// and set them in the user's Session
Cookie[] cookieAfter = client.getState().getCookies();
request.getSession().setAttribute("cookie",cookieAfter);
}
}
public String getHtml() {
return xml;
}
}
On Aug 18, 2005, at 7:52 PM, Gustavo Hexsel wrote:
I believe you're right. Things might get tricky if you need the
credentials present in the HttpState too, but it doesn't appear to
be your
case.
I'm guessing that, while the user's session is active, it's
easier to keep
the whole HttpState in it, to avoid creating and setting cookies
all the
time. But I see that HttpState isn't serializable so you might be
out of
luck there.
[]s Gus
-----Original Message-----
From: Keith Campbell [mailto:[EMAIL PROTECTED]
Sent: August 18, 2005 5:48 PM
To: HttpClient User Discussion
Subject: Re: multiple instances of httpclient
Hi again,
I think I may have answered my question but please tell me if I'm on
the right track or not ....
I think I can maintain multiple user sessions using one instance of
HttpClient if I do something like the following:
Maintain one instance of HttpClient for all users.
Support multiple users by getting the HttpState and storing Cookies
to each user's session.
So ... for each session, first thing to do is get the cookies from
the session if there are cookies there, clear any existing cookies
from the HttpState, set the cookies from the session to the
HttpState, execute the get or post, retrieve the cookies from the
HttpState and set them again in the user session.
Is this the correct way to go about doing what I want to do?
Keith
On Aug 18, 2005, at 6:59 PM, Keith Campbell wrote:
Hi all,
A quick question for the list please. I've been struggling with
this for a couple of days now w/o much success.
I have a servlet which is used to send requests (using HttpClient)
to another web application where:
1) each user must login -- each user logs in using GET by passing a
user id as a parameter
2) each user's session must be persistent
3) multiple users will be using the application and each must
maintain a unique session
To do this, I've been trying to instantiate HttpClient, in my
servlet, once per user session. And I'd like to be able to store/
retrieve this instance in the user session. But HttpClient is not
serializable ....
How do I accomplish this functionality?
Thanks in advance,
Keith Campbell
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