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From "Williams, Allen" <awill...@harris.com>
Subject RE: Session IDs & XMLHttpRequests
Date Mon, 21 May 2007 20:22:17 GMT
Thanks, Dave & Frank.

I've followed both your suggestions.  The very first
lines in the servlet print out the various parameter, attributes, &
cookies.
Here's what I get:

-- QUOTE --
******************
doPost entering
May 21 16:16:23: Session Attributes

Session Attributes
May 21 16:16:23: Session isNew()= true
May 21 16:16:23: No attributes in this scope

May 21 16:16:23: Request Attributes

Request Attributes
May 21 16:16:23: No attributes in this scope

May 21 16:16:23: Parameters

Request Parameters
owner = 6
ajaxreq = getfora
type = 0


May 21 16:16:23: Cookies
May 21 16:16:23: 'JSESSIONID'='97E2CA20966390CCBC851738E71F3053'
May 21 16:16:23: Found 1 cookies
-- END QUOTE --

As I said in my earlier post, the session being returned by getSession()
is a new one;
when I call it like getSession(false) it return a null session.
Therefore, it contains
no attributes.  The parameters are, of course, exactly what I expected.
As you can see,
there is the JSESSIONID cookie, but, for some reason, the servlet isn't
using it, or it
is not valid.

Again, according to Sun, everyone one of the API functions to manipulate
session IDs are
deprecated, so I can't even kludge it up.  I have no idea if that is a
valid session ID or
not.

Also, I used Firebug to examine the XMLHttpRequest.  I'm not too sure
what I'm looking for.
There was no reference to cookies, and all the stuff that I set was OK.
Anyway, it seems to
be getting the cookie.

Any ideas as to why the session wouldn't use this cookie, or why this
cookie might be invalid?
In the process of this debugging, I have seen two JSESSIONIDs come over,
one valid, one not.

Thanks again for the help.


> -----Original Message-----
> From: Frank W. Zammetti [mailto:fzlists@omnytex.com] 
> Sent: Monday, May 21, 2007 3:29 PM
> To: Tomcat Users List
> Cc: users@tomcat.apache.org; aladdin@csunv.com
> Subject: Re: Session IDs & XMLHttpRequests
> 
> I can say with 100% certainty that a servlet invoked with 
> XMLHttpRequest
> **DOES** have the same access to server-side objects as a non-AJAX
> request.  I say this based on two applications in production 
> that do this
> all day long, one Struts-based, one not.  I also say it based 
> on a number
> of other applications, some using other frameworks, some using plain
> servlets, all that do this as well, with no problems.
> 
> Now, the two production apps, which are very much AJAX-based, not just
> using it here and there, are running on Websphere, so that leaves the
> possibility that there's something going on with Tomcat.  However, I
> generally develop under Tomcat, including most of those other apps I
> mentioned, and never observed this problem.
> 
> This isn't to say what your seeing isn't truly an issue, I 
> have no doubt
> it is... but, the only difference I can conceive of, based on all this
> experience, between an AJAX request and a normal POST/GET, is 
> the session
> cookie not being passed in with the AJAX request.  I could 
> believe that
> might happen, and I could also believe it may be different 
> from browser to
> browser (don't misunderstand, I have no knowledge of this 
> being the case,
> but it wouldn't shock me).
> 
> As another poster suggested, I would begin by monitoring the requests
> going across in Firefox with Firebug, and perhaps 
> TamperData... you should
> be able to see every detail of the request and response with those...
> compare an AJAX request with a plain form sumission or link 
> click and see
> if you notice any difference... I'd bet dollars to donuts 
> you'll find some
> header missing, or something along those lines.
> 
> But, unless there's some peculiarity to your server setup or 
> environment,
> I can tell you for sure there's no fundamental difference to 
> the server
> between the two types of requests, and by extension, to the
> servlets/filters that execute to service the request.
> 
> Frank
> 
> -- 
> Frank W. Zammetti
> Founder and Chief Software Architect
> Omnytex Technologies
> http://www.omnytex.com
> AIM/Yahoo: fzammetti
> MSN: fzammetti@hotmail.com
> Author of "Practical Ajax Projects With Java Technology"
>  (2006, Apress, ISBN 1-59059-695-1)
> and "JavaScript, DOM Scripting and Ajax Projects"
>  (2007, Apress, ISBN 1-59059-816-4)
> Java Web Parts - http://javawebparts.sourceforge.net
>  Supplying the wheel, so you don't have to reinvent it!
> 
> On Mon, May 21, 2007 2:33 pm, Williams, Allen wrote:
> > I had posted this question to four different Java fora over 
> four days
> > and gotten zero replies, when it occurred to me how stupid 
> not to ask
> > the community that wrote Tomcat.  I was just going to post 
> this, which
> > is a summary that describes what I've found so far:
> >
> > -- QUOTE --
> > In the interest of informing the community, I'm publishing 
> the results
> > of four days of testing and debugging of XMLHttpRequests 
> and attributes.
> > This has led me to the conclusion that servlets invoked with an
> > XMLHttpRequest do not have the same access to server-side objects
> > (actually, attributes) as those invoked via the normal URL 
> mechanism. I
> > don't know why, because if I insert a filter, the filter 
> gets executed,
> > albeit the first time with the wrong session ID.
> >
> > I began this odyssey when a filter in place to check if a 
> user's session
> > had timed out would fail the first time when invoked with an
> > XMLHttpRequest, but would work each time thereafter. What I 
> discovered
> > there was that there were two JSESSIONID cookies stored and 
> being sent
> > in the browser and the jsp and other servlets were requesting the
> > correct one. The xml request was not, it was requesting the (old? I
> > don't know) invalid JSESSIONID. One would think, "OK, I'll 
> just read the
> > cookies in my servlet, check each ID with
> > request.isRequestedSessionIdValid(), and force the right 
> one". Wrong.
> > All of the http session APIs that allow one to manipulate 
> the session ID
> > and force a good one are deprecated, according to Sun's web 
> site, so the
> > programmer isn't allowed to find & use a good session ID.
> >
> > In order to progress while I waited vainly for a reply, I 
> just removed
> > the filter from the servlet's path so it didn't invoke it. 
> I want the
> > filter to check, but decided to move on in the meantime. 
> That's when I
> > discovered that, evidently, the servlet does not get a 
> valid session ID
> > either.
> >
> > I had the following line in my XMLHttpRequest servlet:
> >
> > [code]
> > HttpSession sess= req.getSession();
> > [/code]
> >
> > This seemed to execute and work fine, until I needed to access
> > session-scoped attributes I had defined in other pages or 
> servlets. The
> > were repeatedly null. When I changed the above line to this:
> >
> > [code]
> > HttpSession sess= req.getSession(false);
> > [/code]
> >
> > the reason was apparent: the servlet was generating a brand 
> new session
> > for me. So, for some reason, XMLHttpRequests don't get the same
> > treatment that normal servlets get. I'm going to have to go 
> and modify a
> > lot of code to pass stuff around as query parameters in 
> URLs, which I
> > really don't want to do for both aesthetic & security 
> reasons, but see
> > no alternative. Hopefully, there really is someone out 
> there that knows
> > more about this than I do and can explain to the community 
> & me what's
> > going on.
> > -- END QUOTE --
> >
> > 1. So the last paragraph has my main question in it: why 
> can't I access
> > attributes in a servlet invoked via an XMLHttpRequest?  
> However, I have
> > a another important question and a couple of ancillary ones as well:
> >
> > 2. What is the difference in the servlet invocation between 
> a regular
> > URL invocation & an XMLHttpInvocation?
> >
> > 3. How can I get my filter to work?  I. e., get it the 
> correct session
> > ID?
> >
> > 4.  WHY are all the session manipulation APIs deprecated, 
> and, at least
> > according to Sun's web site, not being replaced?  It seems 
> unusual to be
> > removing control from the programmer/software engineer 
> instead of trying
> > to give him more control over his environment.  With those 
> APIs I could
> > have fixed this (well, kludged it up, anyway).
> >
> > If you need me to post any code, I'll be glad to, but it's 
> really pretty
> > straightforward.  In fact, when I started this adventure, 
> the servlet
> > was empty except for print statements, and the filter has 
> been in place
> > & working for months.
> >
> > Thanks!!
> >
> > anw
> >
> >
> > 
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> >
> 
> 
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