PT,
The issue your link describes is close, but differs on a
number of important points. It claims to be specific to
PDFs and a version of IE that I am not using (SP1, my
problem is manifesting in SP2), and the headers it lays out
as causing problems (Cache-control) I am using without
problem. It doesn't mention the 'Pragma: no-cache' header
at all.
That said, it seems an easy bet that the problems are deeply
related. Clearly it would be surprising if the 'Pragma:
no-cache' issues is not caused by an interoperability
problem between flash player and IE. My uneducated guess is
that the flash player may be trying to get at the loaded
data by pulling stuff out of the cache after IE has loaded
it, but in the case of a Pragma: no-cache there is nothing
in the cache to find. Though in that case I would expect
the Cache-Control header I'm using to cause the same problem
so it's not entirely clear, unless that Cache-Control header
is just not being respected by IE6...
I had removed them to simplify the problem demonstration,
but it may be interesting to note that if you add the lines:
header('Expires: Sat, 1 Jan 2000 00:00:00 GMT');
header('Cache-Control: no-store, no-cache, must-revalidate, post-check=0,
pre-check=0');
to the php code below, you will see that they have no effect
on whether the test works or fails, at least in IE6 sp2. It
is only the Pragma header that causes the failure I am
seeing.
Bottom line: What I really must find out here is whether it
is possible through some combination of HTTP headers and/or
Laszlo settings to effectively prevent IE from caching
dynamic data loaded to serverless datasets while using SSL
to secure the communication. This is a very high priority
customer requirement for my application and could actually
prevent me from using Laszlo or Flash in future versions if
I am unable to find a practicable workaround.
Sincere thanks for your interest in this case,
Cameron
> From: P T Withington [mailto:[EMAIL PROTECTED]
> Sent: Friday, December 02, 2005 9:17 AM
>
> GTFW for 'ie cache control https' reveals: http://
> support.microsoft.com/default.aspx?scid=kb;en-us;812935
>
> It would appear to be an IE bug.
>
> On 1 Dec 2005, at 21:13, Cameron Brown wrote:
>
> >
> > Ye List,
> >
> > Executive Summary:
> >
> > Dataset loading does not work if communicating over HTTPS
> in IE6 and
> > the server sends a 'Pragma: no-cache' HTTP header.
> >
> > The Details:
> >
> > I've been having trouble with my serverless lzx app
> breaking when run
> > over HTTPS in IE6. It works fine over HTTP in IE, and fine
> for both
> > HTTP and HTTPS in Firefox 1.0.7.
> >
> > I first noticed the problem a few months ago, using Laszlo 3.0. It
> > did not go away in 3.0.2. I let it slide for a while since Firefox
> > provided a workaround if HTTPS was required, but the
> coincidence of a
> > disgruntled IE-wed customer and the release of Laszlo
> > 3.1 brought it back to my attention. The basic problem was
> that over
> > HTTPS in IE6, my datasets which load XML data from my app
> server were
> > not getting any data when making requests. Instead I'd
> just get the
> > (3.1) error:
> >
> > LzLoadQueue.serverlessOnDataHandler load failed from URL ' /cmd/
> > authinfo ', no data received.
> > Failure to load data in serverless apps may be caused by
> Flash player
> > security policies. Check your data server crossdomain.xml file
> >
> > I only use server-relative paths for URLs, and loading
> works fine in
> > the other client environments, so I knew it wasn't actually a
> > crossdomain.xml problem. Also I could see that the server
> was getting
> > the request properly and replying properly. So I tried
> messing around
> > with the headers of the reply and lo and behold getting rid of
> > 'Pragma: no-cache' fixed the problem.
> >
> > The only thing I'm worried about now is whether dropping the
> > 'Pragma: no-cache' is now going to cause some version of
> some browser
> > to start caching the data coming from the server -- that would be a
> > disaster. I am still able to use the headers:
> >
> > Expires: Sat, 1 Jan 2000 00:00:00 GMT
> > Cache-Control: no-store, no-cache, must-revalidate, post-check=0,
> > pre-check=0
> >
> > They haven't caused any trouble. And I suspect that they will be
> > sufficient to prevent caching in important browsers, right? Any
> > reassurances will be appreciated.
> >
> > Anyway, here's some code to demonstrate the problem:
> >
> > ===============================================================
> > PHP for the server side ("/prag-nc-test.php"):
> > ===============================================================
> > <?
> > // Pragma: no-cache breaks serverless loads under https in
> IE, // but
> > works for http in IE and http and https in Firefox
> >
> > header('Pragma: no-cache');
> >
> > print('<result>Irrelevant</result>');
> > ?>
> > ===============================================================
> >
> > ===============================================================
> > LZX Client:
> > ===============================================================
> > <canvas height="350" width="100%" debug="true" proxied="false">
> > <debug x="5" y="40" height="300" width="800"/>
> > <dataset type="http" name="testds"
> > autorequest="false"
> > ontimeout="canvas.handleTimeout()"
> > onerror="canvas.handleError()"
> > ondata="canvas.handleData()"
> > src="/prag-nc-test.php"/>
> >
> > <method name="handleData">
> > Debug.write((new Date())+": Request succeeded.");
> > </method>
> > <method name="handleError">
> > Debug.write((new Date())+": Request got an error -- sorry.");
> > </method>
> > <method name="handleTimeout">
> > Debug.write((new Date())+": Request timed out (after
> "+(getTimer
> > ()-canvas.reqTime)+" ms) -- sorry.");
> > </method>
> >
> > <view x="5" y="5">
> > <text valign="middle">Request URL:</text>
> > <edittext width="300" id="srcTxt" text="$once
> > {canvas.datasets.testds.src}"/>
> > <button text="Start Request">
> > <method event="onclick">
> > canvas.reqTime = getTimer();
> > var d = canvas.datasets.testds;
> > if (srcTxt.text) {
> > Debug.write((new Date())+": Setting URL to '"+srcTxt.text
> > +"'...");
> > d.setAttribute('src', srcTxt.text);
> > Debug.write((new Date())+": value set.");
> > }
> > Debug.write((new Date())+": Sending request to
> "+d.src+"...");
> > d.doRequest();
> > </method>
> > </button>
> > <simplelayout axis="x"/>
> > </view>
> > </canvas>
> > ===============================================================
> >
> > I created a JIRA issue for the problem: http://www.openlaszlo.org/
> > jira/browse/LPP-1156
> >
> > Regards,
> > Cameron Brown
> >
> > _______________________________________________
> > Laszlo-dev mailing list
> > [email protected]
> > http://www.openlaszlo.org/mailman/listinfo/laszlo-dev
>
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