POST redirects (is it even possible?)

[Anon]

There are two ways for me to phrase this question. First, the simple way:

Is there a way (via a built in function, external free library, or even through extensive coding) to do a POST redirect, or even anything which looks like one, using PHP? I need to be able to (in PHP) submit data to a form and redirect the browser to the output from a CGI app, using the POST method (not the GET method).

The complex way:

I need to construct a "waiting for remote host" page. You fill out a form which posts to a PHP page which does something to the input (doesn't matter what), displays "Transferring from remote host", then POSTs to a CGI app, and redirects you to the output of that application. The key, as far as I can tell, is being able to both POST and redirect through PHP at the same time (as I have been able to do either alone successfully).

Anyone who can find a solution or even a workaround to this problem will be a bonafide superhero as far as I'm concerned. I've been trying to figure this out for a couple days now, and all my google searching has turned up nothing of interest.

Thanks,
-taavo
(There are no x's in my email address)

[screaming]

Taavo,

First off, you might want to check out a spiffy PHP script called 'Snoopy' @ http://snoopy.sf.net.

Now for my own explanation:

If I understand your question correctly, you need to be able to POST to a URL using a PHP script only, instead of a normal form. I had this problem with something else I was working on. In order to fix it I had to figure out what the POST method really did so I could replicate it in a script.

So without further ado, here's what it looks like in PHP:

function post_form() {
$my_web = fsockopen("web.server.com", 80, $errno, $errstr, 5);
if (!$my_web) {
$return_str = "Error $errno while trying to connect to <a href=\"http://web.server.com\">http://web.server.com</a>! ($errstr)";
return $return_str;
}
$submit_str = "exactly=what&the=query&string=looks&like=normally";

$header_str  = "POST /tr HTTP/1.0\n";
$header_str .= "Host: web.server.com\n";
$header_str .= "User-Agent: Mozilla/4.0 (compatible; MSIE 5.5; Windows NT 5.0)\n";
$header_str .= "Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, */*\n";
$header_str .= "Content-type: application/x-www-form-urlencoded\n";
$header_str .= "Content-length: ".strlen($submit_str)."\n\n";

fwrite($my_web, $header_str.$submit_str, strlen($header_str.$submit_str));

}

So there you have it.

Hopefully this is what you were after... 🙂

/Steve

[screaming]

Oops. I missed a step when i was rewriting it for here 🙂

Make sure you change this line:

$header_str = "POST /tr HTTP/1.0\n";

to reflect the path of the CGI script:

$header_str = "POST /path/to/program.cgi HTTP/1.0\n";

/Steve

[Anon]

Thanks for the rapid response. Unfortunately, neither Snoopy (which I wish I'd heard of before I wrote my own redirect and POST code) nor your code seems to be able to do what I need, to display the results of a form POST in a new page, not just printing them on the current page.

The problem I need to solve is the following:

The user submits a form, a new page with "transferring now" pops up, and then a new page with the results pops up.

Basically, the web app I'm writing has to perform some operations on remote web pages and display the results, and my client wants it to be clear to the user that when the form takes five seconds to submit, it's because the remote host (frequently a site overseas) is slow, and not because our site is slow. The only solution I can think of is putting up a "transferring now" window until we've got the data from the remote host.

I can't just display the "transferring now" page and then display the results from the form, because I don't have a way to clear "transferring now" from the top of the page.

I have been looking into using JavaScript/DHTML with some hidden divs to make the "transferring now" text disappear and the results appear, but I can't come up with a way to make the different DIVs appear and disappear with appropriate timing (none of the page displays at all until the whole thing has loaded in IE at least, so by that time we should just be displaying the results).

The simplest solution, superficially at least, is coming up with a way to make PHP do the exact same thing a web browser does when it submits to a form: post and redirect at the same time.

Any solutions or workarounds would, as I've said before, be highly appreciated. At this point I'm prepared to tell the client that it can't be done.

Thanks again for your rapid response.
-taavo

[screaming]

Okay, I think i understand your problem. I threw together a test script of my own so that I could see what youre talking about.

The good news: I think we can get it to work.

The bad news: It's cludgy.

I think you said in your previous post that you're posting to a CGI that's on your own site? Then I assume that cgi goes and does some things with some other server out there? Okay. If that's the case, then what if you passed some kind of specific string relating to that exact browser instance to the cgi (a session ID, for example), then that CGI will write out a temp file when it's done.

You can use this temp file, a meta refresh tag, and a php script to keep displaying "Transfering now" until the cgi is done processing..

So, this is how it would work:

1) The browser loads the initial form that exists in a PHP page.
2) user submits form.
3) PHP script POSTs to the cgi, then returns to the browser something like:

<head>
<title>Transerring now</title>
<meta http-equiv=Refresh content="5; URL=http://web.server.com/path/to/php.script.php">
</head>
<body>
<center><font size="+3">Transferring now</font></center>
</body>

4) Inside the PHP script is a conditional based on the existence of some file that the cgi script is going to output.

5) Once the cgi script is done processing, it redirects it's output to the aforementioned temp file.

6) The next time the browser refreshes the PHP script, the script will see the file exists, and display it!

What do you think?

/Steve

[kparker]

Yes, meta refresh is definitely the way to go, but if there's some way to uniquely identify the "transaction" you can get by without the tmp file: just have your first script add <b>?id=some_identifying_mark</b> to the url in the meta refresh.

[screaming]

If you don't have a temp file, how would you store the reply from the cgi?

/Steve

[Anon]

I was afraid that would be the solution. I've been praying there would be a way for me to avoid redirecting all of my output into a temporary file. I'm not sure if the hackyness of the solution is worth the benefits of a "transferring now page."

Anyway, thanks again for your response. It's places like this that make being a web developer such a great job (that and the free coke).

-taavo

[Anon]

It's possible, and it's clean. No temporary files, no ugly, hideous mess of code. Just a little bit of javascript hackery.

I have the input form submit (via post) to the php below (target.cgi is the final cgi).

Obviously this won't work for non-Javascript enabled browsers, so a submit button could be thrown in there to be used manually.

--
echo "<head></head>";
echo "<body onLoad='document.loader.submit()'>";
echo "Transferring from remote host: <i>$input_URL</i>";
echo "<form name='loader' action='target.cgi' method='POST'>";
while (list($name, $value) = each($HTTP_POST_VARS))
echo "<input type='hidden' name='$name' value='$value'>";

echo "</form></body>";

Woo hoo!

-taavo