Anybody knows good tuts on PHP & HTTP caching ? Or come inside and tell me :)

Amn

Hi All!

I am new to PHP, but managed to do some work lately. Now I am just wondering, are there any default headers PHP or Apache send that have to do with cache ?

Does the browser reevaluate the whole PHP script every time I hit Reload in my browser, or not ?

How about other content types ? If I generate CSS stylesheet with PHP (using header("Content-Type: text/css"); ) is the CSS sent from the PHP processor every time ?

Also, I will happily read tutorials on this instead 😉

But thanks again, the forums have helped me much already. PHP looks much better than Cold Fusion, it was a fool-tool 🙁 blah!

ZibingsCoder

Well, I think you may be misunderstanding something here. PHP is not parsed by the client's browser, it's parsed by the server which receives the requrest from the client. Thus the reason it's called a server-side language.

As to your question with caching, the HTTP headers work as they should with any other web language that can send them. I know for a fact that you can use caching methods with PHP, but off the top of my head I can't remember the headers you'd need to send. Though...

// Check if the client has the same page cached
if (isset($_SERVER["HTTP_IF_MODIFIED_SINCE"]) &&
   ($_SERVER["HTTP_IF_MODIFIED_SINCE"] == $tsstring)) {
   header("HTTP/1.1 304 Not Modified");
   exit();
}
// Inform the user agent what is our last modification date
else {
   header("Last-Modified: " . $tsstring);
}

That's an example from the php.net website. They use that in their pages, and it kind of gives you the basic idea. Possibilities to using that are pretty much endless, so, go at it!

[edit-addendum]

Btw, as to the other content-types, you're right on the money. You can use PHP to display images simply by manipulation of headers. It's a very very useful thing to do.

As to ColdFusion...there's always a use somewhere for every language. Best to know as many possible. You never know when a random, well-paying, state-job will pop up in ColdFusion. 😉

Amn

Thanks man, thanks for extensive reply.

I was aware that PHP is a server side processor, there was a typo in my post 😉 I meant "server" not "browser", but doesn matter now 😉

I found a neat function called session_cache_limiter and session_cache_expires (off my head) , they effectively eliminate caching per page, they validate a document for a time range of 180 minutes by default, i.e. the browser gets a header telling it, that the page will expire in two hours, so it doesn't attempt retrieving it from the server. Very nice 😉

After working with Cold Fusion for 3 years, I stopped seeing anything attractive in it, frankly. I am a C++ programmer, so for me it makes more sense to use PHP and not the awful <CF... tag syntax. There are more reasons by which i can OBJECTIVELY name CF as inferior to PHP, one of them is XHTML incompliency of CF - lone tags cannot be ended with /> while PHP uses what is known as XML server side application ( <? ... ?> ). Also, Cold Fusion is commercial application server costing more than 2000$, webspace providers usually steer away from it, while PHP is everywhere, and I as web developer dont have to sit on the phone support finding out what and where about CF. REgular Expressions in CF are something out of their own heads, only partialy supporting Perl syntax. The few things I appreciate about Cold Fusion are:

1) CF parses content between its tags, while PHP parses content only within its XML application tag definition (<?php ...),

2) CF is very fast, at least not much slower than PHP (I believe PHP is faster in many functions, i.e reg exp, etc)

3) CF abstracts SQL database access, which i think is a very good thing to do, as SQL standard should be better supported and perhaps, enjoy a strict ratification like XHTML and CSS

Thats it.
Sticking to PHP though 😃

Cheers.

bubblenut

Originally posted by Amn

1) CF parses content between its tags, while PHP parses content only within its XML application tag definition (<?php ...),

2) CF is very fast, at least not much slower than PHP (I believe PHP is faster in many functions, i.e reg exp, etc)

3) CF abstracts SQL database access, which i think is a very good thing to do, as SQL standard should be better supported and perhaps, enjoy a strict ratification like XHTML and CSS

I don't see why you would need to parse things outside the <?php ?> tags. The point is you place things which do not need to parsed outside the scope php thus increasing efficiency.
Don't know of any benchmarking reports and am too lazy to search 😃 I would like to see some if you know of any respected ones though.
Agreed. Check out PEAR:😃B

Cheers
Bubble

Amn

Originally posted by bubblenut
1. I don't see why you would need to parse things outside the <?php ?> tags. The point is you place things which do not need to parsed outside the scope php thus increasing efficiency.

Yes, I understand the reasons, but CF doesn't parse the whole page either, it only parses its own tags (like PHP) and in addition all the content between CFOUTPUT tags. That PHP doesn't have, to my knowledge. The benefits are debatable of course, it makes the page more difficult to read when all those CFOUTPUT tags are scattered around.

drew010

you can try these headers:

header("Cache-Control: private"); header("Pragma: no-cache");
header("Expires: " . date("r", strtotime("-1 year")));