Cache the previous page?

[Brian]

Re: Cache the previous page?

C.J. Garibay wrote:
[color=blue]
> I'm pretty sure you can not manipulate a visitor's browser's
> cache settings.[/color]

Correct, you cannot manipulate such settings.

--
Brian (remove ".invalid" to email me)

http://www.tsmchughs.com/

[Brian]

Re: Cache the previous page?

Bill H wrote:
[color=blue]
> I know sessions and cookies, where I'm at a bit of a loss is the
> mechanics of sending the user back to a cached page instead of
> executing the query.[/color]

You don't need sessions, nor cookies, to encourage caching. In fact,
they are likely to *prevent* caching. See my other response for how to
encourage caching by user-agents (and proxies).
[color=blue]
> Wouldn't 'referer' or JS "back page" be good in-so-much as I only
> want to address a back page not if they have visited the page.[/color]

No. KISS (keep it simple, stupid!). :-) Use what's already available.
[color=blue]
> If they hit the "show units" button I want a new query to run.[/color]

I'm afraid I don't know what this button does. You'll need to provide a
url if I need to see this part to help you.

--
Brian (remove ".invalid" to email me)

http://www.tsmchughs.com/

[C.J. Garibay]

Re: Cache the previous page?

Bill H wrote:
[color=blue]
> On Fri, 13 Aug 2004 21:22:04 GMT, "C.J. Garibay"
> <cj.garibay@_RE MOVE_THIS_comca st.net> wrote:
>
>[color=green]
>>Bill H wrote:
>>
>>[color=darkred]
>>>On Fri, 13 Aug 2004 19:56:30 GMT, Bill H <maylar69@hot----.com> wrote:
>>>
>>>
>>>
>>>>On Fri, 13 Aug 2004 19:36:01 GMT, "C.J. Garibay"
>>>><cj.garibay @_REMOVE_THIS_c omcast.net> wrote:
>>>>
>>>>
>>>>
>>>>>Bill H wrote:
>>>>>
>>>>>
>>>>>
>>>>>>On Fri, 13 Aug 2004 17:10:07 GMT, "C.J. Garibay"
>>>>>><cj.garib ay@_REMOVE_THIS _comcast.net> wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>>Bill H wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>>I have a routine that displays 60 items (with thumbnails) per page.
>>>>>>>>You can click any item and displays a new page with item details. When
>>>>>>>>the user back pages it runs the query again to display all the items.
>>>>>>>>Is there a way to cache that page and images so that second query
>>>>>>>>doesn 't execute?
>>>>>>>>
>>>>>>>>I do offer a pop-up window using Java but is not the default and not
>>>>>>>>used by many. I'd really like to get rid of that second query. ;)
>>>>>>>>
>>>>>>>>TIA
>>>>>>>
>>>>>>>Bill,
>>>>>>>
>>>>>>>You could use a cookie to determine if the visitor has already seen the
>>>>>>>page, then have your php act accordingly.
>>>>>>>
>>>>>>>Why are you using Java for a pop-up window? That seems like overkill;
>>>>>>>JavaScri pt would make more sense.
>>>>>>>
>>>>>>>C.J.
>>>>>>
>>>>>>
>>>>>>So sorry, I meant JS.
>>>>>>
>>>>>>That sounds like a good approach I'm simply not clear on the "how to."
>>>>>>I fairly now to creating apps for the Internet (yes, it shows ;)). How
>>>>>>would one Google this? I don't mean to be stupid but.... ;) :)
>>>>>>
>>>>>
>>>>>If you're fairly new to creating web apps, this may take a little work
>>>>>on your part. Your best bet is to read through the relevant parts of
>>>>>the online PHP documentation (which is excellent and has user
>>>>>contribute d examples), and then Google anything in the documentation you
>>>>>don't understand.
>>>>>
>>>>>Main PHP documentation:
>>>>>http://www.php.net/manual/en/index.php
>>>>>
>>>>>PHP cookies function:
>>>>>http://www.php.net/manual/en/function.setcookie.php
>>>>>
>>>>>PHP sessions:
>>>>>http://www.php.net/manual/en/ref.session.php
>>>>>
>>>>>As far as the "how to" is concerned, what you're doing is referred to as
>>>>>keeping track of the user's state. There are generally two ways to do
>>>>>this -- cookies, or sessions. Cookies may be the easier way to go for a
>>>>>beginner .
>>>>>
>>>>>When the visitor first visits your page, your PHP script should check
>>>>>for the presence of a cookie that's associated with that page. If the
>>>>>user _doesn't_ have a cookie, then the PHP script runs it's query,
>>>>>decides what images to send for that page and also sends a cookie with
>>>>>the location of those images. If the user _does_ have a cookie for that
>>>>>page, then the PHP script just sends the images that are listed in the
>>>>>cookie instead of running another query.
>>>>>
>>>>>C.J.
>>>>
>>>>Thanks so much for the reply. I know sessions and cookies, where I'm
>>>>at a bit of a loss is the mechanics of sending the user back to a
>>>>cached page instead of executing the query.
>>>>
>>>>Wouldn't 'referer' or JS "back page" be good in-so-much as I only want
>>>>to address a back page not if they have visited the page. If they hit
>>>>the "show units" button I want a new query to run.
>>>>
>>>>It's this only back page to a cached page that I'm a little at a loss
>>>>about - did any of that make sense? ;) :)
>>>
>>>
>>>hmmm I see holes in my approach here... if a user hits "back page" on
>>>a specfic page is there a way to temporary overide browser settings
>>>and not refresh?
>>>
>>>So I come in the top run the query, drop a cookie that says "kilroy
>>>was here" and then overide the browser setting on the next pass if the
>>>cookie is present. Now the how to overide part, should I ask that in
>>>HTML group? Maybe I have enough of a clue now to Google. :)
>>>[/color]
>>
>>Bill,
>>
>>Unfortunately , you can't override the browser's settings. When a user
>>hits the back button on his browser, it will either display the content[/color]
>[color=green]
>>from the local cache or send a GET request to the URI to check if the[/color]
>[color=green]
>>page has changed since it was last cached locally (depending on how the
>>browser's cache settings are set).
>>
>>The only thing you have control over in this situation is your server.
>>So if your server is hit with another GET request, your only recourse is
>>to check the visitor's state to see if he's already requested the URI in
>>question.
>>
>>There _may_ be a way to override a browser's cache settings using
>>JavaScript (emphasis on may), but I doubt it. At any rate, PHP is
>>definitely unable to affect a browser's cache settings.
>>
>>You can check with an HTML newsgroup or JavaScript newsgroup (or even an
>>IE and/or Mozilla newsgroup), but I'm pretty sure you can not manipulate
>>a visitor's browser's cache settings.
>>
>>C.J.[/color]
>
>
> Roger that C.J.
>
> Actually Rob Allen offered a smart solution that I have to believe
> would have dawned on me at some point. ;) That is to save the result
> ID's of the query to an array and simply use those when the user
> returns... thanks Rob! :)
>[/color]

Well, that's what I was trying to suggest when I said:

"If the user _doesn't_ have a cookie, then the PHP script runs it's
query, decides what images to send for that page and also sends a cookie
with he location of those images."

C.J.

[Bill H]

Re: Cache the previous page?

On Fri, 13 Aug 2004 22:57:16 GMT, "C.J. Garibay"
<cj.garibay@_RE MOVE_THIS_comca st.net> wrote:
[color=blue]
>Bill H wrote:
>[color=green]
>> On Fri, 13 Aug 2004 21:22:04 GMT, "C.J. Garibay"
>> <cj.garibay@_RE MOVE_THIS_comca st.net> wrote:
>>
>>[color=darkred]
>>>Bill H wrote:
>>>
>>>
>>>>On Fri, 13 Aug 2004 19:56:30 GMT, Bill H <maylar69@hot----.com> wrote:
>>>>
>>>>
>>>>
>>>>>On Fri, 13 Aug 2004 19:36:01 GMT, "C.J. Garibay"
>>>>><cj.gariba y@_REMOVE_THIS_ comcast.net> wrote:
>>>>>
>>>>>
>>>>>
>>>>>>Bill H wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>>On Fri, 13 Aug 2004 17:10:07 GMT, "C.J. Garibay"
>>>>>>><cj.gari bay@_REMOVE_THI S_comcast.net> wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>>Bill H wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>>I have a routine that displays 60 items (with thumbnails) per page.
>>>>>>>>>You can click any item and displays a new page with item details. When
>>>>>>>>>the user back pages it runs the query again to display all the items.
>>>>>>>>>Is there a way to cache that page and images so that second query
>>>>>>>>>doesn' t execute?
>>>>>>>>>
>>>>>>>>>I do offer a pop-up window using Java but is not the default and not
>>>>>>>>>used by many. I'd really like to get rid of that second query. ;)
>>>>>>>>>
>>>>>>>>>TIA
>>>>>>>>
>>>>>>>>Bill,
>>>>>>>>
>>>>>>>>You could use a cookie to determine if the visitor has already seen the
>>>>>>>>page, then have your php act accordingly.
>>>>>>>>
>>>>>>>>Why are you using Java for a pop-up window? That seems like overkill;
>>>>>>>>JavaScr ipt would make more sense.
>>>>>>>>
>>>>>>>>C.J.
>>>>>>>
>>>>>>>
>>>>>>>So sorry, I meant JS.
>>>>>>>
>>>>>>>That sounds like a good approach I'm simply not clear on the "how to."
>>>>>>>I fairly now to creating apps for the Internet (yes, it shows ;)). How
>>>>>>>would one Google this? I don't mean to be stupid but.... ;) :)
>>>>>>>
>>>>>>
>>>>>>If you're fairly new to creating web apps, this may take a little work
>>>>>>on your part. Your best bet is to read through the relevant parts of
>>>>>>the online PHP documentation (which is excellent and has user
>>>>>>contribut ed examples), and then Google anything in the documentation you
>>>>>>don't understand.
>>>>>>
>>>>>>Main PHP documentation:
>>>>>>http://www.php.net/manual/en/index.php
>>>>>>
>>>>>>PHP cookies function:
>>>>>>http://www.php.net/manual/en/function.setcookie.php
>>>>>>
>>>>>>PHP sessions:
>>>>>>http://www.php.net/manual/en/ref.session.php
>>>>>>
>>>>>>As far as the "how to" is concerned, what you're doing is referred to as
>>>>>>keeping track of the user's state. There are generally two ways to do
>>>>>>this -- cookies, or sessions. Cookies may be the easier way to go for a
>>>>>>beginne r.
>>>>>>
>>>>>>When the visitor first visits your page, your PHP script should check
>>>>>>for the presence of a cookie that's associated with that page. If the
>>>>>>user _doesn't_ have a cookie, then the PHP script runs it's query,
>>>>>>decides what images to send for that page and also sends a cookie with
>>>>>>the location of those images. If the user _does_ have a cookie for that
>>>>>>page, then the PHP script just sends the images that are listed in the
>>>>>>cookie instead of running another query.
>>>>>>
>>>>>>C.J.
>>>>>
>>>>>Thanks so much for the reply. I know sessions and cookies, where I'm
>>>>>at a bit of a loss is the mechanics of sending the user back to a
>>>>>cached page instead of executing the query.
>>>>>
>>>>>Wouldn't 'referer' or JS "back page" be good in-so-much as I only want
>>>>>to address a back page not if they have visited the page. If they hit
>>>>>the "show units" button I want a new query to run.
>>>>>
>>>>>It's this only back page to a cached page that I'm a little at a loss
>>>>>about - did any of that make sense? ;) :)
>>>>
>>>>
>>>>hmmm I see holes in my approach here... if a user hits "back page" on
>>>>a specfic page is there a way to temporary overide browser settings
>>>>and not refresh?
>>>>
>>>>So I come in the top run the query, drop a cookie that says "kilroy
>>>>was here" and then overide the browser setting on the next pass if the
>>>>cookie is present. Now the how to overide part, should I ask that in
>>>>HTML group? Maybe I have enough of a clue now to Google. :)
>>>>
>>>
>>>Bill,
>>>
>>>Unfortunatel y, you can't override the browser's settings. When a user
>>>hits the back button on his browser, it will either display the content[/color]
>>[color=darkred]
>>>from the local cache or send a GET request to the URI to check if the[/color]
>>[color=darkred]
>>>page has changed since it was last cached locally (depending on how the
>>>browser's cache settings are set).
>>>
>>>The only thing you have control over in this situation is your server.
>>>So if your server is hit with another GET request, your only recourse is
>>>to check the visitor's state to see if he's already requested the URI in
>>>question.
>>>
>>>There _may_ be a way to override a browser's cache settings using
>>>JavaScript (emphasis on may), but I doubt it. At any rate, PHP is
>>>definitely unable to affect a browser's cache settings.
>>>
>>>You can check with an HTML newsgroup or JavaScript newsgroup (or even an
>>>IE and/or Mozilla newsgroup), but I'm pretty sure you can not manipulate
>>>a visitor's browser's cache settings.
>>>
>>>C.J.[/color]
>>
>>
>> Roger that C.J.
>>
>> Actually Rob Allen offered a smart solution that I have to believe
>> would have dawned on me at some point. ;) That is to save the result
>> ID's of the query to an array and simply use those when the user
>> returns... thanks Rob! :)
>>[/color]
>
>Well, that's what I was trying to suggest when I said:
>
>"If the user _doesn't_ have a cookie, then the PHP script runs it's
>query, decides what images to send for that page and also sends a cookie
>with he location of those images."
>
>C.J.[/color]

lol! Sorry, it was never about the images really so it just didn't
click... I see it now. Rob spoke the language I was thinking in is
all. But I certainly thank you for offering a solution was was too dim
to see! :)

Brian is saying that I can do what I'm asking for with headers alone
with would be the easiet of course. Think I'll grab a book and bring
myself up to speed in terms of the headers.

You've all be great! and I thank all of you!

[Brian]

Re: Cache the previous page?

Bill H wrote:
[color=blue]
> Brian is saying that I can do what I'm asking for with headers alone
> with would be the easiet of course. Think I'll grab a book and bring
> myself up to speed in terms of the headers.[/color]

Or just go online. An excellent tutorial on caches and headers:

http://www.mnot.net/cache_docs/

--
Brian (remove ".invalid" to email me)

http://www.tsmchughs.com/

[Bill H]

Re: Cache the previous page?

On Fri, 13 Aug 2004 17:57:54 -0400, Brian
<usenet3@juliet remblay.com.inv alid> wrote:
[color=blue]
>Bill H wrote:
>[color=green]
>> I have a routine that displays 60 items (with thumbnails) per page.
>> You can click any item and displays a new page with item details.
>> When the user back pages it runs the query again to display all the
>> items. Is there a way to cache that page and images so that second
>> query doesn't execute?[/color]
>
>Of course, using standard http cache headers. The simplest method for
>images is to store them as static files, and let your server do the
>work. Be sure to configure the server to set explicit freshness info for
>maximum caching. For the page that displays the thumbs and data, you can
>use cache-control headers.
>
><?php
>header("Cach e-Control: max-age=600"); // 10 minutes
>?>
>
>The time should take into account how often you update the data on which
>the query is based. If it's only once per week, then increase the
>cache-control max-age value to a couple of hours. NB: Headers *must* be
>sent **before** any data is sent.
>
>
><?php
>header("Cach e-Control: max-age=7200"); // 2 hours
>?>
>
>This may accomplish what you want without further fuss. If you want to
>do more, then consider determining when you last modified the data, and
>send a Last-Modified header. Then, when there's a request for the
>thumbnails page, process the request headers, looking for
>If-Modified-Since. If the user's copy is still fresh, send "304 Not
>Modified" and exit the script.
>
>I've done all this -- and for sevearal pages with thumbnails, as well
>for individual photo pages and a catalogue -- for a photography site:
>
>http://www.julietremblay.com/
>
>The cache-control stuff is dead easy. The Last-Modified stuff is a
>little dicey, but if you're serious, then give it a try. Feel free to
>ask me if you run into trouble. I have links plus my own code to offer.
>
>HTH[/color]

This was too easy, thanks Brian! It gives me just the behavior I was
looking for.

Cheers,
Bill

[Brian]

Re: Cache the previous page?

Bill H wrote:[color=blue]
> Brian wrote:
>[color=green]
>> The cache-control stuff is dead easy. The Last-Modified stuff
>> is a little dicey,[/color]
>
> This was too easy,[/color]

Cache-control, I assume you mean. If you think parsing
If-Modified-Since is "too easy" then you're a better coder
than I!
[color=blue]
> It gives me just the behavior I was looking for.[/color]

Great! I only wish other authors were as observant and conscientious
about caching. Too many php driven sites ignore it completely, wasting
bandwidth and making their sites quite a bit slower.

--
Brian (remove ".invalid" to email me)

http://www.tsmchughs.com/