Monthly Archives: October 2010

As found on the web (October 27th)

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frank Frank voelt zich een beetje dom als hij ziet hoe half Vlaanderen plots rechercheur, aanklager, verdediging, rechter en jurylid met buitengewone kennis van (moord-)zaken is geworden..
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frank Frank is nu ècht een man van middelbare leeftijd; deze nacht met geblokkeerde rug (en een zoveelste appelflauwte) de ziekenwagen in gemoeten. al terug thuis, maar moet rusten en haffels pillekes nemen ….
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More power to the reader with RSS and mail-subscriptions

As I’m a self-confessed believer in the power of RSS and as this blog is both about web technology (written in English) and more personal stuff (in Dutch), I’ve decided to offer separate RSS-feeds for these two categories. Moreover I’ve also enabled mail-subscriptions in Feedburner., so if you want you can receive my ramblings by mail.

That means that from now on you have these subscription-links to choose from:

I’ve thought about publishing to a Facebook-page and Twitter as well, but that just seems so … over the top, no?

Fire and Fox don’t make no Firefox

Apparently the Firefox-brand is  that strong that some want to be associated with it. But I’m not sure Mozilla (the not-for-profit or the corp) is fine with the blatant … “re-use” of their artwork.

The irony; Fox security offers fire- & theft-detection. But never mind, we’ve got Firefox 4 (beta7) to look forward to, haven’t we?

As found on the web (October 20th)

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frank liked 2 videos.
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frank posted Tech Support.
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Drink water, geen gebakken lucht (Blog Action Day)

We gaan vandaag even lekker kort door de bocht, het is Blog Action Day, geen Blog Nuance Day.

Flessenwater-producenten verkopen gebakken lucht. Ze prijzen hun waren aan als waren ze wonderen der zuiverheid, terwijl sommige mineraalwaters niet eens geschikt zijn om babymelk te maken omwille van te hoge concentratie aan metalen en mineralen.

En toch slagen reclamejongens, die ingehuurde waterdragers der flessentrekkers, er op slinkse manier in om U en mij bijzonder milieu- en portemonnee-onvriendelijk te laten handelen. Want we hebben allemaal toegang tot een alternatief dat 100 tot 500 keer goedkoper, veel milieuvriendelijker en minstens even gezond is; kraantjeswater.

Kijk naar onderstaande YouTube, bekijk die mooie infograph hiernaast even in detail en koop morgen een mooie glazen karaf om ‘s morgens met kraantjeswater te vullen. Geef uw water gerust een mooie klinkende Franse naam, dat doet drinken. Eau Futée misschien?

The Story of Bottled Water (2010)

Watch this video on YouTube.

Enkele bronnen:

As found on the web (October 13th)

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frank liked Caribou – Sun.
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Drupal, mod_cache & RFC2616 caching

Suppose you’re setting up a Drupal-based site for which you have to implement a caching reverse proxy and for reasons beyond your comprehension Varnish (or even Squid) are not an option. Oh no, you’re stuck with Apache’s mod_proxy and mod_cache! What should you do?

First of all, Drupal 6 doesn’t like reverse proxies. If you don’t want to wait for version 7, which should do better in this respect, you might want to look at Pressflow. This Drupal 6 “distro” has everything on board to work with reverse proxies. So install Pressflow (or try to apply this out of date diff to stock Drupal) and in the Performance-screen set “Caching Mode” to “External” and “Page Cache Maximum Age” to the number of minutes you consider a cached page valid. Voila, you’re done in Drupal (edit: almost, as you might also want to change the $base_url in sites/default/settings.php to reverse proxy URL after you configured Apache).

Next up: Apache! A simple configuration like this one should do the trick:

ProxyRequests Off
ProxyPass /rp_drupal http://localhost/pressflow
ProxyPassReverse /rp_drupal http://localhost/pressflow
CacheEnable disk /rp_drupal/
CacheRoot c:/TEMP/apacache
CacheDefaultExpire 3600

OK, this must surely work, no? Well it should, but it doesn’t! When setting your Apache-loglevel to debug you’ll see “not cached” entries in your error-log, with the following reason:

Expires header already expired, not cacheable

Expires in the past, what does Pressflow think it’s doing deep down in includes/bootstrap.inc?

// HTTP/1.0 proxies do not support the Vary header, so prevent any caching
// by sending an Expires date in the past. HTTP/1.1 clients ignores the
// Expires header if a Cache-Control: max-age= directive is specified (see RFC
// 2616, section 14.9.3).
drupal_set_header('Expires', 'Sun, 11 Mar 1984 12:00:00 GMT');
// [...]
$max_age = variable_get('cache', CACHE_DISABLED) == CACHE_AGGRESSIVE && (!isset($_COOKIE[session_name()]) || isset($hook_boot_headers['vary'])) ? variable_get('page_cache_max_age', 0) : 0;
$default_headers['Cache-Control'] = 'public, max-age=' . $max_age;

Darn, those Pressflow-guys seem to have read up on their RFC’s! And indeed, 2616 confirms that cache-control’s max-age overrules expires;

If a response includes both an Expires header and a max-age directive, the max-age directive overrides the Expires header, even if the Expires header is more restrictive. This rule allows an origin server to provide, for a given response, a longer expiration time to an HTTP/1.1 (or later) cache than to an HTTP/1.0 cache.

Mod_cache’s code seems to take a much simpler approach; at line 503 it decides not to cache based on an Expires-header in the past, totally dismissing the potential presence of cache-control’s max-age.

else if (exp != APR_DATE_BAD && exp < r->request_time)
    {
        /* if a Expires header is in the past, don't cache it */
        reason = "Expires header already expired, not cacheable";
    }

But you’re not interested in code which does or does not adhere to whatever RFC some spec-buffs came up with, you just want to cache your frigging’ Drupal-site! Well, fear not little hacker-boy, here’s some Apache-magic to cure your ailments, to be copy/pasted in the config before ProxyPass and ProxyPassReverse:

<Location /rp_drupal>
     SetEnvIf Request_Protocol "HTTP/1.1" expires_overrule
     # homework: add a SetEnvIf to see if cache-control max-age is present
     Header unset Expires env=expires_overrule
</Location>

So there you have it, a rudimentary caching setup for Drupal (in the guise of Pressflow) using nothing but Apache’s mod_proxy and mod_cache. Now go do your homework and test and do some finetuning and test some more. Happy caching!