During development sometimes I hide a server behind a shared password for http basic auth, based on an Apache configuration (if you still want to use .htpasswd but don't have Apache and htpasswd installed you can still generate the password entries using openssl). nginx can use the same format of .htpasswd files by using the HttpAuthBasicModule. But sometimes I need a service to crawl pages on the server (for example Drupal's linkchecker module). And sometimes storing the basic auth login and password in a script isn't wanted or advisable. Instead we can configure nginx to skip authentication when connecting from localhost/127.0.0.1.

Open up your nginx configuration which already contains your auth_basic directives. Assuming you are running a PHP site and you have a "location ~ \.php$" block, make it look more like this:

location ~ \.php$ {
  satisfy any;
  allow 127.0.0.1;
  deny all;
 
  auth_basic            "Restricted";
  auth_basic_user_file  /yoursite/path/.htpasswd;
}

Remember that the order of the allow/deny directives matters. More on the nginx_http_access_module module.

The problem is this. ImageCache is a great simple way to transform random images into useful dimensions, etc. But sometimes the uploaded image is already exactly the quality and even dimensions we want. But after imagecache module runs, the file size is actually larger than the original while the quality has gone down, despite JPG image quality being 100% (default is set to 75%). One workaround can be to re-sharpen the image (imagecache_sharpen) but this also loses some quality.

1. Check that the uploaded image (metadata saved as CCK field, file stored directly in sites/default/files) has not been degraded in quality.

2. Check that minimum/maximum resolution for the image fields (CCK) are set to 0 (no restriction) so that they aren't accidentally resized at the upload to CCK step.

3. Run "drush imagecache-flush" in case you have files left over from a recent imagecache configuration change.

4. Try replacing GD with ImageMagick. If you stick with GD, and try compiling a newer GD library. ImageMagick by default can output higher quality images than GD.

How does Drupal's image resizing and processing work?

ImageCache goes through imageapi which uses different image processing functions based on the library (by default GD and ImageMagick support are provided) used.

Any resizing operation will result in a change (loss) in quality. That is to be expected since upsizing creates new pixels from single original pixels without having new information (unlike the magical effects of zooming into images on CSI shows) and downsizing will generally cause information to be lost and many pixels will "store" the information from several surrounding pixels.

So only operations that keep the image the same dimensions or crop the image (in which case the cropped portion has the same dimensions in both old and new files) will retain the same quality and avoid any blurring.

When using PHP's GD, Drupal will make calls to imagecopyresampled which will affect image quality unless image width and height are kept the same or cropping is performed. This is partly due to imagecopyresampled and partly the way it is called. "Fastimagecopyresampled" is a possible replacement: (from http://us.php.net/manual/en/function.imagecopyresampled.php#77679) - this is a higher quality version of PHP's imagecopyresampled. It does result in higher quality but requires hacking Drupal code instead of overriding any hooks.

I've found that it's better to use ImageMagick than GD. The only remaining problem is that for similar quality images, the file size is something like twice as big after ImageMagick processing. You could mess around with ImageMagick's quality settings by hacking Image API code or by copying imageapi_imagemagick.module into a custom module and configuring it for use instead. But you risk breaking quality for other images. I haven't found the reason why IMagick makes image file sizes larger.

I've been doing some testing on a plethora of content delivery networks using cloudharmony.com's speedtest service. Testing from multiple ISPs in Vietnam, during the most recent undersea cable outage, it becomes clear that, although none of the CDNs publicly have datacenters in Vietnam, a small handfull of networks like Edgecast CDN (via http://www.speedyrails.com/) come out on top as winners (except for an anomalous reading of small file size downloading from one ISP). In these tests, performance of poor hosts relative to the top was as much as 20 times slower, meaning CDN selection without taking into consideration the real world results in Vietnam can mean you're throwing a lot of money away. Poorly performing content delivery networks were more or less not any faster than hosting in the US.

Limelight CDN also had some of the best overall results, better than Edgecast in some cases.

VoxCAST CDN had a surprisingly low latency time suggesting it could be closer to Vietnam than anything in Singapore, but VoxCAST (Internap) do have a Singaporean datacenter which is probably just faster than other points in Singapore. Unfortunately, the transfer speeds were too low. Internap's CDN taken into consideration alone fared poorly. Edgecast state they use Equinix Singapore Exchange so it may be worth looking into colocating there.

Windows Azure CDN had some promising results in some tests whereas other tests failed. I didn't investigate further when CDNs failed, assuming they should not fail.

What may be more surprising is who isn't the winner here: Amazon

Amazon EC2 instances in both Singapore and Tokyo (just for comparison) performed poorly both in terms of latency and throughput. Amazon's CloudFront service did no better.

Asia-America Gateway undersea cable outage

At the time of writing, the AAG internet cable that connects to Vietnam at Vung Tau's landing station, thus providing FPT (although Viettel and VNPT do also use AAG) in Ho Chi Minh City and its subscribers with international bandwidth to Hong Kong, Singapore, and points beyond in the US, has been cut or damaged again. The cable experiences cuts both at the Vung Tau cable landing station as well as in the main trunk when all traffic along the cable would be affected. It is one of several international links to Vietnamese ISPs such as SEA-ME-WE 3 (but not SEA-ME-WE 4) which connects to Vietnam in Da Nang and links Southeast Asia with East Asia, Australia, the Middle East, and Western Europe. TVH and TGN-Intra Asia Cable System also land in Vung Tau connecting Southern Vietnam to the greater Internet. Vietnam also has terrestrial internet connections to China.

[Update: The AAG cable is being repaired from October 25, 2012 until November 4.]

Writing Vietnamese is a pain. You have several different input systems to choose from (VNI, Telex, VIQR, etc.) and they all require some effort to memorize and get used to. But as it turns out most Vietnamese text can be understood without those accent (diacritic) marks at all. Vietnamese people are accustomed to texting (sms) each other using Vietnamese words written without marks - because their phones often don't support Vietnamese characters. But it's better to have the marks and emails and posts on forums often do. GMail even supports a Vietnamese software keyboard built into the interface now.

But if Vietnamese people can understand Vietnamese without diacritics, can computers? Turns out there is software that can take unaccented Vietnamese text and ADD the diacritics!

Let's take some text:

Chuyến phiêu lưu khám phá bỏ nhà ra đi đầu tiên của bạn vào năm bao nhiêu tuổi? 
- Nghĩ lại thì thấy hồi xưa mỗi lần mà bị mẹ la là hay giận, bỏ nhà đi lắm, vì lúc nào cũng nghĩ mình đúng hết. Giận thì giận nhưng mà đi lang thang rồi lại về, hoặc về trong tình trạng được tìm thấy và lại tiếp tục bị mắng :D

Then we strip the accents and put it into a few websites to see the results.

http://vietnameseaccent.com/

Chuyến phiêu lưu khám phá bỏ nhà ra đi đầu tiên của bạn vào năm bao nhiêu tuổi?
- Nghĩ lại thì thấy hồi xưa mỗi lần mà bị mẹ là lạ hay gián, bỏ nhà đi làm, vì lúc nào cũng nghĩ mình dùng hết. Gian thi giản nhưng mà đi lang thang rồi lại về, hoặc vê tròn

http://vietlabs.com/vietizer.html

chuyến phiêu lưu khám phá bỏ nhà ra đi đầu tiên của bạn vào năm bao nhiêu tuổi?
- nghĩ lại thì thấy hồi xưa mỗi lần mà bị mẹ là là hay gian, bộ nhà đi làm, vì lúc nào cũng nghĩ mình đứng hết.
gian thì giản nhưng mà đi lang thang rồi lại về, hoặc về trọn

http://www.easyvn.com/tiengviet/index.php

Chuyến phiêu lưu khám phá bỏ nhà ra đi đầu tiên của bạn vào năm bao nhiêu tuổi?
- Nghĩ lại thì thấy hồi xưa mỗi lần mà bị mẹ là là hay giận, bỏ nhà đi lắm, vì lúc nào cũng nghĩ mình đúng het. Gian thì giận nhưng mà đi lang thang rồi lại về, hoặc về tron

The results are nearly the same except for the last word: 'tron'. This is because the real word is "trong" but it got cut off in the de-accenting process! So each different software took a different guess as to what the word was, but it was the wrong word to begin with.

All in all, they do a pretty good job and probably better than even some native Vietnamese speakers due to the fact that some tones are mixed up!