I was doing some research into Amazon’s fulfillment centers today and had trouble finding them. After finding their addresses, I put them all on a Google Map here
View Amazon Fulfillment Centers in a larger map
Author: Brandon (Page 7 of 29)
APISigning.com has been signing Amazon Product Advertising requests for a couple of years now. Amazon recently announced their Simple Email Service that makes it easy to send emails via an API. The SES API requires that requests be authenticated using some cryptographic functions that are not easily available on all platforms or programming languages. In those cases, developers can use the APISigning SES Service to calculate the correct signature and perform the request on their behalf.
APISigning has free accounts that effectively allows 10k signing requests each month. Users who require additional requests can subscribe to a paid account with higher limits.
For some reason Windows can’t figure out how to move some files around on disk. When attempting to shrink a volume, it will only allow you to shrink it to where the last immovable file is located. These are some things I found necessary to temporarily get rid of those immovable files so that an NTFS volume could be shrunk
1- Disable System Restore (Right click on Computer => Properties => System Protection => System Restore)
2- Disable Virtual Memory (Right click on Comptuer => Properties => Advanced System Settings => Performance (Settings) => Advanced Tab => Virtual Memory (Change) => No Paging File => Set.
3- Run Disk Cleanup to get rid of Thumbnails, Temporary Internet Files, and a bunch of other files that it makes no sense why they are immovable.
4- Restart the computer to have #1 and #2 take effect
Try to shrink the volume again. If it still is unreasonably large, you will then have to look at Event Viewer to find which file is at the boundary.
1- Right click on Computer => Manage => Event Viewer => Windows Logs => Application.
2- Click on Filter Current Log, and put ‘259’ for the Event ID
3- Click on the latest event and look through the detail to find the problematic file. You can then attempt to delete that file (or set of files) manually. You may have to restart into safe mode to delete some files
It took me about 5 loops of doing the above before I was finally able to shrink my volume to the size that I wanted. After successful, you can then re-enable the features that you want (namely System Restore and Virtual Memory)
KnitMeter Has Been Upgraded
KnitMeter.com was originally started over four years ago in December of 2007 as a small project that my wife thought would be useful. Since then, the site hasn’t changed much, but it has managed to grow to thousands of users who have knit nearly 20 thousand miles of yarn. I’ve received numerous requests and have finally gotten a chance to impliment what many of you have been requesting for a while now. New features on the site include:
- Users can now add entries for knitting, crocheting, and spinning
- Completely new and modernized design and logo
- You can customize your widgets directly on KnitMeter.com rather than editing the code for the widget on your website
- The website and the KnitMeter Facebook Application are now completely integrated. Entries added in one will be displayed and counted in the other
- The Facebook application can (again) publish your entries to your news feed, but only when you tell it to
- You can chose to make your profile public, which will display some of the most recent entries on the KnitMeter home page with a link to your website
- Added several new timeframes, including specific calendar years (ie: I knit 4.3 miles in 2010)
- Numerous technical changes that should make the site faster to use and make it easier to make future changes
These new features have been rolled out over the past couple of weeks. I appreciate the patience of those who have dealt with a few bugs over that time, and I believe that everything should be pretty bug-free now. I encourage you to check out the new site and to start adding up the mileage for your own projects. The next major milestone will be when we have gone through enough yarn to go around the earth (about 24,901 miles). At the present rate, we should hit that figure in about 3-5 months.
Happy Knitting, Crocheting, and Spinning,
Brandon Checketts
KnitMeter.com
I will sometimes run into an error inside an OpenVZ guest where the system complains about running out of memory. This is usually seen as a message containing “Cannot allocate memory”. It may even occur when trying to enter into the container
[root@host ~]# vzctl enter 908 entered into CT 908 -bash: /root/.bash_profile: Cannot allocate memory
This particular error can be difficult to troubleshoot because OpenVZ has so many different limits. The “Cannot allocate Memory” error is a pretty generic error, so Googling it doesn’t necessarily yield any useful results.
I’ve found that the best way to track down the source of the problem is to examine the /proc/user_beancounter statistics on the host server. The far right column is labeled ‘failcnt’ and is a simple counter for the number of times that particular resource has been exhausted. Any non-zero numbers in that column may indicate a problem. In this example, you can see that the dcachesize parameter is too small and should be increased
[root@host ~]# cat /proc/user_beancounters
Version: 2.5
uid resource held maxheld barrier limit failcnt
908: kmemsize 5170890 5776435 43118100 44370492 0
lockedpages 0 0 256 256 0
privvmpages 53561 55089 1048576 1048576 0
shmpages 2 2 21504 21504 0
dummy 0 0 0 0 0
numproc 30 38 2000 2000 0
physpages 6136 7392 0 9223372036854775807 0
vmguarpages 0 0 65536 65536 0
oomguarpages 6136 7392 26112 9223372036854775807 0
numtcpsock 8 8 360 360 0
numflock 5 6 380 420 0
numpty 0 1 16 16 0
numsiginfo 0 2 256 256 0
tcpsndbuf 140032 0 10321920 16220160 0
tcprcvbuf 131072 0 1720320 2703360 0
othersockbuf 151320 156864 4504320 16777216 0
dgramrcvbuf 0 8472 262144 262144 0
numothersock 107 109 5000 5000 0
dcachesize 3408570 3413265 3409920 3624960 81
numfile 724 957 18624 18624 0
dummy 0 0 0 0 0
dummy 0 0 0 0 0
dummy 0 0 0 0 0
numiptent 10 10 128 128 0
You can do a little investigation to see what each particular limit does. I will usually not dig too deep, but just double the value and try again. You can set a new value using the vzctl command like this:
[root@host ~] vzctl set 908 --dcachesize=6819840:7249920 --save
Most website designers have been using CSS for page layout for several years now, but I occasionally see some websites that continue to use HTML tables for layout. As I’ve been focusing on website performance lately, I’ve found some references that modern browsers render sites using tables for layout slower than they do sites that use CSS. I decided to investigate and confirmed that there are many possible situations where sites using large tables will appear to load much slower than those using CSS. I put together two pages to confirm:
This page uses <div> elements for layout
and
This pages uses a large table for layout
On both pages I’ve added a 5-second sleep near the end of the page to show what might happen if the server was slow, if there were network problems, or any other number of things may have happened.
Notice that the page created using a table changes a lot after the delay. I’ve tried it in Firefox 3 which extends the main (yellow) content section all of the way to the right until it receives the rest of the document, at which point it has to shrink that part to make room for the section on the right. Internet Explorer behaves even worse. It leaves a blank white page until after the delay, at which point it draws the whole table.
By contrast, the page created with CSS positioning shows all of the content above the delay and has it in the correct position. When the rest of the document is sent it just fills in the appropriate content, but doesn’t have to re-arrange anything on the page.
This is a really quick script I came up with to generate a Code-39 Barcode. Many thanks to
Matthew Welch who created the Free 3 of 9 Barcode Font. PHP’s imagettftext function makes this pretty simple.
The $barcode_font referenced below is available from the link above ‘3 of 9’ font. The $plain_font is just a font file that I copied from /usr/share/fonts/default/Type1/ on a Linux box.
This script create a nice looking barcode with the text underneath it like this:
< ?php
$number = isset($_GET['number']) ? $_GET['number'] : '';
$barcode_font = dirname(__FILE__).'/fonts/FREE3OF9.TTF';
$plain_font = dirname(__FILE__).'/fonts/plain.pfb';
$width = 200;
$height = 80;
$img = imagecreate($width, $height);
// First call to imagecolorallocate is the background color
$white = imagecolorallocate($img, 255, 255, 255);
$black = imagecolorallocate($img, 0, 0, 0);
// Reference for the imagettftext() function
// imagettftext($img, $fontsize, $angle, $xpos, $ypos, $color, $fontfile, $text);
imagettftext($img, 36, 0, 10, 50, $black, $barcode_font, $number);
imagettftext($img, 14, 0, 40, 70, $black, $plain_font, $number);
header('Content-type: image/png');
imagepng($img);
imagedestroy($img);
?>
UPS doesn’t seem to be too big of a fan of Perl or PHP. They provide some powerful functionality through their API’s and their documentation is sufficient, but doesn’t contain examples of anything except for Visual Basic or Java. Fortunately their is an open source project called UPS-PHP that aims to fill that gap by providing some classes for interacting with UPS’s APIs. The UPS-PHP project seems to have lost steam though as the latest updates were over a year ago.
The latest version of the UPS shipping API requires the user to go through a process of creating test transactions, then voiding some transactions in a sandbox environment prior to allowing you access to the production environment. You have to email them every request and response that you send and received for the test transactions as well as various images and HTML documents that were created from their responses.
I added some logging ability to the UPS-PHP class responsible for sending and receiving the responses. A patch is available here if anybody else wants to try it. You basically call the new methods setDebugDir() and setTransaction() on the ‘ups’ object. Those tell it which directory to log to, and which filename to use respectively.
Usage would look something like this:
$debug_dir = "{$_SERVER['DOCUMENT_ROOT']}/upsdebug/".date('Y')."/".date('m');
// make sure that $debugdir exists... Create it if necessary
$upsConnect->setDebugDir($debug_dir);
$upsConnect->setTransaction(time());
$upsConnect->setTemplatePath('../../xml/');
$upsConnect->setTestingMode(1); // Change this to 0 for production
$upsVoid = new upsVoid($upsConnect);
$upsVoid->buildRequestXML($ShipmentIdentificationNumber);
At this point your $debugdir would have two files in it. One with the XML request and the other with the XML response, suitable for zipping up and sending to UPS for approval.
I ran into a problem today when dealing with a very simple SQL Query. The query simply calls a stored procedure on the MySQL server. This is a trivial app, so I was using the very basic mysql_connect(), mysql_query() functions. The result wasn’t being returned an mysql_error() was saying that the error was:
PROCEDURE db.procedure_name can't return a result set in the given context
Of course ‘db.procedure_name’ was the actual name of the procedure I was calling. Googling for the error seemed to indicate that the MySQL client library was old, but this is on a fairly modern CentOS 5.5 server with the php-mysql package at version 5.1.6.
After a bit of experimenting, I found that I was able to change to using the mysql improved versions of the PHP functions and that worked fine
$dbconn = mysql_connect($dbhost, $dbuser, $dbpass);
$result = mysql_query("CALL db.procedure_name('arg1', 'arg2', 'arg3')", $dbconn)
$row = mysql_fetch_assoc($result);
Becomes
$dbconn = mysqli_connect($dbhost, $dbuser, $dbpass);
$result = mysqli_query($dbconn, "CALLdb.procedure_name('arg1', 'arg2', 'arg3')");
$row = mysqli_fetch_assoc($result);
Note that changing from mysql_query to myqli_query needs the parameters reversed.
After making that change I’m able to run the stored procedure correctly.
I was fortunate to be selected to give a presentation at the 2010 Southeast Linux Fest held this year in Greenville, SC. The topic was MySQL replication which I picked from a similar presentation I gave about about 1.5 years ago at my local LUG. I’ve configured plenty of replicated servers and I think that I understand it well enough to explain it to others.
The 2-hour presentation is about half slides and half demo. Throughout the course of the presentation I set up a simple master-slave. Then I add a second slave. Taking it a step farther I set up the three servers to replicate in a chain, and finally I configure them to replicate in a full circle so that changes made on one are propagated to all of the others. I intentionally do things that break replication at certain points to show some of the limitations and configurable features that can help it to work.
Slides for the presentation are available OpenOffice format.
The presentation was recorded, so hopefully the SELF team will have those videos available shortly.