If you have a model that uses set_table_name you may hit a snag when trying to use fixtures and unit tests. The solution is twofold: name the fixture file using the legacy table name, and use the set_fixture_class method in your unit test. I coudn’t find this method mentioned in Agile Web Development with Rails, and there’s only a brief mention on the rubyonrails.com site. Still, some web searches turned up the answers.
Here is a simple example:
A few days ago Google made their “My Maps” announcment and since then there has been nothing but buzz buzz buzz about it. So I figured I would take a minute to show how someone can use this new tool from Google to create their own embedded maps for their site.
Steven pointed out that someone was looking for a way to stream to S3 using PHP and said I should figure out how to get it going. Since he made a patch to let you stream data with Ruby using S3 I figured I should do one for PHP. There may be better ways of doing this but since I’ve already done it with C using curl I figured that would be the fastest way.
(more…)
After reading this post on the S3 forum I realized that other people are thinking about doing some of the same stuff I have. paolonew was looking for a way to for a way to create URLs to S3 objects that expired. I did this a while back when I was thinking about how to host objects that I wanted to protect with some outside scheme. The confusion on the forum seemed to be about the timestamps used to expire the URL. For PHP it is fairly easy.
To clear up the expiration time issue I think these two steps are needed:
1) Keep in mind that the HTTP header dates must be in GMT.
2) The PHP function time() returns the seconds since the epoch January 1 1970 00:00:00 GMT). Notice here this is in GMT as well.
3) The HTTP Date header you see in a response from an S3 server is the time on that server. The machine you use to sign your request should be synced with that time. I think a good guess is that all the Amazon servers are synced with the atomic clock.
There isn’t much to securing a URL after you have that tucked away. Here is an example that will sign a URL so that it is valid for 60 seconds:
<?php
require_once('Crypt/HMAC.php');
echo getS3Redirect("/test.jpg") . "\\n";
function getS3Redirect($objectName)
{
$S3_URL = "http://s3.amazonaws.com";
$keyId = "your key";
$secretKey = "your secret";
$expires = time() + 60;
$bucketName = "/your bucket";
$stringToSign = "GET\\n\\n\\n$expires\\n$bucketName$objectName";
$hasher =& new Crypt_HMAC($secretKey, "sha1");
$sig = urlencode(hex2b64($hasher->hash($stringToSign)));
return "$S3_URL$bucketName$objectName?AWSAccessKeyId=$keyId&Expires=$expires&Signature=$sig";
}
function hex2b64($str)
{
$raw = '';
for ($i=0; $i < strlen($str); $i+=2)
{
$raw .= chr(hexdec(substr($str, $i, 2)));
}
return base64_encode($raw);
}
?>
The hex2b64 function was pulled from the amazon S3 PHP example library.
Techcrunch has a good review by Frank Gruber of the look and feel of mapping services. I think it is notable that ESRI’s service is not included in the review. I think it is at least as good as the mapquest service. I may have to find time to redo my review of the acuracy of each again and a more technical evaluation of each.
I recently had an opportunity to use ESRI’s ArcSDE again. It is a spatial database interface and in this instance I was using the java api. I wanted to change what used to be a query using a rectangle into a query using a circle. For some reason parts of the java api for ArcSDE require a C library or something. I gave up pretty quickly on trying to make their arc function work since the documentation wasn’t very clear on how it worked. Instead I decided to figure out how to approximate a circle with a polygon and use that instead. Here is the result of that research.
One of the downsides of the ruby S3 example code is that it doesn’t support streaming of data (it loads the entire file into memory). It turns out, however, that all that is needed to stream data is a tweak to the ‘request’ method in Net::HTTP.
require 'net/http'
require 'S3'
require 'pp'
#
# Replace the request method in Net::HTTP to sniff the body type
# and set the stream if appropriate
#
module Net
class HTTP
alias __request__ request
def request(req, body = nil, &block)
if body != nil && body.respond_to?(:read)
req.body_stream = body
return __request__(req, nil, &block)
else
return __request__(req, body, &block)
end
end
end
end
#
# Connect to s3 using the ruby API provided by Amazon
#
conn = S3::AWSAuthConnection.new("[PUBLIC]", "[PRIVATE]", false)
#
# Stream a testfile to S3
#
open("testfile") do |stream|
pp response = conn.put('BUCKET_NAME',
"testfile",
stream,
{
"x-amz-acl" => "public-read",
"Content-Type" => "text/plain",
"Content-Length" => FileTest.size("testfile").to_s
}
)
end
#
# Send a testfile in memory to S3
#
pp response = conn.put('BUCKET_NAME',
"testfile",
File.read('testfile'),
{
"x-amz-acl" => "public-read",
"Content-Type" => "text/plain"
}
)
A few notes about the code
We have a couple of fairly high traffic sites that have large images designed to be used for desktop backgrounds. To save a bit of bandwidth, we decided to give Amazon’s S3 webservice a spin.
Signing up was fairly painless. They required a credit card (so they could bill us $.15/G storage and $.20/G transfer). After I signed up I quickly received an email that contained a link to my public and secret keys.
This is a fairly new service and the client tools are just getting started. For my purposes of uploading several images, I decided to use jSh3ll to ‘browse’ my S3 storage and a custom ruby script to upload a large amount of files.
After downloading and installing jSh3ll, I created my first bucket:
(more…)
I’ve been evaluating a couple different mapping software packages recently and the other day I noticed that the same addresses geocoded (for those who don’t know what geocoding is you can find out more about it here) to different locations. They are mostly the same but I figured it was interesting enough to do some more digging and see how different mapping services compared.I looked at the following services. Some of them are commercial services with open apis (ESRI and mapquest) and some of them are non-commercial services with open apis (yahoo and google although google does not have a geocoding api).
For google I viewed the resulting values for latitude and longitude that were generated from a search for the address. For yahoo and ESRI I used their REST geocoding apis and for mapquest I used their java api to their commercial service since their openapi service is only in beta currently.I took 5 addresses located at different points in the US and one in Canada and mapped the returned latitude and longitude from each service. Here are the results:
(more…)
Cincinnati 513.298.1865
Virginia 7875 Promontory Court Dunn Loring, VA 22027
Kentucky 12910 Shelbyville Road Suite 310 Louisville, KY 40243 502.245.6756
© 2010 Mission Data