The Real Cost of Data Roundtrip
By Szymon Lipiński
October 3, 2012
Sometimes you need to perform some heavy database operations. I don’t know why very often programmers are afraid of using databases for that. They usually have some fancy ORM which performs all the operations, and the only way to change the data is to make some SELECT * from a table, create a bunch of unneeded objects, change one field, convert those changed objects into queries and send that to the database.
Have you ever thought about the cost of the roundtrip of data? The cost of getting all the data from database just to send changed data into the database? Why do that if there would be much faster way of achieving the same results?
Imagine that you have quite a heavy operation. Let’s make something which normally databases cannot do, some more complicated operation. Many programmers just don’t know that there is any other way than writing this in the application code. Let’s change all the HTML entities into real characters.
The HTML entities are a way of writing many different characters in HTML. This way you can write for instance the Euro currency sign “€” in HTML even if you don’t have it on your keyboard. You just have to write € …
database optimization postgres
Setting user ownership of nginx and Passenger processes
By Brian Buchalter
October 2, 2012
Do this now on all your production Rails app servers:
ps ux | grep Rails
The first column in the results of that command show which user runs your Rails and Passenger processes. If this is a privileged user (sudoer, or worse yet password-less sudoer), then this article is for you.
Assumptions Check
There are several different strategies for modifying which user your Rails app runs as. By default the owner of config/environment.rb is the user which Passenger will run your application as. For some, simply changing the ownership of this file is sufficient, but in some cases, we may want to force Passenger to always use a particular user.
This article assumes you are running nginx compiled with Passenger support and that you have configured an unprivileged user named rails-app. This configuration has been tested with nginx version 0.7.67 and Passenger version 2.2.15. (Dated I know, but now that you can’t find the docs for these old versions, this article is extra helpful.)
Modifying nginx.conf
The changes required in nginx are very straight forward.
# Added in the main, top-level section
user rails-app;
# Added in the appropriate http section among your other Passenger related …hosting rails security
Ubuntu Dual Monitor Setup on Dell XPS
By Steph Skardal
October 1, 2012
Over the weekend, I received a new desktop (Dell XPS 8500 with NVIDIA graphics card) and troubleshot dual monitor setup on Ubuntu. Because I spent quite a while googling for results, I thought I’d write up a quick summary of what did and didn’t work.
One monitor was connected via HDMI and the other through DVI (with a VGA to DVI adaptor provided with the computer). When I started up the computer in Windows, both monitors were recognized immediately. Besides configuring the positioning of the monitors, Windows was good to go. But when I installed Ubuntu, the DVI/VGA monitor was recognized with incorrect resolution and the monitor connected via HDMI was not recognized at all. I tried switching the unrecognized monitor to a VGA/DVI connection, and it worked great by itself, so I concluded that it wasn’t an issue with a driver for the HDMI-connected monitor.
Many of the Google results I came across pointed to troubleshooting with xrandr, but any xrandr commands produced a “Failed to get size of gamma for output default.” error and any progress beyond that was shut down. Another set of Google results pointed to using “nvidia-detector”, but there …
ubuntu
Defense in Depth
By Zed Jensen
September 28, 2012
“Defense in depth” is a way to build security systems so that when one layer of defense fails, there is another to take its place. If breaking in is hard enough for an attacker, it’s likely that they’ll abandon their assault, deciding it’s not worth the effort. Making the various layers different types of defense also makes it harder to get in, so that an attacker is less likely to get through all the layers. It can also keep one mistake from causing total security failure.
For example, if you have an office with one door and leave it unlocked by accident, then anyone can just walk in. However, if you have an office building with a main door, then a lobby and hallways, and then additional inner locked doors, then the chance of accidentally leaving both unlocked is small. If you accidentally leave the inner door open or unlocked, someone can only get into the office if they first get through the outer door.
Another example of defense in depth is making and maintaining offsite computer backups. The chance of an office being destroyed and all your data with it is low, but not zero. If you maintain offsite backups, then your losses in a catastrophe are reduced.
Another way to decrease …
security backups
Test Web Sites with Internet Explorer for Free
By Greg Davidson
September 26, 2012
Browser Testing
While many Web Developers prefer to build sites and web applications with browsers like Chrome or Firefox it’s important for us to keep an eye on the browser market share for all web users. Internet Explorer (IE) still owns a large piece of this pie and because of this, it is important to test sites and applications to ensure they work properly when viewed in IE. This poses a potential problem for developers who do not use Windows.
Although I use OS X on my desktop, I have Windows virtual machines with IE 6,7,8,9 and 10 installed. I also have a Linux virtual machine running Ubuntu so I can check out Chrome/Chromium and Firefox on that platform. In the past I had tried solutions like MultipleIEs but wasn’t satisfied with them. In my experience I’ve found that the best way to see what users are seeing is to have a virtual machine running the same software they are.
I did some IE8 testing for a colleague a short time ago and suggested she should give VirtualBox a shot. Her response was “You should write a blog post about that!”. So here we are.
Free Tools
VirtualBox is a free virtualization application similar to Parallels or VMWare. These …
browsers environment testing tips tools virtualization
Piggybak: An Update on End Point's Ruby on Rails Ecommerce Engine
By Steph Skardal
September 24, 2012
With the recent release of one of our client sites running on Piggybak, Piggybak saw quite a few iterations, both for bug fixes and new feature development. Here are a few updates to Piggybak since its announcement earlier this year.
Admin: Continues to Leverage RailsAdmin
Piggybak continues to leverage RailsAdmin. RailsAdmin is a customizable admin interface that automagically hooks into your application models. In the case of the recent project completion, the admin was customized to add new features and customize the appearance, which can be done in RailsAdmin with ease.
As much as I enjoy working with RailsAdmin, I think it would be great in the future to expand the admin support to include other popular Rails admin tools such as ActiveAdmin, which has also gained popularity in the Rails space.
Refund Adjustments
When Piggybak first came out, there was little in the way to allow orders to be monetarily adjusted in the admin after an order was placed. One requirement that came out of client-driven development was the need for recording refund adjustments. A new model for “Adjustments” is now included in Piggybak. An arbitrary adjustment can be entered in the admin, …
ecommerce piggybak rails
Insidious List Context
By Jeff Boes
September 20, 2012
Recently, I fell into a deep pit. Not literally, but a deep pit of Perl debugging. As a result, I’m here to warn you and yours about “Insidious List Context(TM)”.
(Note: this is a fairly elementary discussion, for people early in their Perl wizardry training.)
Perl has two contexts for evaluating expressions: list and scalar. (All who know this stuff cold can skip down a ways.) “Scalar” context is what non-Perl languages just call “normal reality”, but Perl likes to do things … differently … so we have more than one context.
In scalar context, a scalar is a scalar is a scalar, but a list becomes a scalar that represents the number of items in the list. Thus,
@x = (1, 1, 1); # @x is a list of three 1s
# vs.
$x = (1, 1, 1); # $x is "3", the list size
In list context, a list of things is still a list of things. That’s pretty simple, but when you are expecting a scalar and you get a list, your world can get pretty confused.
Okay, now the know-it-alls have rejoined us. I had a Perl hashref being initialized with code something like this:
my $hr = {
KEY1 => $value1,
KEY2 => $value2,
KEY_TROUBLE => …interchange perl
Rails 4 Highlights
By Steph Skardal
September 20, 2012
I watched this recent video What to Expect in Rails 4.0 presented by Prem Sichanugrist to the Boston Ruby Group. Here are a few high-level topics he covered in the talk:
- StrongParameters: replaces attr_accessor, attr_protected, moves param filtering concern to the controller rather than the model. Moving param filtering concern to the controller allows you to more easily modify user attribute change-ability in controllers (e.g. customer-facing vs admin).
- ActiveSupport::Queue: Discussed at RailsConf, add queueing support to Rails, e.g.:
# Add to queue
Rails.queue.push UserRegistrationMailerJob(@user.id)
# Control queue configuration (asynchronous, synchronous or resque, e.g.
config.queue = [:asynchronous, :synchronous, :resque]
-
Cache Digests: Rails 4.0 introduces cache key generation based on an item and its dependencies, so nested cache elements properly expire when an item is updated.
-
PATCH verb support: Support of HTTP PATCH method (_method equals “patch”), which will map to your update action is introduced in Rails 4.0.
-
Routing Concern: Rails 4.0 introduces some methods to help clean up your duplicate routes.
-
Improvements to ActiveRecord::Relation …
ruby rails