Table of Contents

Here is the list of our projects in alphabetical order:

• bounces-handler — Email Bounces Processing System with Rails plugin to prevent Rails mailers from sending any messages to a blocked addresses.
• db-charmer — ActiveRecord Connections Magic (slaves, multiple connections, etc).
• easy-prof — Simple and easy to use Ruby code profiler, which could be used as a Rails plugin.
• Fast Sessions — Sessions class for ActiveRecord sessions store created to work fast (really fast).
• loops — Simple background loops framework for Ruby on Rails and Merb.
• magic-enum — Method used to define ENUM-like attributes in your model (int fields actually).
• rlibsphinxclient — A Ruby wrapper for pure C searchd client API library.
• rscribd — Ruby client library for the Scribd API.
• Rspec Cells — A library for testing applications that are using Cells in RSpec.
• Scribd Desktop Uploader — A fully native Cocoa Macintosh uploader app for the Scribd.com website.

bounces-handler

Bounces-handler package is a simple set of scripts to automatically process email bounces and ISP’s feedback loops emails, maintain your mailing blacklists and a Ruby on Rails plugin to use those blacklists in your RoR applications.

This piece of software has been developed as a part of more global work on mailing quality improvement in Scribd.com, but it was one of the most critical steps after setting up reverse DNS records, DKIM and SPF.

Links: Project Home Page on GitHub | Introduction Blog Post | RDoc Documentation.

db-charmer

DbCharmer is a simple yet powerful plugin for ActiveRecord that does a few things:

• Allows you to easily manage AR models’ connections (switch_connection_to method)
• Allows you to switch AR models’ default connections to a separate servers/databases
• Allows you to easily choose where your query should go (Model.on_db methods)
• Allows you to automatically send read queries to your slaves while masters would handle all the updates.
• Adds multiple databases migrations to ActiveRecord

It requires Ruby on Rails version 2.3 or later. The main purpose of this plugin is to put all the databases-related code we have been using in Scribd for a while into a single easy-to use package.

Links: Project Home Page on GitHub | Test Rails Application on GitHub | RDoc Documentation.

easy-prof

Simple and easy to use Ruby code profiler, which could be used as a Rails plugin. The main idea behind the easy-prof is creating check points and your code and measuring time needed to execute code blocks. Here is the example of easy-prof output:

From this output you can see what checkpoints takes longer to reach, and what code fragments are pretty fast.

Links: Project Home Page on GitHub | Introduction Blog Post | RDoc Documentation.

Fast Sessions

FastSessions is a sessions class for ActiveRecord sessions store created to work fast (really fast). It uses some techniques which are not so widely known in developers’ community and only when they cause huge problems, performance consultants are trying to help with them.

FastSessions plugin was born as a hack created for Scribd.com (large RoR-based web project), which was suffering from InnoDB auto-increment table-level locks on sessions table.

So, first of all, we removed id field from the table. Next step was to make lookups faster and we’ve used a following technique: instead of using (session_id) as a lookup key, we started using (CRC32(session_id), session_id) — two-columns key which really helps MySQL to find sessions faster because key cardinality is higher (so, mysql is able to find a record earlier w/o checking a lots of index rows). We’ve benchmarked this approach and it shows 10–15% performance gain on large sessions tables.

And last, but most powerful change we’ve tried to make was to not create database records for empty sessions and to not save sessions data back to database if this data has not been changed during current request processing. With this change we basically reduce inserts number by 50-90% (depends 0n application).

All of these changes were implemented and you can use them automatically after a simple plugin installation.

There is a fork patched by mudge for full compatibility with Ruby on Rails version 2.3 or later.

Links: Project Home Page on Google Code | Introduction Blog Post | Fork on GitHub Compatible with Rails 2.3 and Later.

loops

loops is a small and lightweight library for Ruby on Rails, Merb and other frameworks created to support simple background loops in your application which are usually used to do some background data processing on your servers (queue workers, batch tasks processors, etc).

Originally loops plugin was created to make our own loops code more organized. We used to have tens of different modules with methods that were called with script/runner and then used with nohup and other not so convenient backgrounding techniques. When you have such a number of loops/workers to run in background it becomes a nightmare to manage them on a regular basis (restarts, code upgrades, status/health checking, etc).

After a short time of writing our loops in more organized ways we were able to generalize most of the loops code so now our loops look like a classes with a single mandatory public method called run. Everything else (spawning many workers, managing them, logging, backgrounding, pid-files management, etc) is handled by the plugin itself.

Links: Project Home Page on GitHub | Introduction Blog Post | RDoc Documentation.

magic-enum

Method used to define ENUM-like attributes in your model (int fields actually). It’s easier to show what it does in code rather than to explain in plain English:

is identical to

This plugin was originally developed for Best Tech Videosand later was cleaned up in Scribd repository and released to the public.

Links: Project Home Page on GitHub | RDoc Documentation.

rlibsphinxclient

A Ruby wrapper for pure C searchd client API library. It works much faster than any Ruby client for Sphinx, so you can check it to ensure you application works as fast as possible.

Please note: this is *highly experimental* library so use it at your own risk.

Links: Project Home Page on GitHub | RDoc Documentation.

rscribd

Ruby client library for the Scribd API. This gem provides a simple and powerful library for the Scribd API, allowing you to write Ruby applications or Ruby on Rails websites that upload, convert, display, search, and control documents in many formats. For more information on the Scribd platform, visit the Scribd Platform Documentation page.

The main features are:

• Upload your documents to Scribd’s servers and access them using the gem
• Upload local files or from remote web sites
• Search, tag, and organize documents
• Associate documents with your users’ accounts

Links: Project Home Page on GitHub | Scribd Platform Documentation | RDoc Documentation.

Rspec Cells

This plugin allows you to test your cells easily using RSpec. Basically, it adds an example group especially for cells, with several helpers to perform cells rendering.

If you are not sure what is cells, please visit its home page.

Spec for a regular cell could look like:

Links: Project Home Page on GitHub | Cells Home Page | Cells Home Page on GitHub.

Scribd Desktop Uploader

A fully native Cocoa Macintosh uploader app for the Scribd.com website. Supports following features:

• Upload many files at once from your desktop.
• Edit titles, tags, and other metadata before uploading.
• Quickly and easily manage bulk uploads, straight from your desktop.
• Right-click to start uploading files directly to Scribd (Windows only).

Links: Project Home Page on GitHub | Home Page on Scribd.com.

Changelog

• September 9, 2009
  • Fixed a link to GitHub homepage of the rspec-cells plugin.
• September 8, 2009
  • Added rspec-cells plugin.

For the beginning, I’ll post a few key points about user profiles. If you want to add some content to the profile of specific user, you should call profile.setFBML routine. For users that you have not called profile.setFBML for, the actions are read from the content in “Default FBML” section of your application settings. For the most part, this will apply to any user who has not added your application. What is “Default FBML” itself? If you have added application, you will see “Default FBML” on all profiles of users that you have not called profile.setFBML for, and it does not matter, if they have added your application or not (good place to put “Invite” link). The same behavior you would see, if you would call profile.setFBML for all users (and if you are crazy enough.)

Please note, “Default FBML” is cached indefinitely, so wait some time to get your content on profiles. Another thing — you can add only action links to user profiles, that have not added your application, and only your application user will see them. This is most important part of the documentation, and you should completely understand it. More detailed description could be found in the documentation for fb:profile-action tag and profile.setFBML routine.

FBML-content for user profiles

There are 4 profile-specific FBML tags exist:

• fb:profile-action is used to add action links under the user picture.
• fb:subtitle will be shown right under the title of the your application box.
• fb:wide specifies content to be shown when your application box placed in wide column.
• fb:narrow specifies content to be shown when your application box placed in narrow column.

Easy, right? So let’s examine these tags more precisely.

As I said early, fb:profile-action is used to place action links on the user’s profile. Usually you will add one link:

What about following scenario: I want to see the link “View my products” when I’m looking my own profile, “View Taisia’s products”, if I’m looking profile of my wife Taisia (and she has added application too), and “Invite Roman to MyApp” when I’m looking profile of my friend Roman, and he has not added application. Here is the code:

Please note: this example is similar to example on the fb:profile-action documentation page, but has one big difference — it’s working: fb:if-is-app-user uid="profileowner" (in documentation example uid takes default value “loggedinuser”, but we need uid of the profile owner.)

This code will work completely only if you will put it into the “Default FBML” section of your application settings, or if you will call profile.setFBML for user, that has not added your application (but this is madness, what I have talked about early): I have specified action “Invite someone to MyApp” in section, which will be shown only on profile of user that has not added application.

BTW, do not forget to remove all line breaks before updating “Default FBML”, because Facebook replaces them with <br/>.

Another interesting thing you could see from working example: Facebook adds parameter id for all links in profile-action, and it equals to owner’s of the profile ID. In my previous example, if I will navigate to Roman’s profile, I will see hyperlink with URL http://apps.facebook.com/myapp/Invite.aspx?id=603839739. Great!

This example is simple, so let’s move ahead. We have two columns on the profile: left (narrow) and right (wide). You can specify in application settings which one will be default. To put content in wide column, use fb:wide, in narrow column — fb:narrow. Quite clear, right?

One more interesting issue. You can specify as many fb:wide and fb:narrow tags as you wish. All content, specified in fb:wide tags will be shown if you application box placed in wide column, all content from fb:narrow tags — when application box placed in narrow column. You can add content outside one of these tags, and it will be shown in both cases — when application in wide or narrow column. If no content specified for one of column, Facebook will show “No content to display.” text.

When to generate profile FBML?

Your application box on the user’s profile should reflect latest changes related to him. Facebook does not know when to update profile information, so you need to do it by yourself (anyway, only you as application developer know when something changes). So, usually you would call profile.setFBML after some changes in your application (for example, user or his friends added some data), depending on which information you are rendering on the profile. Sometimes it’s a good idea to set default data after user has added your application.

Creating profile FBML content with ASP.NET

For profile content generating I propose to use UserControls:

How to get string to put it into the profile.setFBML? Here is the code:

I’ve added control to the Controls collection to get events fired. If you would call this snippet from OnLoad, only OnInit would be fired in ProfileFBML, so do not forget to call DataBind method to force data binding from OnInit in this case.