Wednesday, July 22, 2009

SC Engine: Part 8 - The Site

- Introduction
- Part One: System Overview
- Part Two: System Overview: Messages and Applications
- Part Three: Screen Scraping
- Part Four: YouTube Parsing
- Part Five: Linking the Video to the Game
- Part Six: Messaging Middleware
- Part Seven: The Console
- Part Eight: The Site

In my final planned post for SC Engine, I'll talk about how the data gets from moving around through all these apps onto the web site.

One application that is really no different than any other in terms of how it is made is called 'web.site_interface'. Here's what it looks like...

Web Site App

You'll notice that the app is simply named "App". I recently did a refactoring that allowed me to create apps based on the module name to make bringing together all the apps very simple. Anyway, in the application's builder method, we see a good example of the application getting a configuration (the password to the site). The 'poster' method is a function that's used to send data using an HTTP post to the web site at the specific location. The entire body of the request is json, and consists of the data and a password. This password, combined with SSL, should give me enough protection to allow updates to the site without worrying about a third party easily swooping in and running whatever commands they want.

On the other side, pylons is waiting in it's update controller...

Update Controller

In case you were wondering, this is similar to how the SC Console works, as well. Really, the controller just converts the json into a dictionary of values, and passes it on to the updater which does the heavy lifting...


In terms of updates, that's all there is to it.

One of the more interesting points is the url generation, such as the following:

Currently, the url routes are a bit hackish...

map.connect('/', controller='main', action='index')
map.connect('/uploader_info', controller='main', action='uploader_info')
map.connect('/contact', controller='main', action='contact')
map.connect('/contact_submit', controller='main', action='contact_submit')
map.connect('/contact_submitted', controller='main', action='contact_submitted')

# Uploads
map.connect('/update/{action}', controller='update')

# Ajax retrieval of commentary
map.connect('/commentary/{game_id}/{author}', controller='commentary', action='view')

# Matches
controller='league', action='match')
controller='league', action='match')
controller='league', action='match')
controller='league', action='match')

# Match set
controller='league', action='view')
controller='league', action='view')
controller='league', action='view')
controller='league', action='view')

# Stages
map.connect('/{league}/{stage_0}/{stage_1}/{stage_2}', controller='league', action='stage')
map.connect('/{league}/{stage_0}/{stage_1}', controller='league', action='stage')
map.connect('/{league}/{stage_0}', controller='league', action='stage')
map.connect('/{league}', controller='league', action='stage')

Eventually, I'm going to need to do matches other than team_one vs. team_two (some leagues have matches that contain four players in a group, and the url would need to have something like "GroupA"), and I figure that when that time comes I'll rewrite how the rule matching works. But, it works for now, and I can see it in one page, so I'm not too concerned with it (a year ago I would've spent another day getting these routes down to five lines of code, one example of how I think I've matured as a programmer recently).

Right now, the SQLAlchemy code that actually retrieves the data is very simple. It suffers from N+1 Select issues, and at some point will need to be rewritten for performance reasons. I won't show any of it because it really is just a matter of get some data by the id and then keep fetching child data. It'll end up with six or more database calls for each page, and at some point I'll want to reduce that number to one. One thought was to use an application to denormalize the data and upload the data already denormalized, but it probably seems like a bunch of work for what could probably be solved with a few minutes of tweaking the SQLAlchemy queries.

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