Developer interview task (Mobile) Author: Pablo Viquez pviquez@pabloviquez.com
The public directory resides in the "src" directory. All other files should be outside the public eye hoewever stil accesible to the web server user.
-
PHP 5.3 or greater ++ PHP Modules:
- PDO
- SimpleXML
-
MySQL 5.x
The app has the following structure:
/-
/batch -> Batch script. This is where batch scripts are
/config -> App configuration. This should be the only place to edit configs
This directory should not be public, however if by any chance its
public, an .htaccess file is also included which prevents serving
the file. If the configuration does not allow .htaccess file, then
it's important to manually change the web server config to deny any
request to ".ini" files inside this directory or the app for that matters.
/docs -> Any relevant documentation
/lib -> PHP library for the app
/sql -> SQL Scripts for the DB creation
/src -> Public html directory
- PHP App Notes
The main idea was to design something that can handle requirements growth, using classes with high cohesion and low coupling.
The design can be divided in 2 main areas, the batch or command line and the web interface.
Both areas are setup with the same configuration file, which is located in the "config/config.ini" file.
This should be the only place to edit configurations.
php batch/rates.php
If by any chance, there's no access to the console, anoter script was created in the front end which does the exact same thing, however in the public site.
To call it make a request to:
http://[localhost || whateverdomain || path ]/process/process.php
The main idea behind this approach was that the comsuption of a 3rd party service of exchange rates does not required to be executed constantly or on real time.
Thats why an asynchronous process (Batch file) was created. This file could be called from a cronjob or task schedule or from the web once per day.
All classes lives inside the "lib" directory. This lib directory is suppoused to be outside the live app, the same goes for the config.ini file.
All app configurations, should be outside the public directory.
There are some issues that could be improved:
-
Dao Class: This class should not be responsible for the DB connection instantiation. The DB instantiation should be moved out of the DAO into a new base class that can be called from any other class. Ideally the DB class should implement the singleton pattern in order to avoid unnecessary DB connections.
-
Batch Process: The process creates a simple batch process, however this could be improved by adding a more roubust process control to detect and log failures and to not run if another one is currently running.
-
Locale aware: This application could benefit from a locale aware setup, that's presenting the currencies according to the user browser locale, for a more I18N friendly app
-
Unit test: Unit test are extremely important, this because they could easily test the internal classes just like the Batch processing.
-
Caching system. The DB results should be cached. The implementation of a caching server; like Memcached or Redis, is critical for optimal performance.
-
Client Side App Notes
The page uses a responsive design, implementing Twitter Bootstrap for faster and more efficient coding.
-
Progressive Enhancement with JavaScript. While smartphones are known to support JavaScript, since this is a donations page, it should support browser with no JavaScript. Right now, if the user does not have JavaScript enabled, it wont be able to switch currencies.
-
Unit test. As part of the quality control best practices, unit testing for the JS is a good idea.
-
The twitter bootstrap CSS file contains a lot of classes that are not being used, for better performance, removing them is a good idea or just download the necessary ones.
-
Even though the requirements didn't state the requirement, I was unable to to a test on Windows Phone or IE. As a thing to improve, I definitely will recommend to do a test for IE compatibility.