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Igor Moiseev Applied mathematician, AI Enthusiast

Learning NoSQL, PHP and Linux

10 Apr 2015

Series of lessons on Linux, Apache, Databases, Git, NoSQL, PHP and scalability of the application.

Part 1: Linux, Web server and Database

Configuring Linux

Now we see how to setup the development environment. First download Linux (for ex. Linux Mint www.linuxmint.com/download.php) and install on Pen Drive following this tutorial www.ubuntu.com/download/desktop/create-a-usb-stick-on-windows.

You may wish to install it as the second OS on your PC, see the manual www.everydaylinuxuser.com/2014/07/how-to-install-linux-mint-alongside.html.

When the Linux is up and running,

Linux Mint

the first to do is to upgrade it to the final release

$ sudo apt-get update; sudo apt-get dselect-upgrade

and reboot.

Statring with shell

What is “the shell” and why bother? The shell is a program that takes your commands from the keyboard and gives them to the operating system to perform. Nowadays, we have graphical user interfaces (GUIs) in addition to command line interfaces (CLIs) such as the shell. To open one simply click “Menu” and type “terminal”

Terminal in Linux Mint

So why bother? 95% of servers is running Linux, most of them are headless – without GUI!

Linux Server Share in Internet

So as we’ve seen before simple command like this one

$ sudo apt-get update; sudo apt-get dselect-upgrade

upgrades the entire operating system, or installs the web server

$ sudo apt-get install apache2

Package managing apt-get

APT, the Advanced Packaging Tool, provide rapid, practical, and efficient way to install packages that would manage dependencies automatically and take care of their configuration files while upgrading.

Commands

Installation commands

$ sudo apt-get install <package name>

Maintenance commands

Update sources

apt-get update

Upgrade all installed packages

apt-get upgrade

Upgrade all installed packages and tell APT to use “smart” conflict resolution system, and it will attempt to upgrade the most important packages as kernel etc.

apt-get dselect-upgrade

Remove package

apt-get remove <package_name>

Search available package

apt-cache search <search_term>

Search for installed package

dpkg -l *<search_term>*

GIT

GIT is a distributed revision control system with an emphasis on speed, data integrity, and support for distributed, non-linear workflows. Git was initially designed and developed by Linus Torvalds for Linux kernel development in 2005, and has since become the most widely adopted version control system for software development.

$ sudo apt-get install git-core

Github

GitHub is a web-based Git repository hosting service, which offers all of the distributed revision control and source code management (SCM) functionality of Git as well as adding its own features.

GitHub for Mac And Windows

GitHub offers very handy utilities for Mac and Windows that enables managing repositories via graphical interface.

  • GitHub for Mac: https://mac.github.com/
  • GitHub for Windows: https://windows.github.com/

GitHub for Mac

Editors and IDE

For Web development there is a big choice of editors and IDE-s available. Let’s consider some of them

Sublime Text

Sublime Text is a sophisticated text editor for code, markup and prose. You’ll love the slick user interface, extraordinary features and amazing performance.

Sublime Text

NetBeans IDE

NetBeans provides full IDE functionality and is a typical choice for PHP web development.

NetBeans IDE

Exercises

Exercise 1

Please install Apache web server and create “Hello world” page.

Exercise 2

Install GIT. Register un account su GitHub and Install the GIT Gui.

Exercise 4

Please install MySQL server, MySQL PHPMyAdmin and MySQL Workbench. Create test database.

Exercise 5

Clone repository https://github.com/ccoenraets/wine-cellar-php and configure Apache and MySQL to run application.

####Hints

$ sudo a2enmon rewrite
  • permit path rewrite
$ sudo nano /etc/apache2/sites-enabled/000-default.conf

<VirtualHost *:80>

...

    <Directory /var/www/html>
            Options FollowSymLinks
            AllowOverride All
            Order allow,deny
            Allow from all
    </Directory>

...

</VirtualHost>
  • clone repository into cellar folder
/var/www/html$ sudo git clone https://github.com/ccoenraets/wine-cellar-php.git cellar`

Exercise 6 (advanced, requires knowledge of basics of NodeJS e NPM)

Install Ghost Blogging platfowm https://github.com/TryGhost/Ghost and create one post

Hints

Part 2: RESTful Web Services

Web Server

At first install Apache web server, we suppose Ubuntu 14.04 installed on server,

$ sudo apt-get install apache2

Then let’s assume the name of the website is example.com, so we configure Apache to serve content for this website from the folder /var/www/html/example.com

$ sudo nano /etc/apache2/sites-available/example.com.conf

And put the VirtualHost description

<VirtualHost *:80>
    ServerName  www.example.com
    ServerAlias example.com

    DirectoryIndex index.html index.php index.htm
    DocumentRoot /var/www/html/example.com/public

    <Directory "/var/www/html/example.com/public">
        Options MultiViews FollowSymLinks
        AllowOverride all
        Order allow,deny
        Allow from all
    </Directory>

    # Logfiles
    ErrorLog  /var/log/apache2/example.com/error.log
    CustomLog /var/log/apache2/example.com/access.log combined
</VirtualHost>

Create corresponding folders

$ sudo mkdir -p /var/www/html/example.com/public /var/log/apache2/example.com/

and enable the website

$ sudo a2ensite 
Your choices are: 000-default default-ssl example.com
Which site(s) do you want to enable (wildcards ok)?
example.com
Enabling site example.com.
To activate the new configuration, you need to run:
  service apache2 reload

then reload conf

$ sudo service apache2 reload

PHP Composer

Here we’ll see how to create a simple PHP web service with the help of Composer. Composer is a tool for dependency management in PHP. It allows you to declare the dependent libraries your project needs and it will install them in your project for you.

$ cd /var/www/html & rm -rf example.com

now clone the source code

$ /var/www/html$ sudo git clone https://github.com/moiseevigor/learning-nosql-php example.com

Switch to the folder of the project

$ cd example.com

And switch to “Hello world” branch

$ git checkout -b hello-world origin/hello-world

Install composer

$ sudo curl -sS https://getcomposer.org/installer | sudo php

and configure dependences

$ sudo ./composer.phar install

The latter will create folder vendor in current folder, that will contains all PHP libraries that our project will depend on.

PHP Server

To run the application just simply switch to public

$ cd public

and start built-in web server on localhost.

$ php -S localhost:8080

Note, the built-in web server is available only for version of PHP >5.4.

Now open browser on https://localhost:8080/hello/world or try it via telnet

$ telnet localhost 8080
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
GET /hello/world HTTP/1.1
host: localhost

HTTP/1.1 200 OK
Host: localhost
Connection: close
X-Powered-By: PHP/5.5.9-1ubuntu4.6
Content-Type: text/html

Hello, world

Project Learning NoSQL e PHP

Project Learning NoSQL e PHP, https://github.com/moiseevigor/learning-nosql-php, contains a number of branches. After previous step we find ourselves at hello-world branch.

/var/www/html/example.com (models)$ git branch
  master
* hello-world
  controllers
  models

You need to explore the project in the following order

  • hello-world: basic routing and functionality
  • controllers: introduction of Controller and advanced routing
  • models: introduction of Models and Doctrine ORM

To switch between branches you need to execute

$ git checkout -b hello-world origin/hello-world
$ git checkout -b controllers origin/controllers
$ git checkout -b models origin/models

After every switch you need to update libraries with

$ ./composer.phar update

Part 3: Databases NoSQL vs SQL

Allow optional trailing slash in Apache with Rewrite module

27 Feb 2015

Apache’s handy mod_rewrite module is helping to correct this unfortunate human typos.

At first let’s check whether the Apache’s mod_rewrite is enabled.

# a2enmod rewrite
Module rewrite already enabled

If it was not, then reload configuration

# service apache2 reload
 * Reloading web server config apache2                      [OK]

to assure that the rewrite will work you need to assure the one more thing, it is AllowOverride option in the VirtualHost configuration

<VirtualHost *:80>

...

<Directory /var/www/example.com/htdocs>
        Options FollowSymLinks
        AllowOverride All
        Order allow,deny
        Allow from all
</Directory>

....

</VirtualHost>

Now put the following snippet into .htaccess located in the folder of your website (/var/www/example.com/htdocs)

RewriteEngine On

# remove trailing slash
RewriteCond %{HTTPS} off
RewriteRule ^(.+[^/])/$ https://%{HTTP_HOST}/$1 [R=301,L]
RewriteCond %{HTTPS} on
RewriteRule ^(.+[^/])/$ https://%{HTTP_HOST}/$1 [R=301,L]

That’s it, happy re-writing!

Encode string to HTML entities via jQuery

27 Feb 2015

The follwoing will encode your string to HTML entities

jQuery('<div />').text('Some text with <div>html</div>').html()

and the output will look like

"Some text with &lt;div&gt;html&lt;/div&gt;"

To decode we just switch methods

jQuery('<div />').html('Some text with &lt;div&gt;html&lt;/div&gt;').text()

produces

"Some text with <div>html</div>"

The jQuery magic!

Subversion commands

24 Feb 2015

Delete recursively the .svn directories

$ rm -rf `find . -type d -name .svn`

Find files not under the version control

$ svn status | grep -e ^?

How to remove all deleted files from repository

$ svn st | grep '^!' | awk '{print $2}' | xargs svn delete --force

grep on folder with excluding of .svn dirs

$ grep -r 'content_graphic' assets/js --exclude=*\.svn*

Find all tables without primary key in MySQL

17 Feb 2015

Search across all databases (schemas) for tables without primary key

The following query obtains the list of tables without primary key, those who destroys the database performance

SELECT 
    t.TABLE_NAME
FROM INFORMATION_SCHEMA.TABLES AS t
LEFT JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE AS k
ON (
       t.TABLE_NAME = k.TABLE_NAME
   AND k.CONSTRAINT_SCHEMA = t.TABLE_SCHEMA
   AND k.constraint_name = 'PRIMARY'
)
WHERE 
    t.TABLE_SCHEMA NOT IN ('information_schema', 'performance_schema', 'mysql', 'sys')
AND k.constraint_name IS NULL;

In this example, the INFORMATION_SCHEMA.TABLES table is used to find all t. The TABLE_NAME column is selected, and the WHERE clause is used to filter system related databases.

LEFT JOIN is used to join with table KEY_COLUMN_USAGE and filter the tables that do not have a primary key.

Restrict search for tables without primary key to a specific databases (schema)

SELECT 
    t.TABLE_NAME
FROM INFORMATION_SCHEMA.TABLES AS t
LEFT JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE AS k
ON (
       t.TABLE_NAME = k.TABLE_NAME
   AND k.CONSTRAINT_SCHEMA = t.TABLE_SCHEMA
   AND k.constraint_name = 'PRIMARY'
)
WHERE 
    t.TABLE_SCHEMA NOT IN ('information_schema', 'performance_schema', 'mysql', 'sys')
AND t.TABLE_SCHEMA = '<database name>' -- put database name here
AND k.constraint_name IS NULL;

A friendly advise, the result list of these queries should be an Empty set.

Happy querying!