COAP:COAP-3110/week6

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COAP 3110
COAP:COAP-3110
COAP:COAP-3110/term project
COAP:COAP-3110/week1
COAP:COAP-3110/week2
COAP:COAP-3110/week3
COAP:COAP-3110/week4
COAP:COAP-3110/week5
COAP:COAP-3110/week6
COAP:COAP-3110/week7
COAP:COAP-3110/week8

Week 6 learning goals

  • Plugin installation and management (continued)
  • Migrating from a development server to a hosting company
  • A first glance at the REST protocol

Monday

Plugin installation continued.

Wednesday

Web hosting providers

Free hosting exists (see below). Prices for low cost hosting start around 3 Euros / month, but you have to add fees for a domain name to that if you want your own.

Well-known free (read the fine print)

You can search the web for alternatives, e.g. read TechRadar, but be careful. Cross-check information about a provider.

Well-known cheap, HostGator is best according to PC Mag

Recommended local (Geneva, Switzerland)

  • Infomaniak (10 CHF / month). Probably one of the best in that range (quality/speed)
  • HostPoint (10CHF/month, 30 day trial)

Domain name registration

  • Most hosting companies will provide that service
  • You many check if they are accredited with ICANN (i.e. first-level registrars)

Moving a platform from a local server to a hosting organization

  • Moving a Wordpress from a local server to an other target is fairly easy most of the time. However, many things can go wrong ...
  • Consider googling for tutorials, e.g. "move wordpress site from localhost to remote server" (or similar).

Executive summary:

  • Create a new database and a new database user on the target site.
  • Move all files in the wordpress directory including uploads (or install a new system and just move the upload)
  • Dump the SQL (data), repair data in the SQL, e.g. web addresses, then import the *.sql on the target
  • Adapt the wp-config configuration file (database name, database user, etc.)

Local preparation

  • Dump the whole database to a *.sql file, e.g. w.sql.
  • Since free/cheap provider may work with and older version of MariaDb/MySQL: Edit the SQL and replace utf8mb4 by utf8.
  • Important: Repair all URLs that point to your old host, e.g. replace http://localhost/w/ by the new absolute URL, e.g. http://coap3110-demo.atwebpages.com/w/ (Remark: I really cannot understand why Wordpress is doing this)
  • Create a copy of the wp-config.php file and edit some settings (see below).

New host preparation

Most often, the hosting company will not let you create random database names since a same MySQL or MariaDB server is shared with many many users. You will have to use a specific tool from the control panel to create databases and database users.

(1) Carefully read the FTP (File transfer) instructions

  • You will need a hostname for file upload (not necessarily the same as your website name), a username and a password.
  • You may have to deposit your files in a specific directory that is exposed to the web and that represents the "root" of your domain.
  • You may have to install an FTP client on your machine. We recommend WinSCP (Windows) and Cyberduck (Mac), but there are many other alternatives.
  • Most cheap hosting companies only allow for unencrypted FTP (port 21). Good FTP clients like WinSCP will suggest secure "SFTP" transfer per default. You will have to change that to "FTP"

Write down:

  • Name of FTP server
  • Name of web directory
  • FTP user name and password (if different from the user name for the provider's web site)

(2) Create a new database

On free hosting platforms, you probably only will be allowed to use a single database and you cannot change its name. Usually, you cannot use Phpmyadmin for database creation, try to figure out how to do it through the administration interface. Database names also might include a prefix tied to your username.

  • The database server usually will not sit on "localhost" (same machine as PHP), but on another server.

Write down:

    • full name of the database (may require min/max characters)
    • database user name,
    • database user password (may require different types of characters)
    • database server name (not localhost)

(3) Create your sub-domain on the new host if needed.

Usually a free provider requires you do that. In other other words, you will then have an URL like your_subdomain.provider.com. Write that down.

Transfer php files, configuration file and database dump

(1) Move all the PHP files from local to new target

  • Your target directory may not be writable. The administration interface allows to unlock a directory. Make sure to do this recursively.
  • Copy the whole WordPress directory to the new host, using an FTP or SFTP client or a WebClient (depending on the hosting company). Carefully evaluate what your target directory should be. If you only plan to host a single wordpress site, then you could copy the contents of the Wordpress directory to the target's web root directory. Otherwise copy the directory, e.g. /.../web_directory/w

(2) Create a new configuration file

On the local host (again):

  • Create a backup copy of wp-config.php, e.g. wp-config.local.php
  • Create a new copy of wp-config.php, e.g. wp-config.new.php
  • Edit config.new.php and configure it with the parameters for the new host.

(3) Import the database to the new host

  • Make sure to select the right database first (if you got a choice) on the host.
  • Import the *.sql database file to the target site, using PhPMyAdmin or another client

(4) Copy the local wp-config.new.php file to the target site and rename it to wp-config.php

Example taken from 000webhost.com:

As you can see the hosting organization may force you to adopt some prefix, i.e. the a3966289 would represent your user id. 

define('DB_NAME', 'a3966289_w');

/** MySQL database username */
define('DB_USER', 'a3966289_user');

/** MySQL database password */
define('DB_PASSWORD', 'XXXXXXXX');

/** MySQL hostname */
define('DB_HOST', 'mysql5.000webhost.com');

Trouble

  • Your provider may use an old mysql version that does not support the extend utf8mb4 character set. Open the *.sql file in a text editor and replace utf8mb4 by utf8. If that is the case, you also need to make change in wp-config.php.
  • You forgot to replace the absolute URLs in the SQL code, for example, your new WP site may attempt to access "localhost". If you are in doubt with respect to your domaine name, execute a phpinfo.php file that includes a phpinfo(); statement.

A first glance at REST

According to Wikipedia, “A Web service is a service offered by an electronic device to another electronic device, communicating with each other via the World Wide Web. In a Web service, Web technology such as HTTP, originally designed for human-to-machine communication, is utilized for machine-to-machine communication, more specifically for transferring machine readable file formats such as XML and JSON. In practice, the Web service typically provides an object-oriented Web-based interface to a database server, utilized for example by another Web server, or by a mobile application, that provides a user interface to the end user. Another common application offered to the end user may be a mashup, where a Web server consumes several Web services at different machines, and compiles the content into one user interface.”

There exist several types of web services, e.g. the more traditional stack built around SOAP.

Currently, REST is the most popular mechanism used by more light-weight portals and more generally speaking all sorts of services that deal with information, as opposed to commercial transactions for example.

Hands on wordpress

By default, WordPress does not have a REST API, so we will have to install a plugin

(1) Please install the Wordpress plugin:

(2) Get a list of posts from one of your colleagues web site.

Have a look at:

Do it:

Hands on data from a MediaWiki

(1) Retrieve all COAP 3110 pages from edutechwiki

Have a look at:

(2) Example that returns JSON code for COAP 3110

Parameters

  • action=query - will tell the API to do a query
  • list=categorymembers - returns a list of members of a category
  • cmtitle= - defines the Category to look for
  • format=... - defines the format to return.

Resulting datastructure (example) 

{"batchcomplete" : "",
 "query" : {"categorymembers":[
                              {"pageid":9883,"ns":106,"title":"COAP:COAP-3110"},
                              {"pageid":9902,"ns":106,"title":"COAP:COAP-3110/week1"},
                              {"pageid":10230,"ns":106,"title":"COAP:COAP-3110/week2"},
                              {"pageid":10232,"ns":106,"title":"COAP:COAP-3110/week3"},
                              {"pageid":10278,"ns":106,"title":"COAP:COAP-3110/week4"},
                              {"pageid":10279,"ns":106,"title":"COAP:COAP-3110/week5"},
                              {"pageid":10280,"ns":106,"title":"COAP:COAP-3110/week6"},
                              {"pageid":10293,"ns":106,"title":"COAP:COAP-3110/week7"},
                              {"pageid":10292,"ns":106,"title":"COAP:COAP-3110/week8"}
           ]}
}

(3) Get category pages from from Wikipedia, i.e. complete the URL below


Idea: WP has a complex category system for games, e.g. look at Video Game genres or Video games by genre. Pick a sub sub category and list the pages, e.g. the Civilization series.

You may have to adapt the query if a category includes many entries.

(4) How would you display information obtained from a REST call with PHP ? Do you think that there are tools that might help ?

Homework 5

  • Retrieve and display information from a wordpress site or another site
  • Details TBA.
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