Native Language Support

PHP is a great language for developing dynamic web sites. Some do it for fun while others for
business. It is true that a great part of the web is in English. However, if you are
targeting a worldwide audience, then neither English nor Esperanto alone is an option.

If you need to deliver content in several languages, it is a good idea to explore several
alternatives. However, some alternatives may not be suitable for dynamic websites. Added to that, there is
the overhead of time spent in maintenance. To further complicate things, your needs may not be totally in line with
the resources you have at your disposal. Therefore, it is advisable to choose an alternative
that suits you best.

I found myself in positions which required me to deliver content in both English and Spanish, and in one
project a third language. Here are the possibilities I explored:

• Explicit links for each language
• Use Apache’s mod_negotiation
• Use GNU Gettext support in PHP
• Write your own

This article gives a brief introduction to the first three possibilities, but then we will go about the fourth
solution which suited the requirements best, given the set of constraints. I am assuming that the reader is at least
familiar with PHP programming and the use of PHP classes.

Principles of content negotiation

Before we go into exploring the various options, we should understand the basics of content
negotiation and how that applies to the development framework. Then, you will be able to
develop a web application that can deliver its content in the language of choice of your
visitor.

By simply configuring the web browser, the user can set it up in a way that his or her
preferred language is used when available. Several languages can be specified in a prioritized
list, by setting up the preferences or option of the browser.

And this list of preferred languages on every request made to the site. This
action is totally transparent to the user, as the information gets sent in the Accept-Language
header, for example:

Accept-Language:  bg, es, en-US, fr

Here our visitor has chosen Bulgarian, US English, Spanish and French in that order. Notice
that you can even specify regional variants. The first two characters are a language code as
specified in an ISO standard. This language code may be followed by a dash and a region
code.

As an example, if the request arrives to a website whose content is entirely in Russian, then
the list is exhausted and the visitor will get Russian text whether (s)he likes it or not. Now,
assuming the website has both English and Spanish content (the 2nd and 3rd options), then
the visitor will receive pages in Spanish. Why? Simply because here Spanish had higher
priority with respect to English.

Sometimes, the web server itself can manage the content negotiation, if configured to do so.
Otherwise, the request for a particular language is ignored. Alternatively, the application that
delivers the content takes the decision of which language it is to use. This is exactly what we
will do later.

Before going further, I would like to point out that the content negotiation is not just
dealing with human languages. For example, it also negotiates the kind of information the
client can take by means of MIME types, but that is beyond the scope of this article.