Make your localized JSF app more slim by placing your localized Strings outside as static files

An app localized in 107 different languages gets big because of all the translated text. I reduce the size by 30% by placing these translations outside the app - here is how. This is a somewhat technical post on how I proceeded, and the gains it brought.

Why externalizing the translations outside the app?

Java makes it very easy to create a localized web app, see my previous blog post on how I translated nocodefunctions in 107 languages quickly and at no cost.

One of my key objectives for nocodefunctions is to make it painless to maintain and easy to extend with new features: best insurance for the longevity of the project. This broad objective is served by several tactical goals:

  • reducing the number of dependencies
  • relying on well maintained, lean dependencies (aka: not Guava)
  • adding tests
  • decoupling strictly the view from the business logic (the first attempt and now the app is entirely decoupled)
  • relying as much as I can on static files rather than on a database, because I find that it adds a substantial cost of maintenance. So far nocodefunctions doesn’t rely on a db.

Applying these principles, the frontend of the app is now a single, smallish 13Mb war file (all deps included!), which is a 10 x reduction in size compared to last year.

In such a slim app, I realized the text files containing the translations make up for 30% of it: 16 Mb uncompressed, 3Mb when compressed in the app. It is a bit a waste of time to include them at each compile and deployment cycle, given that it is purely static content. What if I could put them on a separate folder, outside the app? The app would read the files at deployment time, and whenever the users would start a session.

Turns out, it is a bit harder than I thought.

Steps to make it work

Translations in the app: painless

When the translations are in the app, the principle is pretty simple:

  1. you get the language (the Locale) that the user wants, either as the default language of their browser or from a drop down menu.
  2. you retrieve the text corresponding to this langage, using this idiom:
ResourceBundle textsInOneLanguage = ResourceBundle.getBundle(<path to the package containing all translation files in your app >, <language chosen by the user >);

That’s it, then you can just do:

textsInOneLanguage.getString("title of home page")

and it will return the title of the home page in the language that the user had chosen.

Getting translated files outside the app: a different story.

JSF (the Java framework for front end dev) that I am using is placing two difficulties in the way:

  • using the ResourceBundle as above, you can not specifiy a path to resources placed outside the app
  • you would usually use a PropertyResourceBundle for this, but JSF doesn’t accept it.

So… ? To solve the issue, my goto resource is Bauke Scholtz and Arjan Tijms’s “Definitive Guide to Jakarta Faces (the new name of JSF) in Jakarta EE 10”:

The Definitive Guide to Jakarta Faces in Jakarta EE 10

Their solution is about loading translations from a database, not static files in a folder, but hey. The code is pretty complicated and I didn’t understand everything of it. In the end and thanks to this head start, I could get it to work, cutting almost all the code to one tiny file:

 * Copyright Clement Levallois 2021-2023. License Attribution 4.0 Intertnational (CC BY 4.0)
package net.clementlevallois.nocodeapp.web.front.i18n;

import jakarta.faces.context.FacesContext;
import java.util.Enumeration;
import java.util.Locale;
import java.util.ResourceBundle;
import java.util.logging.Level;
import java.util.logging.Logger;
import net.clementlevallois.nocodeapp.web.front.backingbeans.SingletonBean;

 * @author LEVALLOIS
public class I18nStaticFilesResourceBundle extends ResourceBundle {

    ResourceBundle rb;
    Locale current;

    public Object handleGetObject(String key) {
        return getCurrentInstance().getObject(key);


    public Enumeration<String> getKeys() {
        return getCurrentInstance().getKeys();

    public ResourceBundle getCurrentInstance() {
        Locale locale = FacesContext.getCurrentInstance().getViewRoot().getLocale();
        if (rb == null || !locale.equals(current)) {
            rb = simpleMethodToGetResourceBundle(locale);
            current = locale;
        return rb;

    public ResourceBundle simpleMethodToGetResourceBundle(Locale locale) {
        try {
            File i8nFolderAsFile = new File(SingletonBean.getExternalFolderForInternationalizationFiles());
            URL[] urls = {i8nFolderAsFile.toURI().toURL()};
            ClassLoader loader = new URLClassLoader(urls);
            rb = ResourceBundle.getBundle("text", locale, loader);
            return rb;
        } catch (MalformedURLException ex) {
            Logger.getLogger(I18nStaticFilesResourceBundle.class.getName()).log(Level.SEVERE, null, ex);
        return null;


Just a couple of notes:

  • SingletonBean.getExternalFolderForInternationalizationFiles() returns the path to the folder containing the .properties files, as a String
  • the String text is the convention I used to name my properties file:,, etc.

So when a user visits the app, a SessionScoped bean is initiated and it triggers:

        Locale locale = FacesContext.getCurrentInstance().getViewRoot().getLocale();
        I18nStaticFilesResourceBundle dbb = new I18nStaticFilesResourceBundle();
        ResourceBundle localeBundle = dbb.simpleMethodToGetResourceBundle(locale);

(also check the class ActiveLocale, which provides the logic to change the language through a dropdown menu and through a url param).

As usual for localization in a JSF app, the faces-bean.xml config file must include the list of supported languages. With translation files situated outside the app: instead of pointing to the package of the app where the properties files are located, the <resource-bundle><base-name> property must now point to the class extending ResourceBundle that you have just created (see above):


And… that’s it. The live version is visible at The source code is on Github.


First, I now know better how to load static property files from outside a Java web app, which is surely going to serve me again. Then:

  • the app shrunk from 13.4 Mb to 10.3Mb, which is 23% smaller.
  • as a result: compiling my app now takes ~ 11 seconds, as compared to ~ 17 seconds before. The fight against long builds continues! ✊
  • I can now fix translations without taking the app down. Just editing the txt files, they will be taken into account next time a visitor browses the app. Great! 🌈

Next steps

I couldn’t find a documentation on this quite mainstream use case. Writing this blog post, I hope it will serve future users.

About me

I am a professor at emlyon business school where I conduct research in Natural Language Processing and network analysis applied to social sciences and the humanities. I teach about the impact of digital technologies on business and society. I build nocode functions 🔎, a click and point web app to explore texts and networks. It is fully open source. Try it and give some feedback, I would appreciate it!

 Date: August 21, 2023

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