hop-dev-manual/modules/ROOT/pages/internationalisation.adoc

[[Internationalisation-Internationalisation]]
= Hop internationalisation

== Introduction

Hop is already being used in many countries across the world where different languages are spoken.  As such internationalisation represents the support for multiple languages in our software.  Since it is such a long word it is typically abbreviated to i18n.

== How is it configured?

In the Hop configuration file ```hop-config.json``` there is an entry called ```LocaleDefault``` which points to the locale string that you want to use.
Such a locale string is always in the format: language code, underscore and country.  For example, the default is en_US for English in the US.

You can change the locale you want to use in the configuration file or in the Hop GUI under the Tools / options menu.

== Translating strings

=== In Java code

Suppose we're working on a class in file ```src/main/java/org/apache/hop/p1/Foo.java```
What we want to do is have an easy way to get our hands on a translated String.
The easiest way to do this is with the standard BaseMessages class.
For example, you can see the following pop up all over the place in the Apache Hop source code:

[source]
----
org.apache.hop.i18n.BaseMessages.getString(PKG, "Foo.MyMessage");
----

If references a PKG variable typically defined at the top of the class like this:

[source]
----
private static final Class<?> PKG = Foo.class; // For Translator
----

By doing this we know the location of the message bundles that will be used for translations.
In this case the message bundles will be looked for in

[source]
----
src/main/resources/org/apache/hop/p1/messages/
----

For the default locale ```en_US``` it will point to a file called messages_en_US.properties in that folder:

[source]
----
src/main/resources/org/apache/hop/p1/messages/messages_en_US.properties
----

In that file we can place an entry:

[source]
----
Foo.MyMessage = My own personal message
----

=== In annotations

Many plugin and GUI annotations support i18n as well. Unfortunately it is not possible to use the method explained above to resolve keys into strings.  Because of this we use the following format:

[source]
----
i18n:package:key
----

For example, the main File menu in the Hop GUI is defined with an annotation:

[source]
----
@GuiMenuElement(
      root = ID_MAIN_MENU,
      id = ID_MAIN_MENU_FILE,
      label = "i18n::HopGui.Menu.File",
      parentId = ID_MAIN_MENU)
----

With the ```i18n:``` prefix the Hop GUI registry knows that it can translate this using the given package and key.
If there is no package defined it simply means: use the package from the current class.
In our example it is ```org.apache.hop.ui.hopgui``` which means that we can find the message bundles for this class in ```ui/src/main/resources/org/apache/hop/ui/hopgui/messages/``` and for locale ```en_US``` in :

[source]
----
ui/src/main/resources/org/apache/hop/ui/hopgui/messages/messages_en_US.properties
----

In there we can find the English translation:

[source]
-----
...
HopGui.Menu.File=&File
....
-----

== Translator concerns

If you think that it's quite a bit of a pain to figure out the keys, locations, locale and so on: we agree!
To make i18n easy and translating fun we created a tool called Hop Translator.
Translator allows you to provide strings for the keys that you use in your source code.  It will create the message bundles in the right location, in the right format (in UTF-8) and with the right Apache license header.

To run translator simply build the code and then:

[source]
-----
cd assemblies/client/target/
unzip -q hop-*.zip
cd hop
sh hop-translator.sh translator.xml ../../../../
-----

In other words, run Translator and point it to the location of the source code you want to analyze.

=== Do not be too smart

Translator uses a simple Java code scanner to look for patterns like

* PKG
* BaseMessages.getString
* "i18:

So please give Translator a chance to pick up the i18n keys as well as the package in which they're being used.
As much as possible, define the PKG variable to the same class as the one you're working in.  This will prevent message bundles from becoming too large and perhaps difficult to merge later on.