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The Vaadin4Spring I18N Extensions
=================================

This package contains some classes to make it easier to work with internationalization. They are not
related to Vaadin, but might still be useful in applications that use Vaadin4Spring.

# Composite Message Source

A composite message source is an implementation of the Spring ```MessageSource``` interface
that resolves messages by querying all beans in the application context that implement the
[MessageProvider](MessageProvider.java) interface. 

The idea behind this is to make it possible to build modular UI applications that all share a single message source.
Each module would have its own message provider, and would use either ```I18N``` or the application context directly
to retrieve localized strings. The modules would be completely separated on a source code level, but during runtime they
would all run inside a single application context.

## Enabling the Composite Message Source

You can enable the composite message source by adding the ```@EnableCompositeMessageSource``` annotation to your
Spring configuration. This will add the message source to your application context.

After this, create as many ```MessageProvider``` beans as you want. You can either implement the interface from
scratch, or use the [ResourceBundleMessageProvider](ResourceBundleMessageProvider.java). The latter reads messages from
resource bundles with a specific basename and encoding (check the JavaDocs for more information).

## Example

In the main application:

```java
@EnableAutoConfiguration
@EnableCompositeMessageSource
@ComponentScan
@Configuration
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
    ...
}
```

In the UI module:

```java
@Configuration
public class MyModule {
    @Bean
    MessageProvider communicationMessages() {
        return new ResourceBundleMessageProvider("mymodule.messages"); // Will use UTF-8 by default
    }
    ...
}
```

Finally a tip: If you are building a modular application, it is good practice to prepend the messages with some kind
of module identifier, for example a Java package name. That way you can avoid naming conflicts when additional modules
are added in the future.