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OTASlang: Over The Air Smart Language loading for java |
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How to hotswap an apps entire language text on the fly. |
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Carl Whalley, 04-Jul-2003 |
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| Screenshots |
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At first only English is available
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English menus
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Refresh discovers new languages available
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French was chosen so the language list becomes localised too
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Now the menus are in French
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| I18n |
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Some wit once coined the i18n abbreviation for internationalisation with good reason. In today's global marketplace, any shortcuts
to ensuring your products reach the widest audience are very welcome indeed. Take smartphones for example. These beauties can load
software after they are shipped - in fact users quickly begin to treat them like their PC and load whatever apps, games or utilities
take their fancy. For the developers though there is a problem - what language does your user speak? Traditionally, you'd have to
perform separate builds for each one, swapping in the various string resources at build time and hoping you'd got it right in order to
avoid a costly re-release. Now, with the advent of smarter java phones like the P800, there are other interesting possibilities
in this area.
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With smartphones, you are dealing with a device that can connect to a remote server on demand. This means you can load data, any data,
into your app - even data the app uses intrinsically to operate. That's where smart language loaders come in. Described here is such
a system, which provides smart language resources on demand over-the-air, hence "OTASlang". Furthermore, because it can do this when any new
languages become available or are changed, it's much more future-proof. The system presented here is a freely available demonstratation
of the commercial OTASlang service. The app loads all the language resources at once. It doesn't
need to connect again unless the user wants to change language or refresh the current one. Smartphone resources, whilst growing nicely with
each new model, are still finite. There's no need to hold multiple language sets per app when you can hotswap new ones whenever needed.
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| From Server to Client |
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OTASlang is implemented in java at both the server and client ends. The client asks the server for the language resources and the server
responds with the full set. The client then stores them locally. The application which uses those resources will have been written so that
each item displayed is given an ID code and loaded in at runtime. This is no different to the traditional way: all displayable items
are abstracted and are never hardcoded in the body of the app. Another advantage to using a smart language loader relates to the fact
that only one build is required for all languages. Many applications require signing before they can be deployed and it's only a
matter of time before this becomes mandatory. In any event, building 10 separate versions of the app for 10 languages means the developer
has to pay for signing 10 times over: a concern for smaller operations.
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| PersonalJava |
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The version described here is for the Sony Ericsson P800 running PersonalJava. This demonstration is shipped with a small test app to
illustrate dynamic menus, dialog boxes etc. When first run, there is only one language available, "English". You can discover which
languages the server supports with the "Refresh" button. The app will connect to the server and update this list. You can then choose
one of the languages with "Done" and see the changes in the various controls.
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| Usage |
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The framework requires the installation of the language server on a J2EE server. It's implemented as a few servlets that draw
on standard java property files in response to the client requests. This could be developed further via the use of an SQL database, for
example. No special protocol is defined between the two, the language key/value pairs are simply sent in the "ID=Value;" format.
The client receives a set of these and stores them locally as a properties file, in effect copying the language from the server
to its own persistent storage. Java has handled unicode since its inception - the default encoding is UTF-8, so basic character
accents shouldn't be a problem. To use the framework in a real app you would abstract all the strings into a properties file,
say "ENGLISH.properties", and store this on the server. The client looks for "Language.properties" locally so a copy on the client
is needed with this name. New language installation means storing, for example, "FRENCH.properties" on the server alongside the
English one and serving it when required. You should install the language server at whatever URL you want and point the entry
"LanguageServer= " in the client file "OTASlang.properties" at it. The language server with the test app is running
at http://www.java-technical.com/otaslang, however if load gets too heavy this will be reviewed.
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| Tips |
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Plan the language system as early as possible, certainly before any code is written.
Consider building a "neutral" language that won't be used in production but acts as the default for development. Including the
keys in the displayed values (where possible) can help UI troubleshooting a great deal.
To ease layout issues you may want to define a "padding" language. This is where each entry consists purely of padding
characters that fill up the fields to their maximum, for example "XxxxxxxxxX". When deployed, it will look a little
odd (!!) but will assist greatly with UI field length checking. You could then automate tests for candidate production
languages against it.
Consolidate languages for several projects in a common database. The client doesn't care how the languages are sourced, but
if you can identify common strings across projects you will save time and effort translating them more than once. This is
where the "neutral" language can help.
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Download OTASlang sample application (SIS to run on P800).
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Documentation OTASlang client.
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Documentation OTASlang server.
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