As Struts get used in more and more environments, we run into the bleeding edges
once in a while. One place that was recently discovered is that some
application servers insist on application scope beans (i.e. servlet context
resources) being Serializable under certain circumstances. (Note -- this is not
a spec requirement issue; it is a container-specific restriction).
The Struts example application is not going to work in such an environment,
because of the way that the pseudo-database is architected and used. However, a
more serious issue is that the MessageResources class (used to store the
application resources for your internationalized message strings) is not
Serializable, and it cannt be made so -- because the underlying
java.util.ResourceBundle family of classes are not Serializable.
There is an additional headache that is caused by the current implementation --
it relies on loading properties files to initialize the message strings. For
languages that use ISO-8859-1 character sets, that is pretty easy -- just edit
the files with a text editor and you are done. For other character sets,
however, you have to remember to run "native2ascii" on the properties files
after editing.
To deal with both of these problems, I propose to create a new MessageBundle
class, which will be Serializable. The external API will be very much like
MessageResources, so minimal code changes will be required. The key difference
will be in how it is initialized. I propose to load the messages from an XML
file (so that you can declare the character set, and use an XML-based editor).
For the Struts example app, the file would look like this:
<?xml version="1.0" encoding="ISO-8859-1" ?>
<!DOCTYPE struts-messages PUBLIC
"-//Apache Software Foundation//DTD Struts Messages 1.0//EN"
"http://jakarta.apache.org/struts/dtds/struts-messages_1_0.dtd">
<struts-messages default="en_US">
<!-- Messages for US English -->
<locale locale="en_US" xml:lang="en-US">
<message name="button.cancel" value="Cancel"/>
<message name="button.confirm" value="Confirm"/>
...
</locale>
<!-- Messages for Spanish -->
<message name="button.cancel" value="..."/>
<message name="button.confirm" value="..."/>
...
<locale locale="es" xml:lang="es">
...
</locale>
</struts-messages>
The existing mechanism (MessageResources) would remain available in 1.0 for
backwards compatibility, but would be deprecated in favor of MessageBundle in
future versions.
What do you think?
Craig McClanahan
