DB messages and bean definitions

[slavikm]

Is there currently any support for loading messages from a DB?
It is easier to enable administrators to change messages on the fly for a running application.
On the same subject, are there any plans to enable bean configuration through DB tables instead of XML? It would be great to be able to configure application context through DB tables and then force a reload of the context to enable dynamic bean additions and reconfigurations.

Slavik.

[ojolly]

So far, there is none afaik
But it is easy to provide an implementation of MessageSource via the AbstractMessageSource in which you resolve message request by reading a value in database.
I'll have a look at it this afternoon to provide a patch if you're interested.

Olivier

[slavikm]

I was thinking of a more complete solution enabling both messages and bean definitions to be specified in DB tables.
Some things to consider:
1. Locale sensitive messages
2. Caching - enabling invalidates
3. Dirty table to mark changes in DB tables
4. Reload on demand hooks
5. Probably more stuff...

If there are more users interested in such a solution, perhaps this can be designed and added to Spring officially.

Slavik.

[ojolly]

A basic solution isn't that bad :
1. MessageSource are locale sensitive
the table could be message VARCHAR(xx), locale VARCHAR(xx)
hence the sql code uses either the code and the locale to grab a message. If not found, we could revert to query where the locale IS NULL.
2. It can be useful indeed, but isn't it as expensive as the real query ? Caching is only useful if the checking of caching is significantely faster than the real job in itself. So, regarding point 3, a dirty table is likely to be useless as a SELECT dirty FROM dirty_table WHERE code=? AND locale=? is as expensive as the real SELECT message FROM message_source_...
Eventually, a timed cache can be used. For instance, for one minute, if the code has been resolved, it would trigger an sql query.
4. easy and useful method, right, just like the ReloadableRessourceBundleMessageSource implementation
5. I don't see much thing there, eventually whether a missing message for the given code and locale should try with locale IS NULL or directly return a missing message.

[joostdenboer]

What about extending the messages?

For a portal application I would like the messages to have a priority, start/enddate and to which site the message applies because a message could apply to only one site in the portal and not to others.

I'm thinking about either extending the MessageSource to provide a Message object which also holds info about priority so you can for example change the color in the display depending on priority. This would also need a new tag to retrieve this Message.
Or I'm thinking about adding the site and priority to the message key. But this has the disadvantage that you would need to query for all priotities.