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https://issues.apache.org/jira/browse/CONFIGURATION-414?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Oliver Heger resolved CONFIGURATION-414.
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Resolution: Not A Problem
Ralph is right, JIRA is not the appropriate forum for these kinds of questions.
However, as this ticket exists, I think I can answer your question here as well.
Commons Configuration provides the classes {{ConfigurationFactory}} and
{{DefaultConfigurationBuilder}} (the latter is a more powerful successor of the
former and should be used by new applications). These classes support loading
of multiple configuration sources and combining them to a composite
configuration. You can influence how the composite configuration is
constructed, so it serves different use cases. For instance, you can instruct
{{DefaultConfigurationBuilder}} to create a union configuration which contains
the sum of all properties.
Another supported mode is called an _override configuration_ which should be
similar to your use case (if I understand it correctly): When a property is
queried the available configuration sources are searched in the order they were
loaded. The first value found is returned. So you can load an
application-specific configuration first and then a generic one. Properties
defined in the application-specific configuration file override properties in
the generic file. If a property is not found in the application-specific
configuration, it is searched in the generic configuration.
Variable substitution is also supported and works the same way.
More information is available in the user's guide at
http://commons.apache.org/configuration/userguide/user_guide.html, in the
sections "Using a Configuration Factory" and following ones and "Using
DefaultConfigurationBuilder".
I am going to close this ticket. If you have further questions, please send
them to the user mailing list. If you have more specific feature requests, you
can open new JIRA tickets.
> Support inheritance for configuration
> -------------------------------------
>
> Key: CONFIGURATION-414
> URL: https://issues.apache.org/jira/browse/CONFIGURATION-414
> Project: Commons Configuration
> Issue Type: New Feature
> Reporter: garpinc
>
> Some time ago I created a contribution for jconfig which completed the work
> described here: http://www.jconfig.org/ConfigurationInheritance.html
> Jconfig seems however to be no longer maintained and I never found a home for
> the code.
> Basically jconfig would allow for a -D option to be specified in the JVM
> which would allow an application to decide which xml config file to start
> with per environment and at that point inheritance would take over. In each
> config file it supported a 2 level hierarchical structure. Therefore you can
> group certain properties into categories. There is one default category
> called "general".
> so how it would work is as follows:
> you ask for property "myapplication:theproperty" first it would look in the
> first config file pointed to from the -D option and see if a category
> "myapplication" and a property within "theproperty" was defined.. If not it
> would follow the extends xml config to determine the same for that category
> and property and so on and so forth.. In addition if after looking
> specifically for the category property combination it is not resolved then it
> would look for the same property in the general category once again starting
> with the first config and following the extends.
> In addition if a property value contained a place holder i:e
> ${mycategory2:myproperty2} it would resolve that using the same hierarchical
> procedure before returning that value in the config.
> The usecase here of this in practice is as follows...
> On the app server classpath we maintained a config xml file that contained
> the general category for storing properties that were specific to environment
> vs application.
> This xml config would extend app config file in the application itself
> the app config file in the application has a category that was specific to
> the application i.e: myapplication and properties that were application
> specific
> this file then extended another library config file which kept default
> properties that were specific to frameworks in the general category
> so hence properties for app, framework or libraries can be defined or
> overridden at any level. In the environment, in the application or in the
> global library configuration
> It lead to great flexibility..
> Is there anything quite like this is Commons Configuration and if not how
> likely would you be to work with me to get the code I have based on jconfig
> to port to this solution?
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