[infinispan-dev] Infinispan configuration

[Vladimir Blagojevic]

On 6/8/09 2:36 PM, Vladimir Blagojevic wrote:
> On 6/8/09 6:25 AM, jason.greene at redhat.com wrote:
>> Sure, just like it is now. Of course you don't even need Dom. The 
>> advantage of jaxb is that it will keep the parsing logic and schema 
>> in synch. Manual approaches tend to be a bit more brittle and 
>> limited, just like the current approach. Unless of course you take 
>> the time to do it right, but that is no small task.
> Exactly. It has to be done properly. I will post details of a proposed 
> solution for a peer review before I blindly continue on.
>
Hi,

I looked through code, current configuration bean classes, and here is 
what we currently have. Each complex xml element (has nested elements) 
from configuration file is represented by one configuration bean class. 
Furthermore, we have many cases where one bean class at the same time 
models multiple simple child xml elements (has only attributes, no 
nested elements). For example, configuration and global xml elements are 
represented by Configuration and GlobalConfiguration beans, while at the 
same time both Configuration and GlobalConfiguration beans represent at 
least a dozen other simple xml elements, children of global and 
configuration elements. This is totally ok and probably done for sake of 
simplicity and convenience.

I think we need at least two annotations. ConfigurationElement 
annotation matches xml element. ConfigurationElement annotating a bean 
class captures the fact that the certain bean represents certain xml 
element from configuration. Of course, each bean class can have more 
than one ConfigurationElement annotation thus matching our model. 
ConfigurationAttribute annotation matches xml attribute. 
ConfigurationAttribute annotates setter of bean method and can only 
annotate a method where a matching parent ConfigurationElement is 
declared. I am not sure about the final details for attributes of these 
annotations but here are the sketches.

@Retention(RetentionPolicy.RUNTIME)
@Target( { ElementType.TYPE})
public @interface ConfigurationElement {
     String parent();
     String description() default "";
     Class<?> readParserClass() default Void.class;
}

@Retention(RetentionPolicy.RUNTIME)
@Target( { ElementType.METHOD})
public @interface ConfigurationAttribute {
     String parentElement();
     String name();
     String allowedValues() default "";
     String defaultValue() default "";
     String description() default "";
}




Output configuration documentation algorithm
https://jira.jboss.org/jira/browse/ISPN-89

find all annotated configuration bean classes
sort beans by path (breadth-first or whatever)

for each annotated bean
     resolve all annotated ConfigurationElement(s)
     for each ConfigurationElement
         output needed metadata
         find matching ConfigurationAttribute children from annotated 
setter methods of bean class
         for each ConfigurationAttribute
             output needed metadata
         end for
     end for
end for





Read xml configuration algorithm
https://jira.jboss.org/jira/browse/ISPN-96

element = dom global element
beanGlobal = visitElement(element)

element = dom configuration element
beanConfiguration = visitElement(element)

...

ConfigurationBean visitElement(Dom element)
find configuration bean with matching path name and create instance of it
reflect all bean setter methods that are annotated and store annotation 
references
traverse dom element children and match them to stored setter bean 
annotations
     - if parameter for bean setter method is a simple type
         invoke bean setter with converted String attribute value read 
from xml
     - else
         invoke bean setter with returned value of visitElement(element)

return bean