[Digester] new stuff?

[Reinhard <un...@public-files.de>]

Hello,

I work on a config/definition-manager and I have a working sample, where I can 
switch between reading config from XML-files or read the config from 
database.
To achive that, I created a counterpart to Digester, which allows rule-based 
processing of database content similar to the original Digester.

I would like to know, whether someone is interested in that work and/or 
whether the devolopers like to integrate it in the digester project, or 
another commons project?

Any comment is welcome.

regards, Reinhard

Re: [Digester] new stuff?

[Reinhard <un...@public-files.de>]

thank you robert, for your attention.

robert burrell donkin wrote:
> i don't know whether this sounds like genius or madness. certainly, it's a
> novel idea. it'd be really cool if you'd be willing to open source the code.

Hey, it's ok to call it madness. But if some find it useful ...
And I already have the feedback, that others find it useful.
Of cause I'm willing to open the code. I not, I would not write here for 
comments.

> ... but the question is where...

May be, I should clarify a bit.

I startet with struts/tiles where I was working on skin-support without having 
java-code in jsp-files. To test/debug the definition-factory I build a 
dummy-application, which now has evolved to the config-manager. But that's 
nothing to integrate in commons-digester.

I already had the meta-model of an application in the database.

My first step was, to build XML-files, that reflect the meta-model and process 
this stuff with standard-digester (also to learn usage of the digester).
From the struts-user-list I know, that I'm not the only, thinking about 
config-data in database.

I looked around, but found no support for processing content from database 
based upon rules, like the digester does.
So I worked on that.

Another plan was, keep the application independant from the config-source.
Now, what I did was to have the manager read the config-source from file.
Currently there are 3 levels of sources:

1. XML-files
2. XML-data put into database
3. standard database content

The first 2 sources use the standard digester.
The last is processed with my new created digester.
Ok, it's not a big thing, cause I don't have lots of XML-problems with 
database, but ... it works.

My digester is similar to the original:

<snip type="application-code">

public void loadDefinitions(AbstractSourceDefinition source, 
					    String moduleName, 
					    Locale locale, 
					    DefinitionRoot root) 
throws DefinitionException, IOException {	
	try { 
		DefinitionRuleset rs = source.getRuleset();
		Connection conn = getConnection(source);
		Digester	digester = new Digester();
			
		digester.push(root);
		rs.addRules(digester);
		digester.read(conn);
		conn.close();
	} catch(SQLException sx) {
		...
</snip>
 
Both digesters create and fill the same objects.
The (application-specific) ObjectCreationFactories vary and for that I created 
subpackages under the logical definition-packages i.e.:
 
...definition
...definition.xml
...definiton.db

Naturally both digester need their own rulesets. To achive it, I created a 
Ruleset having the digester-parameter of type Object. To abstract classes 
convert the Object to the right Digester-Type and so the subclasses don't 
have to care about the digester-path.

I don't think, that this part is right-placed at the database-section. It's 
the same abstraction level like digester and as I created some of the same 
rules like CallMethodRule, CallParamRule, ObjectCreateRule, ...
having all the same interface for usage.
One vision is change i.e. CallParamRule to a facade which uses 
xml.CallParamRule or db.CallParamRule depending on the context.

Ok, may be, you still call me madness. I'm some kind of special ;-)
But that's a small part the visions I'm working on.

The ConfigManager becomes part of a bigger chain, where I'm working on a 
special dynabean. But that's not ready at all.

Any comment and/or criticism is appreciated.

regards Reinhard

Re: [Digester] new stuff?

[robert burrell donkin <ro...@blueyonder.co.uk>]

i don't know whether this sounds like genius or madness. certainly, it's a 
novel idea. it'd be really cool if you'd be willing to open source the 
code. but the question is where...

this is probably a poor fit for jakarta commons - our database stuff is 
(very, very) gradually migrating to db.apache.org. if there are any 
db.apache.org folks out there who fancy taking this forward then now's 
probably a good time to speak up...

- robert

On Wednesday, September 10, 2003, at 04:06 PM, Reinhard wrote:

> Hello,
>
> I work on a config/definition-manager and I have a working sample, where 
> I can
> switch between reading config from XML-files or read the config from
> database.
> To achive that, I created a counterpart to Digester, which allows 
> rule-based
> processing of database content similar to the original Digester.
>
> I would like to know, whether someone is interested in that work and/or
> whether the devolopers like to integrate it in the digester project, or
> another commons project?
>
> Any comment is welcome.
>
> regards, Reinhard
>
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