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From cos...@dnt.ro
Subject RE: config diag, etc
Date Wed, 04 Aug 1999 17:38:39 GMT
> implementable in other languages, we should first work on a CORBA IDL for
> the config API, then work out a reference implementation of the API in java.
> To the reference impl we could add RMI and JNDI hooks that would be outside
> the scope of the API (which would be the IDL) but put there to hook more

Ok, I'm totaly lost. One moment someone talks about XML ( a file format),
then about DOM ( and API for accessing XML files), LDAP( a wire protocol),
JNDI ( a java API to access any directory service), and so on. 

It would be very usefull to split this discution in 3 subtopics, and
have separate threads:

1. What API will be used by Tomcat ( and all other Java Clients of
Our Config Service). Since tomcat is writen in Java, I guess it's a Java
API ( and can't be XML :-).

- DOM - it's a standard API, but for something else ( i.e. document
model/manipulation, not configuration/management API )
 
- JNDI ( a Java API !) - it's a standard extension and used a lot in Java,
and it's designed to access hierarchical information, name services and
directories. Directories services are used by Novel, M$, Cisco, etc to
_configure_ their products - and JNDI seems to be the Java API for that.

- Java classes with setXXX() methods ( sort of BeanInfo) ( like in JMX -
and similar with the way Apache configure modules ): each client will
define few methods, and the Config Service will call them with the actual
data. ( in Apache the module define C callbacks which are called by the
config API when the keyword is read )
This is the most powerfull aproach - since you can do anything in the
callback, and the config service is clearly separated. 
( well, the problem in Apache is that few modules start reading and
parsing the file by themself ) 


2. What API can be used by a non-Java application to access the
configuration. 
IMHO, at least for Apache the natural way is to use callbacks. It is
possible to have a mod_config_ldap, mod_config_xml, etc - i.e. Apache can
access the same config information.

Is it possible to use the same API in C and Java?  


3. What file format do we want to use - and if it is a requirement to have
a "real" file or we want to support directory services ( not by exporting
it to a file, and then parsing again the file ) ( and loosing all the
security, access control, replication, events of a real directory service) 
For file format - XML seems to be the choice. 

I don't understand if directory services will have to export the data in
XML (?) or not.

4. What data structure/model we want to use. That seems to be clear in
James document, if everyone agree we can clear this item.

If you read this far, and you think CORBA is the best solution.
Please take a look at "Management Facilities Architecture" ( 119 pages,
with IDLs and all ). 
Another aproach would be to use the Naming service ( again, it can speak
with a directory service or read a flat file - a XML implementation will
be wellcomed ). (  Corba objects are "configured" using the Naming
service )  

Costin ( confused )


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