[Firefly-dev] Patrons management

[firefly-dev]

Hi,

I would like to ask you one thing about patrons management.
In the cvs repository there is a file called patron.xml whose purpose is
still not very clear to me.
I really hope you do not intend to manage patrons with xml files, it
would be a nightmare. 

Just think about a simple loan, in the db you have to store the user_id
of the patron who loaned the book, and where do you take it from if it
is not in the db ?  from the xml file ?  
This mean that you have to parse the xml file(which require to create a
sax parser to go through the file until it founds what we need, or even
worse create a dom representation of the entire file in the memory) and
put in the query the results of the parsing operation.
This is *terribly* slower than a simple db operation, at least a million
time to be optimistic, and don't forget the overhead caused by the
network connection(and the encriptions of the data with ssl).
Also you must take care of concurrent access to files, what if two of
the staff modify at the same time a patron's details ? In the worst case
this may empty or erase the file...

I use often xml at work and it sure has many uses but it can't and must
not replace a db.

Actually I see two possible uses for xml in this project:

1. an hipothetical "registry" that serves as a glue between core app and
plugins. 
This is absolutely required if a plugin is written in a different
language than the core, plugins and core can exchange data between
themselves in an xml format (soap, wddx etc...), without requiring CORBA
or stuff like that.

2. we can retrieve data from the db in an xml format suitable to be
transformed with an xslt stylesheet(this can be easily been done with
openjade but I don't think windows has something like that...) in the
formats we want.

Another thing, considering the features of this app and especially its
"modular" nature, I would like to discuss with you about a more object
oriented development approach.


Let me know what do you think.


Marco