The best way to store user data

[Kevin Fonner]

I am writing a web calander and contact manager app. The delima is how to store the data. I want a flexible method that will allow me to store data for as little as five users to systems as much as 50 users or possibly more. For larger systems I think it's a no brainer to have the system talk to a database server. but for smaller enviroments I such as only five people on a system I have been toying around with the idea of storing data into an XML document. One for contacts and another for calendar data such as appointments. However XML documents seem as if they can be quite touchy when updating data. If the power were to be roved on the device storing the data and it was halfway through updating the document it could destroy the integrety of the XML document and cause problems. I know the wonderful thing about XML documents is that everything is human readable but I like the integrety of the data to be as sound as possible.
Just looking for opinions.

[Karthik Guru]

i guess people use LDAP Server to store user information.
you might want to check out iplanet's LDAP server.
Might be a good exercise and you w'd end up learning JAAS and LDAP
IPlanet Directory Server
good luck.

[Sean MacLean]

There are also some xml-based "relational db's" kicking around. Basically, you're storing your info as xml text files but the interface gives you basic relation db update, create, delete, etc type funcitonality. Don't know the particulars - I just recall seeing a couple of implementations recently.
Sean

[Kevin Fonner]

We'll I hate to run any type of data server because on the smaller scale I am trying to keep it quite efficient with memory. I have been tossing the idea of some type of jdbc-xml driver but havn't seen a economical way (low or no licensing fee) of utilizing this method yet.

[Sean MacLean]

Check this out.
http://xml.apache.org/xindice/
Sean

[Kevin Fonner]

I found this!!
http://www.fawcette.com/javapro/2001_12/magazine/features/jodonahue/default_pf.asp
I think it could work...