What would be the ideal solution to periodically/automatically pull the data from different sources (Db2, mysql, xml ect) and store this data locally in XML format or in DB?
PHP is my preferred language.
Is Object relational mapping a solution to it?
For periodic scheduling of jobs, have a look at cron (assuming your on a Linux machine). A cron job is language agnostic and can run anything that can be run from the command line.
Object Relational Mapping (ORM) is a technique to map database tables to objects. While you can use this to help solve your problem, it is not really relevant.