Currently I need to implement the following steps with Spring batch:

1. Read table data from data source A;
2. Read table data from data source B based on the column values I get from data source A at step 1 as search criteria;
3. Write what I get at step 2 to some other place

Technically I have no problem dealing with step 1 and step 3, but anyone could advise how to tackle step 2? I understand that after step 1 I can get a rowMapper class that maps each row of data to my domain object, in this case how to pass the column values (domain object attributes) as the parameters to step 2?