AIF web service for "picking list registration"

Hi Everyone,

I need to create web service for “picking list registration” in ax 2009. So, I need to create a query for this, in order create a document service via (Tools>Development Tools>Application Integration Framework>Create document service).

1)how to analyse it and create a query for this service(like tables that I needed and the joins I need to put in the query)?

2)another doubt: when I need to go for custom service instead of using (Tools>Development Tools>Application Integration Framework>Create document service).