o Use the XML writer API to instead of creating gigantic strings.
Types:
page index: positive integer
page type: enum: abc (post), xyz (page)
/?atompub=service
Returns a application/atomsvc+xml resource
A list of all posts of a type (post or page)
/?atompub=list&page_type=&page=
Mime type: application/atom+xml
Atom id: /?atompub&page_type=
/?atompub=list&page_type=&page=&parent=
Mime type: application/atom+xml
Atom id: /?atompub&page_type=