Retrieving a list of categories
Before a client can retrieve a list of categories associated with a blog or collection (such as a photo album), the client must first retrieve the URL associated with the service.categories link relation found in the Atom Introspection document (see Retrieving a list of blogs) corresponding with that blog.
Here is an excerpt from an Atom introspection document. The service.categories link relation contains a reference to the URL from which a list of categories can be retrieved.
<feed xmlns="http://purl.org/atom/ns#">
...
<link xmlns="http://purl.org/atom/ns#"
type="application/x.atom+xml"
rel="service.categories"
href="http://www.typepad.com/t/atom/weblog/blog_id=64534/svc=categories"
title="SOAP::Lite"/>
...
</feed>
Once you have retrieved the service.categories URL, an Atom client can perform an authenticated HTTP GET against it. The document returned will contain a list of categories associated with the corresponding category.
Sample Request
GET /t/atom/weblog/blog_id=1/svc=categories HTTP/1.1
Host: www.typepad.com
X-WSSE: my credentials
Sample Response
HTTP/1.1 200
Content-Type: application/atom+xml
<?xml version="1.0" encoding="utf-8"?>
<categories xmlns="http://sixapart.com/atom/category#" xmlns:dc="http://purl.org/dc/elements/1.1/">
<dc:subject>Books</dc:subject>
<dc:subject>Travel</dc:subject>
<dc:subject>Movies</dc:subject>
</categories>
