Update: This information has been incorporated into the AtomPub page on http://codex.wordpress.org.

This is only here until I can find somewhere sensible to put it. Feel free to point out errors or improvements by commenting on this other post, or send me questions (and answers, because it's likely I won't have a clue!)

  1. Where should my atom client publish resources?http://example.com/blog/wp-app.php/service
  2. How can I test if AtomPub is working on my blog?Use Tim Bray's Ape. Or follow Sam Ruby's instructions.
  3. I'm getting a 401 Credentials Required error when I access the service, even though I provided the correct username and password. What's going on?It's likely that PHP is running as a CGI rather than as an Apache module, so HTTP Authentication won't work out of the box. You can check this by running the phpinfo() function on the server and looking for the SERVER_SOFTWARE entry. It will have something like PHP-CGI in there somewhere. To work around this, create a file called .htaccess in your blog directory and add this to it
    RewriteEngine on
    RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization},L]
    More generic instructions to get HTTP Authentication working when PHP is run as a CGI can be found here.
  4. When I try to PUT or DELETE I get a 403 Forbidden error. What's going on?Some firewalls drop PUT and DELETE operations. Unfortunately, if you don't control the firewall, there's not much that can be done. Perhaps I'll start a grass roots campaign and people can lobby their hosting companies. Of course, you can still retrieve and publish resources, so all your AtomPub goodness is not lost.