A really useful WordPress feature is support for hosting multiple sites from the same core install. I used to run WordPress-MU for this purpose before it was rolled into the main version. If you have control of DNS you can easily have sites as subdomains, or even map a seperate domain to a subsite using a plugin such as WordPress MU Domain Mapping.

Since I use SSL with a wildcard certificate this also means I can securely administer wordpress subsites via https://subsite-example.glenscott.net while having a public non-ssl url of http://subsite-example.tld.

I recently installed the plugin WP-To-Twitter to use on a subsite, and found that when posting updates to twitter, wordpress unfortunately provides it with the http://subsite-example.glenscott.net/link-to-post permalink instead of the http://subsite-example.tld/link-to-post permalink. This doesn’t seem to be the fault of either plugin as MU Domain Mapping is using some smoke and mirrors rewriting to display the mapped http://subsite-example.tld domain while the plugins in the secure wordpress admin URL (including wp-to-twitter) rightly see the site as if it is located at https://subsite-example.glenscott.net. I tried a few combinations of changing the site_url and home_url values in the network admin –> sites panel, but only succeeded in breaking my domain mapping. Until domain mapping is baked into the wordpress core I suspect this will continue to be an issue.

I’m not a wordpress/plugin dev by any stretch but I spent a couple of hours looking through the code for wp-to-twitter and concocted a (temporary) hack which is now posting the correct permalink to twitter. I would have been happy with hardcoding the domain value since the plugin is only being used on one site, but in the end I learned a few things about core wordpress PHP functions and came up with a solution which should work for multiple subsites / domains.

I based part of this solution on the post here:
http://premium.wpmudev.org/forums/topic/permalinks-converted-to-those-domain-based

Here’s the code:

Add the following function to wp-content/plugins/wp-to-twitter/wpt-functions.php

Edit the following in wp-content/plugins/wp-to-twitter/wpt-truncate.php

That’s it; the ‘Tweet Now’ box in the post editor should use the domain mapped link.

For many moons I’ve been attempting to get the server functionlity of the OpenID plugin working with my wordpress install and been stumped on the following two errors:

First, any hit on the OpenID /openid/server url (I am using non-default permalinks) generated the following :

Fatal error: Call to undefined function add_options_page() in
/path/to/wp-content/plugins/wp-contact-form/wp-contactform.php on line 200

This was pretty obviously a conflict with WP-Contactform. Disabling this plugin made the above error go away, so I’ll be looking for a replacement for it soon.

Once the contactform error was worked around by disabling the plugin, the following appeared:

Fatal error: Call to a member function needsSigning() on a non-object in
/path/to/wp-content/plugins/openid/Auth/OpenID/Server.php
on line 1495

This would happen when I tried to specify my URL (whether main blog or wordpress author url) as an openid – it would seem to be working, go through the logon process then generate the error and the authentication process would abort.

After much googling (not much out there but this was helpful, sort of) and a good period of waiting and trying new versions of the OpenID plugin as they were released, the solution / workaround turned out to be extremely simple. It was a plugin conflict (doh) and a process of elimination identified the culprit and main show stopper: the cryptographp plugin.

No idea why but once it was disabled things worked fine. I was using this plugin to generate protective captchas for my comment forms. I replaced it with Simple CAPTCHA. (Its worth noting that in the 15 minutes or so I had no CAPTCHA active, I had already received a bot comment spam – and my site isn’t heavily trafficked by any means). I might choose another solution at some point from the plethora available, but for the time being, Simple Captcha gets the job done fine.

So thats about it. In a nutshell, some seemingly unrelated plugins were conflicting, disabling them and replacing with alternatives fixed it.

Now I can use glenscott.net as an OpenID, and my visitors have a nice simple OpenID login option on comments pages =)