As shown in the documentation, the OpenLink Virtuoso "universal server" supports the XML Storage System, MetaWeblog, Blogger, and Moveable Type APIs, which enables it to host weblogs created with Radio and other weblogging tools.
This is my first exposure to Virtuoso, but in an article for InfoWorld, Jon Udell makes it sound like Radio's big brother:
At the core, it's a SQL engine that not only supports ODBC but can attach foreign databases through ODBC. Then came the layers: an e-mail server, a news server, an application server, a SOAP stack, Java and .NET bindings, a WebDAV server, and XML storage, indexing, and transformation. The goal was always business process integration, but that was difficult to explain.
Data moves from a SOAP service in Radio UserLand, through an auto-generated WSDL wrapper, into a database stored procedure, which calls out to the Web through a C# extension and stores results in an indexed XML database. Then an XPath-enabled SQL query gathers results, converts them to XML, and virtualizes them as a WebDAV resource, which Excel finally reads and analyzes.
Pricing starts at $5,000 for the server and $600 for the client.
I'm currently using PyCS, an open source clone of the Radio Community Server written in Python, to provide comments and trackback functionality. The trackback feature is in early beta, so my guess is that the problem is on my end.
Virtuoso sounds great.
Placed a comment re. this post on my blog:
I was hoping to use the CommentAPI from my system but Userland doesn't appear to have this yet :-) I also used Virtuoso's trackback functionality from my blog to ping re. this post, but the url for the tracback source in your trackback page is incorrect (I am also investigating this on my side just in case it is a problem with Virtuoso's trackback client).
The Trackback Ping was a Virtuoso problem :-(
I've updated my post so that the new Trackback ping comes through, and hopefully verifying the fix.
I've narrowed the Trackback Ping problem down to Zempt (the Blog Client used for pings 1,2,and 4. While Ping #3 worked and this came Virtuoso's Blog Posting Client.