In the physical world, you can ride a ferry from Calais to Dover (you know, where the bluebirds are flying). In the semantic web world, you can fact tag text with the OpenCalais web service and sentiment tag it with the OpenDover web service, which, contrary to its U.K.-influenced name, actually hails from a company in Holland, Byelex Multimedia Products.

Its approach to sentiment-based tagging is to parse text against domain specific and general collocation vocabulary sets, to help with the word disambiguation issues, according to company founder H.E.R.M. Vissia. Plans are afoot to make the web service available as an API soon through Mashery, so that developers can use it as one source for creating applications that marketers, research companies, and others can use to automate insight into opinions on topics, trends, services and the like that surface in tweets and blogs. (Developers have single-sign-on access through Mashery to other semantic web service APIs we’ve written about here, including Primal, YoLink, Zemanta and zoominfo.)

“Especially in the Semantic Web it’s about mashups,” says Vissia. “There’s a data source and there and there, and I have this bright idea to bring them together and come up with a brand new service. That’s what this system is about.” As an example of how developers might build mashups that leverage its technology, Vissia looks to the financials industry. Imagine a bank or other financial institution that wants to understand how a Fortune 500 company is written about in blogs and tweets, and using the Open Dover service to accumulate that sentiment, and how the relationship between its positive perception at the current moment is reflected in its stock price, a feed delivered through a stock ticker API. “It’s not just about marketers finding out if a razor is going to sell well,” based on expressed sentiment, he says. “We are just scratching the surface at the moment.”

Since its launch last year at DrupalJam, where it previewed a module that can be plugged into a Drupal CMS, so that each document created in a blog or review page is automatically tagged based on sentiment, it’s expanded from covering two subject domains to a little over a dozen. Added to flight and hotel are domains for economics and finance, the law, health and various product categories.

Here users can try out the Sentiment Search app the company built as a demonstration of its OpenDover technology.

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