Geospatial Semantic Web Blog

OpenSearch is a collection of specifications that describe how search results can be shared between search engines and meta-search engines. A recent discussion thread on the GeoRSS mailing list brought about a debate over whether OpenSearch’s Geo extension is better than OGC’s Catalogue Service and vice verse.

OpenSearch was founded by A9 Inc., a subsidiary of Amazon.com. It’s a widely adopted specification on the Web today. Popular web search engines implement OpenSearch protocols and service descriptions. Modern browsers like IE7 and Mozilla Firefox have built-in support for OpenSearch extensions. For example, when you enter the string (e.g., “sea”) in the Firefox’s Search Engine toolbar, the toolbar will automatically display a list of possible matching keywords (e.g., “sears”, “search engines”, “sears.com” and “seattle times”). This feature is built-on the OpenSearch specification.

Some people see OpenSearch to be a direct competitor of other Web service description languages and specifications, including CSW, OWL-S and WSDL. I would agree with this thinking only if OpenSearch were designed to solve problems that others are trying to solve. In reality, this is not the case.

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OpenURL is a framework for describing and transporting shared metadata about information objects on the Web. It’s a standard defined by the National Information Standards Organization (NISO).

Why do we need OpenURL?

The OpenURL is needed because conventional web links do not take into account the identity of the user: they take all users to the same target. This causes some problems. For example, when more than one institution provides access to copies of the same electronic article, the link from citation to full text should resolve to a copy that is accessible to the user. Since different users have access to different digital libraries, the link should resolve in a user-specific fashion.

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The Open Geospatial Consortium (OGC) published a video demonstration of OGC Web Services. This video was produced in part of the OGC Interoperability Program (IP). IP is a global, hands-on and collaborative prototyping program for rapid development of proven candidate specifications for consideration for consensus adoption and public release by the OGC Specification Program.

In the video demonstration, the use of advanced OGC technology is covered. This includes Sensor Web Enablement (SWE), Geo Processing Workflow (GPW), Geo-Decision Support (GeoDSS), Geo-Digital Rights Management (GeoDRM), CAD/GIS/BIM (CGB), OGC Location Services (OpenLS) and Compliance Testing (CITE).

See the video demo page.

I come across an interesting web application called InstaCalc. It allows users to easily create shareable calculators and embed them in web pages. Read more about this application at TechCrunch.

To show you how it works, I put together a shareable InstaCalc for the 25 most common RDF namespaces (source: swoogle 2006/08).

Here is a screenshot:

Geonames.org is a popular GIS web service built on the simple REST framework. Not only it’s excellent platform for building innovative web applications that require access to GIS data and geocode services, but also it’s a poor man’s solution to ArcGIS Server (sort of).

A Java API for accessing Geonames web service has been released. Check out the project page at its SF.net page. Look at this page for a quick code example. If you need more information, see its Javadoc page.

MetaCarta GeoParser API is an experimental web service that provides a unified RESTful interface to the MetaCarta LocationFinder and GeoTagger. It takes a document or query string as input and extracts locations referenced in the text. It returns this information in these formats:

• XML in two flavors: “geomarkup” and “locations”
• Javascript for faster import into AJAX apps
• PNG showing the locations

This service is very similar to Geonames search. Both Geonames and GeoParser allow free text search, and both support feature lookup by location names. However, the search of the GeoParser API has few distinctive features that differ from which of the Geonames’s service.

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