Wednesday, March 16, 2005

A9 Launches "Open Search" - Vertical Search, Syndicated


"We want OpenSearch to do for search what RSS has done for content."
OpenSearch is a collection of technologies, all built on top of popular open standards, to allow content providers to publish their search results in a format suitable for syndication. You can
see how this works on

Many sites today return search results as an tightly integrated part of the website itself. Unfortunately, those search results can't be easily reused or made available elsewhere, as they are usually wrapped in HTML and don't follow any one convention. OpenSearch offers an alternative: an open format that will enable those search results to be displayed anywhere, anytime. Rather than introduce yet another proprietary or closed protocol, OpenSearch is a straightforward and backward-compatible extension of RSS 2.0, the widely adopted XML-based format for content syndication.

Any site that has content—and a search box—can choose to return results in OpenSearch RSS. This includes travel sites, classifieds, encyclopedias…. If you can provide search results for something, it probably can fit into the OpenSearch model. Returning OpenSearch results is easy—the format is the standard set of XML elements, plus three additional elements designed to support navigation between pages.

OpenSearch is comprised of:
OpenSearch RSS: XML format for providing open search results.
OpenSearch Description Documents: XML files that identify and describe a search engine.
OpenSearch Aggregators: Sites, such as, that can display OpenSearch results.

OpenSearch is not a search engine—it is a way for search engines to publish their search results in a standard and accessible format. And because OpenSearch is built on top of standard RSS, existing tools—such as blog readers—can read OpenSearch results natively. While existing RSS tools can't take advantage of all of the advanced features that OpenSearch offers, this backward compatibility guarantees a rich set of client applications for OpenSearch today.

If you are a content developer and already have a search engine for your site, you will want to read through the documentation on OpenSearch RSS and the OpenSearch Description, along with the OpenSearch Query Specification.

Alternatively, existing search engines can be wrapped so that HTML search results are translated into OpenSearch RSS results. Please keep in mind that you will need the permission of the search engine itself before wrapping someone else's search results. Some content providers will encourage this, and will gladly allow their search results to be syndicated. Be sure to explicitly check the terms of use of any content you wish to redistribute.

This is just the beginning of OpenSearch. We look forward to hearing your suggestions and feedback about how this model can be extended in the future to support all types of search and customer experiences.