Google Commerce Search (GCS) is a hosted search solution for online retail sites. Powered by Google, Commerce Search is a fast, flexible, and familiar option for online retailers. GCS allows administrators to customize their search engines in various ways, with features including synonyms, advanced spelling, and targeted promotions within search.
GCS is basically 'site-search' for your retail website. When customers visit your website and search or browse for items, the engine powering and delivering the results is GCS. While GCS allows you to adjust the ranking of the results displayed to visitors on your website, it does not promote or demote those items in natural Google organic results on Google.com or Google Product Search. See our main Product page for a summary of the new features or our FAQ for general questions.
The diagram below shows how GCS works: retailers will upload their product catalog to Google where it gets parsed, indexed and ranked. When a visitor on your website searches for an item, your webserver will submit their query to GCS via a simple API call. The return from that call will be the search results in plain XML or JSON preranked organically or adjusted by your ranking rules. You can take the result XML to render then display to the customer. Each successive query or refinement (faceted search) starts the GCS query Request-Response model over again.
The diagram above is an overview of how GCS works when rendered at the webserver. Since GCS is a simple XML request-response flow, the same search results rendering can be done at the client directly on a user's web browser. The implementation details for the Feeds and query results rendering can be found in the appropriate sections in this document.