Although a simple database query such as "List existing customers with a postal code for Argleton" is a trivial piece of in-house software development, probably through SQL, this is a simplistic example.
An existing search engine such as Bing or Google is encouraged to web crawl this site, as they would normally do so anyway.
[i] Search as a service may also be particularly useful for mobile applications, where the client device is limited for storage, processing speed and connection bandwidth.
In these cases, however, the search engine providers are closely coupled to the content databases.
The remoting service passes only the query and the results, not the content metadata to populate the search indexes.