Site search API
Sitefinity CMS Search uses the Publishing system in order to collect data that should be indexed. It registers the SearchIndexOutboundPipe that listens for changes in Sitefinity CMS and pushes them to the search index, using the active Search service.
The following diagram shows how a page content is pushed to the Search service index when the user publishes it. Other content in Sitefinity CMS is indexed in a similar manner. The difference between indexing different content types is that each of them comes from a different InboundPipe.