This diagram depicts search engine integration: Asset framework detects changes/additions to assets and fires off events. Registered listeners queue the changes, using a persistent queue implementation. A given event can be queued into one or many persistent queues. Each queue can be thought of as the source of data for a search index. Once asset events are queued, a background process empties the queue contents and routes them to the Search API. The Search API chooses the appropriate (configurable) search engine vendor implementation to start the indexing process.