The indexer loops over all OLAT data to analyse and generate a new index.
The indexer structure is given through the spring config defaultconfig.xml at org.olat.search.service._spring.
Each indexer analyse his content and pass tha context to his child elements.
E.g. GroupIndexer goes further to GroupFolderIndexer, GroupForumIndexer, GroupWikiIndexer for each group.
The indexer can runs in two modes :