So far, we looked at many ways of getting documents into the system. They can come in multiple formats such as CSV, XML, and JSON. They can be pushed to Solr in message bodies or query strings and pulled by Solr from an external XML file or a database. They can come pre-structured or extracted and mapped from binary files.
But whichever way the documents arrive in Solr, they have something in common. They have to go through one or another Update Request Handler.
And at that point, we have one more chance to modify and normalize the content of the document before it gets sent to the collection using the UpdateRequestProcessor plugins and update chains.
UpdateRequestProcessor plugins are somewhat ...