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Welcome to the SolrIndexChangeAlert wiki!

Solr Index Change Alert is a WebSocket application developed using Spring Boot, that is used to monitor Apache Solr Index files for any type of alterations/changes and the creation of new index files and the deletion of existing index files. The web application utilizes WebSocket protocol communication between the client browser and the service deployed and running in Apache Tomcat.

When the Solr Index Change Alert Web application war file is deployed in Apache Tomcat, the user can view the front end application running at http://hostName:portNum. They will be able to connect to the service via a WebSocket. They then can start the Solr Index Change Monitor background thread. This thread is running a FileAlterationMonitor that has a reference to a FileAlterationObserver. The FileAlterationObserver will observe file alterations and then invoke a registered IndexChangeListenerImpl event listener. The IndexChangeListenerImpl has a reference to an instance of a StompMessageClient that it uses to send AlertMessages to the Websocket application endpoint /app/alertMessage. The incoming AlertMessages are then received by the controller of the Solr Index Change Alert service and are processed by its onMessageReceived method, which then routes ResponseMessages to the subscribed topic endpoint /topic/responseMessage which the web browser client is subscribed to. The messages will then be displayed in a table for review.

When something is added/removed/changed to the Solr indexes, a message is sent to the web browser, so the client is updated in real time and the user knows instantly when things are added/removed/changed without having to refresh the page or do some kind of polling.

Solr Index Change Alert Web application Chart.js plot of real-time Solr data from Fusion 3.