Pinging Search Engines
A ping is basically an HTTP GET request that, in the context of a Google Sitemap, is sent to a search engine to notify of the need to re-crawl the Sitemap.
SiteTree can ping Google both upon request and automatically whenever a new web page is published. When the ping concerns the Google Sitemap, SiteTree always pings Bing and Yahoo! as well.
The full integration of SiteTree into the workflow of WordPress and the constant feedbacks given about the pinging events make SiteTree a reliable tool when the need comes for pinging search engines.
The Pinging Bar
The main element of the user interface of the pinging facility is the Pinging Bar, designed to be inconspicuous yet always visible, as to give immediately accessible information about the pinging events and to provide the user with a labour-saving mean to send pings on request.
In the leftmost edge of the bar you can find the Pinging Dot, an indicator that can change shape according to the status of the automatic pinging functionality: when the automatic pinging is ON, it's a circle, otherwise it has the shape of a disk.
About the Automatic Pinging
For the News Sitemap the automatic pinging is always ON, and cannot be disabled. Instead for the Google Sitemap is turned OFF by default, and can be enabled at any time by clicking on the switch control you find in the Pinging Bubble, accessible by hovering over the Pinging Dot.
When the automatic pinging is enabled, pings are sent whenever the permalink of a newly published page is added to the Sitemap, regardless of whether or not the Pinging-On-Request is temporarily idle.
Before Your First Ping
In order for your pings to be regarded by Google as legitimate requests of re-crawling, you have to submit your Google Sitemap's URL, and eventually the one of your News Sitemap, through the Google Search Console. It's not mandatory to do that before SiteTree sends out its first ping, but it is strongly recommended.