When configuring data ingestion from polling type feeds, ArcGIS Velocity allows you to specify the feed polling interval. You can choose to poll the feed at an interval or at a recurring time. For example, you may want to poll a website every 30 seconds to return the latest observations.
A feed polling schedule dictates how often Velocity will poll a source of observations and load events. A feed polling schedule only applies to the following feed types:
The default polling interval is once every minute. If you configure an HTTP Poller feed with a 1-minute polling interval, every minute while this feed runs, ArcGIS Velocity will send a request to the website to retrieve observations.
It is important to note that feeds cannot be scheduled to poll more frequently than every 10 seconds. This restriction is in place to protect external sites being polled by feeds, such as a web server or an ArcGIS feature service, from being overloaded by the frequency of inbound requests. A polling interval cannot be set lower than every 10 seconds.
When a polling interval is set, the polling occurs on regular clock intervals, as opposed to the start time of the feed. The time interval begins at midnight local time for the user who created the feed. For example, if a feed is set to poll for data every 5 minutes and the feed is started at 8:03 a.m., the first request for data will occur at 8:05 a.m., the next at 8:10 a.m., and so on. Or, for example, if a feed it set to poll every 8 hours and the feed is started at 10 a.m., the first request will occur at 4 p.m., the next at midnight, and the following at 8 a.m. the next day.
Use caution when defining the feed polling interval. At each interval, ArcGIS Velocity will make a request to the specified connection properties for the feed to retrieve data accordingly. For a Feature Layer feed, if the request returns more features than the feature layer's supported max return record count, there would be multiple requests to load all queried features incrementally. Therefore, it is essential to ensure that the remote server or service hosting the data source you are polling is capable of returning responses within the polling interval specified.
A recommended best practice is to test the response time of a query request to this feature layer, using the same query that you apply in the feed configuration. The polling interval should never be set to a shorter interval than the typical response time of your feature layer query.