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 can poll a website every 30 seconds to return the latest observations.
A feed polling schedule dictates how often Velocity polls 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 one-minute polling interval, every minute while this feed runs, Velocity sends a request to the website to retrieve observations. 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. Therefore, the polling interval must always be at least 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. If a feed is 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.
Caution:
Do not set the polling interval to a shorter interval than the typical response time of your feature layer query. At each interval, Velocity makes 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. It is recommended that you test the response time of a query request to this feature layer using the same query that you apply in the feed configuration.
When setting up the Velocity feeds, the recurrence value for seconds can be set to a factor of 60 (between 10 and 30) for a consistent and predictable runtime.