The HTTP Simulator feed type in ArcGIS Velocity simulates events in real time using a web-accessible file according to a specified rate and quantity of features.
Examples
The following are example use cases for the feed:
- An emergency management operations specialist replays historical data in support of preparedness exercises for future events.
- A data analyst wants to test real-time visualization and analytics using their existing data.
Usage notes
Note the following when working with the feed:
- When simulating track-based data, sort the data first by time stamp; then sort by track ID.
- After configuring feed connection parameters, configure input data to define the schema and the key parameters.
- Velocity logs a warning during parsing if fields tagged as START_TIME or END_TIME contain null values. When the Convert to current time parameter is set to true, the feed overrides the time fields with the current system time, so features include valid time stamps.
Parameters
The following are the parameters for the feed:
| Parameter | Description | Data type |
|---|---|---|
| URL | The full URL to the externally accessible simulation file. | String |
| Field separator (optional) | The character or delimiter that separates field values in the simulation file. The default is a comma. | String |
| Features per execution (optional) | The number of records (features) to simulate at a time. If the data is sorted by time stamp and track ID, and there are an equal number of observations for each track, set the parameter to the number of unique tracks in the data. The default is 1. | Integer |
| Interval for sending events (milliseconds) (optional) | The interval at which the specified number of features per execution value is sent. The default is 1000. | Integer |
| Repeat simulation (required) | Specifies whether the simulation restarts automatically from the beginning when it reaches the end of the file. The default is true. | Boolean |
| Time field index (required) | The numerical index of the date field in the dataset. The default is 0. For example, if the date field is the second field, the index is one. | Integer |
| Convert to current time (required) | Specifies whether the time values in the dataset are converted to the current time as the data is simulated, allowing mapping apps to treat the data as real-time data. The default is true. | Boolean |
Considerations and limitations
Consider the following when using the feed:
- The HTTP Simulator feed supports delimited text files only.
- The simulation file must be publicly available on the internet and the size of the file cannot exceed 16 MB. If the file size exceeds 16 MB, features may not be ingested.