Real-time data concepts
Real-time data is temporally enabled data that streams in from a Tracking Server connection or a GPS connection. This facilitates the viewing of tracking features as they occur in real time. Specific needs for real-time tracking of data include emergency response systems, commercial fleet tracking systems, threat detection for defense and intelligence agencies, and satellite tracking systems.
Setting up real-time connections to Tracking Server
To receive real-time data in Tracking Analyst from Tracking Server, a real-time data connection must first be defined as a tracking service in Tracking Server. If tracking services are established in Tracking Server, it only takes a few clicks to connect to them from Tracking Analyst. To understand how to create tracking services using the Tracking Server Manager interface, consult the Tracking Server user documentation.
To enable real-time data output, you must first set up a connection to Tracking Server. After setting up such a connection, you can add the real-time service as a layer in ArcMap or ArcGlobe. The data is displayed on the map as it is received from the server.
The term real-time is sometimes referred to as near real-time, because data must travel from its input data source through network connections and Tracking Server before it appears on your map. The time it takes to display your real-time data depends on the communication links to the applications you're using, server speeds, and network speeds. The data you receive from Tracking Server is as close to real-time information as possible, given these constraints, and is sufficient for most tracking needs.
The purge rule
The purge rule defines how real-time data is stored in system memory. Tracking Analyst stores real-time data completely in memory to maximize performance. To limit the amount of memory consumed, real-time data must occasionally be removed, or purged, from the system memory.
Adding a GPS connection as a tracking layer
Tracking Analyst allows you to add a data feed from a locally connected GPS unit as a real-time tracking layer in ArcMap. By adding your GPS connection as a layer in Tracking Analyst, you gain the capabilities of Tracking Analyst, such as tracking symbology and the ability to play back the data. You also gain the capability to save your GPS data as a tracking layer.
This functionality builds on the capabilities offered by the GPS toolbar. Before you can add a GPS connection as a tracking layer, you must connect your GPS device, configure the GPS toolbar for use with your device, and open a connection.
Displaying future events
The ability to display future events is an additional feature provided on the Time tab of the Layer Properties dialog box, enabled by checking the Display Future Events check box. Checking this check box ensures that all real-time data received from a Tracking Server connection is displayed. If this check box is unchecked, there is a possibility that some tracking features will not be displayed because Tracking Analyst treats them as though they occurred in the future. This can happen as a result of inconsistencies in time zones, inaccuracies in your system clock, or the properties of your real-time data.
Configuring the Tracking Display for real-time data
If you are working with real-time tracking layers, data is constantly streaming into Tracking Analyst. The Tracking Display Configuration dialog box is provided to allow advanced users to configure the data display update settings used by Tracking Analyst to refresh the map. If you are an advanced user, you can configure the display update settings to be more optimal for refreshing the real-time tracking layers on your map.