What does Tracking Server track?

Tracking Server helps you monitor entities through time as they move or change. Observations of these entities are events, which can take one of the following forms:

• Dynamic: Events that move such as airplanes, vehicles, animals, storms, and satellites
• Discrete: Events that occur independently from a string or series such as lightning strikes, crime incidents, and automobile accidents
• Stationary: Events monitored from a nonmoving entity such as a weather station or traffic sensor
• Changing: Events indicating change or growth such as population studies or money distribution

Observations and Objects

Events are organized into observations and objects. An observation records an event and contains the date and time, attributes, and possibly the geometry or shape information. In some cases, the attribute and geometry information is contained separately, in an object component. An object describes an event and contains attributes and possibly the geometry information.

If all the necessary information for an event is contained in the observation, it is called a simple event. When static information is stored separately from the observation, the observation is joined with the object to define a complex event. In the case of a complex event, the observation and object are combined in a single message using a join field, which is typically a unique identifier, such as a TrackID or EventID.

Messages

Events are conveyed to and from Tracking Server in the form of data messages. Tracking Server receives and sends messages that contain data, commands, command responses, and status. These messages are formatted using message definitions, which you create in the Tracking Server Manager.

Data Links versus Server Connections

Data links and server connections provide the mechanism to communicate with Tracking Server using a well-defined component technology application program interface (API). The two mechanisms provide a communication metaphor using different architectural approaches. Both methods require a message definition to parse data messages into fields.

Data links are embedded components that are consumed by Tracking Server and run inside of its process space, while server connections are generally external applications that use the server connector component to communicate with the tracking message server.

Tracking Services

Data messages coming to and from the tracking message server component can be organized into a logical representation of data called a tracking service. These services are conveyed to and from the server via the Tracking Server Connector data link. The Tracking Server Connector data link operates like a pipe carrying water, where the tracking services are the “water.”

You will specify the simple or complex nature of the incoming data when you create the tracking service. For simple data messages, the service will use only an observation message definition. For complex data, the service will use both an observation and an object message definition. The service’s message definition specifies which messages are presented to users as real-time data streams into desktop client applications such as ArcGIS Tracking Analyst or Web-based client applications such as Tracking Viewer.