Overview of the Tracking Gateway

The Tracking Gateway allows communications with Tracking Viewer, Tracking Analyst, and custom clients. All input and output from the Tracking Gateway comes and goes in the form of messages. A standard Tracking Server installation utilizes a single Tracking Gateway, but multiple Gateways can be used.

Using Multiple Tracking Gateways

Tracking Server provides the capability to distribute messages to multiple Tracking Gateways. This feature provides a solution to scale infrastructures that support large numbers of clients subscribing to real-time messages. Client applications, such as ArcGIS Tracking Analyst and Tracking Viewer, subscribe to real-time feeds via a Tracking Server gateway. Tracking Server Gateway is a Java application that can run within the context of a servlet engine. As such, it can be deployed on multiple servlet engines.

Caution:

The Tracking Server installation only deploys a single Tracking Server Gateway to the same machine where Tracking Server is installed. All others must be deployed manually.

Tracking Server also provides a user interface to configure settings for each Gateway’s IP and port. Once a Tracking Gateway is up and running and Tracking Server is connected to it, it will receive messages being published through the Tracking Server Connector Data Link. Messages will be distributed equally to all connected Tracking Gateways.

With multiple gateways enabled, the performance of real-time messages into client applications still depends on the number of client connections to the same server. Client applications such as Tracking Analyst and Tracking Viewer allow users to dynamically create connections to Tracking Server, but other types of connections can be created too. Regardless of how connections are created, they must be managed so that they do not connect to a fully loaded server. Connections should be distributed to help balance the load.

Tip:

There is no set limit for the number of gateways that Tracking Server can be connected to at once. You will have to take issues under consideration such as data rate and hardware and determine what is appropriate for your own environment and servlet choice. A general rule of thumb would be no more than two to four gateways per Tracking Server.

Managing Gateway History

Tracking Server gateways can hold limited history so that clients logging on will receive a more complete picture of the current situation of the tracking data. Upon establishing a new connection, the client application receives all the data currently stored in the gateway history, as well as new data messages sent to the gateway after the connection is established.

You can choose the history setting on the Services tab on the Tracking Server Connector data link. You can also clear the history if needed. The history settings you can choose from are:

• No History
• Last Known Event
• Last n Seconds of Event
• Last n Events