About Data Links
Data Links
A data link is a component of the real-time message server that receives data from a source, transmits data to a client, manages Tracking Server settings, or performs a combination of these functions.
Data links are one mechanism for getting real-time data into or out of Tracking Server. Data links rely on message definitions to understand and parse the data to be processed.
Data links can be categorized in three groups:
- Input: Supplies data messages to Tracking Server. Usually connects to the data source and provides a conduit for the data coming from these external systems and devices. Input data links are message format specific. They will send data to Tracking Server, parsed according to the message definitions set in Tracking Server Manager. The Generic Input data link included with Tracking Server is an example of an input data link that supplies Tracking Server with outside data.
- Output: Sends data messages from Tracking Server to clients or, in special cases, back to Tracking Server itself. This type of data link is responsible for pushing data to clients. The Feature Logger and Tracking Server Connector data links included with Tracking Server are examples of output data links, carrying data from Tracking Server to various clients and destinations.
- Administrator: Provides Tracking Server management functions. Tracking Server Manager uses this kind of data link to communicate with Tracking Server.
Data links provide feedback on their status to Tracking Server. Tracking Server uses the Microsoft Windows COM security and authentication model for user access.
Data Links Provided with Tracking Server
Tracking Server contains several out-of-the-box data links: Tracking Server Connector, Generic Input, and Feature Logger. These data links provide methods for users to connect to real-time data and output data for archival storage.
The Tracking Server Connector data link is required to output real-time data from Tracking Server to client applications. The Generic Input data link offers ways to bring data into Tracking Server. The Feature Logger data link is used to output data from Tracking Server into a database.
Tracking Server Connector
Tracking Server Connector is a special data link that transfers data from Tracking Server to Tracking Viewer, Tracking Analyst, and other client applications via the Tracking Client Gateway. The Tracking Server Connector data link must be running for either Tracking Viewer or Tracking Analyst to connect and receive real-time data.
Generic Input Data Link
The Generic Input data link helps you ingest incoming XML or CSV data from external sources into Tracking Server. The Generic Input data link provides an interface capable of establishing multiple connections using TCP/IP and UDP transport protocols to submit data messages to Tracking Server. Connections using TCP/IP can be run in a server configuration or a client configuration. The server configuration allows multiple data feed clients to connect and submit data messages to Tracking Server. In the client configuration, the data link can be used to connect to a single existing data feed server to receive data messages.
Feature Logger
The Feature Logger data link provides the capability to store real-time data messages by allowing you to save real-time data to a geodatabase. Feature Logger is a data link that. You can select which messages, based on their message definition ID, are to be logged. Then as real-time data messages come into Tracking Server and the Feature Logger data link, the data link will determine if this message has been selected for logging. Messages can be logged to personal geodatabases or to an RDBMS via ArcSDE.
Custom Data Links and Server Connections
Data messages can travel from their sources to Tracking Server and then on to clients by way of either data links or direct server connections. When custom code development is required to maximize the functionality of Tracking Server, custom data links and other server connections can be developed to filter or manipulate data messages to manage the volume and kind of data coming through.
Although data links and server connections both serve the same purpose, they differ architecturally and provide different benefits. They both use COM technology to communicate with the Tracking Server, and they both require a message definition to parse data messages into fields. However, there are some important differences between the two data conveyance methods that are outlined in more detail in the "Tracking Server SDK" documentation. Depending on your preferences, you may choose one method over the other.
To help developers create custom code, the Tracking Server SDK provides templates to help set up and develop a variety of custom components, including data links and server connections. For more information on using the templates, refer to the "Tracking Server SDK" documentation.