Creating a Message Definition

The real-time message server depends on the message definition to determine whether to accept or reject incoming data messages. Be sure to define the correct field order to match that of the incoming data.

When creating a message definition, be sure to include a track identifier field, or Event ID. In addition, all observation message definitions must also include a Timestamp field that contains temporal information for the event.

Caution:

If your incoming data is complex (contains attribute data in a separate table), you will need to create an observation message definition and an object message definition.

Tip:

You may need to import a message definition if you are using a custom data link or application to receive data. The server needs the message definition to parse the incoming data. Also, you may need to export a message definition if you plan to share your custom code with another user.

Creating a New Message Definition

Steps:

1. Start Tracking Server Manager from the Start menu.
2. Click the Message Definitions tab.
3. Click New. The New Message Definition dialog box appears.
4. Click Observation or Object, depending on the type of message definition you want to create.
5. Click Next.

   If your incoming data is complex, you will need to create an observation message definition and an object message definition.

6. In the Name field, type a name for the new message definition.
7. Click the Data Time Zone drop-down arrow and choose the native time zone from which your data is coming.
8. Click Spatial Reference to specify the spatial reference system for the data.
9. Click Add to define a new field to be included in the message definition. A new field appears in the panel, with default values of FieldName and String 64.
10. In the Name column, type a name for the field you are defining.
11. In the Type column, click and choose a field type from the drop-down list that appears.

    Be sure to include an identifying field that indicates the Event ID for the event.

    
12. Click the check box beside the field you want to designate as the Event ID.
13. Click the up and down arrows to change the order of the fields in the message definition.

    Field order is important, as it must match exactly that of the incoming data. The real-time message server will reject any data message that does not have its fields appearing in the correct order.

14. Click a field and click Remove to delete it.
15. Click OK when finished.

Caution:

The message definition ID is a unique ID number that ties the message definition to messages sent in Tracking Server. If you are developing some form of connection to Tracking Server to transmit messages, you must ensure your message uses the same message definition ID as listed in the message definition. If Tracking Server receives a data message and cannot match it to a message definition ID, the message is ignored.

Tip:

Message definitions have restrictions on their names and the names of their columns to allow Tracking Server to support logging to SQL-compliant databases and to publish their messages on messaging systems. Appendix C: Reserved Words identifies the reserved words restricted by SQL.