10.6.1 Overview
This function set provides an interface for a text messaging service. Client devices of this function set include in-premises displays and other text messaging display devices. Server devices of this function set include ESIs or a back office server, depending on system design. The Response function set is used in conjunction with the messaging function set to allow client devices to confirm the viewing of messages and report advanced responses.
Servers expose messages to client devices in the form of separate messaging URIs. Each messaging URI instance will contain information that a client device can use to display the message appropriately. For example, start time, duration of event, text to display, etc.
10.6.2 List ordering
For list ordering purposes, the MessagingProgramList, TextMessageList, and the ActiveTextMessageList SHALL be ordered based on the criteria in Table 44.
Table 44 —Message list ordering
Resource name | Primary key | Secondary key | Tertiary key |
MessagingProgram | mRID (descending) | N/A | N/A |
TextMessage and ActiveTextMessage | dateTimeInterval.start (ascending) | createdDateTime (descending) | mRID (descending) |
10.6.3 Application guidelines/behavior
10.6.3.1 MessagingProgram
MessagingProgram server and client devices SHALL be capable of internally storing and supporting at least one MessagingProgram instance. A MessagingProgram server and client device SHOULD be capable of supporting three unique MessagingProgram instances.
10.6.3.2 TextMessage
MessagingProgram server devices SHALL be capable of internally storing and supporting at least one MessagingProgram instance. MessagingProgram server devices SHOULD be capable of internally storing and supporting three unique TextMessage instances. Additional information for common application features that the Messaging function set will perform can be found in 10.2, the common application functionality section of this document.
Messaging client devices SHALL be capable of internally storing and supporting at least one unique TextMessage instance, per supported MessagingProgram instance. As a highly RECOMMENDED recovery mechanism, when a maximum of storage of events has been reached and additional TextMessage instances are available on the server(s), clients SHOULD prioritize local storage and give preference to TextMessages with start times in the near future and to events with a higher PriorityType.
Devices can obtain text messages from many sources. It may be very common to have multiple Messaging function set servers in a HAN. FunctionSetAssignments and MessagingProgram.primacy are used to indicate which messaging servers in the HAN the device should prioritize. MessagingPrograms indicated in FunctionSetAssignments SHALL be of higher priority than those found through discovery. MessagingProgram.priority SHALL be used as a secondary determinant of a message’s priority.
10.6.4 LogEvents
There are no LogEvents generated by this function set.