Messages take DIALOG and DIRECTION attributes, which identify the dialog on which the message should be sent, and the direction in which it should be sent. The given name identifies the message type, as defined in the schema. (The example shown in Scenario Definitions, Roles, and Dialogs uses the name InitialDP, and presumes that the callControl schema defines message type InitialDP.)
When the definition specifies a DIRECTION, the value must be A_TO_B or B_TO_A. When not set, it defaults to A_TO_B. Some messages may only be sent in a particular direction. For example, the OpenRequest message in all CGIN schemas may only be sent in direction A_TO_B.
Local messages
Some messages types are only sent or received locally, rather than sent across the network. For example in IN services, a provider abort is sent from the protocol stack to the application locally. These types of messages are supported using the LOCAL_TO_A and LOCAL_TO_B attributes. Below are two examples. The first defines a close message, sent by role B to the local stack; the second defines a provider abort message generated and delivered by role B’s local stack:
| Close message | Provider abort message |
|---|---|
Close
(DIALOG SSP-SCP, LOCAL_TO_B, DIRECTION B_TO_A)
{
prearrangedEnd "true";
}
|
ProviderAbort
(DIALOG SSP-SCP, LOCAL_TO_A, DIRECTION B_TO_A) ;{noformat}
|
Delays and timeouts
Message timing can be affected by specifying the following attributes on a message element:
-
DELAY— indicates the number of milliseconds to delay before sending the message; applies only to messages sent by the simulator -
TIMEOUT— indicates the number of milliseconds which can pass before timing out when waiting to receive the message; attribute applies only to messages received by the simulator.
|
The simulator calculates the delay or timeout from the last message it received or sent within the scenario |
|
You can specify a default delay or timeout on a dialog, or scenario definition, or globally. |
Fields
The message element contains field elements, which describe the expected fields of the network message. These may in turn contain sub-fields, when used to present a composite data type. The name of the field element corresponds to the field name in the protocol schema. (The example shown in Scenario Definitions, Roles, and Dialogs presumes that the InitialDP message type may take a callingPartyNumber field.)
Message Ordering
The importance of the order messages are sent and received may be configured. See information on ignored ordering for more details.
