70 evaluates every incoming message addressed to the client and validates the message
currency based on the configuration of the client Validity Policy. Messages received by the DMS in a valid state are forwarded to the client unaltered. Messages received by the
DMS in an invalid state are either flagged with a “non-current” tag or dropped to prevent transmission to the client. The client’s Validity Policy defines how the data validation
module deals with messages containing non-current data. If currency metadata is not found in a message, the Data Validation Module will not perform data validation and
forwards the message to the client unaltered. The currency of each message received is recorded in a log as either “Meets Currency” or “Exceeds Currency” for future analysis
by stakeholders.
The Data Validation Module calculates the latency of the message transmission to the client by the DMS. The latency of each message is logged by the Data Validation
Module and compared against an acceptable limit hard coded in the DMS to determine whether the DMS transmission latency is within acceptable levels. The latency of each
successful client – DMS message transmission is recorded in a log as either “Meets Latency Requirements” or “Exceeds Latency Requirements” and stored for future
analysis by stakeholders.
The Data Validation Module monitors the rate in which notification messages are received from subscription based ground services. The reception rate is compared against
the subscription interval client configured in a subscription based ground service. Disparities between the rate of received notification messages and rate configured by the
aircraft client are logged by the Data Validation Module for future analysis by stakeholders.
13.1.1 DMS Currency Validation
The purpose of the DMS Currency Validation function is to ensure that data received by the DMS is valid before it is transmitted to the client. To determine message validity, the
reception time of the message by the DMS is compared to currency metadata i.e. AIXM Time Slice in the message. The currency metadata describes the time period in which
the message is current. Messages received outside of the time period described by the currency metadata are considered invalid. Messages received in a invalid state are tagged
as such and either dropped or forwarded to the client, depending on the configuration of the client validation policy. The messages that are received in a valid state are forwarded
to the client unaltered.
13.1.1.1 Recommended Approach
During session negotiation, a client will specify in its Validity Policy whether or not the Data Validation Module is to perform the following Currency Validation:
1. Flagging non-valid messages. ONOFF 2. Dropping non-valid messages. ONOFF
71 The Data Currency Validation feature searches for currency metadata in all received
messages addressed to the client. The messages are parsed by the DMS to locate currency timestamps e.g. AIXM Time Slice that describes the validity of the
information contained in the message. Messages containing no currency metadata are forwarded to the client unaltered by this feature. When currency metadata is found, the
Data Currency Validation feature compares the message currency timestamp to the time of message reception by the DMS. Messages received with currency metadata containing
a timeframe outside of the DMS reception time are considered invalid by this feature. Invalid messages are either dropped, or an “invalid” tag is inserted into the message
SOAP header, and then forwarded to the client. What the Validation Module does with invalid messages is dependent on the configuration of the Validity Policy set by the
client.
When the Data Validation Module is configured to drop invalid messages, invalid messages are dropped from the transmission queue to prevent message transmission to
the client. If the Data Validation Module is configured to flag invalid messages, a “valid false valid” tag is inserted into the SOAP messages header. This tag alerts
the client that the message received is invalid. Every message received by the Data Currency Validation feature is recorded as being either valid or invalid in a log and stored
for future analysis by stakeholders. The contents of the log are used to generate a single metric describing the number of invalid message received by the DMS. The metric is
generated with the following formula:
of messages received for a client minus of out-of-valid timeframe msgs of messages received for a client
13.1.2 Client Latency Validation
