DCT Antares SB, Руководство пользователя

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3.10. REMOTE HOST SOFTWARE
5. The server should not use a keep-alive mechanism. Using the
unit’s keep-alive option or a periodical report event are the pre-
ferred methods. See the
XAKA
message for keep-alive options.
6. The server should have an association between unit’s ID and
corresponding TCP socket so any user-query can be correctly
routed. There are two ways for the server to know the unit’s
ID:
(a) Extract the ID from the “
;ID=
” postfix of every incoming
TAIP message.
(b) Send an ID query to an open socket for which the ID is
unknown with the >
QID
< command.
The second option is preferred as with the first one exists the
possibility for the server to have open TCP connections with
unknown IDs every time an unit opens a connection but it has
nothing to report. There is a workaround for this: Having the
unit send a re-connection event so every time the connection
is opened the server knows who did open it. In order to do
so use the
Axx
signals creating an event that sends a report
every time the
A
signal associated to the corresponding IP-type
Destination becomes true.
However it is more efficient and simple to use the second option,
when possible, as it does not generate an extra report and makes
it possible for the user to tell the unit to eliminate the “
;ID=
”
postfix from every message thus saving consumption bytes.
3.10.2 Working with UDP
In order to have the unit start connecting to an AVL server, an IP-
type
Destination has to be configured first. The configuration flag
for this Destination must indicate an UDP host. Refer to the Desti-
nations section on the Configuration chapter. The following are the
general requirements for an AVL server working with units on UDP:
1. The AVL server has to be able to listen UDP datagrams on a
given port.
2. The port number has to be the same port number used on the
unit’s IP-type Destination and it has to be clear of any Firewall,
NAT and/or router restriction.
3. The server should not use a keep-alive mechanism. Using a
periodical report event generated by the unit is preferred.
4. The server should have an association between the unit’s ID and
the information from the last inbound UDP message received
from the unit. This information is the last incoming message’s
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