Sound Control Protocol for ew D1

SSC Developer‘s guide for evolution wireless D1 | 19/56
General SSC Address Schema
5.1.9.1 Subscription notification rate parameters
Optional subscription request parameters related to notification rate:
• "min" minimum notification period (ms), 0=none, default 0
• "max" maximum notification period (ms), 0=none, default 0
• "bw" maximum bandwidth for replies (byte/s), 0=unlimited, default 0
If "min" is 0, then notifications are not sent when a subscribed address changes in value, they are only
sent based on the "max" period. If "min" is greater than 0, notifications are sent after the specified
time duration has elapsed, even if the value of the subscribed address is unchanged.
If "max" is 0, then notifications are only sent when a value changes, or based on the "min" period. If
"max" is greater than 0, then notifications are sent not earlier before the specified time duration has
elapsed, even if the subscribed address changes value in the meantime.
If "bw" is greater than 0, then the bandwidth consumed for notification replies is tracked by the SSC
Server, and notifications are suppressed when the specified bandwidth would be exceeded. If any
notification has been suppressed due to bandwidth limitation, the SSC Server SHOULD send a noti-
fication about the actual value of the subscribed address as soon as the bandwidth limitation can be
met again. The bandwidth calculation MAY be approximate, and the SSC Client MUST NOT rely on a
byte-exact bandwidth limitation.
If multiple subscriptions are requested with a common set of optional parameters, then the optional
parameters MUST be interpreted as if all of the requests had been issued separately, each request
with the identical set of parameters. Especially, the "bw" parameter imposes the specified bandwidth
limit for each subscribed SSC address separately; it is not a summary limit for all of the requested
subscriptions.
The SSC Server SHOULD ignore any unknown subscription parameters. Parameter name "internal" is
reserved and MUST NOT be used in SSC Client requests.
5.1.9.2 Subscription cancelling and expiration
The SSC Server MUST terminate a subscription in these cases:
• the subscribed client cancels the subscription explicitly
• a maximum number of notifications has been sent
• a maximum lifetime relating to the begin of the subscription expires
• the SSC Client closes the connection
• the transport layer of the SSC connection signals a communication error
If the SSC Server decides to terminate the connection because the lifetime or notification count ex-
pires, then it MUST inform the SSC Client by sending an error reply "310 – subscription terminated"
to the SSC address that terminates subscription together with or immediately after the last subscrip-
tion notification.
Optional subscription request parameters related to termination:
• "cancel" "true" cancels the subscription (default false).
• "count" maximum number of notifications to send, default 1000
• "lifetime" maximum lifetime (s) of the subscription, default 10s
The SSC Client may renew a subscription at any time, thereby resetting all of the lifetime limitations.
To renew a subscription, the SSC Client re-requests it; there‘s no difference between an initial sub-
scription request and a renewal request.
5.1.9.3 Subscribing to multiple addresses
The SSC Client MAY request multiple subscriptions in a single request; either by providing them
explicitly as SSC Address Tree, or by specifying address patterns as subscription addresses, or even
both in the same request.
The SSC Server MAY either treat all those subscription requests separately, as if the addresses had
all been requested for subscription individually. In this case all the subscription notifications would
each contain the SSC Method Reply to a single subscribed address.
Alternatively, the SSC Server MAY bundle subscription notifications which happen to be sent at the