MAX_SUBSCRIBE_ID

A publisher sends a MAX_SUBSCRIBE_ID message to increase the number of subscriptions a subscriber can create within a session.

The Maximum Subscribe Id MUST only increase within a session, and receipt of a MAX_SUBSCRIBE_ID message with an equal or smaller Subscribe ID value is a 'Protocol Violation'.

MAX_SUBSCRIBE_ID
{
  Type (i) = 0x15,
  Length (i),
  Subscribe ID (i),
}

• Subscribe ID: The new Maximum Subscribe ID for the session. If a Subscribe ID Section 7.4 equal or larger than this is received by the publisher that sent the MAX_SUBSCRIBE_ID, the publisher MUST close the session with an error of 'Too Many Subscribes'.

MAX_SUBSCRIBE_ID is similar to MAX_STREAMS in ([RFC9000], Section 4.6), and similar considerations apply when deciding how often to send MAX_SUBSCRIBE_ID. For example, implementations might choose to increase MAX_SUBSCRIBE_ID as subscriptions close to keep the number of subscriptions available to subscribers roughly consistent.