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IoT Platform:Limits on server-side subscriptions

Last Updated:Dec 08, 2023

This topic describes the limits on server-side subscriptions.

Limits on AMQP subscriptions



Authentication timeout

An authentication request is immediately sent after a connection is established. If the authentication fails within 15 seconds, the server terminates the connection.

Data timeout

After a server establishes a connection to IoT Platform, the heartbeat timeout period must be specified by using the idle-timeout parameter in Advanced Message Queuing Protocol (AMQP). The timeout period ranges from 30 to 300 seconds. If no frames are transmitted within the heartbeat timeout period, IoT Platform closes the connection.

After the connection is established, the server must send ping packets within the heartbeat timeout period to maintain the connection. If no ping packets are sent within the heartbeat timeout period, IoT Platform terminates the connection.


If the connection is established by using an Alibaba Cloud SDK, the server does not need to send ping packets to maintain the connection. During the keep-alive period that is provided by the SDK, make sure that the main process does not exit.

ACK timeout

If an AMQP server fails to receive a receipt message from a client within 30 seconds after the AMQP service forwards a message to the client, an ACK timeout occurs.

Policy for message pushing retries

Messages may not be consumed in real time due to specific issues. For example, if consumers disconnect from IoT Platform or messages are consumed at a low speed, messages are accumulated in these cases.

  • After disconnected consumers re-connect to IoT Platform and start to consume messages at a stable speed, IoT Platform pushes the accumulated messages to the consumers.

  • If consumers fail to consume the pushed messages, the queue in which accumulated messages reside may be blocked. When the messages fail to be consumed, IoT Platform retries to push the accumulated messages to the consumers after approximately 1 minute.

Maximum number of saved messages

Each consumer group can retain a maximum of 100 million messages.

Message retention period

One day.

Maximum push rate for real-time messages

Each connection can be used to process a maximum of 1,000 transactions per second (TPS). A maximum of 128 connections can be established.

Maximum push rate for accumulated messages

A consumer group can process a maximum of 200 TPS.


To prevent a large number of accumulated messages, make sure that consumers are connected to IoT Platform and the consumers send ACK responses to messages that are pushed by IoT Platform.

Maximum number of consumer groups with which a product can be associated


Maximum number of products with which a consumer group can be associated


Maximum number of topics to which a consumer group can subscribe



A topic whose name contains wildcard characters can represent multiple topics but is counted only as one topic. For example, if a consumer group subscribes to the /asde****/+/user/get topic of the asde**** product, the topics of all devices that belong to the product are subscribed but only one topic is counted.

Maximum number of consumer groups

An Alibaba Cloud account can create a maximum of 1,000 consumer groups.

Maximum number of consumers

Each consumer group can have a maximum of 128 consumers.

Maximum number of connection requests

Each consumer can initiate a maximum of 100 connection requests within 1 minute.


Consumers indicate AMQP clients that are used to receive IoT Platform messages. These consumers are not devices.

Limits on MNS subscriptions

For information about the limits of Message Service (MNS) server-side subscriptions, see the limits on MNS queues in the MNS limits topic.

  • After you create an MNS server-side subscription, you are charged for MNS queues regardless of whether IoT Platform forwards messages to MNS queues.

  • The maximum size of a message that can be received by an MNS queue is 64 KB. If the size of a message exceeds the limit, the message is discarded.