This article describes the limits of Simple Message Queue (formerly MNS) topics.
Regional limits
Topics are unavailable in the UAE (Dubai) region.
Quota limits
You can create a maximum of 1,000 topics. Each topic can be subscribed to by a maximum of 100 users.
Message pushing limits
You can specify only one SMQ queue or topic to receive a message. For information about the API operations that you can call to manage SMQ queues, see List of RESTful API operations by function. For information about the API operations that you can call to manage SMQ topics, see List of RESTful API operations by function.
If you need to send messages to a specified application, call an API operation to create a queue that is available only for the application.
What can I do if I want to use an SMQ topic in a region where topics are unavailable?
To resolve this issue, you can create a topic in a region where topics are available and enable the public endpoint of the topic. For example, your Elastic Compute Service (ECS) instance resides in the UAE (Dubai) region where topics are unavailable. You can create a topic in the Singapore region where topics are available and enable the public endpoint of the topic and the ECS instance. The ECS instance can then access the topic over the Internet.
The latency of accessing the topic over the Internet is higher than that of accessing the topic over an internal network. We recommend that you use the Internet only for local debugging.