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Topic Concepts

Last Updated: Mar 21, 2017

Topic

Topic is the destination and the storage address of message in the message Pub/Sub model.

Account

The user id of Alibaba Cloud which consists of a sequence of numbers.

Publisher

The client sending message to the topic, it’s also known as “producer”.

Subsciber

The client receives the message from topic. The owner of topic has authorization of subscribing the owned topic.

Subscription

The relationship between message subscriber and topic. The message which publisher sends to topic can only be received by subscribers.

Endpoint

The address that the subscriber used to receive messages, such as http address, email address and phone number(for SMS) etc.

TopicURL

Indicator in format: “http(s)://$AccountId.mns.$Region.aliyuncs.com/topics/$TopicName” in which $AccountId means the user account id(uid), $Region is the name of region where AliCloud Message Service provides service, $TopicName is the name of topic.

Message

The unit of information transferred from publisher to subscriber through topic. There is an unique MessageID for every message in the same topic but may be duplicated in different topics.

Every message will be kept for 1 day after sending to topic. The message existing over 1 day will expire and be recycled soon.

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