1. Real-time: Ensuring real-time access to messages is a necessary ability for interactive scenes.
For a real-time messaging system, the word "real-time" well expresses the basic requirements of the system. Chatting with your friends via WeChat, the results waited half a day for the other party to receive it, basically there is no intention to chat; in the live broadcast scene, if the fans in the host’s interactive message room have to wait a long time to receive it, it is difficult to get Fans have a desire to actively participate. Real-time performance is divided into: short polling, long polling, and WebSocket (long link).
2. Reliability: "No loss of messages" and "No repetition of messages" are preconditions for trustworthy systems.
If "real-time" is the basic prerequisite for instant messaging to be widely used in various social and interactive fields, then the reliability of messages is another important feature that real-time messaging services can be "trusted". Generally speaking, the reliability here generally includes two aspects. Do not lose news. "Message loss" is an unacceptable bug in interaction. In some scenarios, it may lead to poor service availability or even unavailability. For example, the loss of the signaling message of "all members mute" in the live broadcast room may cause some uncontrollable situations in the live broadcast room. The message is not repeated. Message repetition will not only cause unnecessary harassment and confusion to users, but may also cause more serious business anomalies. For example, the "gift-sending" message in the live broadcast room is repeated for some reason. If it is not handled properly, it may cause user losses. .
3. Consistency: The consistent experience of "multi-user" and "multi-terminal" can greatly improve the experience of using the IM system .
The consistency of messages generally means that the same message needs to be displayed in a consistent order in multiple people and multiple terminals. For example, for a single chat scenario, consistency means that the sender’s message sending order is the same as the receiver’s receiving order; for a certain message in a group, we hope that the order of messages received by other people in the group is the same For multiple terminal devices of the same user, we hope that the messages sent to this user can be consistent on multiple devices. An IM system that lacks "consistency" guarantees often leads to "wonderful misunderstandings" and "tragedies" related to language disorder. On the Internet, you can imagine several important work content sent to subordinates, leaders, or partners. If the messages are messed up, the consequences may be more serious.
4. Security: "Data transmission security", "data storage security" and "message content security" provide comprehensive privacy protection in three major guarantees.
Because instant messaging is widely used in various private social and small-scale social circles, users have relatively high requirements for the privacy protection capabilities of the system. From the perspective of system security, the first requirement is "data transmission security", the second is "data storage security", and the last is "message content security".