1. Why use Message Queue ah?
Three: decoupling, asynchronous, clipping
1) Decoupling:
2) Asynchronous
3) clipping
2, message queues are what advantages and disadvantages?
advantage:
Has been said above, it is to have its corresponding benefits in Special Scenes decoupling, asynchronous, clipping
Disadvantages:
Reduce system availability : the more dependent on external systems introduced, the more easy to hang, you had A system call interface is BCD three systems like, four people ABCD system properly, nothing issue, you add a partial MQ come in, if MQ hung up zezheng? MQ hung up, the entire system crashes, you do not what would be finished.
Increase system complexity : add MQ abruptly come in, how do you ensure that the message is not repeated consumption? How to deal with the case of message loss? How to ensure that the order of message delivery? The bulk of the big head, a lot of questions, endless suffering
Coherence : A system to process over direct return is successful, people think that you request will be successful; but the problem is that if the three systems where BCD, BD two write library system is successful, the results of C write library system failed , Zezheng? You data is inconsistent.