In monomer applications , All in one application , But as the business grows , The functions of the system gradually become huge , Monomer application in development 、 Deployment and other aspects of efficiency is gradually low , It's getting more and more difficult to develop collaboration , Problems, etc. . therefore , It is necessary to split the system .
But in the microservices architecture , More and more services are being split up , The calling relationship between the whole system will become more and more complex , Each service management will become more and more difficult . Well, there's a lot of this 、 How to manage a system with complex dependencies becomes a problem .
At this time, we need a registry for service governance .
What is a registry
First , In the microservices architecture , What is a registry ？
A picture to summarize , It's an address book ：
It stores the information of each service , And then provide it to those in need , At the same time, maintain all kinds of expired content .
Principle of Registration Center
In microservices , There are three very important roles ： Registry Center 、 Service providers 、 Serving consumers . The correspondence is as follows ：
The corresponding process is as follows ：
- Each service startup information is registered in the registry , The registry stores registration data .
- After successful registration of each service , Upload service health information to the registration center to keep alive .
- Each service consumer subscribes service information to the registry when it starts , Get service address list , The registry synchronizes to service subscribers when the service list changes .
- Each service consumer invokes the service provider .
According to the information in the picture above , The functions of the registry are listed as follows ：
- Service registry ： The core function of the registry , Record the information of each service provider , Such as service name 、IP、 Port, etc . Maintain service subscriber information .
- Service registration 、 Logout interface ： For service providers to register and cancel services .
- Health check and service removal ： Provide health information reporting interface , For registration service to upload health information to keep service alive . At the same time, the invalid nodes can be removed in time and synchronized to the service subscribers .
- Service subscription and change notification ： For service consumers .
Registry implementation mechanism
There are two modes of service registration ： Self registration mode 、 Third party registration mode .
Self registration mode
Each service registers and cancels itself from the registry , At the same time, upload health information to the registration center to keep the registration valid .
advantage ： The implementation is simple , No additional components need to be deployed .
shortcoming ： The coupling degree is high , The server needs to adapt to the registry .
Third party registration mode
Each service instance does not need to register and log out directly to the registry itself , And you don't need to pay attention to your health information , These things are done directly by third-party components .
advantage ： Services and registries are decoupled , There is no need for services to be adapted according to the registry .
shortcoming ： Third party components need to be highly available , The introduction of third-party services also increases the complexity of the system .