Glossary

Microservice

Microservice is a service concept, that is, a process that provides a service.

Each service has its own service functions. APIs that are not restricted by languages are open to other systems (HTTP frequently used).

Multiple microservices form an application.

Instance

An instance is the minimum running and deployment unit of a microservice. Generally, it corresponds to an application process. A microservice can be deployed in multiple containers or VMs to enable multiple instances to run at the same time.

Configuration

The configuration in the microservice scenario is to control the values of some variables in the program code. For example, dynamic configuration is to dynamically change the values of some variables during microservice running.

Namespace

Used for tenant-level configuration isolation. Namespaces isolate configurations in different environments. For example, resources (such as configurations and services) in the development and test environments are isolated from those in the production environment.

Configuration set

A set of configuration items is called a configuration set. Generally, a configuration file is a configuration set that contains all system configurations.

Configuration set ID

ID of a configuration set in Nacos. A system or application can contain multiple configuration sets, and each one can be identified by a name.

Group

Group of configuration sets in Nacos. It is one of the dimensions according to which configurations are organized. The configuration sets are always grouped by a meaningful string to differentiate the configuration sets with the same Data ID. When you create a configuration on Nacos, the group name is replaced by DEFAULT_GROUP by default if not specified.

Protection threshold

Protect threshold is related to the proportion of healthy instances in a cluster. When the proportion of healthy instances to the total instance is smaller than this value, all instances are returned to the client regardless of the health of the instance. If the protect threshold is not triggered, Nacos returns only healthy instances to the client.

Dark launch

Before the configuration is officially released, a small part of the configuration is released and verified. If this part is correct, the whole configuration will be officially released, reducing the risk.

Weight

Instance-level configuration. Weight is a floating-point number. The greater the weight, the greater the traffic that the instance expects to be allocated.

Metadata

Description of Nacos data (such as configurations and services), such as the service version and weight. From the scope of action, it is divided into meta-information of service level, meta-information of virtual cluster, and meta-information of instance.

Version

In the microservice scenario, a version is used to mark the iteration record of a microservice to facilitate management of different iterations of a microservice.

Service contract

A service contract in the microservice scenario is a microservice API constraint specification based on the OpenAPI definition and defines APIs on the server and consumer.

NOTE:

• By default, service contract is used in Java chassis.
• By default, service contract is not used in Spring Cloud. If it is used, the following dependencies need to be introduced:

  <dependency>  
      <groupId>com.huaweicloud</groupId>  
      <artifactId>spring-cloud-starter-huawei-swagger</artifactId>  
  </dependency>

Application

A software system that completes a complete service scenario. An application consists of multiple microservices, which can discover and call each other.

Environment

A logical concept established by the service center, which can be development or production. Microservice instances in different environments are logically isolated and cannot be discovered or called by each other.

Governance policy

A concept in microservice governance. It refers to a method used for governance. Each governance policy can be bound to a service scenario. A policy cannot be bound to multiple service scenarios. Different governance policies can be bound to the same service scenario.

Service scenario

A condition for a governance policy to take effect. A service scenario can be bound to multiple governance policies.