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title: “Service Definition” lang: en ref: service-definition permalink: /docs/users/service-definition/ excerpt: “Service Definition” last_modified_at: 2017-08-15T15:01:43-04:00 redirect_from:

• /theme-setup/

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Concept Description

A service definition identifies a microservice. It defines the service name, version, and the application that the service belongs to. The service definition can also contain extended information defining the attribute metadata of a service.

Scenario

To define a new microservice or modify its basic information, you may need to create and modify service definitions.

Configuration

This section describe the following configration items related to the microservice.yaml file in the src\main\resources\ directory.

Configuration on Item	Default	Range	Mandatory	Description	Remarks
APPLICATION_ID	-	-	Yes	Indicates an application name.	-
service_description.name	-	-	Yes	Indicates a microservice name	The microservice name should be unique within an application. The name can contain digits, uppercase and lowercase letters, hyphens(-), underscores(_), and periods(.); and can neither start nor end with punctuations. The naming rule is as follows: ^[a-zA-Z0-9]+$|^[a-zA-Z0-9][a-zA-Z0-9_-.]*[a-zA-Z0-9]$.
service_description.version	-	-	Yes	Indicates a service version.	-
service_description.properties	-	-	No	Configures microservice metadata(in the microservice.yaml file).	-
service_description.propertyExtendedClass	-	-	No	Configures microservice metadata(through the PropertyExtended API).	The configurations returned through the API will overwrite those with the same keys in the configuration file.
instance_description.properties	-	-	No	Configures instance metadata(in the microservice.yaml file)
instance_description.propertyExtendedClass	-	-	No	Configures microservice metadata(through the PropertyExtended API).	The configurations returned through the API will overwrite thos with the same keys in the configuration file.

NOTE：

• The metadata of a service is registered to the service center with the service. It is changed together with the service version. Changing metadata in the service center will keep the version unchanged.
• By default, one microservice can be called by only one APPLICATION_ID. You can set allowCrossApp=true in microservice properties to access a microservice acroos APPLICATION_ID.

Sample Code

APPLICATION_ID: helloTest #Application name
service_description: #Service description
  name: helloServer #Microservice name
  version: 0.0.1 #Service version
  properties: #Metadata
    allowCrossApp: false
    key1: value1
    key2: value2
  propertyExtendedClass: org.apache.servicecomb.serviceregistry.MicroServicePropertyExtendedStub
instance_description: #Instance description
  properties: #Metadata
    key3: value3
  propertyExtendedClass: org.apache.servicecomb.serviceregistry.MicroServicePropertyExtendedStub