Try to support spring-cloud-gateway

[zaneChou1]

I have try to support spring-cloud-gateway in ServiceComb-java-chassis.

I have used spring-cloud-gateway to run demo program in java-chassis. The result is correct and forwarding function of gateway is OK.

but when I use use gateway-webflux to write the following code , some errors have occurred.

@RestSchema(schemaId="gatewaySampleController ")
@RequestMapping("/")
public class GatewaySampleController {
    @Value("${remote.home}")
    private URI home;
    @GetMapping("/test")
    public Mono<ResponseEntity<byte[]>> proxy(ProxyExchange<byte[]> proxy) throws Exception {
      return proxy.uri(home.toString() + "/image/png").get();
    }
}

The error message is as follows :

java.lang.IllegalStateException: ServiceComb init failed.
	at org.apache.servicecomb.core.SCBEngine.init(SCBEngine.java:220) ~[classes/:na]
	at org.apache.servicecomb.core.CseApplicationListener.onApplicationEvent(CseApplicationListener.java:81) ~[classes/:na]
	at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172) ~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE]
	at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165) ~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE]
	at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139) ~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:400) ~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:354) ~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE]
	at org.springframework.boot.context.event.EventPublishingRunListener.running(EventPublishingRunListener.java:103) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
	at org.springframework.boot.SpringApplicationRunListeners.running(SpringApplicationRunListeners.java:78) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:343) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1255) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1243) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
	at gateway.GatewaySampleApplication.main(GatewaySampleApplication.java:21) [classes/:na]
Caused by: java.lang.Error: generate operation swagger failed, gateway.GatewaySampleController:proxy
	at org.apache.servicecomb.swagger.generator.core.SwaggerGenerator.scanMethods(SwaggerGenerator.java:276) ~[classes/:na]
	at org.apache.servicecomb.swagger.generator.core.SwaggerGenerator.generate(SwaggerGenerator.java:140) ~[classes/:na]
	at org.apache.servicecomb.core.definition.schema.AbstractSchemaFactory.generateSwagger(AbstractSchemaFactory.java:102) ~[classes/:na]
	at org.apache.servicecomb.core.definition.schema.ProducerSchemaFactory.createSchema(ProducerSchemaFactory.java:115) ~[classes/:na]
	at org.apache.servicecomb.core.definition.schema.ProducerSchemaFactory.createSchema(ProducerSchemaFactory.java:54) ~[classes/:na]
	at org.apache.servicecomb.core.definition.schema.AbstractSchemaFactory.getOrCreateSchema(AbstractSchemaFactory.java:58) ~[classes/:na]
	at org.apache.servicecomb.core.definition.schema.ProducerSchemaFactory.getOrCreateProducerSchema(ProducerSchemaFactory.java:76) ~[classes/:na]
	at org.apache.servicecomb.provider.rest.common.RestProducerProvider.init(RestProducerProvider.java:45) ~[classes/:na]
	at org.apache.servicecomb.core.provider.producer.ProducerProviderManager.init(ProducerProviderManager.java:51) ~[classes/:na]
	at org.apache.servicecomb.core.SCBEngine.doInit(SCBEngine.java:238) ~[classes/:na]
	at org.apache.servicecomb.core.SCBEngine.init(SCBEngine.java:209) ~[classes/:na]
	... 12 common frames omitted
Caused by: org.apache.servicecomb.foundation.common.exceptions.ServiceCombException: [simple type, class reactor.core.publisher.Mono] is abstract class. Must be a concrete type.
	at org.apache.servicecomb.swagger.extend.ModelResolverExt.checkType(ModelResolverExt.java:114) ~[classes/:na]
	at org.apache.servicecomb.swagger.extend.ModelResolverExt.resolve(ModelResolverExt.java:130) ~[classes/:na]
	at io.swagger.jackson.ModelResolver.resolve(ModelResolver.java:183) ~[swagger-core-1.5.12.jar:1.5.12]
	at io.swagger.converter.ModelConverterContextImpl.resolve(ModelConverterContextImpl.java:100) ~[swagger-core-1.5.12.jar:1.5.12]
	at io.swagger.jackson.ModelResolver.resolve(ModelResolver.java:234) ~[swagger-core-1.5.12.jar:1.5.12]
	at org.apache.servicecomb.swagger.extend.ModelResolverExt.resolve(ModelResolverExt.java:125) ~[classes/:na]
	at io.swagger.jackson.ModelResolver.resolve(ModelResolver.java:183) ~[swagger-core-1.5.12.jar:1.5.12]
	at io.swagger.converter.ModelConverterContextImpl.resolve(ModelConverterContextImpl.java:100) ~[swagger-core-1.5.12.jar:1.5.12]
	at io.swagger.converter.ModelConverters.readAll(ModelConverters.java:83) ~[swagger-core-1.5.12.jar:1.5.12]
	at org.apache.servicecomb.swagger.generator.core.utils.ParamUtils.addDefinitions(ParamUtils.java:116) ~[classes/:na]
	at org.apache.servicecomb.swagger.generator.core.processor.response.DefaultResponseTypeProcessor.process(DefaultResponseTypeProcessor.java:39) ~[classes/:na]
	at org.apache.servicecomb.swagger.generator.core.OperationGenerator.createResponseProperty(OperationGenerator.java:426) ~[classes/:na]
	at org.apache.servicecomb.swagger.generator.core.OperationGenerator.scanResponse(OperationGenerator.java:413) ~[classes/:na]
	at org.apache.servicecomb.swagger.generator.core.OperationGenerator.generate(OperationGenerator.java:181) ~[classes/:na]
	at org.apache.servicecomb.swagger.generator.core.SwaggerGenerator.scanMethods(SwaggerGenerator.java:272) ~[classes/:na]
	... 22 common frames omitted

To my opinion , the question occurs between gateway-webflux and swagger . According to error message, servicecomb swagger seem can not resolve abstract class. But the type used by webflux is Flux and Mono related to reaction time programming, and they are abstract classes. So, How to solve it?

What about other's opinion?please feel free to let me know.

[wujimin]

you build this gateway for internal microservice to invoke 3rd service?
not for 3rd invoke internal microservice?

[zaneChou1]

I used 3rd invoke internal microservice by spring-cloud-gateway.

[wujimin]

for this scenes, no need to declare the controller to be a RestSchema
just use @RestController, and set configuration servicecomb.provider.rest.scanRestController to false

[zaneChou1]

OK, I have do it as your suggestion , program running is current . thanks for your suggestion.
But I am a bit curious , for another scenes(internal microservice to invoke 3rd service) , have any different in handler way?

[wujimin]

currently, edge just designed for 3rd invoke internal microservice

because our governance working based on contract(swagger),
so if need to support internal microservice to invoke 3rd, concrete datatype is still necessary

[wujimin]

Clear and concrete contract is very important

I've seen many projects where the input/output of methods is abstract, such as Object, which looks very flexible and can express anything.
But a very bad result is that no one can tell what its input/output is. Everything is hidden in the implementation logic.
A method has different inputs/outputs in different scenarios, and one method has many different functions.
Such projects must rely on manual maintenance documentation to describe their own contracts, but no project can synchronize documents and actual implementations in a timely manner.

So, so far, ServiceComb still recommends using explicit input/output so that the framework can automatically generate the correct contract, automatically supporting governance, and without having to manually maintain the contract document.

[zaneChou1]

OK, thanks for your explanation.

I will submit a PR to support spring-cloud-gateway in servicecomb-java-chassis.

So , I want to get some advice for submitting a PR in java-chassis.

And what should I do to make sure PR pass 'continuous-integration/travis-ci' in java-chassis.

[wujimin]

thanks for your coming PR.
when your create a PR, there is a checklist show there, just like: #1084

but change "mvn clean install" to "mvn clean install -Pit"

"it" profile is automatic integration test, it will start and stop ServiceCenter and test processes, maven does not know where is ServiceCenter, so we find ServiceCenter by the following rules:

• invoke http://localhost:30100/version to check if ServiceCenter already running
• invoke System.getenv("serviceCenterHome") to find where it install
• invoke docker run -p "127.0.0.1:30100:30100" servicecomb/service-center

[zaneChou1]

OK, thanks for your suggestions.
I have submitted PR . And PR has passed continuous-integration/travis-ciin java-chassis.