I'm configuring a sample application using this example:
http://projects.spring.io/spring-cloud/spring-cloud.html#spring-cloud-feign-inheritance. In this section http://projects.spring.io/spring-cloud/spring-cloud.html#spring-cloud-ribbon it is said that:
Feign already uses Ribbon, so if you are using #FeignClient then this
section also applies
Does that mean that #FeignClient uses Hystrix too? Does the call to feign client execute inside hystrix command? if so, what is the proper way to pass hystrix configuration?
There are samples that wrap calls to feign client with #HystrixCommand. Is it a correct way?
There is an open ticket to support hystrix with feign. Currently, you need to wrap calls to feign clients with hystrix.
please use semaphore isolation:
hystrix:
command:
default:
execution:
isolation:
strategy: SEMAPHORE
Related
Any idea please about the best way to use for back to back communication ?
spring cloud OpenFeign or WebClient/RestTemplate ?
I think Feign client should be used when spring cloud gateway need to
communicate to other microservices, whereas WebClient/RestTemplate should be used for back to back communication.
Am I wrong ?
WebClient (RestTemplate - deprecated to support WebClient)
Supports reactive call
underlying HTTP client libraries such as Reactor Netty
Part of spring framework - WebFlux || Doc will give you more
Comes in 2 flavour - Annotation and functional way
Personally I found it very useful while working with OAuth2 creating bean webClient, before making call it needs to be authenticated with token, ServerOAuth2AuthorizedClientExchangeFilterFunction will ease each call with just one time configuration
OpenFeign
Reactive - need to use 3rd party - com.playtika.reactivefeign
Fits best if you want call in blocking way
Part of Spring cloud
Netflix fully transferred Feign to the open-source community under a new project named OpenFeign
I use springcloud to build the system, including many microservices。 For some interface calls, I use resttemplate annotated by #LoadBalance to implement load balancing, and use eureka as a registry center. However， when I call interfaces between different micro services, resttemplate sometimes will connect to wrong service. For example, I have service A, B, C, when service A call a service B's interface, resttemplate annotated by #LoadBalance will find the actual ip&port from eureka by service name first, and then build the actual url and send the request to target server, but sometimes, it will find the service C's ip&port when I call service B's interface, which cause a fail invoking. This case occurs infrequently but nerver disappear, I have been troubled for a long time, could anyone give me some suggestions? Thanks.
I learned why yesterday: it is a bug in spring cloud Dalston.RELEASE(https://github.com/spring-cloud/spring-cloud-commons/issues/224), and we happen to use this version. Spring cloud had fixed this bug in Dalston.SR2, and now it works fine
Environment
Spring Boot 1.5.13.RELEASE
Spring Cloud Edgware.SR3
Java 8
Configuration
Eureka client is enabled and working correctly (I have tested and everything's working as I expect).
Some relevant properties from my configuration:
feign.hystrix.enabled=true
eureka.client.fetch-registry=true
spring.cloud.service-registry.auto-registration.enabled=true
service1.ribbon.listOfServers=https://www.google.com
Context
I have an application which speaks to 3 other services using feign clients. Two of these are discovered via Eureka service discovery. These are working well. The final service is an external one with a single static hostname and I do not want this resolved via Eureka. Since I do want Eureka for 2 of these services I would like to keep Eureka enabled.
Question
For the final service I tried adding service1.ribbon.listOfServers=https://www.google.com to the application.properties, however this cases the following error at runtime when invoking the feign client:
Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is com.netflix.hystrix.exception.HystrixRuntimeException: Service1Client#test() failed and no fallback available.] with root cause
pricing_1 |
pricing_1 | com.netflix.client.ClientException: Load balancer does not have available server for client: service1
pricing_1 | at com.netflix.loadbalancer.LoadBalancerContext.getServerFromLoadBalancer(LoadBalancerContext.java:483) ~[ribbon-loadbalancer-2.2.5.jar!/:2.2.5]
My client is configured as follows:
#FeignClient("service1")
public interface Service1Client {
#GetMapping(value = "/")
String test();
}
Thanks in advance for any advice.
Consideration
Since the spirit of Ribbon as I understand it is to act as a client side load balancer and given in my case there is nothing to load balance (I have one fixed static hostname that returns a single A record in DNS). Ribbon actually feels like an unnecessary component - what I really wanted was the Feign client as I like the fact that it abstracts away the lower level HTTP request and object seralization. So I suppose an alternative follow up question is, can I use feign without ribbon - it seems the nice out of the box behaviour would be to use ribbon - even the Javadoc of the #FeignClient annotation says:
If ribbon is available it will be
used to load balance the backend requests, and the load balancer can be configured
using a #RibbonClient with the same name (i.e. value) as the feign client.
suggesting the two are quite closely related even if they are serving different purposes.
As you mentioned, there are two ways to solve your problem.
Use Feign without Ribbon
If you specify url attribute in #FeignClient annotation, it will work without Ribbon like the below.
#FeignClient(name = "service1", url = http://www.google.com)
public interface Service1Client {
#GetMapping(value = "/")
String test();
}
In this case, your other two Feign client will still work with Ribbon and Eureka.
Use Feign with Ribbon and without Eureka
What you are missing is in your configuration is NIWSServerListClassName.
Its default value is com.netflix.niws.loadbalancer.DiscoveryEnabledNIWSServerList and it will use Eureka to retrieve the list of server. If you set NIWSServerListClassName to ConfigurationBasedServerList for a ribbon client (feign client), only that client will work with listOfServers list without retrieving server list from Eureka. And other feign clients will still work with Eureka.
service1:
ribbon:
NIWSServerListClassName: com.netflix.loadbalancer.ConfigurationBasedServerList
listOfServers: http://www.google.com
I just tried to do a attempted a seamless upgrade of a service in a test setup. The service is being accessed by a Feign client. And naively I was under the impression that with multiple instances available of the service, the client would retry another instance if it failed to connect to one.
That, however, did not happen. But I cannot find any mention of how Feign in Spring Cloud is supposed to be configured to do this? Although I have seen mentions of it supporting it (as opposed to using RestTemplate where you would use something like Spring Retry?)
If you are using ribbon you can set properties similar to the following (substituting "localapp" for your serviceid):
localapp.ribbon.MaxAutoRetries=5
localapp.ribbon.MaxAutoRetriesNextServer=5
localapp.ribbon.OkToRetryOnAllOperations=true
ps underneath Feign has a Retryer interface, which was made to support things like Ribbon.
https://github.com/Netflix/feign/blob/master/core/src/main/java/feign/Retryer.java
see if property works - OkToRetryOnAllOperations: true
You can refer application ->
https://github.com/spencergibb/spring-cloud-sandbox/blob/master/spring-cloud-sandbox-sample-frontend/src/main/resources/application.yml
Spencer was quick...was late by few minutes :-)
How to create process with 1 service task - rest which calls
http://www.webservicex.net/currencyconvertor.asmx/ConversionRate?FromCurrency=EUR&ToCurrency=USD
and sets this value as parameter which can be seen later, using jbpm console(kie workbench)? JBOSS docs are mostly for user tasks.
My recommended solution is to create a new WorkItemHandler implementation that calls the web service get the results and inject that as a process variable.
You can see a similar example that calls web services here: https://github.com/droolsjbpm/jbpm-playground/tree/master/customer-relationships-workitems
HTH
There is a REST service task that you can use, available out-of-the-box in the web-based designer (under service tasks, so implemented as a custom service task). The associated handler should also be registered automatically when using the jbpm-installer:
https://github.com/droolsjbpm/jbpm/blob/master/jbpm-installer/conf/META-INF/CustomWorkItemHandlers.conf#L4