Use With Feign

[NumFive5]

Describe the proposal

[cicoyle]

Hi @NumFive5 – thanks for opening the issue! Are you looking to integrate the Java SDK with Feign? If so, could you provide more details on what you're trying to achieve?

[lony2003]

I wrote a frign client for dapr and springboot, you can try this: https://github.com/fangkehou-team/dapr-spring

Edit: I have just checking out the code of Dapr java-sdk and found that It changed a lot for dapr-spring-boot-starter, so it will be not usable for the repo above. So the repo is now archived.

[salaboy]

@lony2003 can you please share here some examples on how Feign clients would be used? I like the idea of simplifying the service to service communication with a declarative client, but I just don't see how this will work in practice. This might be my lack of experience with Feign, so a code example in this issue would help a lot.

[lony2003]

@salaboy just like this example in my project:

Feign client defined here:

@UseDaprClient
@FeignClient(name = "grid-feign", url = "http://method.nep-back-gfb-spring/gfb")
public interface GridFeedbackFeignClient {

    @GetMapping(path = "/list/byUser/{pageSize}/{page}", consumes = "application/json;charset=utf-8", produces = "application/json;charset=utf-8")
    Result<PageResult<List<GridFeedbackDTO>>> getAllByUser(
            @PathVariable Integer page,
            @PathVariable Integer pageSize,
            @RequestHeader HttpHeaders headers
    );

    @PostMapping(path = "/update", consumes = "application/json;charset=utf-8", produces = "application/json;charset=utf-8")
    Result<GridFeedbackDTO> updateGridFeedback(
            @RequestBody UpdateGridFeedbackDTO command,
            @RequestHeader HttpHeaders headers
    );

}

And usage of the client is here:

@Service
public class GfbServiceImpl implements IGfbService {

    private final GridFeedbackFeignClient gridFeedbackFeignClient;

    public GfbServiceImpl(GridFeedbackFeignClient gridFeedbackFeignClient) {
        this.gridFeedbackFeignClient = gridFeedbackFeignClient;
    }

    @Override
    public PageResult<List<GridFeedbackDTO>> getAllByUser(Integer page, Integer pageSize, String token) {
        HttpHeaders headers = new HttpHeaders();
        headers.setBearerAuth(token);

        Result<PageResult<List<GridFeedbackDTO>>> result = gridFeedbackFeignClient.getAllByUser(page, pageSize, headers);

        if (!result.isSuccess()) {
            throw new ResultException("can not get GFB by user", ResultCode.getByValue(result.getCode()));
        }

        return result.getData();
    }

    @Override
    public GridFeedbackDTO updateGridFeedback(UpdateGridFeedbackDTO command, String token) {
        HttpHeaders headers = new HttpHeaders();
        headers.setBearerAuth(token);

        Result<GridFeedbackDTO> result = gridFeedbackFeignClient.updateGridFeedback(command, headers);

        if (!result.isSuccess()) {
            throw new ResultException("can not get GFB by user", ResultCode.getByValue(result.getCode()));
        }

        return result.getData();
    }
}

As Spring Cloud Openfeign has a check of http:// and https:// protocol, the url of dapr feign client must be start with http:// or https://, as there is no need to specify TLS for Dapr RPC, I'd like to use http:// protocol for that (in fact, it's just a meaningless placeholder, so never mind that problem).

I defined the protocol like http://method.<appId>/<methodName> for invokeMethod and http://binding.<bindingName>/<operation> for invokeBinding , please check https://dapr-spring.fangkehou.icu/en/feign/getting-started.html#about-feign-dapr-client for more details.

It can also be used like https://docs.spring.io/spring-cloud-openfeign/docs/current/reference/html/#creating-feign-clients-manually , just replace the client to DaprInvokeFeignClient.

Note that the path parameters like ?a=a&b=b not work, as dapr grpc will urlencode it, don't know if it's my problem for that.

To get Dapr Invoke works with Spring Cloud Openfeign, we would create a Targeter (a interface in Spring Cloud Openfeign) to handle @UseDaprClient annoation, and use @Bean @Primary or @Bean to cover the default Targeter defined in Spring Cloud Openfeign as it defined with @Bean @ConditionOnMissingBean, but I think it may not be suitable for a library (especially for a official library) to have a bean that replace a bean from other libraries, so I wonder your opinion.