Edge's 490 exception is thrown and can be used for business processing

[liuguangrong]

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[codecov-io]

Codecov Report

Merging #2154 (19b5f7f) into master (323d5b7) will decrease coverage by 0.01%.
The diff coverage is 60.00%.

@@             Coverage Diff              @@
##             master    #2154      +/-   ##
============================================
- Coverage     80.76%   80.75%   -0.02%     
  Complexity     1339     1339              
============================================
  Files          1463     1463              
  Lines         40142    40147       +5     
  Branches       3411     3411              
============================================
- Hits          32420    32419       -1     
- Misses         6255     6261       +6     
  Partials       1467     1467              

Impacted Files	Coverage Δ	Complexity Δ
...ansport/rest/client/http/RestClientInvocation.java	93.54% <60.00%> (-1.12%)	0.00 <0.00> (ø)
...pache/servicecomb/config/kie/client/KieClient.java	72.61% <0.00%> (-5.96%)	0.00% <0.00%> (ø%)
.../servicecomb/config/client/ConfigCenterClient.java	52.11% <0.00%> (-0.43%)	0.00% <0.00%> (ø%)
.../servicecomb/registry/discovery/DiscoveryTree.java	100.00% <0.00%> (+3.50%)	0.00% <0.00%> (ø%)

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[liubao68]

Maybe you can add a custom handler to fillful your requirements.

e.g. 'MyHandler implements Handler'

servicecomb.handler.chain.Consumer.defaut: your_current_handlers,myhandler

myhandler can process the exception thrown in RestClientInvocation

[liuguangrong]

https://docs.servicecomb.io/java-chassis/zh_CN/references-handlers/intruduction/

I found it didn't meet my requirements through experiments.

My handler executes before the exception is returned, and does not return to handler after the exception is thrown.

I can't get this exception message.

Is there any other way

[liubao68]

public class MyHandler implements Handler {

  private static final Logger LOGGER = LoggerFactory.getLogger(MyHandler.class);

  @Override
  public void handle(Invocation invocation, AsyncResponse asyncResp) throws Exception {
    LOGGER.info("before");

    invocation.next(response -> {
         LOGGER.info("after");
    });
  }
}

You can find many Handler implementations in servicecomb-java-chassis project.

[Volcannozzz]

I think the handler example given by @liubao68 cannot meet @liuguangrong 's needs. Because the transportHandler is the last handler in the source code.

public class ConsumerHandlerManager extends AbstractHandlerManager {
  @Override
  protected String getName() {
    return "Consumer";
  }

  @Override
  protected String getInnerDefaultChainDef() {
    return "simpleLB";
  }

  @Override
  protected Handler getLastHandler() {
    return TransportClientHandler.INSTANCE;
  }
}

and in AbstractHandlerManager.java

  private List<Handler> createHandlerChain(String chainDef) {
    List<Class<Handler>> chainClasses = convertToChainClass(chainDef);

    List<Handler> handlerList = new ArrayList<>();
    for (Class<Handler> cls : chainClasses) {
      try {
        handlerList.add(cls.newInstance());
      } catch (Exception e) {
        // 在启动阶段直接抛异常出来
        throw new Error(e);
      }
    }
    handlerList.add(getLastHandler());
    return handlerList;
  }

In addition, when the transportHandler calls an exception, it will return the exception information to the caller. Can the exception information be handled by the caller? Hope you provide the calling way and error message stack.

[liubao68]

This handler throw exception , will hanldled in code block after in my example code

[Volcannozzz]

Sorry, maybe we can got the answer from line 86, 125, 544 in RestClientInvocation.java.
so:

  InvokerUtils.reactiveInvoke("pojo", "InvokerEndpoint", "model", args, ClientModel.class, response -> {
    if (response.isFailed()) {
      // do something
    }
  });

Is this okay？
@liubao68 @liuguangrong