public boolean checkService(String serviceName, String methodName) {
        Invoker invoker = invokerMap.get(serviceName);
        return invoker instanceof ProviderProxyInvoker && getMethod(serviceName, methodName) != null;
    }
Check service exists

@param serviceName Service Name
@param methodName  Method name
@return if service and method exists, return true.
remoting/remoting-http/src/main/java/com/alipay/sofa/rpc/server/http/HttpServerHandler.java