Azure APIM Policy - 何时使用<backend> </backend>

Question

https://learn.microsoft.com/en-us/azure/api-management/api-management-howto-policies

    <policies>
  <inbound>
    <!-- statements to be applied to the request go here -->
  </inbound>
  <backend>
    <!-- statements to be applied before the request is forwarded to 
         the backend service go here -->
  </backend>
  <outbound>
    <!-- statements to be applied to the response go here -->
  </outbound>
  <on-error>
    <!-- statements to be applied if there is an error condition go here -->
  </on-error>
</policies> 

何时在策略中使用后端部分？

看起来设置后端 url 也仅在<inbound>节点上完成。

谢谢你的时间。

Answer 1

该部分用于在将请求转发到后端之前对请求进行任何转换\检查，例如，我正在向请求添加标头并验证oauth令牌。