In order to ensure the arrival rate of information request messages, the WeChat server will send the same request message (RequestMessage) multiple times if it does not receive the response message (ResponseMessage) in time. All text content including MsgId, etc. are consistent.

This mechanism ensures the success rate of message reply in situations such as poor network conditions. However, sometimes due to server load and the request process itself taking several seconds to complete, multiple repeated messages Instead, it becomes a burden on the server and may even affect business and data.

In response to this situation, the SDK has added a deduplication setting. You only need to add a sentence when using MessageHandler:

messageHandler.OmitRepeatedMessage = true;//啟用消息去重功能

/// <summary>
 /// 最簡化的處理流程（不加密）
 /// </summary>
 [HttpPost]
 [ActionName("MiniPost")]
 public ActionResult MiniPost(string signature, string timestamp, string nonce, string echostr)
 {
     if (!CheckSignature.Check(signature, timestamp, nonce, Token))
     {
         return new WeixinResult("參數(shù)錯誤！");//v0.8+
     }
 
     var messageHandler = new CustomMessageHandler(Request.InputStream, null, 10);
 
     messageHandler.OmitRepeatedMessage = true;//啟用消息去重功能
 
     messageHandler.Execute();//執(zhí)行微信處理過程
 
     return new FixWeixinBugWeixinResult(messageHandler);
 }

The principle of deduplication is through the context of the current user. Determine whether the MsgId of the current request message and the previous request message are consistent. If they are consistent, the downward execution will be terminated.

File: Senparc.Weixin.MessageHandlers.MessageHandler.cs

public virtual void OnExecuting()
{
    if (OmitRepeatedMessage && CurrentMessageContext.RequestMessages.Count > 1)
    {
        var lastMessage = CurrentMessageContext.RequestMessages[CurrentMessageContext.RequestMessages.Count - 2];
        if (lastMessage.MsgId != 0 && lastMessage.MsgId == RequestMessage.MsgId)
        {
            CancelExcute = true;//重復(fù)消息，取消執(zhí)行
        }
    }
}

For more WeChat public platform development: Request message deduplication related articles, please pay attention to PHP Chinese net!