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There are two situations when WeChat users interact with public accounts: one is when WeChat users send ordinary messages to public accounts; the other is when some operations of WeChat users cause the WeChat server to notify the URL filled in by the developer through event push. This article introduces the processing of public accounts receiving ordinary messages.

The following passage is excerpted from WeChat official development documentation:

1. Regarding retrying message deduplication, it is recommended to use msgid deduplication.
2. If the WeChat server does not receive a response within five seconds, it will disconnect and re-initiate the request, retrying a total of three times. If the server cannot guarantee processing and replying within five seconds, it can directly reply with an empty string. The WeChat server will not do anything about it and will not retry. For details, please see "Send Message-Passive Reply Message".
3. In order to ensure higher security, developers can set up message encryption in the Developer Center of the official website of the public platform. After encryption is turned on, messages sent by users will be encrypted, and messages that the public account passively replies to users also need to be encrypted (but developers sending messages to users through API calls such as customer service interfaces will not be affected). For detailed instructions on message encryption and decryption, please see "Message Encryption and Decryption Instructions" .

Ordinary messages are divided into seven categories: text messages, picture messages, voice messages, video messages, short video messages, location messages and link messages.

When a WeChat user sends a message to a public account, the WeChat server will identify the type of message and send the corresponding message XML data to the developer. Taking a text message as an example, its format is as follows:

<xml>
 <ToUserName><![CDATA[toUser]]></ToUserName>
 <FromUserName><![CDATA[fromUser]]></FromUserName>
 <CreateTime>1348831860</CreateTime>
 <MsgType><![CDATA[text]]></MsgType>
 <Content><![CDATA[Content]]></Content>
 <MsgId>1234567890123456</MsgId>
</xml>

The meaning of each field is as follows

ToUserNameDeveloper WeChat
IDFromUserNameSender      account (an OpenID)
CreateTimeMessage    creation time (integer) MsgTypeMessage
typeContentText         message contentMsgIdMessage
id     , 64-bit integer

After the WeChat server sends the XML data to the developer, the developer determines the type of the message based on the MsgType field. The values ​​of MsgType for different messages are as follows:

Text message text
picture message image
voice message voice
video message video
short video message short video
location message location
link message link

For the XML data format of each message, the following five fields are available for each message, where the value of MsgType varies according to the message type.

<ToUserName><![CDATA[toUser]]></ToUserName>
<FromUserName><![CDATA[fromUser]]></FromUserName>
 <CreateTime>1348831860</CreateTime>
<MsgType><![CDATA[text/image/voice/video/shortvideo/location/link]]></MsgType>
<MsgId>1234567890123456</MsgId>

Let's look at the different fields.

Text Messages

<Content><![CDATA[Content]]></Content> //Text message content

Picture Message

<PicUrl><![CDATA[this is a url]]></PicUrl> //Picture link
<MediaId><![CDATA[media_id]]></MediaId> //Picture message media id, you can call the multimedia file download interface to pull data.

Voice Message

<MediaId><![CDATA[media_id]]></MediaId> //Voice message media id, you can call the multimedia file download interface to pull data.
<Format><![CDATA[Format]]></Format> //Voice format such as amr, speex, etc.

In addition to the above two fields, voice messages also have another field - voice recognition - which needs to be enabled in the official account before it can be used.

<Recognition><![CDATA[]]></Recognition> //Close voice recognition, the content is empty
// Open
<Recognition><![CDATA[Tencent WeChat Team]]></Recognition> //Open voice recognition, the content is the content of the recognized voice

Video Message

<MediaId><![CDATA[media_id]]></MediaId> //The media id of the video message. You can call the multimedia file download interface to pull data.
<ThumbMediaId><![CDATA[thumb_media_id]]></ThumbMediaId> //The media id of the video message thumbnail. You can call the multimedia file download interface to pull data.

Small video message

<MediaId><![CDATA[media_id]]></MediaId> //The media id of the video message. You can call the multimedia file download interface to pull data.
<ThumbMediaId><![CDATA[thumb_media_id]]></ThumbMediaId> //The media id of the video message thumbnail. You can call the multimedia file download interface to pull data.

Location Message

<Location_X>23.134521</Location_X> //Geographic location latitude
<Location_Y>113.358803</Location_Y> //Geographic location longitude
<Scale>20</Scale> //Map zoom size
<Label><![CDATA[Location information]]></Label> //Geographic location information

Link Message

<Title><![CDATA[Ji Yi Blog]]></Title> //Message title
<Description><![CDATA[Ji Yi Blog - A professional technical blog]]></Description> //Message content
<Url><![CDATA[http://www.onmpw.com]]></Url> //Message link

The formats of the various messages are those we showed above.

Next, let's take a look at how developers receive these messages.

function responseMsg()
{
         //get post data, May be due to the different environments
         $postStr = $GLOBALS["HTTP_RAW_POST_DATA"];
         file_put_contents("/tmp/wx.txt", $postStr); //Write the message content to the file for our own observation
    //extract post data
         if (!empty($postStr)){
        //Write the message processing code here
                   libxml_disable_entity_loader(true);
        $postObj = simplexml_load_string($postStr, 'SimpleXMLElement', LIBXML_NOCDATA);
        $fromUsername = $postObj->FromUserName;
        $toUsername = $postObj->ToUserName;
                  $msgType = $postObj->MsgType;
                   //Write different processing according to different message types
                     
    }else {
       echo "";
       exit;
    }  
}
responseMsg() //Calling this function is equivalent to opening this interface for WeChat server to call and push messages

The processing of receiving messages on WeChat public accounts is actually very simple. What we are talking about here is the processing of plain text information, as well as the safe mode and compatible mode. We will talk about it later, so here we will introduce so much.