NETCORE combined with cap event bus to realize distributed transaction - message (2)

One 、CAP Custom configuration in

Configure detailed address

1. DefaultGroupName

 The default value is ：cap.queue.{
     Assembly name }

2. TopicNamePrefix

 by  Topic  Add prefix uniformly . https://github.com/dotnetcore/CAP/pull/780

3. Version

 The default value is ：v1

 This is CAP v2.4  New configuration items introduced in version , It is used to specify the version of the message to isolate the messages of different version services , Commonly used in A/B Test or multi service version scenarios 

4. FailedRetryInterval

 The default value is ：60  second 

 When the message is sent , If sending fails ,CAP The message will be retried , This configuration item is used to configure the interval between retries 

5. SucceedMessageExpiredAfter

 The default value is ：24*3600  second （1 Days later ）

 Expiration time of the success message （ second ）.  When the message is sent or consumed successfully , At time  SucceedMessageExpiredAfter  Seconds from  Persistent  Delete in , You can set the expiration time by specifying this value .

Two 、 Compensation Affairs

In some cases , The consumer needs to return a value to tell the publisher the execution result , So that the publisher can implement some actions , Usually this is within the scope of compensation .
You can notify the upstream by republishing a new message in the code executed by the consumer ,CAP Provides a simple way to do this . You can specify when sending callbackName To get the implementation results of consumers , Usually this only applies to point-to-point consumption

1. Release

1. Publisher , The published routing key is angel news
2. Subscribers who receive the release , Process the message
3. Return processing results
4. Publisher , Call the callback function to
5. Release the news , The routing key is ,image
6. subscriber image, Receive release , Process the message

  _capBus.Publish("angel", contentObj: new Person {
     Id = 1, Name = "11" },callbackName:"image");

[NonAction]
        [CapSubscribe("angel")]

        public Person ReceiveMsg(Person str)
        {
    
            if(str!=null)
            {
    
                Console.WriteLine($" receive {
      str.Id}");
                _log.LogInformation($" I'm a subscriber , The content received is ：{
      str.Id},{
      str.Name}");
                // The result of processing , Return back 
                return str;
            }
            throw new Exception();
        }

 [NonAction]
        [CapSubscribe("image")]
        public void CallBackMsg(Person str)
        {
    
        
            if(str!=null)
            {
    
                Console.WriteLine($" Callback {
      str.Id}");
                _log.LogInformation($" I'm a callback , The contents of the callback are ：{
      str.Id},{
      str.Name}");
            }
            
        }