/node-microservice-react

Primary LanguageJavaScript

Node Microservice

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Micro Services

  1. Posts
  2. Comments
  3. Query Service
  4. Event Bus

TO DO

Comment Moderation

- Comment Service  
	- On create comment emit event   CreateComment with comment info to Event bus
- Event Bus 
	- Publish event to all subscriber
- Moderate Comment Service 
	- Receive CreateComment event
	- Update comment 
	- Emit CommentModerated with updated status to comment to Event bus
- Event Bus 
	- Publish event to all subscriber
- Comment Service  
	- Receive CommentModerated event 
	- Update comment with status
	- Emit CommentUpdated to Event bus
- Event Bus 
		- Publish event to all subscriber
- Query Service
	- Receive CommentUpdated event
	- Update comment

Key Notes

  1. Handling one-to-many relation in microservice For example fetch posts with their all comment
    1. Approach #1 Sync Communication Send all list of post ids to comment service and map comment response to related post and send back to client.
      1. Pros
        1. Easy to understand
      2. Cons
        1. Introduces a dependency between services
        2. if any inter-service request fails, the overall requests fails
        3. The entire request is only as fast as the slowest request
        4. Can easily introduce webs of requests
    2. Approach #2 - Async Communication through Event Bus Introduce Event Bus and Query Service

      1. Event Bus

        1. Listen for post and comment creation
        2. Emit event for both

      2. Query Service

        1. Listen for post and comment creation
        2. Keep in required data structure and update

      3. Pros

        1. Query service has zero dependency on other service
        2. Fast to retrieve data

      4. Cons

        1. Data duplication
        2. Hard to understand