Discussion middleware session

1 Introduction
2 Problem Statement
3 Key designs solutions
4 Limitations with existing approach
5 Solution
- 5.1 Architecture Diagram
- 5.2 Redis Pub/Sub:
- 5.3 Redis Stream:
- 5.4 Discussion Middleware complete session object
6 Different ways of trigger notification service:
- 6.1 Type1:
- 6.2 Type2:
  - 6.2.1 Examples :
7 Clarification needed

Introduction

This document describes the design of discussion middleware session.

https://project-sunbird.atlassian.net/browse/SB-22319

Problem Statement

Storing the required information of nodebb and make it available whenever we required.

Key designs solutions

Identifying required info for nodebb.
Store that info in DMW cache.

Limitations with existing approach

Entire DMW depends on portal session. If any issue occur in portal session then discussion forum also

should affect. By considering this we are implementing cache in DMW itself.

Solution

Initially we stored some of discussion middleware data in portal session. due to this approach our DMW

depends on portal session. So to make DMW independent we are implementing cache with in DMW.

Architecture Diagram

Current architecture diagram Link

Proposed Changes:

Redis:

To pass data from DMW to new notification service, We planned to use Kafka but in the same way we can use Redis Stream/Redis PubSub also.

Redis Pub/Sub:

In DMW we can publish an event and that event can be listened by Notification service and vice versa.

Redis Stream:

We need to create a redis stream in DMW and add the data into the stream. On other side

notification service will receive the data from the stream.

What data we are storing in DMW cache?

We are storing two main objects in DMW cache.

Keys	Data

Keys

Data

User

{"userId": { "uid": "2" }, "userSlug":"content_creator_tn3941","userName": "content_creator_tn3941" }

Context

[{ "sbIdentifier": "c4320769-13cd-43a9-bc73",

"sbType": "group", "cid": "150". }]

We are storing the DMW cache data in Redis Database.

Discussion Middleware complete session object

Schema

Key	Type	Key	Schema

Key

Type

Key

Schema

context

Object

cid

{
"sbIdentifier": String
"sbType": String
"cid": String
}

user

Object

sbUserIdentifier

{
"uid": String
"userSlug": String
"userName":String

“sbUserIdentifier“: String
}

How to access user information from DMW cache.

We can access the user data from cache using sbUserIdentifier as a key. and it will retune the

below data.

{
"uid": "2" ,
"userSlug":"content_creator_tn3941",
"userName": "content_creator_tn3941",
"sbUserIdentifier": "dfer23-dsds332-33drt-td899w"
}

2. How to access context information from DMW cache.

We can access the context data from cache using cid as a key. and it will retune the

below data.

{ 
"sbIdentifier": "c4320769-13cd-43a9-bc73",
"sbType": "group",
"cid": "150"
}

Different ways of trigger notification service:

Type1:

If the parent service have actual notification data along with action data, then we have to send the below formate. And flink job will take this object and process it.

{
  service: "discussion-forum",     // Service Name
  headers: {                       //request tracebility
    sid:  "X-Session-id"           // from headers
    traceID: "X-Request-id"        // from headers
  },
  notifcationData: {               // Actual Notification request payload
    ids: ["sunbird-user-identifiers"], // sunbird identifiers (To which user need to send notification)
    createdBy: {                   // Which User is doing the action
        id: "sunbird-user-identifier",
        name: "sunbird-username",
        type: "User"
    }
    action: {
      category: "discussion-forum" // Service name
      type: "",                    //action type
      template: {
         type: "JSON",
         params: {                 // Based on params notification service will form the notification message
           param1: "",
           param2: "",
           param3: "",
        }
      }
    }
    additionalInfo: {                  // specific to the service & common for all API's of the service. Flink job will parse the object & construct specific to Notfi API
        context: {                     // this is mainly used to know on what context this notification was created.
            cid: "",                   // category id
            sbItendifier: "",          // sunbird Group/Course/Batch identifiers
            sbType: ""                 // type is Group/Course/Batch ... etc
        },
        // based on resp derive the below fields
        category: {
            cid: "",                  // caregory (Under which category this notification created)
            title: "",                // category title
            pid: ""                   // what is parent category id for cid
        }  // Flink job has to call API;s to get names of these below (cid, tid, pid etc)
        topic: {
            tid: "",                    // topic ID
            title: ""                   // Topic title
        }
        post: {
            pid: "",                    // Post id
            title: ""                   // Post tile
        }
    }
}

Example:

Publish topic in kafka with the above data.
Flink job will trigger and receive the kafka topic data(Notification Objcet).
With notification object, Flink job will trigger notification service.

Type2:

Upstream service will use type2 structure, when they do not have information on template . Flink Job will process the data and generate notification api structure and then trigger the notification service. Flink job may call apis or information should be given on the additionalInfo.

Schema Request:

Examples :

Step 1: Group service will push the event in the below format

Group Activity Added Notification Used Case:

Step 2: Flink job will receive the data from Kafka and group processor job will take the based on the value at service field.
Step 3: Processor job create the necessary template for the group operation action.type and create a notification api request object and call notification service api for processing.

Clarification needed

When DMW cache expired but user tried to do some actions then need to show one message. Also need message string : @Manimegalai Mohan .