slidingWindowRedisChatArchitecture

We'll think about the 2 store architecture in the next phase of building the chat app.

Original App JWT:
    Issued by MainServer on user login.
    Broad permissions, long expiry.

Chat Session JWT:
    Generated for every chat group or dm for each user...
    The JWT is generated via a shared secret.
    set default session lifeTime to 7 days for the JWT

The redis chat storage management:
    - The chatsession has a key value for the metadata, which stores the last time the message was entered into the chat session - crucial part of metadata, required to set the TTL
    - The chat session has a messages List, where messages are pushed onto the List with content upto the N most recent messages to avoid eviction.

    On each new message:
        -// push message
        redis.rpush("chat_12345:messages", JSON.stringify(msg));
        // trim to keep only last N (protects against eviction)
        redis.ltrim("chat_12345:messages", -N, -1);
        // reset TTL on both keys to 7 days
        redis.expire("chat_12345:metadata", 7*24*3600);
        redis.expire("chat_12345:messages", 7*24*3600);


All the above would work for dms

But now how do we deal with group chats?
 Refer the MicroService Design Document for the architecture...