Lists out differences between protocols

[compulim]

(request from @krishna0209)

Feature Request

As we start planning to support different protocols, we should consider their differences and how Web Chat could adapt:

• File upload
  • We only support uploading a single file at a time
  • We don't support text message piggybacked to the file upload activity
  • Since Direct Line do not report attachment sizes, we use channel data to keep attachment sizes. This is an optional feature
  • Some services may support asynchorous file scanning for uploaded files, so the UI can block download before the scanning complete
• Server timestamp
  • All outgoing activities are server-timestamped, so we can maintain a correct order of transcript
• Outgoing activities acknowledgements
  • All outgoing activities are ACK after they are received/being processed by the bot. This is equivalent "read receipt" (email) or "double blue ticks" (WhatsApp)
• Channel data (per-activity in-band storage)
  • We keep a client activity ID in channel data for "read receipt"
• Heartbeat
  • User idle or typing indicator
  • Browser is active
• Notification of app switching
  • Connection is frozen, no incoming or outgoing is expected
  • Connection is killed and should reconnect on next opportunity
  • Push notification for frozen connection
• Queueing up of messages that failed to send
  • Is the protocol queuing up the failed messages?
  • How to retry? Is it by resending the whole activity?
• Connectivity
  • Is the connection already established before sending to Web Chat?
  • Who is responsible to call the connect() function
• Retry
  • On retry, should the protocol send a new bubble or just retrying the existing one?
    • Retrying existing one: the UI can color the bubble when they are successfully sent
• User ID and conversation ID
  • Today, some parts of Web Chat requires knowledge of user ID
  • Can we remove that part from Web Chat?
• Adapter should have a way to send extra information to customization component of Web Chat
  • For example, sending a customized avatar image from adapter to Web Chat
• Update activity
  • Activity with same ID will be replaced, including timestamp
  • Timestamp change will affect the order of message and is by design
• Acknowledging activities
  • Currently, the acknowledgement is used for pausing scroll, e.g. the developer set "pause scroll after 3 activities"
  • If the protocol supports conversation history, we might want to tell the adapter we have acknowledged up to which activities

Added from #2506:

• Disconnects (online/offline)
• Update/Edit messages

[Enhancement]

[corinagum]

Related to file upload: #628

[corinagum]

re-adding the customer tags since this is coming directly from a customer.