ADR: UI of discussions xblocks after MFE rollout

Background

Forum upgrades will be rolled out in 2 phases (see https://2u-internal.atlassian.net/wiki/spaces/PT/pages/94503105/WIP+Discussions+project+overview):

1. New discussions experience (MFE)

2. In-context discussions

xblocks will not be visible to learners in courses using in-context discussions (see [Milestone Rollout Plan]: v1.7 In-context discussions). However, the rollout of in-context discussions (v1.7) is at least 6-8 weeks away from today (21st July) and running courses will only be migrated to v1.7 when they create a re-run. For self-paced courses, the new run could take 12 to 18 months.

Discussions xblocks have a UI that is independent of discussions tab (see https://2u-internal.atlassian.net/browse/INF-356).

In this document, we need to evaluate the options and pros/cons of the UI (MFE or legacy) we want to render for xblocks, after MFE rollout.

What are the options?

1. Keep rendering the legacy UI in xblocks for the foreseeable future

   1. Pros: No dev time and cost will be spent on a feature that we plan to deprecate eventually (~2 years)

   2. Cons: Content created in MFE and interacted with in legacy, and vice versa, may create some incompatibility. Here one that i’m aware of:

      1. Images uploaded in MFE do not show in legacy

      2. More investigation required

2. Embed sidebar view inside discussion xblock view - sidebar will show inside iframe of xblock

   1. Cons: Will require modifications to sidebar (dev work in range of ~ 60hours)

3. Render xblock discussion topic in sidebar, when show discussion button is clicked.