joystream/testnets/rome/specification/runtime/forum-module.md

Forum Module

Table Of Contents

• Design
• Dependencies
• Name
• Concepts
• State
• Events
• Dispatchable Methods
  • create_category
  • update_category
  • create_thread
  • moderate_thread
  • add_post
  • edit_post_text
  • moderate_post
  • set_forum_sudo
• Non-dispatchable Methods

Design

Motivation

This module holds the basic content and structure of a hierarchical topic based forum with trivial sudo moderation. It allows a blockchain to have direct assertible custody of the forum governance and function. Systems which depend critical on reliable and fair asynchronous public discourse will benefit from this functionality.

Structure

The structure of the forum is a collection of category trees. A category tree has of two types of nodes, a category or a thread. A category node represents a topic category, with a name and associated intended scope of discussion topics. A thread node represents an actual thread of one or more posts.

Posts and threads

A thread is a sequence of posts, in a given category, which has some initial post from the original author, and title. A post exists in the context of a thread, and has some position in thread post sequence, as well as a body text. Both have a corresponding author and creation date. The text in a post can be edited by any time by the original author, however the history of all texts are available in the state.

Users

Forum users can create threads in categories, and post to existing threads. This module does not maintain its own set of forum users, but rather depends on some external module for this. The rationale for this is to allow reuse of the module with a diversity of user management systems, without requiring that runtime developer must keep user set synchronised, or waste state space.

Forum sudo

There will be a single account, called the forum sudo account. This account is set by the Sudo of the runtime, and can

• Create a category: Can either be a new root category, or if parent category is referenced, it would be a subcategory.

• Archive|Delete (Unarchive|Undelete) a category: Results in category being marked as archived or deleted, while it and all corresponding threads, posts and subcategories remain in the state. It is however no longer possible to delete or mutate anything in the category in any way, such as adding posts, creating threads or subcategories, etc. Well-behaved UIs will not render deleted categories. In what follows a category is said to be directly archived or deleted, if its applying directly to that category, and indirectly if it applies to some ancestor category. The only distinction between archiving and deletion in the runtime is that a directly deleted category cannot be unarchived.

• Moderate a post in a thread: Results in post being marked as moderated, with a corresponding rationale for the moderation added, but it remains in the system state. It is not longer possible to edit the post text, and well-behaved UIs will not render such posts.

• Moderate a thread: Results in thread being marked as moderated, with a corresponding rationale for the moderation added, but it remains in the system state. It is not longer possible to moderate posts, edit post texts or add posts to the thread. Well-behaved UIs will not render such threads.

Limits

There is a maximum depth to a category tree. This is because doing any mutation will require traversing the category tree to the root to check for whether there has been any deletion or archiving along the path to the root, and there needs to be a bound on this, herein called MAX_CATEGORY_DEPTH.

Name

Forum

Dependencies

• ForumUserRegistry: An external module which holds actual user state, allowing it to be queried based on a corresponding account, and recovering some representation of a user.

Concepts

• ForumUser: Represents an actual forum user, which is provided by ForumUserRegistry dependency.

• ForumSudoId: Identifies a forum sudo authority.

• ModerationAction: Represents a moderation outcome applied to a post or a thread. Includes a moderation date, a text rationale and the ForumSudoId of moderator.

• Post: Represents a thread post, and includes initial text, identifier for the corresponding Thread, a position, an optional ModerationAction, a vector of identifiers for PostTextEdit instances ordered chronologically by edit time, creation date and identifier of ForumUser creator. Is identified with an integer which is unique across all instances in all categories.

• PostTextEdit: Represents a revision of the text of a Post, includes new text and revision date.

• Thread: Represents a thread, and includes a title, identifier for the corresponding Category, a position, an optional ModerationAction, number of unmoderated posts, number of moderated posts, creation date and identifier of ForumUser creator. Is identified with an integer which is unique across all instances in all categories.

• Category: Represents a forum category, and includes a title, short topic description text, creation date, deletion status, archival status, number of subcategories, number of unmoderated threads, number of moderated threads, optional Category identifier for parent category and ForumSudoId of creator. Is identified with an integer which is unique across all instances in all categories.

State

• categoryById: Map Category identifier to corresponding instance.

• nextCategoryId: Identifier value to be used for the next Category created.

• threadById: Map Thread identifier to corresponding instance.

• nextThreadId: Identifier value to be used for next Thread in threadById

• postById: Map Post identifier to corresponding instance.

• nextPostId: Identifier value to be used for for next Post created.

• forumSudo: Optional ForumSudoId of forum sudo.

Events

Each event has payload as sublist

• CategoryCreated: A category was introduced

  • category identifier

• CategoryUpdated: A category had its direct archival and/or deletion status updated to a new value.

  • category identifier
  • whether deletion status was changed, if so to what
  • whether archival status was changed, if so to what

• ThreadCreated: A thread was created with.

  • thread identifier

• ThreadModerated: A thread was moderated.

  • thread identifier

• PostAdded: A post was introduced.

  • post identifier

• PostModerated: A post was moderated.

  • post identifier

• PostTextUpdated: A post had the post text edited.

  • post identifier
  • edit number of new text

• ForumSudoSet: A new forum sudo was set by root.

  • optional account for old forum sudo
  • optional account of new forum sudo

Dispatchable Methods

create_category

Payload

• origin: call origin
• parent: not set, or category identifier of parent
• title: text title
• description: description text

Description

Add a new category.

Errors

• Bad signature
• forumSudo does not match signature
• parent is set, but does not exist
• parent is set, but is (directly or indirectly) archived or deleted category
• category depth exceeded, see MAX_CATEGORY_DEPTH.
• title invalid
• description invalid

Side effect(s)

• categoryById extended with new Category under old value of nextCategoryId as identifier
• nextCategoryId incremented
• if parent is not root, then subcategory count

Event(s)

• CategoryCreated

update_category

Payload

• origin: call origin
• categoryId: id of category to update
• archive: whether to archive
• deleted: whether it is deleted

Description

Update a category.

Errors

• Bad signature
• forumSudo does not match signature
• categoryId does not match any category
• category with categoryId is directly deleted, cannot be unarchived
• category with categoryId is indirectly archived or deleted, cannot be updated in any way

Note: We don't mind directly archived/deleted categories from being re-archived/deleted respectively, we just ignore

Side effect(s)

• category in categoryById under key categoryId has archival and deletion status equal to archive and delete, respectively, and if parent is set, then it will have number of subcategories decremented if delete is true, but category was perviously not.

Event(s)

• CategoryUpdated with new status values, as they apply

create_thread

Payload

• origin: call origin
• categoryId: identifier of category where thread should be created
• title: thread title text
• text: text of initial post

Description

Create new thread in category.

Errors

• Bad signature
• Signer is not forum user
• categoryId not a valid category
• categoryId is (directly or indirectly) archived
• categoryId is (directly or indirectly) deleted
• title not valid
• text not valid

Side effect(s)

• threadById extended with new Thread instance under old value of nextThreadId as identifier
• increment unmoderated thread count of category with identifier categoryId
• nextThreadId incremented

Event(s)

• ThreadCreated

moderate_thread

Payload

• origin: call origin
• threadId: identifier of Thread to delete
• rationale: text rationale

Description

Moderate thread.

Errors

• Bad signature
• forumSudo does not match signature
• threadId does not match any thread
• rationale invalid
• thread already moderated
• thread in (directly or indirectly) archived category
• thread in (directly or indirectly) deleted category

Side effect(s)

• corresponding Thread instance in threadById has ModerationAction set
• update moderated and unmoderated thread count of corresponding category

Event(s)

• ThreadModerated

add_post

Payload

• origin: call origin
• threadId: thread in which to add post
• text: text of post

Description

Adding post to thread

Errors

• Bad signature
• Signer is not forum user
• thread with identifier value threadId does not exist
• thread with identifier value threadId is moderated
• category of thread is (directly or indirectly) archived
• category is (directly or indirectly) deleted

Side effect(s)

• postById extended with new Post instance with under old value of nextPostId as identifier
• nextPostId updated
• unmoderated posts updated in corresponding thread

Event(s)

• PostAdded

edit_post_text

Payload

• origin: call origin
• postId: post to be edited
• new_text: new text

Description

Edit post text

Errors

• Bad signature
• postId does not correspond to a post
• Signer does not match creator of post with identifier postId
• post with identifier postId is moderated
• category is (directly or indirectly) archived
• category is (directly or indirectly) deleted

Side effect(s)

• Post with identifier postId has its edit vector with new PostTextEdit instance at front

Event(s)

• PostTextUpdated

moderate_post

Payload

• origin: call origin
• postId: post to be edited
• rationale: text rationale

Description

Moderate post

Errors

• Bad signature
• forumSudo does not match signature
• postId does not match any post
• rationale invalid
• post already moderated
• thread already moderated
• thread in (directly or indirectly) archived category
• thread in (directly or indirectly) deleted category

Side effect(s)

• corresponding Post instance in postById has ModerationAction set
• update moderated and unmoderated post count of corresponding thread

Event(s)

• PostModerated

set_forum_sudo

Note: I am not sure how to do this one, I am not familiar with Substrate Sudo functionality.

Payload

• newForumSudo: optional account of new proposed forum sudo

Description

Set forum sudo.

Errors

• Bad signature
• Not root origin

Side effect(s)

• forumSudo equals newForumSudo

Event(s)

• ForumSudoSet