Classification of the systems for public discussion

Domain entities

The following entities are common for every public discussion system:

Content - the target information of the system. Distribution of this information is the primary goal of the system.
User registered in the system and producing content.

Depending on the type of the system, there may be additional domain entities. For example:

Resource - the platform, where the content is published. Resources are identified by an addresses.
Moderator - a special user, which has extended rights.

By the type of subscription:

By the security of the data channels:

data channels provide confidentiality, authenticity and integrity of the content
data channels provide authenticity and integrity of the content, but not confidentiality
data channels provide integrity of the content, but not authenticity or confidentiality
data channels provide neither of confidentiality, authenticity and integrity of the content

By privacy:

personal data is hidden from all other participants
personal data is available only for the owner of the resource and the moderators
personal data is freely available to other participants

By the right to access the content:

open (everyone can became a user of the system and receive any content without any third party permission)
author-moderated (author of the content manages the right to access the content)
owner-moderated (owner of the resource or moderators manage the right to access the content)

By the right to create content:

open (any user can create any content)
author-moderated (in order to create derived content, user must obtain permission from the author of the original content)
owner-moderated (in order to be able to create some content, user must obtain permission from the owner of the resource or from the moderators)

By the right to manage content:

open (any user can manage any content)
author-managed (content is managed by its author)
owner-managed (content is managed by the owner of the resource or the moderators)

By the type of subscription: subscription to the topic of the content
By the security of the data channels: data channels provide authenticity and integrity of the content, but not confidentiality
By privacy: personal data is freely available to other participants
By the right to access the content: open (everyone can became a user of the system and receive any content without any third party permission)
By the right to create content: open (any user can create any content)
By the right to manage content: open (any user can manage any content)

By the type of subscription: subscription to the address of the resource offering the content
By the security of the data channels: data channels provide confidentiality, authenticity and integrity of the content
By privacy: personal data is available only for the owner of the resource and the moderators
By the right to access the content: open (everyone can became a user of the system and receive any content without any third party permission)
By the right to create content: owner-moderated (in order to be able to create some content, user must obtain permission from the owner of the resource or from the moderators)
By the right to manage content: author-managed & owner-managed (content is managed by its author, the owner of the resource or the moderators

By the type of subscription: subscription to the authors of the content
By the security of the data channels: data channels provide confidentiality, authenticity and integrity of the content
By privacy: personal data is available only for the owner of the resource and the moderators
By the right to access the content: author-moderated (author of the content manages the right to access the content)
By the right to create content: author-moderated & owner-moderated
By the right to manage content: author-managed & owner-managed