Entities are all things that exist in the App. Rails calls them "Models". Some of the Entities are "Resources".

Primary

MediaEntry

most important Resource in the App
has 1 MediaFile
- has 1 Preview
has MetaData

Concerns:

MetaData
Permissions

Preview

Every MediaEntry is "previewable" (in the UI) as an image. The image can come from several sources:

either by a compiled preview from the associated MediaFile
- images are compiled locally using imagemagick
- videos are processed with zencoder, a framegrab is used as image
- sounds can be "converted" to waveform image, ala soundcloud (AsAService: auphonic)
or a generic image, possibly representing the mime-type of the MediaFile

A presenter like Presenter::ResourceThumbnail makes the decision which image is used. The MediaEntryController#preview action is only tasked with serving the specific compiled Previews (the generic thumbnail is )

TODO: sizes! (not Previews are not just used for thumbs; how to handle small originals)

Preview of Sets

“Das Preview eines Sets kommt vom ‘Cover’, User-gewählter Entry (aus dem Set) der das Set visuell repräsentiert. Wenn kein ‘Cover' vorhanden ist, nehmen wir aus der Liste der Einträge, die direkt im Set liegen, sortiert nach der (mögl. gespeicherten) Sortierung des Sets, den ersten von dem wir eine visuelle Darstellung haben. Wenn so kein ‘Cover’ gefunden wird, nehmen wir das generische Preview für ein Set.”

MediaFile

[TODO]

Collection

Formerly known as Set.

is a Resource
is a MediaResource
has a list of MediaEntries
belongs to creator=User

FilterSet

A saved filter.

has many MediaEntries, NOT through "normal" Relations, but because they filter matches them!

Concerns:

Permissions

Person

a generic (real-world) Person (German: "Juristische Person")
can be linked to (equal to) a User
can be linked to MetaDatum of type MetaDatumPerson (i.e. "Author")

Relations

User, rails-type: has_one, effectively enforced by unique constraint on index

User

User with account/login

Relations

person, rails-type: belongs_to, null: false

Group

list of Users
is manually defined by a User
not to be confused with InstitutionalGroup

Relations

users: list of Users, rails-type: has_many

Notes

Supertype of InstitutionalGroup, implemented as STI-table

Secondary

InstitutionalGroup

An externally-defined Group, synced with an LDAP-Directory.

has a list of Users ("Members"), which by definition must have User-ID from the same Directory.

Notes

Subtype of Group, implemented as STI in the groups table

Concerns

Entities that have similar relations to several [Resources][]s are called Concerns.

[Relation][]s

https://wiki.zhdk.ch/madek-hilfe/doku.php?id=relationship

"Entrusted Resources"

A Resource is "entrusted" to a User if they have "view" Permissions on the Resource, either directly or via their membership in a Group. Therefore, a Resource with "view" Permissions for "Public" can never be "entrusted" because it is already public.

"Privacy Status"

public: "Public" has "view" Permission
private: No Person or Group has "view" Permission
shared:
- if User is the owner and any Person or Group has "view" Permission
- if User is not the owner and has "view" Permission (directly or via Group membership)

Permissions

Almost like UNIX. Notable Differences:

'owner' is not a 'Class' (it's more like root, for this thing)
there is no 'execute', but 'fullsize'
there is no 'write', but distinct 'edit_data' and 'edit_permissions'

[Responsible][]

for MediaEntry, [MediaSet][], FilterSet, there is always exactly 1 owner
- => responsible_user: User
has super-permission "Delete and Change owner" (Löschen und Verantwortlichkeit übertragen)
implicitly has all the granular permissions listed below (if applicable)

Per-Subject

More granular permissions can be granted on MediaEntrys, [MediaSet][]s and FilterSets, for User, Groups, [APIClient][], as well as "public".

"Public" permissions apply to any request, logged in or not.

Example: When checking if a MediaResource is visible to the User, we'll need to combine (UNION) the permissions of the following subjects: - the Public; and, if the User is logged in (there is a current_user), also - the User itself - all Groups the User is member of - TODO: The implicit Permissions of the [Responsible][] are already handled by the [Permissions][] module (?)

subject/permission	data_and_preview	edit_data	fullsize	edit_permissions
MediaEntry	get metadata and previews	edit metadata	get full size	edit permissions
↳ User	✔	✔	✔	✔
↳ Group	✔	✔	✔	-
↳ [APIClient][]	✔	-	✔	-
↳ "public"	✔	-	✔	-
Beschreibung	betrachten	Metadaten editieren	Original exportieren & in PDF blättern	Zugriffsberechtigungen ändern


[MediaSet][]	get metadata and previews	edit metadata and relations	-	edit permissions
↳ User	✔	✔	-	✔
↳ Group	✔	✔	-	-
↳ [APIClient][]	✔	✔	-	-
↳ "public"	✔	-	-	-
Beschreibung	betrachten	Metadaten editieren & Inhalte hinzufügen	-	Zugriffsberechtigungen ändern


FilterSet	get metadata and previews	edit metadata and filter	-	edit permissions
↳ User	✔	✔	-	✔
↳ Group	✔	-	-	-
↳ [APIClient][]	✔	✔	-	-
↳ "public"	✔	-	-	-
Beschreibung	betrachten	Metadaten editieren & Filtereinstellungen ändern	-	Zugriffsberechtigungen ändern

Copyright

This is a generic description which applies to all countries which have signed and implemented the ??? Copyright Treaty. This is not about trade- and other marks nor about patents.

Every "Creative Work" (encoded by a MediaFile) can have one or more authors in a legal sense

IF the the Work falls into the public domain, none of the following is relevant! There MAY still be authors in an historic/cultural/moral/ sense but as far as copyright law (and this "algorithm") is concerned, the "public" now "owns" all the rights, similar to Air. Conditions for the public domain also differ by country, but generally

all authors are dead for more than 70-90 years
the work has been published for more than 70-90 years
if the author(s) relinquished his rights by declaring the work to be in the public domain and it was created in a country that allows this (for example the USA, but not Germany).

Any of those authors has "the right to copyrights" IF the "creative contribution" was significant

  - which is defined per kind of media…, e.g.
      - Photos always apply if made by human!
      - Fonts not "different" enough from just Alphabet "Letters"
      - Music, Film, etc: "I know it when I see it"

This decision can NOT be made programmatically, we have to rely on the user to correctly tell us the copyrighted status, which can be true or false (when it's in the public domain) or null if unknown.

There are actually several distinct rights the author(s) has by law, the German term "Urheberrechte" is more clear in this sense:

"commercial rights", aka "what the term copy-right means"
- publishing (to the public)
- copying
- distributing copies (to the public)
"moral rights"
- being named as the author
- not having the work destroyed/defaced
- visiting the work (some countries)
- get payed a share if the work is sold for profit (some countries)
several more…

The only two to "transfer the right of executing" any of the "copyright rights" is by LAW or in form of a LICENSE. A License MUST specify

the (list of) WORKs
the list RIGHTS being licensed
to WHOM
WHERE
WHEN
under which CONDITIONS
BOOL: exclusive or not
BOOL: can be sub-licensed

A LAW usually specifies the same properties. While it's not a License in the legal sense, both can be technically handled in the same way: a thing that transfers rights to a work to one more entities, with the above properties.

A LICENSE also has a SOURCE property, which is either

a specific LAW, or
a specific contract between the author(s) and one more third parties
a License "for the public", published with the work (Free Software, CreativeCommons)

Which RIGHTS can be licensed also depends on the country: The commercial right can always be licensed, but many countries restrict licensing of some moral rights ('like being named').

Note: Reading this list it becomes clear that simple copyleft licenses like BSD, MIT or WTFPL define almost the absolute minimum of a valid license.

There is 1 Swiss LAW that is very important in the context of Madek (actually a chain of several laws up to the federal level…): For all Works created at the ZHdK by employees (as part of their work) or students (as part of their studies), the commercial rights are transferred to the ZHdK (this applies to all almost all Universities).

The ZHdK bylaws state about these rights

they can be used by the university in any way
the creator can negotiate terms for own usage by case
conditions of usage for third parties
- e.g. publishing for PR, caption must include "(c) ZHdK, Name of Creator"
"sub-licensed" on a department-level, they can alter conditions
- e.g. caption must include "(c) Department Design ZHdK, Name of Creator"
- a department could also put all students works under CC-BY-NC-SA

TL;DR: There is no Model "Copyright", but a 'copyrighted' attribute on MediaFiles. A Model "License" would be enough to represent all the ways to transfer rights.

For the user, the UI could stay roughly the same but allow more options. There can be some specific hints if we know about the context from Metadata about the File or the User (e.g. Link to the official University explanation about the above situation when the User is a student or employee).

The current schema could be migrated from the MetaData, but would require manual intervention because right now the field 'Copyright' is just a string, and has no consistent usage. It is mostly used like if (copyrighted==true) then creator.name else 'Public Domain', but for the ZHdK-Works mentioned above it is often: if (license.where(source: 'special-zhdk-rules') then 'ZHdK' else creator.name. (Option: leave the old field, but don't allow it to be used for new entries (deprecation))

Special

MediaResource

Either a MediaEntry or a Collection or a FilterSet (polymorphic).

Formerly a "real" Model, now just a convention between Presenters and Decorators (so they only exist in the UI).

A more technical definition: Anything that can be put in a Collection, i.e. every Model for which there is a collection_$something_arcs table.

Abstract

Resource

distinct kind of thing (noun)
not the "R" in "REST", but REST is all about Resources
it's also what "MVC" and "CRUD" are about:
most standardized part of the app
- "resourceful" routes
- "resourceful" model/view/controllers