Assignment 4: Backend Design & Implementation (alpha)
Data modeling
Abstract data model
concept Authentication
purpose
provide authentication
principle
after registration, returns the object associated with provided credentials if they're right
state
registered: set User
username, password: registered -> one String
actions
register(name, pwd: String, out u: User)
authenticate(name, pwd: String, out u: User)concept Authentication
purpose
provide authentication
principle
after registration, returns the object associated with provided credentials if they're right
state
registered: set User
username, password: registered -> one String
actions
register(name, pwd: String, out u: User)
authenticate(name, pwd: String, out u: User)concept Session[User]
purpose
provide authentication for extended period
principle
after a session starts (and before it ends), authentication won't be needed again, until the session is ended.
state
// if a session goes inactive, it's removed from
// the relation
user: Session -> one User
actions
start(u: User, out s: Session)
getUser(s: Session, out u: User)
end(s: Session)concept Session[User]
purpose
provide authentication for extended period
principle
after a session starts (and before it ends), authentication won't be needed again, until the session is ended.
state
// if a session goes inactive, it's removed from
// the relation
user: Session -> one User
actions
start(u: User, out s: Session)
getUser(s: Session, out u: User)
end(s: Session)concept Tag[Item]
purpose
provide systematic classification
principle
after associating tags to objects, when given a set of tags, returns a set of objects that have those tags associated (has to include all of them)
state
tags: set Tag
tagging: tags -> many Item
actions
setTagToItem(tag: Tag, item: Item)
deleteTagFromItem(tag: Tag, item: Item)
allWithTag(tag: set Tag, out u: set Item)concept Tag[Item]
purpose
provide systematic classification
principle
after associating tags to objects, when given a set of tags, returns a set of objects that have those tags associated (has to include all of them)
state
tags: set Tag
tagging: tags -> many Item
actions
setTagToItem(tag: Tag, item: Item)
deleteTagFromItem(tag: Tag, item: Item)
allWithTag(tag: set Tag, out u: set Item)concept TextToImage[Post]
purpose
create images that convey the tone of a text
principle
for every post, there'll be a thumbnail, a visual representation of the tone in the text.
state
thumbnails: set Thumbnail
assignments: thumbnails -> many Post
actions
generateImage(post: Post, out u: Thumbnail)
deleteThumbnail(post: Post)concept TextToImage[Post]
purpose
create images that convey the tone of a text
principle
for every post, there'll be a thumbnail, a visual representation of the tone in the text.
state
thumbnails: set Thumbnail
assignments: thumbnails -> many Post
actions
generateImage(post: Post, out u: Thumbnail)
deleteThumbnail(post: Post)concept Feed[Item, User]
purpose
bring together content from multiple sources into a single, centralized location
principle
add objects to a feed, that can be retrieved when lookup (sorted differently according to whom it belongs)
state
items: set Item
feeds: set items
assignments: feeds -> many User
actions
createFeed(user: User, out u: Feed)
addToFeed(item: Item, user: User, out u: Feed)
removeFromFeed(item: Item, user: User)
lookupFeed(user: User, out u: Feed)concept Feed[Item, User]
purpose
bring together content from multiple sources into a single, centralized location
principle
add objects to a feed, that can be retrieved when lookup (sorted differently according to whom it belongs)
state
items: set Item
feeds: set items
assignments: feeds -> many User
actions
createFeed(user: User, out u: Feed)
addToFeed(item: Item, user: User, out u: Feed)
removeFromFeed(item: Item, user: User)
lookupFeed(user: User, out u: Feed)concept Post[User]
purpose
allow users to contribute to the community
principle
after creating content, it is made into an object that allows removing and editing
state
posts: set Post
author: posts -> User
content: posts -> String
actions
addPost(text: String, out u: Post)
removePost(post: Post)
editPost(newText: String, out u: Post)concept Post[User]
purpose
allow users to contribute to the community
principle
after creating content, it is made into an object that allows removing and editing
state
posts: set Post
author: posts -> User
content: posts -> String
actions
addPost(text: String, out u: Post)
removePost(post: Post)
editPost(newText: String, out u: Post)concept Highlight[Post]
purpose
set apart important items among a set of items
principle
after adding or removing objects and their dates, given a date, returns a summary of the most important objects related to that date
state
dateToPosts: Date -> many Post
highlights: Date -> Highlight
actions
addPost(date: Date, post: Post)
removePost(date: Date, post: Post)
getHighlights(date: Date, out u: Highlight)concept Highlight[Post]
purpose
set apart important items among a set of items
principle
after adding or removing objects and their dates, given a date, returns a summary of the most important objects related to that date
state
dateToPosts: Date -> many Post
highlights: Date -> Highlight
actions
addPost(date: Date, post: Post)
removePost(date: Date, post: Post)
getHighlights(date: Date, out u: Highlight)app ADDapp
include Authentication
include Session
include Post
include Feed[Post.Post]
include TextToImage[Post.Post]
include Tag[Post.Post]
include Highlight[Post.Post]app ADDapp
include Authentication
include Session
include Post
include Feed[Post.Post]
include TextToImage[Post.Post]
include Tag[Post.Post]
include Highlight[Post.Post]Diagram
