Use Case Diagram for Facebook

Let’s begin building Facebook’s use case diagram and understanding its components’ relationship. First, we will define the different elements of our Facebook system, followed by the complete use case diagram of the system.

System

Our system is Facebook.

Actors

Now, we’ll define the main actors of Facebook.

Primary actors

• User: This actor can create a personal profile that includes their information. They can create posts, pages, and groups, and interact with other users by sending friend requests and messages, commenting on posts, and more.

Secondary actors

• Page/Group Admin: The admin is in charge of performing numerous operations, including blocking or unblocking users from groups or pages, deleting an existing group, and changing the group’s privacy.

• System: This is responsible for sending notifications for new friend requests, messages, comments, etc.

Use cases

In this section, we’ll define Facebook’s use cases. We have listed them according to their interactions with a particular actor.

Note: Some use cases will occur multiple times because they are shared among different actors in the system.

User

• Add/update profile: To add information like work, education, and places of visit details, or to update an existing profile

• Follow/unfollow user: To follow or unfollow other users

• Send message: To send a message to other users

• Send friend request: To send a friend request to other users

• Create/like/follow/share page: Create a new page or perform actions including liking, following, or sharing an existing page.

• Create/join/leave group: To either create a new group or perform actions like joining or leaving an existing group

• Invite users to group: Invite other users to an existing group.

• Add/update/delete post: To add a new post, update the content of the post, or delete an existing post

• Like/comment/share post: To like a post, comment on a post, or share a post

• Add/update/delete/like comment: To add a new comment, update the content of the comment, like a particular comment, or delete a comment

• Accept/reject friend request: To accept or reject a friend request from another user

• Update privacy: To update the privacy settings of the profile

• Search users/groups/pages/posts: To search for other users, any existing groups or pages, or any posts made by users

• Accept/Reject friend request: To accept or reject a friend request from another Facebook user

• Accept/Reject group join invitation: To accept or reject a group joining invitation from another Facebook user

• Like/Comment/Share Post: To like, comment, or share any post visible to users on Facebook

Page/Group Admin

• Block/unblock page user: To block or unblock a user from a page

• Block/unblock group user: To block or unblock a user from a group

• Change a group’s privacy: To change the privacy settings of a group (from public to private and vice versa)

System

• Send new friend request notification: To send a notification of any friend request sent by another user

• Send message notification: To send a notification of any new messages

• Send new post notification: To send a notification of any new posts

• Send comment notification: To send a notification of any comments on your or others’ posts

Relationships

This section describes the relationships between and among actors and their use cases.

Generalization

• The “Page/Group Admin” has a generalization relationship with the “User” as the admin can perform all the tasks a normal user can perform.

Associations

The table below shows the association relationship between actors and their use cases.