Modeling

Hiya guys i have an assignment where I have to model a social network application and wanted to ask about identifying my actors for my use case diagrams. I identified students and teachers and made assumptions for an administrator but teachers and students share the same use cases like login and log off also would family friends and acquaintance be actors or just come under users? just a kick to get me thinking in the right direction. I am open to any suggestions for the task below.

Thanks

Description: The purpose of this assignment is to exercise your skills in system and software
modeling and planning. Your task in this exercise will be to develop a system model (object,
functional and dynamic models) of a new social media application. This new social media application
will be used within this master program. There are a lot of requirements, but its key requirements are
organized as follows:
• Relationships: The system should allow students to get registered. The users can engage in
three different types of connections: family, friend and acquaintance. Teachers can get
engaged in this social network as well. The same rules apply for them as well.
• Content-sharing: Users of the system should be able to exchange messages within a system
as well as e-mail to external services. The system should enable the uploading and sharing of
different media types (i.e., pictures, video and audio). Teachers in the system can share the
teaching materials and other learning resources. This can be facilitated also using external
services (such as slideshare.net, youtube.com, picasa.com, vimeo.com, mendeley.com, etc.).
• Grouping: Users are allowed to initiate a closed group of users. The characteristics of the
group are that it is private, the data and content there is only available to its member. Each
group has an administrator that decides about allowing the members. Furthermore she/he
can send invitations to invite members that are already users and those outside the system,
via email.
• Mobility: The social network should have mobility support as well. The mobile client of this
social network should allow users to login, send messages, and upload the content. Creating
groups will not be available over mobile interface.Activities: Within this network, users can
get engaged in different activities, such as polls, creating own wikis, sharing bookmarks etc.
Specifically teachers that are involved in this network have the opportunity to share their
course calendar from Moodle into the group for that particular course.
• External services: The system should allow authentication through external services (i.e.,
users can authenticate via their Facebook accounts). Furthermore, it should provide an API
so users can create their own customizable clients for interacting with this social network.
Furthermore, they should be able to mashup the data within network with other external
services such as Google Maps, Twitter, Facebook etc.