Use cases

Background

Alice is a researcher at a lab and she is in the process of starting a new project. She is trying to recruit people to join her research team to work on her new project. Alice thinks that her friend Bob who is a researcher at a different lab might be interested in joining her team.

Use case A - Alice wants to invite Bob to join her Synapse team.

Workflow

Mockups

Use case B - Alice wants to invalidate the invitation she sent previously.

Workflow

Mockups

Use case C - Bob wants to create a Synapse account and accept Alice's invitation.

Workflow

Mockups

Use case D - Bob wants to sign in to his existing Synapse account and accept Alice's invitation.

Workflow

Mockups

Use case E - Bob wants to create a new Synapse account but doesn't want to accept Alice's invitation yet.

Workflow

Mockups

Flow Diagram

Discussion about the rationale behind some design decisions

We always want to allow Bob to choose the account he joins Alice's team with. This led to the following design decisions:

• In earlier versions of the design, if the email entered by Alice was already associated with an existing Synapse account, a membership invitation to that account would be created instead of sending an email invitation. The current design changes this behavior and instead, the system always sends an email invitation to Bob and the membership invitation to the Synapse account isn't created.
• Even if Bob is already signed in to Synapse in his browser, clicking on the invitation link should always ask Bob to sign in again. This avoids the case where Bob accidentally joins the team with the account with which he is currently signed in.

Bob should not be automatically added to the team after registering a new account / signing in to his account, but instead he should need to manually accept the membership invitation. This separates the process of registering for a Synapse account and joining the team, giving Bob the chance to explore Synapse without committing to join Alice's team.

Proposal

Use cases to support

I propose to support all the use cases except use case B. After multiple discussions about the necessity of use case B, I have come to the conclusion that it's an edge case that would incur significant development cost for little benefit. Supporting it would require our system to keep track of the invitation sent by Alice in some form, which is a requirement that none of the other use cases impose on us.

Models to implement

Related models: AccountSetupInfo, MembershipInvtnSubmission

Services to implement

Related services: POST /principal/available, POST /account, POST /session, POST /membershipInvitation

Example implementation with Synapse web client

As the use cases above, the inviter is Alice and the invitee is Bob.

1. Alice invites Bob to her team by entering his email address.
2. Web client constructs an EmailInvitation using Bob's email address and Alice's team's id, then uses it to send a POST /emailInvitation request to the backend.
3. Backend constructs a signed MembershipInvtnSignedToken with Bob's email address, Alice's team's id, Alice's id and a null inviteeId (because we don't know Bob's account's id yet).
4. Backend serializes the MembershipInvtnSignedToken, embeds it into an invitation link to the web client and sends the link to Bob's email address.
5. Bob clicks on the link and does one of the following:
   1. Registers a new Synapse account. ^[1]
      
      1. Web client checks that Bob's email address is a valid account alias through POST /principal/available.
      2. Web client constructs an AccountSetupInfo ^[2], then uses it to create Bob's account through POST /account and receives a session token.
   2. Signs in to his existing Synapse account.
      1. Web client retrieves a session token through POST /session.
6. Web client deserializes and validates the MembershipInvtnSignedToken in the link, then sets the inviteeId to the id of the account Bob used (extracted from the session token).
7. Web client re-signs the MembershipInvtnSignedToken, then uses it to send a POST /tokenMembershipInvitation request to the backend.
8. Backend validates the MembershipInvtnSignedToken and uses it to create a MembershipInvitation from Alice's team to Bob's account.
9. Web client receives backend's 201 response, then directs Bob to his profile's Team tab, where he has a pending MembershipInvitation to Alice's team
10. Bob accepts Alice's invitation (using the existing MembershipInvitation services).

[1] Note that this process is a bit different from the normal registration workflow because we are avoiding to have to validate Bob's email address. It'd be nonsensical to ask Bob to validate his email address because he reached this state by clicking a link sent to that very email address. Also note that this workflow only allows Bob to register the email address to which the invitation link was sent.

[2] Note that the web client needs to construct a valid emailValidationToken, making up a timestamp in the process.

Alternative implementations