Sequence diagrams for backend

Sequence diagrams

Buy and sell routes

@startuml
actor client as C
participant server as S
database Database  as DB

C->S: /api/trading/{buy,sell} of stock S at price P
group if market currently open
 
S->S: get cur_price of S & current portfolio balance
group if (sufficient funds / stocks) && (cur_price ACCEPTABLE (w.r.t P))
 S->DB: start TXN
 S->DB: update client portfolio
 S->DB: insert new trade & end TXN
 DB-->S: OK
 S-->C: return updated portfolio
 else otherwise
 S-->C: failed
end
else otherwise
S-->C: failed - market closed
end
@enduml

User Authentication

@startuml
actor client as C
participant server as S
database Database as DB

group if user not logged in
C->S: POST /auth/register Register for new user

group if username / email does not already exist
S->S: Hash password using bcrypt.hash
S->DB: Store username / email / hashed_password into DB
DB->S: OK
S->S: Login a uer / Get Cookies for session

else otherwise
S->C: Return Error message
end


C->S: POST /auth/login Login a user
group if username / password combination is correct
S->S: Login a user / Get Cookies for session

else otherwise
S->C: Return Error message
end
else otherwise

C->S: POST /auth/logout Logout a user
S->S: Logout a user / Remove Cookies for session
end
@enduml