Churras da Trica

An app to schedule brazilian barbecues. The whole app treats the event as a generic vanue like stocks on the stock market in which peers can buy shares, participate on those ventures, and, in the case of this app, which happens to only support one type of venture; Barbecue Parties.

Software Specification Document

Type Fact Graph¹

graph TD      
      share --> stock; 
      stock --> share-holder;
      share-holder --*--> user;

Caption:

An arrow always points towards the predecessor.
"?" means zero or one predecessor.
"*" means zero or more predecessor.
The entity at the tail of an arrow is always of cardinality "n".
The successor captures the predecessors, therefore, immutable.
The label always refer to the predecessor.

Facts ¹

fact Stock {
      ipoDate: datetime
      description : string
      createdAt: DateTime
      notes: string*     
}

fact Share {
      value: decimal
      owner: ShareHolder
}

fact ShareHolder {
      user: User
}

fact User {
      username: string
      password: SecureString
}

Immutable records of historical events. You cannot update or destroy a Fact, only create new ones To change a system you need to introduce new facts Consists of two elements: fields and predecessors.

When dealing with facts, be aware of:

Each location has it's own facts
Locations exchange facts
Eventual consistency is reach between locations
Decisions are based on local history

Queries ¹

query marketCapitalization (s: Stock) {
      MATCH 
}

query shareHolders (s: Stock) {
      MATCH
}

query sharePrice (s: stock) {
      MATCH
}

How to run

dotnet run

References

Michael L. Perry, ed. (2020) The Art of Immutable Architecture: Theory and Practice of Data Management in Distributed Systems