README.md

Catalog service provides a GraphQL API for searching flights.

Implementation

Catalog is comprised of GraphQL API implemented using AppSync, DynamoDB as a database, and all compute logic runs off Apache Velocity Template (VTL).

GraphQL API

Catalog API provides a custom query to search for flights on a given schedule. It enforces fine-grained authorization to allow for create, update, read and list (CRUD) operations on flights for Admin and back-end systems such as ETL.

Configuration

CRUD operations are auto-generated using Amplify off our API schema.

Operation	Name	Description
query	getFlightBySchedule	Fetches flights directly from Flight DynamoDB table

These auto-generated operations are not currently being used and might change if we implement an Admin view to simulate a travel agency/support center: getFlight, listFlights, createFlight, updateFlight, deleteFlight.

type Flight 
    @model(subscriptions: null)
    @key(name: "ByDepartureSchedule", 
        fields: ["departureAirportCode", "arrivalAirportCode", "departureDate"],
        queryField: "getFlightBySchedule")
{
    id: ID!
    departureDate: String!
    departureAirportCode: String!
    departureAirportName: String!
    departureCity: String!
    departureLocale: String!
    arrivalDate: String!
    arrivalAirportCode: String!
    arrivalAirportName: String!
    arrivalCity: String!
    arrivalLocale: String!
    ticketPrice: Int!
    ticketCurrency: String!
    flightNumber: Int!
    seatAllocation: Int @deprecated(reason: "use seatCapacity instead. seatAllocation will be removed in the stable release.")
    seatCapacity: Int!
}

Integrations

Front-end

Catalog provides a GraphQL Flight data type and a getFlightBySchedule query. Using @key, Flight implements a Global Secondary Index (GS) to fetch flights by airports and departure date using getFlightBySchedule query as opposed to listFlights scan operation.

Decisions log

Decision	Description	Timeframe
Deprecated seatAllocation field	New seatCapacity field better express intent while seatAllocation would need a seat map when reserving a flight. Both fields are no longer required and use @deprecated to demonstrate sunsetting a field.	Shortly after Twitch season (September '19)