diff --git a/src/repository.ts b/src/repository.ts
new file mode 100644
index 0000000..8cc3210
--- /dev/null
+++ b/src/repository.ts
@@ -0,0 +1,86 @@
+// If types match closely, we can use TypeScript "casting"
+// to convert from data repo to GraphQL schema
+
+export interface ISystem {
+  id: string;
+  name: string;
+}
+
+export interface ICoordinates {
+  latitude: number;
+  longitude: number;
+}
+
+export interface IRoute {
+  id: string;
+  name: string;
+  color: string;
+  polylineCoordinates: ICoordinates[];
+  systemId: string;
+}
+
+export interface IStop {
+  id: string;
+  name: string;
+  systemId: string;
+  coordinates: ICoordinates;
+}
+
+export interface IShuttle {
+  coordinates: ICoordinates;
+  id: string;
+  name: string;
+  routeId: string;
+  systemId: string;
+}
+
+export interface IEta {
+  secondsRemaining: number;
+  shuttleId: string;
+  stopId: string;
+}
+
+export interface IOrderedStop {
+  nextStopId: string;
+  previousStopId: string;
+  routeId: string;
+  stopId: string;
+}
+
+/**
+ * Repository interface for data derived from Passio API.
+ * The repository is not designed to have write locks in place.
+ */
+export interface Repository {
+  // Getter methods
+
+  getSystems(): Promise<ISystem[]>;
+  getSystemById(systemId: string): Promise<ISystem>;
+
+  getStopsBySystemId(systemId: string): Promise<IStop[]>;
+  getStopById(stopId: string): Promise<IStop[]>;
+
+  getRoutesBySystemId(systemId: string): Promise<IRoute[]>;
+  getRouteById(routeId: string): Promise<IRoute>;
+
+  getShuttlesBySystemId(systemId: string): Promise<IShuttle[]>;
+  getShuttleById(shuttleId: string): Promise<IShuttle[]>;
+
+  getEtasForShuttleId(shuttleId: string): Promise<IEta[]>;
+  getEtasForStopId(stopId: string): Promise<IEta[]>;
+  getEtaForShuttleAndStopId(shuttleId: string, stopId: string): Promise<IEta[]>;
+
+  getOrderedStopByRouteAndStopId(routeId: string, stopId: string): Promise<IOrderedStop[]>;
+  getOrderedStopsByStopId(stopId: string): Promise<IOrderedStop[]>;
+  getOrderedStopsByRouteId(routeId: string): Promise<IOrderedStop[]>;
+  getNextOrderedStopFromOrderedStopId(stopId: string): Promise<IOrderedStop | null>;
+  getPreviousOrderedStopFromOrderedStopId(stopId: string): Promise<IOrderedStop | null>;
+
+  // Setter methods
+  addOrUpdateSystem(system: ISystem): Promise<void>;
+  addOrUpdateRoute(route: IRoute): Promise<void>;
+  addOrUpdateShuttle(shuttle: IShuttle): Promise<void>;
+  addOrUpdateStop(stop: IStop): Promise<void>;
+  addOrUpdateOrderedStop(orderedStop: IStop): Promise<void>;
+  addOrUpdateEta(eta: IEta): Promise<void>;
+}
\ No newline at end of file