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sequenceDiagram
autonumber

participant Client
participant Metadata Server
participant Data Server
Client->>Metadata Server: PollFlightInfo(FlightDescriptor)
Metadata Server->>Client: PollInfo{descriptor: FlightDescriptor', ...}
Client->>Metadata Server: PollFlightInfo(FlightDescriptor')
Metadata Server->>Client: PollInfo{descriptor: FlightDescriptor'', ...}
Client->>Metadata Server: PollFlightInfo(FlightDescriptor'')
Metadata Server->>Client: PollInfo{descriptor: null, info: FlightInfo{endpoints: [FlightEndpoint{ticket: Ticket}, …]}
Note over Client, Data Server: This may be parallelized
Note over Client, Data Server: Some endpoints may be processed while polling
loop for each endpoint in FlightInfo.endpoints
    Client->>Data Server: DoGet(Ticket)
    Data Server->>Client: stream of FlightData
end
