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Pair programming #10.md

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  • Length of a list in OCaml:
let rec length lst =
  match lst with
  | [] -> 0
  | el :: rest -> 1 + length rest

is the same with List. length (example in the dashboard)

  • From let hashtbl = Hashtbl.create 256, the 256 is the size of hashtbl

  • we wanted to localize IPs - dbip is a way to do it but it’ll take like 3.7GB and we don’t want that
    • DB-IP is an online geolocation IP database. Users can look up IP addresses to find out locations of the IP addresses, as well as download and access the IP database. The DB-IP API allows developers to access and integrate the functionality of DB-IP with other applications
    • suggestion: get IP -> counties (and hash those). we need to use ocaml mmdb - OCaml bindings to the MaxMind Geo IP database (also known as GeoIP2)
    • downloaded some dependencies to integrate ocaml-mmdb, and also updated Dream so in dune-project & in dream-dashboard.opam, we rewrite (dream (>= 1.0.0~alpha3)) + mmdb, digestif (for ip using)
    • updated Dream so it changed API - meaning that Dream’s API also changed so it broke few things like router -> should be changed to route in middleware
    • the Uri means host and the localhost8080 means no host
    • turned out mmdb is not that suitable since this Dream library to use binding to C library (so don’t need mmdb dependency anymore)
    • added a file called ‘dbip_asset’ but then realized this can’t be streamed because it's too large
    • then created ip_info.ml file to integrate a json file with OCaml = yojson
    • for the ip, we have to first “query” if the info we get is really ip or not — in let query_dbip ip =..
    • the reason why we declare hyper is because it helps us to use HTML with it
    • Reference: How to convert JSON schema into the OCaml/ReasonML type
    • Yojson: JSON library for OCaml. This library parses JSON data into a nested OCaml tree data structure
    • needed to decode yojson -> decided to use ppx_deriving for json => [@@deriving yojson] (generate code for decode)
    • set the queries 1000 per a day
    • bind and match is the same thing but bind is more compact
    • changed ssl to hyper and that makes some clashes, one of which is https should change to http
    • SSL (Secure Sockets Layer): SSL is a secure protocol that works on the top of HTTP to provide security
    • then the query was failing so thought maybe bc of the header so we put user-agent, hyper