airport-distance

Airport distance calculator

Introduction

It's a simple example for calculating airport distances.

All examples are tested on Linux bash (Ubuntu 16.04, x86_64). Examples may work on Windows in Cygwin shells, for example:

Cygwin shell
Git bash
MobaXterm local shell

Restrictions

We need to be able to review your code in a short time frame.

TODO:

Spit the source code to several directories (cmd, util, common, api, etc.) and files
More strict and robust error handling (semantical check)

Please use only a Cloudant client library and standard libraries.

TODO:

Using github.com/golang/glog for better logging
Using github.com/spf13/{pflag,cobra,viper} for better parameter handling
Using github.com/stretchr/testify for making unit tests
Using github.com/moogar0880/problems for providing RFC7807-compliant error messages
More strict and robust error handling
Airports (...) sorted by distance within a user provided radius of a user provided lat/long point.

TODO:

Review ordering rule if distances are equal (different names at same lat/lon position)

Cloudant client library

There is no official Go library at https://cloud.ibm.com/docs/services/Cloudant/libraries?topic=cloudant-supported-client-libraries#su and https://cloud.ibm.com/docs/services/Cloudant?topic=cloudant-third-party-client-libraries.

Finally, IBM-Cloud/go-cloudant was selected with a small extending part.

TODO:

Checking if client libraries support proxy
Solving and upstream increasing max. 200 Cloudant record limitation (paging with bookmarks)

Unofficial libraries:

IBM-Cloud/go-cloudant

https://github.com/IBM-Cloud/go-cloudant is a simple wrapper to https://github.com/timjacobi/go-couchdb, builds _design/view1/_search/geo path postfix.

Does not support non-authentication (password is needed), see:

main_test.go:TestCloudant_IBM_Bluemix_go_cloudant()
https://github.com/IBM-Cloud/go-cloudant/blob/master/cloudant.go#L213

Last commit: Oct 13, 2016

TODO:

Improve and upstream own extension, see cloudant.go, Extension to cloudant.DesignDocument

timjacobi/go-couchdb

https://github.com/timjacobi/go-couchdb supports non-authenticated connection. Does not build _design/view1/_search/geo path postfix.

Last commit: Aug 17, 2016

cloudant-labs/go-cloudant

https://github.com/cloudant-labs/go-cloudant does not build _design/view1/_search/geo path postfix. Skipped.

Last commit: Jun 20, 2018

TODO:

Improve and upstream

obieq/go-cloudant

https://github.com/obieq/go-cloudant/ supports partly building _design/view1/_search/geo path postfix (design part, search part not). Skipped.

Last commit: Sep 29, 2014

Building

Prerequisites:

Go 1.11 or above (tested with go1.11.5 and go1.12.7 linux/amd64)
Go modules environment (supported by Go 1.11 and above, see: GO111MODULE env variable)
(Optional) Golint from github.com/golang/lint
(Optional) Access to https://mikerhodes.cloudant.com for running tests

Source code can be download by below command:

git clone https://github.com/pgillich/airport-distance.git

Golint for optional static code checking can be installed by below command:

GO111MODULE=off go get -u golang.org/x/lint/golint

Running optional go test needs access to https://mikerhodes.cloudant.com/airportdb/_design/view1

Building executable binary

Below command builds executable binary:

go build -mod=readonly

Optional: Below commands execute several checks:

go vet -mod=readonly
golint -min_confidence=.3
go test -mod readonly -v

Building Docker image

Docker image build makes go build automatically. Example for building Docker image:

docker build -t pgillich/airport-distance .

Running

All possible CLI parameters are documented in the built-in help, for example:

./airport-distance --help

Running from CLI

Example for starting one operation:

./airport-distance -centerLon 3 -centerLat 2 -radius 500000

Coordinates are set in degree, radius in meter.

Running as a REST service

Example for starting as a service:

./airport-distance -service

Exampe URL for getting an airport list:

http://localhost:8080/list/distance?centerLon=1&centerLat=1&radius=400000

Running in a Docker container

docker run -it --rm -p 8080:8080 --name airport-distance pgillich/airport-distance

Exampe URL for getting an airport is same to above.

Output format

The output/response is always JSON, if all CLI parameters can be parsed:

request: the actual user parameters
errors: a list of error messages, if any
airports: a list of selected airports, sorted by distance (and name, if distance is same)

Distance is provided in meters.

Example for a response:

{
  "request": {
    "Radius": 500000,
    "Center": {
      "Lat": 2,
      "Lon": 3
    }
  },
  "errors": [],
  "airports": [
    {
      "id": "f6d336d85815d9ebc82fa5009fd73b03",
      "name": "Savut",
      "lat": 1,
      "lon": 1,
      "distance": 248568.719240913
    },
    {
      "id": "aa915feea5ecf2f87d0c7bca67cd6f4f",
      "name": "Xakan",
      "lat": 1,
      "lon": 1,
      "distance": 248568.719240913
    },
    {
      "id": "efb9627917c711e4e6852dfb7708172f",
      "name": "Xakan",
      "lat": 1,
      "lon": 1,
      "distance": 248568.719240913
    },
    {
      "id": "f6d336d85815d9ebc82fa5009fd7488e",
      "name": "Xugan",
      "lat": 1,
      "lon": 1,
      "distance": 248568.719240913
    },
    {
      "id": "aa915feea5ecf2f87d0c7bca6777b4f6",
      "name": "Les Ailerons",
      "lat": 0,
      "lon": 0,
      "distance": 400862.6244736863
    },
    {
      "id": "f6d336d85815d9ebc82fa5009fd12f34",
      "name": "Mainz Finthen",
      "lat": 0,
      "lon": 0,
      "distance": 400862.6244736863
    },
    {
      "id": "f6d336d85815d9ebc82fa5009fc56d04",
      "name": "Vilamendhoo",
      "lat": 0,
      "lon": 0,
      "distance": 400862.6244736863
    },
    {
      "id": "f6d336d85815d9ebc82fa5009f4b7181",
      "name": "Sao Tome Intl",
      "lat": 0.378175,
      "lon": 6.712153,
      "distance": 450353.71383098216
    },
(...)

Example for a failed response:

{
  "request": {
    "Radius": 500000,
    "Center": {
      "Lat": 1,
      "Lon": 1
    }
  },
  "errors": [
    "cannot access Cloudant DB: 404 Not Found; {\"error\":\"not_found\",\"reason\":\"BAD_INDEX not found.\"}\n"
  ],
  "airports": []
}

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