Available at [http://192.241.249.201]

REST endpoint is at port 8080, for example: [http://192.241.249.201:8080/cabs/1234]

• To place a cab on the road, click 'Add Cabs' and cabs will be placed anywhere on the map you click. Click 'Done' when finished.
• To remove cabs, click on 'Remove Cabs' and click on the markers to remove the cabs. Click 'Done' when finished.
• 'Remove All Cabs' will remove all the cabs in the database.
• Enter radius (in meters) and a limit (defaults 8) and click 'Query' to visualize the circle and the cabs that fall within (will be highlighted in green).
• You can drag the cabs around to update their locations.
• You can drag the red marker, the query circle's center, to anywhere you'd like and then click 'Query' to see what cabs fall within the new circle.

Should you choose to accept it, your challenge is to build an HTTP server that can quickly find the nearest cabs to a particular client location. Utilize python and you can use a web service framework of your choice. Your server must be able to handle the following CRUD operations:

Insert a new record or update the latitude and longitude of a particular cab

Get the full details of the cab

This action does not have any parameters.

Search for nearest cabs. The returned data does not have to be sorted and should be a list of cab records. DIstance should be calculated based on the Haversine formula.

GET /cabs?latitude=37.763658&longitude=-122.427521=&radius=1000&limit=15

[
 {
   "id": 23706134,
   "latitude": 37.788654783559,
   "longitude": -122.50747748978
 },
 {
   "id": 61344818,
   "latitude": 37.778952285851,
   "longitude": -122.43865835511
 },
 {
   "id": 19485186,
   "latitude": 37.778665475753,
   "longitude": -122.39094602609
 },
 ...
]

Destroy a cab

This action does not have any parameters.

Destroy all cab records

This action does not have any parameters.

Beyond these basic API specs, the challenge is left intentionally open-ended. The are no requirements for which coding language, database, or design you must use, but we do expect that you can defend the decisions you make. The best solutions will be those that go beyond something that “just-works” and have thought about the implications of real-world production environment. For example, which endpoints do you think will be used most frequently?

All latitude and longitude coordinate are based on the WGS84 coordinate system (the same one used by GPS enabled devices).

Go is used as the language of implementation because:

• It's statically typed language but fast compilation makes it feels like a scripting language, while allowing the code base to scale gracefully over time.
• Its performance approaches that of C.
• Manages concurrency elegantly thanks to language constructs like go routines and channels.
• Compiles into a single binary executable. No other dependencies! This makes production deployment trivial:
  • No dependencies on runtime libraries that needs to be installed on each VM host
  • Even for a webapp, the static images, css, js files can be compiled into go source code and embedded in the binary.

Steps to build:

• Install Go

• For easier deployment, the files required for a web UI (e.g. .js and .css files, etc.) can be compiled into the executable binary. To do so, a embedfs utility (written by me) is run that will generate .go source files for each one of the static content files:

  util/embedfs -match=".*" -generated=true -destDir=resources webapp/

This will generate .go source files for each file matched under the webapp directory. The go source files will be placed in the resources/webapp directory.

Note that util/embedfs is a binary compiled for MacOSX. For linux, you can build embedfs from source, from my other github project: [https://github.com/qorio/embedfs]

• From the top level directory, build the binary:

  go build main/findcab.go

This will produce the final executable, findcab, in the current directory.

There are unit tests in different packages that can be run to verify functionality. Do

go test -v

Also, the server can be tested using curl:

curl -i -H 'Accept:application/json' -X PUT -d '{"id":1234, "latitude":55.00, "longitude":55.00}' "http://localhost:8080/cabs/1234"

curl -i -X GET "http://localhost:8080/cabs/1234"
HTTP/1.1 200 OK
Content-Type: application/json
Content-Length: 40
Date: Tue, 17 Dec 2013 20:33:22 GMT

{"id":1234,"latitude":55,"longitude":55}


curl -i -X GET "http://localhost:8080/cabs?latitude=55&longitude=55&radius=500"
HTTP/1.1 200 OK
Content-Type: application/json
Content-Length: 42
Date: Tue, 17 Dec 2013 20:36:02 GMT

[{"id":1234,"latitude":55,"longitude":55}]

curl -i -X GET "http://localhost:8080/cabs?latitude=55&longitude=65&radius=500"
HTTP/1.1 200 OK
Content-Type: application/json
Content-Length: 2
Date: Tue, 17 Dec 2013 20:36:39 GMT

[]

curl -i -X DELETE "http://localhost:8080/cabs/1234"
curl -i -X DELETE "http://localhost:8080/cabs"