GoPal is a simple set of REST apis built on http://golang.org used to validate
sets of words, numbers or phrases as palindromes.
- Palindromes
- Requirements
- Sequence diagrams
- Development
- Building and running
- Testing
- JSON Schema
- Endpoints
- Licence
Palindromes are word, phrases, numbers, or other sequence of characters which reads the same backward as forward ([https://en.wikipedia.org/wiki/Palindrome]).
racecar
Was it a cat I saw?
Dammit I'm Mad
Observe that phrase palindromes ignore punctuation, spaces and capital letters. In other languages where characters have variations due to accent notation, those characters are also converted to their primitive form in order to be considered as a palindrome.
DÁBALE ARROZ A LA ZORRA EL ABAD
SOCORRAM-ME, SUBI NO ÔNIBUS EM MARROCOS
Photenic languages like Japanese require special analisis to be considered as a palindrome. It's required to use their phonetic notation to evaluate them. In order words, ideograms representation (kanji) must be converted to phonetic format (hiragana) before.
竹藪焼けた => たけやぶやけた
私負けましたわ => わたしまけましたわ
Thanks to utf-8 representation, characteres in different languages can be expressed in a single and common encoding, 8-bit based. However, it also introduced new problems. For example, "é" can be either represented as a single character \u00e9 or the combination of e and \u0301. Or the ⁹ and the regular digit 9. Or yet, 'K' ("\u004B") and 'K' (Kelvin sign "\u212A").
Although Go is able to handle character collation quite well using on unnormalized strings, evaluating palindromes in different languages require normalizing the string. To achieve we, I decided using the text/transform and text/unicode/norm packages.
| English | Spanish / Portuguese | Japanese |
|---|---|---|
| racecar | DÁBALE ARROZ A LA ZORRA EL ABAD | たけやぶやけた |
| Go hang a salami, I'm a lasagna hog | ROMA ME TEM AMOR | わたしまけましたわ |
| Rats live on no evil star | SOCORRAM-ME, SUBI NO ÔNIBUS EM MARROCOS | なるとをとるな |
| Live on time, emit no evil | しなもんぱんもれもんぱんもなし | |
| Mr. Owl ate my metal worm | よのなかほかほかなのよ | |
| Was it a cat I saw? | たしかにかした | |
| Dammit I'm Mad |
go1.4+MongoDBcurlor any REST client (I recommend [https://advancedrestclient.com/](Advanced REST Client) )
Add palindrome
List all palindrome
Get palindrome
Delete palindrome
I strongly recommend using a Docker container for development. It may simplify a lot the
development process. I created a Dockerfile.dev I used for development. You can build it doing
the following:
$ docker build --rm --squash -t gopal:dev -f Dockerfile.dev .
There are two things you need to consider to run this application. gopal runs under port 80 and
this image is already exposing it. However, you need to map it to your host. You may also want to
mount the source code into the running container so you can still develop locally. You may do both
things with this command:
$ docker run --rm -p 80:80 -v /gopal/source:/go/src -it gopal:dev
The container entrypoint is a bash instance under /go path. The source is mounted under ./src
and the host machine is listening to port 80. There's a chance your host may already have a web
server running and you may have problems with that. If it's your case, change the mapping port to
something else like this -p 8080:80.
MongoDb isn't running either. So, make sure you have it up every time you run the container
$ /etc/init.d/mongodb start
Also, the first time you run gopal you have to get its dependencies satisfied. Inside the running
container, make sure you execute go-wrapper download to install the dependencies.
- HTTPRouter: lightweight router in
go - MGO: Mongo driver for
go - Transform and Norm: Normalization unicode characters
- Cors: Handles CORS requests
golang has a run command. It's essentially an alias to go build that executes the binary
file and then gets rid of it at the end of the execution. I don't recommend doing using run
as you avoid having to manually specify every file you need to run. gopal as it's a pretty lightweight and simple application that can be built in seconds.
$ go build -o gopal && ./gopal
Use the usual go test to run application tests. If everything is fine you should get a result
like this:
$ go test
PASS
ok _/go/src 0.046s
{
"$schema": "http://json-schema.org/schema#",
"title": "Palindrome",
"type": "object",
"required": ["ID", "phrase", "valid"],
"properties": {
"ID": {
"type": "string",
"description": "Unique identified"
},
"phrase": {
"type": "string",
"description": "Name of the product"
},
"valid": {
"type": "boolean",
"description": "Wether it's a valid palindrome or not"
}
}
}
The JSON Schema above can be used to test the validity of the JSON code below:
{
"ID": "58eedfb5b7fc13821176df2c",
"phrase": "Live on time, emit no evil",
"valid": true
}
List all palindromes entered
Usage:
curl http://localhost:8080/palindrome
Result:
[
{
"ID": "58eedfb5b7fc13821176df2c",
"phrase": "racecar",
"valid": true
}
]
Alternative responses:
null: In case there're no records
Add a new palindrome phrase to be validated.
Usage:
curl -H "Content-Type: application/json" \
-X POST -d '{"phrase": "racecar"}' \
-i http://localhost:8080/palindrome
Result:
HTTP/1.1 201 Created
Date: Thu, 13 Apr 2017 02:30:47 GMT
Content-Length: 0
Content-Type: text/plain; charset=utf-8
Alternative responses:
HTTP/1.1 400 Bad Request: A malformed JSON object was providedHTTP/1.1 208 Already Reported: When the palindrome was already providedHTTP/1.1 500 Internal Server Error: The database server must be down
Display details about a specific palindrome
Usage:
curl -i http://localhost:8080/palindrome/58eee2d7b7fc13821176df2d
Result:
{
"ID": "58eee2d7b7fc13821176df2d",
"phrase": "Live on time, emit no evil",
"valid": true
}
Alternative responses:
HTTP/1.1 412 Precondition Failed: The ID provided isn't a valid hex valueHTTP/1.1 404 Not Found: There's not palindrome for the ID specifiedHTTP/1.1 500 Internal Server Error: The database must be down.
Deletes a given palindrome from its id
Usage:
curl -X DELETE -i http://localhost:8080/palindrome/58eee2d7b7fc13821176df2d
Result:
HTTP/1.1 202 Accepted
Date: Thu, 13 Apr 2017 02:35:25 GMT
Content-Length: 0
Content-Type: text/plain; charset=utf-8
Alternative responses:
HTTP/1.1 412 Precondition Failed: The ID provided isn't a valid hex valueHTTP/1.1 404 Not Found: There's not palindrome for the ID specifiedHTTP/1.1 500 Internal Server Error: The database must be down.
This project is licensed unter Apache License 2.0. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0