[Http Rest Api Help!]

I have a company that needs php tweaking. (My previous programmer couldn't be found anymore)

The client e-mailed me this

"Basically what we need is for you to provide us with an http rest API where we will provide the tracking code and in return you will return to us a JSON object with the status of the delivery

 

As an example:

 

TRACKING CODE: ABCDEFGHIJ

URL:

http://mydomain.com/track.php?code=ABCDEFGHIJ

METHOD: GET

RESPONSE: {"status":2}

 

where 2 is the code for the status shipment which is defined by

 

1 - GOOD

2 - BETTER

3 - BEST"

How and where do I place this? What's "HTTP REST API" and "return to us a JSON object"

 

It's all gibberish to me! Some web guru answer me pls?

 

 

 

Thanks in advance!