Welcome, we will be talking about RESTful web services and HTTP protocol.
In the terminal you can go ahead and clone down the repository.
git clone https://github.com/siucacm/WorkshopFourUse ls to list the files in the current directory.
Use cd directory_name to change your directory.
What's coming up?
GET http://api.icndb.com/jokes/randomThe joke outputted is due to many factors. One of which is Representational state transfer.
REST stands for Representational State Transfer. It is an architectural style to be used for creating web services. With a RESTful web service, you can exchange information with a computer system on the internet.
REST was designed by Roy Fielding in his PhD dissertation. He designed it with the following architectural style constraints:
- Client-Server architectural style
- Stateless
- Cacheable
- Layered system
- Uniform interface
- Code on demand (optional)
HTTP stands for Hypertext Transfer Protocol, it is the base of all data communication for internet. We will be using it to help communicate with RESTful services.
HTTP has many request methods to define the action that will be performed. Four of them are the most important. Important methods:
- GET : Request a resource
- HEAD : Request a resource but no body
- PUT/POST : Adding a resource
- DELETE : Delete a resource
There are some arguments between PUT and POST about which one is used for what :)
Each HTTP request comes with a status code, we are going to focus on 2 of them:
- 200 = Okay
- 404 = Not found
Anything in the 400s is client side error Anything in the 500s is server side error
GET http://stackoverflow.com/Now check a summary
HEAD http://stackoverflow.com/Try any random website and see what you get.
Websites are good use of the HTTP protocol, but an application program interface (API) is way more useful.
API : Set of protocols,tools for building software. Java API (Sounds familiar?)
//The below uses javas api
System.out.println("Hello World");Fetch resources using HTTP
Type in browser: http://quotes.rest/qod.json?category=inspire
Keep on fully refreshing the page. After a while, you will get what is called a rate limit. This prevents people for misusing restful services.
Lets have a look at the API docs here theysaidso.com
GET https://api.ipify.org?format=jsonYou just made GET requests to ipify's API requesting a resource. You may have noticed all of this objects we get are wrapped in braces etc
JavaScript Object Notation is a data-interchange format. Its like a dictionary for those familiar with python. Learn more at JSON.org
To get an understanding on how REST works, we will be looking into the Chuck Norris Joke RESTful API. We can take a look at the API here: https://api.chucknorris.io/.
Let's do the first command listed on the site:
GET https://api.chucknorris.io/jokes/randomWe see that a JSON object is outputted.
The below html script gets a joke from the chuck norris api:
<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
</head>
<body>
<button type="submit" onclick="getchucknorrisjoke()" >Chuck Norris Joke</button>
<p id="joke"></p>
<script>
function getchucknorrisjoke(){
var getJoke = $.ajax({
type: 'GET',
url: 'https://api.chucknorris.io/jokes/random?category=food',
dataType: 'json',
timeout: '3000'
});
getJoke.done(function(response){
$('#joke').html(response.value)
});
}
</script>
</body>
</html>GET http://api.wordnik.com/v4/words.json/wordOfTheDay
Sometimes, you need an API KEY to make requests
Never leave your API KEY hanging about in a publically accessible domain. Its dangerous :)
Instead,export it as an environment variable or throw it in a config file.
export KEY="secretkey"
echo $KEYSometimes, it can be hard to read a gigantic response like here:
GET http://api.wordnik.com/v4/words.jsonWe have some tools for that
#Python ships with a tool to pretty print json object
#The line is a pipe which pipes output of command 1 to input of command 2
GET http://api.wordnik.com/v4/words.json | python -m json.toolNotice how its still a large object. Good guy UNIX ships with some tools that can be handy:
#Go through file slowly
GET http://api.wordnik.com/v4/words.json | python -m json.tool | less
#head and tail are your friendsLets POST some data! Firebase (Backend as a service) allows us to have a database which can be modified through HTTP.
GET https://rest-1663a.firebaseio.com/.json | python -m json.tool
###POST https://rest-1663a.firebaseio.com/.json
### Now enter your object as {"NAME":"LANGUAGE PROFICIENT IN}
### Press CTRL D and give it a couple of seconds.
### Something should pop up in your screen
GET https://rest-1663a.firebaseio.com/.json
#You should see your data
You can modify authentication to change options on who can get and post data.
A small practical use
java -jar APIGetReq.jar
#Type in http://api.forismatic.com/api/1.0/?method=getQuote&format=json&lang=en
Want to learn more? Have a look at the source code and tweak it to display any json object.
Here is a list of a bunch of public apis you can use in your projects