RESTful API

In this blog post I am going to show how to create a resource server api. First we need to understand how it works.

If you want you can use existing authorization server like wso2 identity server. But I created authorization server and resource server both in a single api. There is an endpoint that you can call in order to retrieve the resources.
This is written using node.js. In order to run this on your computer you have to have node.js installed on your comouter.

The sample code is uploaded to the Github and the link is mentioned below.
https://github.com/sajith01prasad/RESTful-API.git 

app.js

As you can see oauth grant type I have given is client_credentials. This has to be mentioned in the request body when you try to get the access token from authorization server.
Also this app tuns on port 4000. You can give any port number here.
There are two endpoints I have created in this. One to get the access token which is "/oauth/token" and the other one is to get resources which is "/profile".
As resources I have hardcoded one value which is name ("sajith") and this comes as a JSON object.


model.js

Here I have created a user first (username = test, password = test) and all the functions that handle requests from client are written in this file.


Run

Now Let's run this resource server using node.js.

To make all get and post requests to the resource server we use RESTclient Mozilla Firefox Add on. You can use other similar products such as Postman for this.

First of all We have to make a POST request to get the access token from the authorization server.
For that we have to send the authorization key in the header.

Authorization : Bearer XXXXXXXXXXXXXXX
And also we have to mention the content type in the header.
Content-Type :  application/x-www-form-urlencoded

If you are using restClient on firefox like I discuss in this blog post you will have to go through the Oauth_data_collection.json file I have provided and type the Authorization Bearer token value manually. In order to find the correct token value you can map it with Content-Type which is application/x-www-form-urlencoded. 
If you do not want to do this manually you can simply import the json file to Advanced rest client extension in Chrome store. A screenshot is provided below.

 Click on Open From File. Then browse the json file and upload it it.
Once you upload it you will see something like this.

Requests are added to the favorites. Click on the first POST request.

Everything you need to send through the request is automatically added to the request. All you have to do is click on send button.


I will show how to do the same thing with RestClient on Mozilla Firefox with creating all the requests manually and of course how to retrieve resources.



Then we have to mention these 3 parameters in the body.
username=test
password=test
grant_type=client_credentials

The URL should be the endpoint that gives us the access token.

http://localhost:4000/oauth/token

When we send this we get the response which has access token in it. This access token also have an expiration time.

Then we have to make a GET request to retrieve the resources we need.

Now our URL is different because we have to call a different endpoint to get these resources which is "http://localhost:4000/profile".
We do not have to mention anything in the body.
In the request header we should send the access token we got in the previous step.

Authization: Bearer XXXXXXXXXXXXXXX

Make sure that the access token is not expired. Otherwise you will get an error message saying that it has expired.

When you sent this request you get a response that contains the resources we specified in the code.
{"name":"sajith","id":"set"} 


Thank you :)