Assignment 3

Naman Singla/Assignment 3/demo.py

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+import os
+from flask import Flask, request, jsonify, make_response
+
+app = Flask(__name__)
+
+tokens = []
+user_data = {}
+
+help_info = '''
+<pre>
+This application has following endpoints:
+/           -->   Returns information about different endpoints
+/get_token  -->   A GET request at this endpoint return a token. Return format:
+                  {
+                      "token" : "<generated token value>"
+                  }
+/register   -->   A POST request at this endpoint saves user data. The request data should be in following format:
+                  {
+                      "username" : "<username of the user being registered>",
+                      "data" : "<data to be saved>",
+                      "token" : "<token value generated earlier>"
+                  }
+                  This endpoint does not return any data on successful completion.
+/get_data   -->   A POST request at this endpoint return user data corresponding to a token. The request format is:
+                  {
+                      "token" : "<token value>"
+                  }
+                  On successful completion, the return data is in following format:
+                  {
+                      "username" : "<username of the registered user>"
+                      "data" : "<data of the user>"
+                  }
+
+On succcessful completion, the response code is set to be 200.
+For /register and /get_data endpoints, if there is some error(i.e. response code is not 200) then the format of return data is:
+                   {
+                       "error" : "<error description>"
+                   }
+</pre>
+'''
+
+def add_header(inp):
+    resp = make_response(inp)
+    resp.headers['Access-Control-Allow-Origin'] = "*"
+    return resp
+
+@app.route("/")
+def index():
+    return add_header(help_info), 200
+
+@app.route("/get_token", methods = ['GET'])
+def generate_token():
+    global tokens
+    token = os.urandom(8).hex()
+    tokens.append(token)
+    return add_header(jsonify(token = token)), 200
+
+@app.route("/register", methods = ['POST', 'OPTIONS'])
+def save_data():
+    global user_data
+    if request.method == 'OPTIONS':
+        resp = make_response()
+        resp.headers['Access-Control-Allow-Origin'] = "*"
+        resp.headers['Access-Control-Allow-Methods'] = "POST, OPTIONS"
+        resp.headers['Access-Control-Allow-Headers'] = "*"
+        return resp, 204
+
+    if request.content_type != 'application/json':
+        return add_header(jsonify(error = "json format required")), 400
+    json_data = request.json
+    if "token" not in json_data:
+        return add_header(jsonify(error = "token value missing")), 400
+    if "username" not in json_data:
+        return add_header(jsonify(error = "username field missing")), 400
+    if "data" not in json_data:
+        return add_header(jsonify(error = "data field missing")), 400
+    if not json_data["token"] in tokens:
+        return add_header(jsonify(error = "invalid token value")), 404
+    if json_data["token"] in user_data.keys():
+        return add_header(jsonify(error = "a user already registered for this token value")), 400
+    user_data[json_data["token"]] = {"username" : json_data["username"], "data" : json_data["data"]}
+    return add_header("User added successfully"), 200
+
+@app.route("/get_data", methods = ['POST', 'OPTIONS'])
+def send_data():
+    if request.method == 'OPTIONS':
+        resp = make_response()
+        resp.headers['Access-Control-Allow-Origin'] = "*"
+        resp.headers['Access-Control-Allow-Methods'] = "POST, OPTIONS"
+        resp.headers['Access-Control-Allow-Headers'] = "*"
+        return resp, 204
+
+    if request.content_type != 'application/json':
+        return add_header(jsonify(error = "json format required")), 400
+    json_data = request.json
+    if "token" not in json_data:
+        return add_header(jsonify(error = "token value missing")), 400
+    if not json_data["token"] in tokens:
+        return add_header(jsonify(error = "invalid token")), 404
+    if not json_data["token"] in user_data.keys():
+        return add_header(jsonify(error = "no user registered with this token")), 404
+    return add_header(jsonify(**user_data[json_data["token"]])), 200
+
+if __name__ == "__main__":
+    app.run(debug = True, port = 12345)

Naman Singla/Assignment 3/index.html

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+<html>
+    <head>
+        <title>Server</title>
+        <style>
+            table, th, td {
+            border: 1px solid black;
+            }
+        </style>
+    </head>
+    <body>
+        <table style="margin: auto;margin-top: 30vh; transform: scale(2,2);">
+            <tr>
+                <th>Register</th>
+                <th>Login</th>
+            </tr>
+            <tr>
+                <td style="text-align: center;"><input id="get_token" type="button" value="Get Token"></td>
+                <td style="border: 0px;"><input id="token2" type="text" placeholder="Input Token"></td>
+            </tr>
+            <tr>
+                <td><input id="username" type="text" placeholder="Username"><br>
+                    <input id="data" type="text" placeholder="Data"><br>
+                    <input id="token1" type="text" placeholder="Token">
+                </td>
+                <td>
+                    <input type="text" placeholder="Username" id="user2" readonly style="margin-bottom: 10px;"><br>
+                    <input type="text" placeholder="Data" id="dat2" readonly>
+                </td>
+            </tr>
+            <tr>
+                <td style="text-align: center;"><input id="register" type="button" value="Register"></td>
+                <td style="text-align: center;"><input id="get_data" type="button" value="Get Data"></td>
+            </tr>
+        </table>
+    </body>
+    <script type="text/javascript" src="script.js"></script>
+</html>

Naman Singla/Assignment 3/script.js

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+function getToken(){
+    var xhttp = new XMLHttpRequest();
+    xhttp.onreadystatechange = function() {
+        if (this.readyState == 4 && this.status == 200) {
+            document.getElementById("token1").value=JSON.parse(xhttp.responseText).token;
+            alert("Your Token is : "+JSON.parse(xhttp.responseText).token);
+        }
+    };
+    xhttp.open("GET","http://localhost:12345/get_token",true);
+    xhttp.send();
+}
+function Register(){
+    var xhttp = new XMLHttpRequest();
+
+    xhttp.onreadystatechange = function() {
+        //alert(xhttp.responseText);
+        if (this.readyState == 4) {
+            if(this.status==200){
+                alert(xhttp.responseText);
+            }else{
+                alert("Sorry, an error occured :\n"+JSON.parse(xhttp.responseText).error);
+            }
+        }
+    };
+    var obj = new Object();
+    obj.username=String(document.getElementById("username").value);
+    obj.data=String(document.getElementById("data").value);
+    obj.token=String(document.getElementById("token1").value);
+    xhttp.open("POST","http://localhost:12345/register",true);
+    xhttp.setRequestHeader("Content-Type","application/json");
+    xhttp.send(JSON.stringify(obj));
+}
+function GetData(){
+    document.getElementById("user2").value="";
+    document.getElementById("dat2").value="";
+    var xhttp = new XMLHttpRequest();
+    xhttp.onreadystatechange = function() {
+        if (this.readyState == 4) {
+            var res = JSON.parse(xhttp.responseText);
+            if(res.error)alert(res.error);
+            if(this.status=200){
+
+                document.getElementById("user2").value=res.username;
+                document.getElementById("dat2").value=res.data;
+            }
+        }
+
+    };
+    xhttp.open("POST","http://localhost:12345/get_data",true);
+    xhttp.setRequestHeader("Content-Type","application/json");
+    var tok=new Object();
+    tok.token=document.getElementById("token2").value;
+    xhttp.send(JSON.stringify(tok));
+
+}
+document.getElementById("get_token").addEventListener("click", getToken);
+document.getElementById("register").addEventListener("click", Register);
+document.getElementById("get_data").addEventListener("click", GetData);