PHP & Web Development Blogs

Today I am going write a blog on how to Monitor Memory and Disk custom metrics and creating alarm in Ubuntu.

To do this, we can use Amazon CloudWatch, which provides a flexible, scalable and reliable solution for monitoring our server.

Amazon Cloud Watch will allow us to collect the custom metrics from our applications that we will monitor to troubleshoot any issues, spot trends, and configure operational performance. CloudWatch functions display alarms, graphs, custom metrics data and including statistics.

Installing the Scripts

Before we start installing the scripts for monitoring, we should install all the dependent packages need to perform on Ubuntu.

First login to your AWS server, and from our terminal, install below packages

sudo apt-get update
sudo apt-get install unzip
sudo apt-get install libwww-perl libdatetime-perl

Now Install the Monitoring Scripts

Following are the steps to download and then unzip we need to configure the Cloud Watch Monitoring scripts on our server:
1. In the terminal, we need to change our directory and where we want to add our monitoring scripts.
2. Now run the below command and download the source:

curl https://aws-cloudwatch.s3.amazonaws.com/downloads/CloudWatchMonitoringScripts-1.2.2.zip -O

3. Now uncompress the currently downloaded sources using the following commands

unzip CloudWatchMonitoringScripts-1.2.2.zip && \

rm CloudWatchMonitoringScripts-1.2.2.zip && \

cd aws-scripts-mon

The directory will contain Perl scripts, because of the execution of these scripts only report memory run and disk space utilization metrics will run in our Ubuntu server.
Currently, our folder will contain the following files:
mon-get-instance-stats.pl - This Perl file is used to displaying the current utilization statistics reports for our AWS instance on which these file scripts will be executed.
mon-put-instance-data.pl - This Perl script file will be used for collecting the system metrics on our ubuntu server and which will send them to the Amazon Cloud Watch.
awscreds.template - This Perl script file will contain an example for AWS credentials keys and secret access key named with access key ID.
CloudWatchClient.pm - This Perl script file module will be used to simplify by calling Amazon Cloud Watch from using other scripts.
LICENSE.txt – This file contains the license details for Apache 2.0.
NOTICE.txt – This file contains will gives us information about Copyright notice.
4. For performing the Cloud Watch operations, we need to confirm that whether our scripts have corresponding permissions for the actions:

If we are associated with an IAM role with our EC2 Ubuntu instance, we need to verify that which will grant the permissions to perform the below-listed operations:

cloudwatch:GetMetricStatistics

cloudwatch:PutMetricData

ec2:DescribeTags

cloudwatch:ListMetrics

Now we need to copy the ‘awscreds.template’ file into ‘awscreds.conf’ by using the command below and which will update the file with details of the AWS credentials.

cp awscreds.template awscreds.conf

AWSAccessKeyId = my_access_key_id

AWSSecretKey = my_secret_access_key

Now we completed the configuration.

mon-put-instance-data.pl

This Perl script file will collect memory, disk space utilization data and swap the current system details and then it makes handling a remote call to Amazon Cloud Watch to reports details to the collected cloud watch data as a custom metrics.

We can perform a simple test run, by running the below without sending data to Amazon CloudWatch

./mon-put-instance-data.pl --mem-util --verify --verbose

Now we are going to set a cron for scheduling our metrics and we will send them to Amazon CloudWatch
1. Now we need to edit the crontab by using below command:

 crontab -e

2. Now we will update the file using the following query which will disk space utilization and report memory for particular paths to Amazon CloudWatch in every five minutes:

*/5 * * * * ~/STORAGE/cloudwatch/aws-scripts-mon/mon-put-instance-data.pl --mem-util --mem-avail --mem-used --disk-space-util --disk-space-avail --disk-space-used --disk-path=/ --disk-path=/STORAGE --from-cron

If there is an error, the scripts will write an error message in our system log.

Use of Options

--mem-used
The above command will collect the information about used memory and which will send the details of the reports in MBs into the MemoryUsed metrics. This will give us information about the metric counts memory allocated by applications and the OS as used.
--mem-util
The above command will collect the information about memory utilization in percentages and which will send the details of the Memory Utilization metrics and it will count the usage of the memory applications and the OS.
--disk-space-util
The above command will collect the information to collect the current utilized disk space and which will send the reports in percentages to the DiskSpaceUtilization for the metric and for the selected disks.
--mem-avail
The above command will collect the information about the available memory and which will send the reports in MBs to the MemoryAvailable metrics details. This is the metric counts memory allocated by the applications and the OS as used.
--disk-path=PATH
The above command will collect the information and will point out the which disk path to report disk space.
--disk-space-avail
The above command will collect the information about the available disk space and which will send the reports in GBs to the DiskSpaceAvailable metric for the selected disks.
--disk-space-used
The above command will collect the information about the disk space used and which will send the reports in GBs to the DiskSpaceUsed metric for the selected disks.

The PATH can specify to point or any of the files can be located on which are mounted point for the filesystem which needs to be reported.

If we want to points to the multiple disks, then specify both of the disks like below:

--disk-path=/ --disk-path=/home

Setting an Alarm for Custom Metrics

Before we are going to running our Perl Scripts, then we need to create an alarm that will be listed in our default metrics except for the custom metrics. You can see some default metrics are listed in below image:



Once we completed setting the cron, then the custom metrics will be located in Linux System Metrics.

Now we are going to creating the alarm for our custom metrics
1. We need to open the cloudwatch console panel at https://console.aws.amazon.com/cloudwatch/home
2. Now navigate to the navigation panel, we need to click on Alarm and we can Create Alarm.
3. This will open a popup which with the list of the CloudWatch metrics by category.
4. Now click on the Linux System Metrics . This will be listed out with custom metrics you can see in the below pictures






5. Now we need to select metric details and we need to click on the NEXT button. Now we need to navigate to Define Alarm step.



6. Now we need to define an Alarm with required fields

Now we need to enter the Alarm name for identifying them. Then we need to give a description of our alarm.

Next, we need to give the condition with the maximum limit of bytes count or percentage when it notifies the alarm. If the condition satisfies, then the alarm will start trigger.

We need to provide a piece of additional information about for our alarm.

We need to define what are the actions to be taken when our alarm changes it state.

We need to select or create a new topic with emails needed for sending notification about alarm state.
7. Finally, we need to choose the Create Alarm.

So its completed. Now the alarm is created for our selected custom metrics.

Finished!

Now the alarm will be listed out under the selected state in our AWS panel. Now we need to select an alarm from the list seen and we can see the details and history of our alarm.

Laravel introduces eloquent relationships from laravel 5.0 onwards. We all know, while we creating an application we all have foreign keys. Each table will be connected to some other. Eloquent make easy to connect each tables easily. Here we will One to one, one to many and many to many relationships. Here we will see three types of relationships,
   
. One to one relationships
    . One to many relationships
    . Many to many relationships

Why Eloquent Relationships

Here we have 2 tables, students and marks, so for join each table,

$student = student::join(‘marks’,’marks.student_id,’=’,students.id’)->where(‘students.id’,’1’)->get();

dd($student);

the above query is to long, so when we connect more tables its too tough we will be having a big query and complicated.

Model Query using Relationships

$student_marks = student::find(1);

dd($student_marks->mark1);

The above example is a simple example of eloquent relationships. We can reduce the first query into a simple one.

ONE TO ONE RELATIOSHIPS

Here we are creating 2 tables:
* Users
* Phones

Now we can see one to one relationships using hasone() and belongsto().

We need to create table using migrations

Create migrations

users table will be created by using

Schema::create('users', function (Blueprint $table) {

 $table->increments('id');

 $table->string('name');

 $table->string('email')->unique();

 $table->string('password');

 $table->rememberToken();

 $table->timestamps();

});

Phones table will be created by

Schema::create('phones', function (Blueprint $table) {

 $table->increments('id');

 $table->integer('user_id')->unsigned();

 $table->string('phone');

 $table->timestamps();

 $table->foreign('user_id')->references('id')->on('users')

 ->onDelete('cascade');

});

After that we need to create model for each tables, as we all know if the table name is laravel table name will be ending with ‘s’ and model name will be without ‘s’ of the same table name.

User model

<?php

namespace App;

use Illuminate\Notifications\Notifiable;

use Illuminate\Foundation\Auth\User as Authenticatable;



class User extends Authenticatable

{

 use Notifiable;



 

 protected $fillable = [

 'name', 'email', 'password',

 ];



 

 protected $hidden = [

 'password', 'remember_token',

 ];



 

 public function phone()

 {

 return $this->hasOne('App\Phone');

 }

}

Phone Model

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;



class Phone extends Model

{

 

 public function user()

 {

 return $this->belongsTo('App\User');

 }

}

For Creating records

$user = User::find(1);

$phone = new Phone;

$phone->phone = '9080054945';

$user->phone()->save($phone);



$phone = Phone::find(1);

$user = User::find(10);

$phone->user()->associate($user)->save();

Now we can get our records by

$phone = User::find(1)->phone;

dd($phone);



$user = Phone::find(1)->user;

dd($user);

ONE TO MANY RELATIONSHIPS

Here we will use hasMany() and belongsTo() for relationships

Now we are creating two tables, posts and comments, we will be having a foreign key towards posts table.


Migrations for posts and comments table

Schema::create('posts', function (Blueprint $table) {

 $table->increments('id');

 $table->string("name");

 $table->timestamps();

});



Schema::create('comments', function (Blueprint $table) {

 $table->increments('id');

 $table->integer('post_id')->unsigned();

 $table->string("comment");

 $table->timestamps();

 $table->foreign('post_id')->references('id')->on('posts')

 ->onDelete('cascade');

});

Now we will create Post Model and Comment Model

Post Model

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;



class Post extends Model

{

 

 public function comments()

 {

 return $this->hasMany(Comment::class);

 }

}

Comment Model

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;



class Comment extends Model

{

 

 public function post()

 {

 return $this->belongsTo(Post::class);

 }

}

Now we can create records

$post = Post::find(1);

$comment = new Comment;

$comment->comment = "Hi Harikrishnan";

$post = $post->comments()->save($comment);

$post = Post::find(1);



$comment1 = new Comment;

$comment1->comment = "How are You?";

$comment2 = new Comment;

$comment2->comment = "Where are you?";

$post = $post->comments()->saveMany([$comment1, $comment2]);



$comment = Comment::find(1);

$post = Post::find(2);

$comment->post()->associate($post)->save();

Now we can get records

$post = Post::find(1);

$comments = $post->comments;

dd($comments);



$comment = Comment::find(1);

$post = $comment->post;

dd($post);

MANY TO MANY RELATIONSHIPS

Many to many is little bit different and complicated than the above two.



In this example, I will create users, roles, and role, users_tables, here each table will be connected each other using the foreign keys.



Using belongsToMany() we will use see a demo of Many to many relationship

Create Migrations

Schema::create('users', function (Blueprint $table) {

 $table->increments('id');

 $table->string('name');

 $table->string('email')->unique();

 $table->string('password');

 $table->rememberToken();

 $table->timestamps();

});



Schema::create('roles', function (Blueprint $table) {

 $table->increments('id');

 $table->string('name');

 $table->timestamps();

});



Schema::create('role_user', function (Blueprint $table) {

 $table->integer('user_id')->unsigned();

 $table->integer('role_id')->unsigned();

 $table->foreign('user_id')->references('id')->on('users')

 ->onDelete('cascade');

 $table->foreign('role_id')->references('id')->on('roles')

 ->onDelete('cascade');

});

Create Models

User Model

<?php

namespace App;

use Illuminate\Notifications\Notifiable;

use Illuminate\Foundation\Auth\User as Authenticatable;



class User extends Authenticatable

{

 use Notifiable;



 

 protected $fillable = [

 'name', 'email', 'password',

 ];



 

 protected $hidden = [

 'password', 'remember_token',

 ];



 

 public function roles()

 {

 return $this->belongsToMany(Role::class, 'role_user');

 }

}

Role Model

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;



class Role extends Model

{

 

 public function users()

 {

 return $this->belongsToMany(User::class, 'role_user');

 }

}

UserRole Model

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;



class UserRole extends Model

{

}

Now we can create records

$user = User::find(2); 

$roleIds = [1, 2];

$user->roles()->attach($roleIds);



$user = User::find(3); 

$roleIds = [1, 2];

$user->roles()->sync($roleIds);



$role = Role::find(1); 

$userIds = [10, 11];

$role->users()->attach($userIds);



$role = Role::find(2); 

$userIds = [10, 11];

$role->users()->sync($userIds);

Now we can retrieve records

$user = User::find(1); 

dd($user->roles);



$role = Role::find(1);

dd($role->users);

Hence laravel Eloquent is more powerful and we do relationships easily compared to native query. We will be having three more relationships in laravel. Ie.., has many, one to many polymorphic and many to many polymorphic. With eloquent relationship we can easily connect the tables each other. One to one relationships we can connect two tables with their basic functionalities. In one to many we will connect with single table with multiple options. In Many to many we will be having more tables.

Hi Guys,
I am sharing you the way to create simple resful apis using php and mysql. We are creating 2 apis here
First is to Loggin a existing user and second is to get list of written blogs by logged in user.

Create any database, i am taking

news

as the database name here, After it create following 2 tables inside it.

CREATE TABLE <code>users</code> (
 <code>id</code> int(11) UNSIGNED AUTO_INCREMENT PRIMARY KEY, 
 <code>name</code> varchar(100),
 <code>email</code> varchar(100),
 <code>password</code> varchar(100),
 <code>createdAt</code> datetime NOT NULL,
 <code>updatedAt</code> timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE <code>blogs</code> (
 <code>id</code> int(11) UNSIGNED AUTO_INCREMENT PRIMARY KEY, 
 <code>user_id</code> int(11),
 <code>title</code> varchar(255),
 <code>summary</code> Tinytext,
 <code>body</code> Text,
 <code>createdAt</code> datetime NOT NULL,
 <code>updatedAt</code> timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP
);

Now putting some dummy data to read via the api

--create 2 entries in users table--
INSERT INTO <code>news</code>.<code>users</code> (<code>id</code>, <code>name</code>, <code>email</code>, <code>password</code>, <code>createdAt</code>, <code>updatedAt</code>) VALUES (1, 'jeetendra singh', '[email protected]', MD5('123456'), '2018-12-28 02:05:12', CURRENT_TIMESTAMP), (2, 'Manvik Singh chaudhary', '[email protected]', MD5('654321'), '2018-12-28 03:08:11', CURRENT_TIMESTAMP);


-- create 2 blogs by userid 1--

INSERT INTO <code>news</code>.<code>blogs</code> (<code>id</code>, <code>user_id</code>, <code>title</code>, <code>summary</code>, <code>body</code>, <code>createdAt</code>, <code>updatedAt</code>) VALUES (1, '1', 'Blog title 1 by jeetendra', 'Blog summary 1 by jeetendra', 'Blog body 1 by jeetendra', '2018-12-28 02:00:00', CURRENT_TIMESTAMP), (2, '1', 'Blog Title 2 by jeetendra ', 'Blog summary 2 by jeetendra ', 'Blog body 2 by jeetendra ', '2018-12-28 05:10:21', CURRENT_TIMESTAMP);

-- create 2 blogs by userid 2
INSERT INTO <code>news</code>.<code>blogs</code> (<code>id</code>, <code>user_id</code>, <code>title</code>, <code>summary</code>, <code>body</code>, <code>createdAt</code>, <code>updatedAt</code>) VALUES (3, '2', 'Blog title 1 by manvik', 'Blog summary 1 by manvik', 'Blog body 1 by manvik', '2018-12-28 02:00:00', CURRENT_TIMESTAMP), (4, '2', 'Blog Title 2 by manvik ', 'Blog summary 2 by manvik ', 'Blog body 2 by manvik ', '2018-12-28 05:10:21', CURRENT_TIMESTAMP);

After creating this create a index.php and put this code for Db connection, login and get all blog method

<?php 
header("Content-Type: application/json; charset=UTF-8");

class DBClass {

 private $host = "localhost";
 private $username = "root";
 private $password = ""; private $database = "news";

 public $connection;

 public function connect(){

 $this->connection = null;

 try{
 $this->connection = new PDO("mysql:host=" . $this->host . ";dbname=" . $this->database, $this->username, $this->password);
 $this->connection->exec("set names utf8");
 }catch(PDOException $exception){
 echo "Error: " . $exception->getMessage();
 }

 return $this->connection;
 }

 public function login($email,$password){

 if($this->connection==null)
 {
 $this->connect();
 }
 
 $query = "SELECT id,name,email,createdAt,updatedAt from users where email= ? and password= ?";
 $stmt = $this->connection->prepare($query);
 $stmt->execute(array($email,md5($password)));
 $ret= $stmt->fetchAll(PDO::FETCH_ASSOC);
 return $ret;
 }

 public function get_all_blogs($Uid){

 if($this->connection==null)
 {
 $this->connect();
 }
 
 $query = "SELECT b.*,u.id as Uid,u.email as Uemail,u.name as Uname from blogs b join users u on u.id=b.user_id where b.user_id= ?";
 $stmt = $this->connection->prepare($query);
 $stmt->execute(array($Uid));
 $ret= $stmt->fetchAll(PDO::FETCH_ASSOC);
 return $ret;
 }

 public function response($array)
 {
 echo json_encode($array);
 exit;
 }
}

$return=array();
$obj = new DBClass();
if(isset($_GET['action']) && $_GET['action']!='')
{
if($_GET['action']=="login")
{
 if(isset($_POST['email']) && isset($_POST['password']))
 {
 $UserData=$obj->login($_POST['email'],$_POST['password']);
 if(count($UserData)>0)
 {
 $return['status']=1;
 $return['_data_']=$UserData[0];
 $return['message']='User Logged in Successfully.';
 }
 else
 {
	$return['status']=0;
	$return['message']='Error:Invalid Email or Password!';
 }
 }
 else
 {
 $return['status']=0;
 $return['message']='Error:Email or Password not provided!';
 }
}
elseif($_GET['action']=="UserBlogs")
{
 if(isset($_POST['Uid']))
 {
 $blogs=$obj->get_all_blogs($_POST['Uid']);
 if(count($blogs)>0)
 {
 $return['status']=1;
 $return['_data_']=$blogs;
 $return['message']='Success.';
 }
 else
 {
	$return['status']=0;
	$return['message']='Error:Invalid UserId!';
 }
 }
 else
 {
 $return['status']=0;
 $return['message']='Error:User Id not provided!';
 }
}
}
else
{
$return['status']=0;
$return['message']='Error:Action not provided!';
}
$obj->response($return);
$obj->connection=null;
?>

Now api file is set, just make the urls pretty(readable form) using .htaccess file, put following code in it

RewriteEngine On
RewriteRule ^api/(.*) index.php?action=

Now your Simple Restful Apis are ready to use, Now Let me show you the postman screenshot where i have used these apis.

Login Api Call:

User Post/Blog Api Call

Hello Guys,

In our Last Blog Post, we have created restful apis,But not worked on its security and authentication. Login api can be public but after login apis should be authenticate using any secure token. one of them is JWT, So i am providing the Steps for Create and use JWT Token in our already created API.


Now its time To Implement JWT Authentication IN our Api, So these are the steps to implement it in our already created Apis

Step 1:Install and include Firebase JWT(JSON WEB TOKEN) in our project with following composer command        

 composer require firebase/php-jwt 

include the composer installed packages

require_once('vendor/autoload.php');

use namespace using following:

 use \Firebase\JWT\JWT; 

Step 2: Create a JWT server side using Firebase Jwt Library's encode method in Login action , and return it to Client

Define a private variable named Secret_Key in Class like following:

 private {
 $payload = array(
 'iss' => $_SERVER['HOST_NAME'],
 'exp' => time()+600, 'uId' => $UiD
 );
 try{
 $jwt = JWT::encode($payload, $this->Secret_Key,'HS256'); $res=array("status"=>true,"Token"=>$jwt);
 }catch (UnexpectedValueException $e) {
 $res=array("status"=>false,"Error"=>$e->getMessage());
 }
 return $res;
 }

In our login action , if the user has been logged in successfully then with the status,_data_ and message just replace the login success code with following code:

$return['status']=1;
$return['_data_']=$UserData[0];
$return['message']='User Logged in Successfully.';

 $jwt=$obj->generateToken($UserData[0]['id']);
 if($jwt['status']==true)
 {
 $return['JWT']=$jwt['Token'];
 }
 else{
 unset($return['_data_']);
 $return['status']=0;
 $return['message']='Error:'.$jwt['Error'];
 }

Step 3: Now with every request after login should have the JWT token in its Post(even we can receive it in get or authentication header also but here we are receiving it in post)

No afetr successfully login you will get the JWt Token in your response,Just add that Token with every post request of after login api calls. So we will do it using postman, Find the screenshot 1 for checking the JWT Token is coming in login api response

Step 4:After reciving the JWt in every after login api call, we need to check whether the token is fine using JWT decode method in After login Apis like

UserBlogs

is a After login Api, So for verify that we are creating Authencate method in class like following:

 public function Authenticate($JWT,$Curret_User_id)
 {
 try {
 $decoded = JWT::decode($JWT,$this->Secret_Key, array('HS256'));
 $payload = json_decode(json_encode($decoded),true);
 
 if($payload['uId'] == $Curret_User_id) {
 $res=array("status"=>true);
 }else{
 $res=array("status"=>false,"Error"=>"Invalid Token or Token Exipred, So Please login Again!");
 }
 }catch (UnexpectedValueException $e) {
 $res=array("status"=>false,"Error"=>$e->getMessage());
 } 
 return $res;
 
 }

Step 5: Cross check the response returned by Authenticate method in

UserBlogs

Action of api , replace the

UserBlogs

Action inner content with following code:

 if(isset($_POST['Uid']))
 {

 $resp=$obj->Authenticate($_POST['JWT'],$_POST['Uid']);
 if($resp['status']==false)
 {
 $return['status']=0;
 $return['message']='Error:'.$resp['Error'];
 }
 else{
 $blogs=$obj->get_all_blogs($_POST['Uid']);
 if(count($blogs)>0)
 {
 $return['status']=1;
 $return['_data_']=$blogs;
 $return['message']='Success.';
 }
 else
 {
 $return['status']=0;
 $return['message']='Error:Invalid UserId!';
 }
 } 
 }
 else
 {
 $return['status']=0;
 $return['message']='Error:User Id not provided!';
 }

Ah great its time to check out the UserBlogs Api, please find the screenshoot for that, Remember we need to put the JWt Token in POST Parameter as we have already recived that Value in Login Api call.



Now if you want to verify that token is expiring in given time(10 minutes after generation time/login time), i am just clicking the same api with same token after 10 minutes and you can see there will not return any data and it is returning status false with following message :





Also if you want to eloborate it more then i suggest you to try with modify Uid value with same token , you will another authentication issue and also if you modify the JWT token also then also you will not get the desired result and get authentication Issue

Thanks for reading out if you want the complete code of this file then please find following:

<?php 
header("Content-Type: application/json; charset=UTF-8");
require_once('vendor/autoload.php');
use \Firebase\JWT\JWT; 

class DBClass {

 private $host = "localhost";
 private $username = "root";
 private $password = ""; private $database = "news";

 public $connection;

 private $Secret_Key="*$%43MVKJTKMN$#"; 
 public function connect(){

 $this->connection = null;

 try{
 $this->connection = new PDO("mysql:host=" . $this->host . ";dbname=" . $this->database, $this->username, $this->password);
 $this->connection->exec("set names utf8");
 }catch(PDOException $exception){
 echo "Error: " . $exception->getMessage();
 }

 return $this->connection;
 }

 public function login($email,$password){

 if($this->connection==null)
 {
 $this->connect();
 }
 
 $query = "SELECT id,name,email,createdAt,updatedAt from users where email= ? and password= ?";
 $stmt = $this->connection->prepare($query);
 $stmt->execute(array($email,md5($password)));
 $ret= $stmt->fetchAll(PDO::FETCH_ASSOC);
 return $ret;
 }

 public function get_all_blogs($Uid){

 if($this->connection==null)
 {
 $this->connect();
 }
 
 $query = "SELECT b.*,u.id as Uid,u.email as Uemail,u.name as Uname from blogs b join users u on u.id=b.user_id where b.user_id= ?";
 $stmt = $this->connection->prepare($query);
 $stmt->execute(array($Uid));
 $ret= $stmt->fetchAll(PDO::FETCH_ASSOC);
 return $ret;
 }

 public function response($array)
 {
 echo json_encode($array);
 exit;
 }

 public function generateToken($UiD)
 {
 $payload = array(
 'iss' => $_SERVER['HOST_NAME'],
 'exp' => time()+600, 'uId' => $UiD
 );
 try{
 $jwt = JWT::encode($payload, $this->Secret_Key,'HS256'); $res=array("status"=>true,"Token"=>$jwt);
 }catch (UnexpectedValueException $e) {
 $res=array("status"=>false,"Error"=>$e->getMessage());
 }
 return $res;
 }

 public function Authenticate($JWT,$Current_User_id)
 { 
 try {
 $decoded = JWT::decode($JWT,$this->Secret_Key, array('HS256'));
 $payload = json_decode(json_encode($decoded),true);
 
 if($payload['uId'] == $Current_User_id) {
 $res=array("status"=>true);
 }else{
 $res=array("status"=>false,"Error"=>"Invalid Token or Token Exipred, So Please login Again!");
 }
 }catch (UnexpectedValueException $e) {
 $res=array("status"=>false,"Error"=>$e->getMessage());
 } 
 return $res;
 
 }
}

$return=array();
$obj = new DBClass();
if(isset($_GET['action']) && $_GET['action']!='')
{
if($_GET['action']=="login")
{
 if(isset($_POST['email']) && isset($_POST['password']))
 {
 $UserData=$obj->login($_POST['email'],$_POST['password']);
 if(count($UserData)>0)
 {
 $return['status']=1;
 $return['_data_']=$UserData[0];
 $return['message']='User Logged in Successfully.';

 $jwt=$obj->generateToken($UserData[0]['id']);
 if($jwt['status']==true)
 {
 $return['JWT']=$jwt['Token'];
 }
 else{
 unset($return['_data_']);
 $return['status']=0;
 $return['message']='Error:'.$jwt['Error'];
 }
 
 }
 else
 {
	$return['status']=0;
	$return['message']='Error:Invalid Email or Password!';
 }
 }
 else
 {
 $return['status']=0;
 $return['message']='Error:Email or Password not provided!';
 }
}
elseif($_GET['action']=="UserBlogs")
{
 if(isset($_POST['Uid']))
 {

 $resp=$obj->Authenticate($_POST['JWT'],$_POST['Uid']);
 if($resp['status']==false)
 {
 $return['status']=0;
 $return['message']='Error:'.$resp['Error'];
 }
 else{
 $blogs=$obj->get_all_blogs($_POST['Uid']);
 if(count($blogs)>0)
 {
 $return['status']=1;
 $return['_data_']=$blogs;
 $return['message']='Success.';
 }
 else
 {
 $return['status']=0;
 $return['message']='Error:Invalid UserId!';
 }
 } 
 }
 else
 {
 $return['status']=0;
 $return['message']='Error:User Id not provided!';
 }
}
}
else
{
$return['status']=0;
$return['message']='Error:Action not provided!';
}
$obj->response($return);
$obj->connection=null;
?>

Hi Guys,
I am sharing you the simple steps by which you can broadcast the web push notifications to your subscriber. In this tutorial we are making a subscriber form and saving information using Ajax and PHP and then through a server side code returning response to current logged in user and showing notification to that user.
Following are the steps to build this system

1. Create a database, I am creating db with name 'web_notifications'

Creating subscribers and notifications tables using following sql statements

CREATE TABLE IF NOT EXISTS <code>subscribers</code> (
 <code>id</code> int(11) NOT NULL,
 <code>name</code> varchar(255) NOT NULL,
 <code>email</code> varchar(255) NOT NULL,
 <code>createdAt</code> timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

ALTER TABLE <code>subscribers</code> ADD PRIMARY KEY (<code>id</code>);

ALTER TABLE <code>subscribers</code> MODIFY <code>id</code> int(11) NOT NULL AUTO_INCREMENT;



CREATE TABLE IF NOT EXISTS <code>notifications</code> (
 <code>id</code> int(11) NOT NULL,
 <code>to_user</code> int(11) NOT NULL,
 <code>title</code> varchar(255) NOT NULL,
 <code>body</code> varchar(255) NOT NULL,
 <code>url</code> varchar(255) NOT NULL,
 <code>is_sent</code> int(11) NOT NULL DEFAULT '0',
 <code>createdAt</code> timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

ALTER TABLE <code>notifications</code> ADD PRIMARY KEY (<code>id</code>);

ALTER TABLE <code>notifications</code> MODIFY <code>id</code> int(11) NOT NULL AUTO_INCREMENT;

2. Now create a db_connect.php file with following code

<?php 
session_start();
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "web_notifications";

$conn = new mysqli($servername, $username, $password, $dbname);
if ($conn->connect_error) {
 die("Connection failed: " . $conn->connect_error);
} 
?>

3. Create a cookies.js file to read and write browser cookies

function WriteCookie(key,content) {
 var now = new Date();
 now.setMonth( now.getMonth() + 1 ); 
 document.cookie = key+"=" + escape(content) + ";";
 document.cookie = "expires=" + now.toUTCString() + ";"
}

function ReadCookie(key) {
 var allcookies = document.cookie;
 cookiearray = allcookies.split(';');
 var CookieData=Array();
 for(var i=0; i<cookiearray.length; i++) {
 k = cookiearray[i].split('=')[0];
 v = cookiearray[i].split('=')[1];
 CookieData[k]=v;
 }
 return CookieData[key];
}

4. Create a ajax file to read and mark is_sent if any notification foun to be sent in database for that user. create file with name 'fetch_notifications.php' with following content

<?php require 'db_connect.php';

$sql = "SELECT id,title,body,url FROM notifications where to_user='".@$_GET['user_id']."' and is_sent='0' ";
$result = $conn->query($sql);

$data=array();
if ($result->num_rows > 0) {
 while($row = $result->fetch_assoc()) {
 $data[]=$row;

 $upd = "update notifications set is_sent='1' where id='".$row['id']."' ";
 $conn->query($upd);

 }
}

if(count($data)>0)
{
 $response=array("status"=>1,"notification"=>$data);
}
else
{
 $response=array("status"=>0,"error"=>"No new notification!");
}

echo json_encode($response);

$conn->close(); 
?>

5. Now code index.php to show subscriber form and on submit insert record into the subscriber table

<?php require 'db_connect.php'; ?>
<!DOCTYPE html>
<html>
<head>
 <title>Web Push Notification Demo</title>
 <script src="./cookies.js" type="text/javascript"></script>
 <link href="
<script src="
<script src="
<link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.1.0/css/all.css" integrity="sha384-lKuwvrZot6UHsBSfcMvOkWwlCMgc0TaWr+30HWe3a4ltaBwTZhyTEggF5tJv8tbt" crossorigin="anonymous">
<?php 
if(isset($_POST['subscribe_form']))
{
 $_SESSION['is_login']=0;
 $username=$conn->real_escape_string($_POST['username']);
 $useremail=$conn->real_escape_string($_POST['useremail']);


 $sql = "INSERT INTO subscribers set name='".$username."',email='".$useremail."' ";
 if ($conn->query($sql) === TRUE) {
 $_SESSION['is_login']=1;
 $_SESSION['Uid']= $conn->insert_id;
 $_SESSION['Uname']= $username;
 ?>
 <script type="text/javascript">
 WriteCookie("Uid","<?php echo $_SESSION['Uid']; ?>");
 </script> 
 <?php
 $msg="<p style='color:green'>You have subscribe for push notification succesfully :)</p>";
 } else {
 $msg="<p style='color:red'>Error in subscribing for notifications</p>";
 }


}

?>
<div class="container">
<?php 
if(isset($msg) && $msg!='')
{
 ?>
 <br>
 <div class="alert alert-info">
 <?php echo $msg; ?>
 </div>
 <?php
}

if(isset($_SESSION['is_login']) && $_SESSION['is_login']==1)
{
 ?>
 <h2>Welcome <?php echo $_SESSION['Uname']; ?></h2>
 <script type="text/javascript"> 

setInterval(function(){ 
 check_notification(); 
}, 10000);

function check_notification()
{ 
 var Uid=ReadCookie("Uid");
 if(Uid!==undefined)
 {
 $.ajax({url: "fetch_notifications.php?user_id="+Uid, success: function(result){ 
 var response=JSON.parse(result);
 if(response.status==1)
 {
 
 response=response.notifications;
 for (var i = response.length - 1; i >= 0; i--) {
 var url = response[i]['url'];
 var noti = new Notification(response[i]['title'], {
 icon: 'logo.png', body: response[i]['body'],
 });
 noti.onclick = function () {
 window.open(url); 
 noti.close(); 
 };
 
 };

 }
 else{
 console.log(response.error);

 }
 
 }

 }); 
 }
}

 
 </script>
 <?php
}
else
{
 ?>
 <h2 class="text-center">Subscribe for Notifications</h2>
 <div class="row justify-content-center">
 <div class="col-12 col-md-8 col-lg-6 pb-5">

 <div class="card border-primary rounded-0">
 <div class="card-header p-0">
 <div class="bg-info text-white text-center py-2">
 <h3><i class="fa fa-envelope"></i> Information</h3>
 <p class="m-0">provide your information</p>
 </div>
 </div>
 <div class="card-body p-3">
 <form method="post">
 <!--Body-->
 <div class="form-group">
 <div class="input-group mb-2">
 <div class="input-group-prepend">
 <div class="input-group-text"><i class="fa fa-user text-info"></i></div>
 </div>
 <input type="text" class="form-control" id="username" name="username" placeholder="Input Your Name Here" required>
 </div>
 </div>
 <div class="form-group">
 <div class="input-group mb-2">
 <div class="input-group-prepend">
 <div class="input-group-text"><i class="fa fa-envelope text-info"></i></div>
 </div>
 <input type="text" class="form-control" id="useremail" name="useremail" pattern="[^@\s]+@[^@\s]+\.[^@\s]+" title="Invalid email address" placeholder="[email protected]" required>
 </div>
 </div>

 <div class="text-center">
 <input type="submit" value="Subscribe" name="subscribe_form" class="btn btn-info btn-block rounded-0 py-2">
 </div>
 </form>
 </div>

 </div>
 


 </div>
 </div>
<?php }?>
</div>



</head>
<body>

</body>
</html>
<?php 
$conn->close(); 
?>

The frontend of your subscription page (index.php) should look like this:




Now we are ready to receive notification in frontend, but we still need to create an admin page from where we can send notification to subscriber(s).

6. Create a table for admin user

CREATE TABLE IF NOT EXISTS <code>admin</code> (
 <code>id</code> int(11) NOT NULL,
 <code>username</code> varchar(255) NOT NULL,
 <code>password</code> varchar(255) NOT NULL,
 <code>createdAt</code> timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

ALTER TABLE <code>admin</code> ADD PRIMARY KEY (<code>id</code>);

ALTER TABLE <code>admin</code> MODIFY <code>id</code> int(11) NOT NULL AUTO_INCREMENT;

INSERT INTO <code>web_notifications</code>.<code>admin</code> (<code>id</code>, <code>username</code>, <code>password</code>, <code>createdAt</code>) VALUES (NULL, 'admin', MD5('123456'), CURRENT_TIMESTAMP);

Following is the code for admin.php to add the notifications to subscriber(s) account also i have inserted following login credentials for admin in admin table:
username:admin
password:123456

7. Now put following code in admin.php

<?php require 'db_connect.php'; ?>
<!DOCTYPE html>
<html>
<head>
 <title>ADMIN PAGE</title> 
 <link href="
<script src="
<script src="
<link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.1.0/css/all.css" integrity="sha384-lKuwvrZot6UHsBSfcMvOkWwlCMgc0TaWr+30HWe3a4ltaBwTZhyTEggF5tJv8tbt" crossorigin="anonymous">
<?php 
if(isset($_POST['login']))
{
 $_SESSION['admin_login']=0;
 $username=$conn->real_escape_string($_POST['username']);
 $password=$conn->real_escape_string($_POST['password']);
 $sql = "SELECT * FROM admin where username='".$username."' and password='".md5($password)."' ";
 $result = $conn->query($sql);
 if ($result->num_rows > 0) {
 $_SESSION['admin_login']=1;
 $msg="<p style='color:green'>Admin Logged-in Successfully :)</p>";
 }
 else {
 $msg="<p style='color:red'>INVALID CREDENTIALS FOR ADMIN</p>";
 } 


}
if(isset($_POST['add_notification']))
{ 
 $title=$conn->real_escape_string($_POST['title']);
 $body=$conn->real_escape_string($_POST['body']);
 $url=$conn->real_escape_string($_POST['url']);
 $users=$_POST['users'];

 foreach ($users as $user_id) {
 $ins = "insert into notifications set to_user='".$user_id."' , title='".$title."', url='".$url."', body='".$body."' ";
 $conn->query($ins);
 }
 $msg="<p style='color:green'>Notification(s) added to subscribers account.</p>";
 
}

?>
<div class="container">
<?php 
if(isset($msg) && $msg!='')
{
 ?>
 <br>
 <div class="alert alert-info">
 <?php echo $msg; ?>
 </div>
 <?php
}

if(isset($_SESSION['admin_login']) && $_SESSION['admin_login']==1)
{
 ?>
 <h2>Welcome Admin, Send notification to Subscriber(s)</h2>

<form method="post">
 
 

<div class="form-group">
 <label for="sel1">Select Subscriber(s):</label>
 <select multiple="multiple" required="required" class="form-control" id="users" name="users[]">
 <?php
$sql = "SELECT id,name FROM subscribers";
$result = $conn->query($sql);

$data=array();
if ($result->num_rows > 0) {
 while($row = $result->fetch_assoc()) {
 echo "<option value='".$row['id']."'>".$row['name']."</option>";
 }
}
?>
 </select>
</div>

 <div class="form-group">
 <label for="email">Title</label>
 <input type="text" required class="form-control" placeholder="notification title here" name="title" id="title">
 </div>
 
 <div class="form-group">
 <label for="email">Message</label>
 <textarea required class="form-control" placeholder="notification message here" name="body" id="body"></textarea> 
 </div>

 <div class="form-group">
 <label for="email">Url</label>
 <input type="url" required class="form-control" placeholder="notification landing/click url here" name="url" id="url">
 </div>
 
 <input type="submit" class="btn btn-primary btn-block" name="add_notification" value="Submit" />

</form>


 <?php
}
else
{
 ?>
 <h2 class="text-center">ADMINISTRATOR</h2>
 <div class="row justify-content-center">
 <div class="col-12 col-md-8 col-lg-6 pb-5">

 <div class="card border-primary rounded-0">
 <div class="card-header p-0">
 <div class="bg-info text-white text-center py-2">
 <h3><i class="fa fa-envelope"></i> LOGIN</h3>
 <p class="m-0">provide admin login credentials</p>
 </div>
 </div>
 <div class="card-body p-3">
 <form method="post">
 <!--Body-->
 <div class="form-group">
 <div class="input-group mb-2">
 <div class="input-group-prepend">
 <div class="input-group-text"><i class="fa fa-user text-info"></i></div>
 </div>
 <input type="text" class="form-control" id="username" name="username" placeholder="Input username here" required>
 </div>
 </div>
 <div class="form-group">
 <div class="input-group mb-2">
 <div class="input-group-prepend">
 <div class="input-group-text"><i class="fa fa-key text-info"></i></div>
 </div>
 <input type="password" class="form-control" id="password" name="password" placeholder="your password here" required>
 </div>
 </div>

 <div class="text-center">
 <input type="submit" value="Login" name="login" class="btn btn-info btn-block rounded-0 py-2">
 </div>
 </form>
 </div>

 </div>
 


 </div>
 </div>
<?php }?>
</div>



</head>
<body>

</body>
</html>
<?php 
$conn->close(); 
?>

The admin page will ask login credentials first then it will look like following screenshot:



Now in your project if you open index.php you have a frontend where user will register themselves to receive notifications, and admin.php is your backend where you can send notifications to users or subscribers


If you face any problem in setup this small project please just let me know in the comments below, or by messaging me.