Hey Friends,

I am sharing a very interesting blog on how to create a chat system in php without using ajax. As we all know ajax based chat system in php is not a good solution
because itincreases the server load and redundant xhr calls on our server.

Instead, I am going to use sockets for incoming messages from and send messages to another user. So lets try them out using the following steps:

Step 1: Cross check in php.ini that sockets extension is enabled

;extension=sockets
extension=sockets

Step 2: Create server.php file

This file will handle the incoming and outgoing messages on sockets, Add following variables in top of the file:

$host = 'localhost';
$port = '9000';
$null = NULL; 

Step 3: After it add helper methods

The following code for handshake with new incoming connections and encrypt and decrypt messages incoming and outgoing over sockets:

function send_message($msg)
{
global $clients;
foreach($clients as $changed_socket)
{
@socket_write($changed_socket,$msg,strlen($msg));
}
return true;
}
function unmask($text) {
$length = ord($text[1]) & 127;
if($length == 126) {
$masks = substr($text, 4, 4);
$data = substr($text, 8);
}
elseif($length == 127) {
$masks = substr($text, 10, 4);
$data = substr($text, 14);
}
else {
$masks = substr($text, 2, 4);
$data = substr($text, 6);
}
$text = "";
for ($i = 0; $i < strlen($data); ++$i) {
$text .= $data[$i] ^ $masks[$i%4];
}
return $text;
}
function mask($text)
{
$b1 = 0x80 | (0x1 & 0x0f);
$length = strlen($text);

if($length <= 125)
$header = pack('CC', $b1, $length);
elseif($length > 125 && $length < 65536)
$header = pack('CCn', $b1, 126, $length);
elseif($length >= 65536)
$header = pack('CCNN', $b1, 127, $length);
return $header.$text;
}
function perform_handshaking($receved_header,$client_conn, $host, $port)
{
$headers = array();
$lines = preg_split("/

/", $receved_header);
foreach($lines as $line)
{
$line = chop($line);
if(preg_match('/\A(\S+): (.*)\z/', $line, $matches))
{
$headers[$matches[1]] = $matches[2];
}
}
$secKey = $headers['Sec-WebSocket-Key'];
$secAccept = base64_encode(pack('H*', sha1($secKey . '258EAFA5-E914-47DA-95CA-C5AB0DC85B11')));
$upgrade = "HTTP/1.1 101 Web Socket Protocol Handshake

" .
"Upgrade: websocket

" .
"Connection: Upgrade

" .
"WebSocket-Origin: $host

" .
"WebSocket-Location: ws://$host:$port/php-ws/chat-daemon.php

".
"Sec-WebSocket-Accept:$secAccept



";
socket_write($client_conn,$upgrade,strlen($upgrade));
}

Step 4: Now add following code to create bind and listen tcp/ip sockets:

$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
socket_set_option($socket, SOL_SOCKET, SO_REUSEADDR, 1);
socket_bind($socket, 0, $port);
socket_listen($socket);
$clients = array($socket);

Ok now a endless loop that will use for handeling incominga nd send messages:

while (true) {
$changed = $clients;
socket_select($changed, $null, $null, 0, 10);

if (in_array($socket, $changed)) {
$socket_new = socket_accept($socket);	$clients[] = $socket_new; 
$header = socket_read($socket_new, 1024);	perform_handshaking($header, $socket_new, $host, $port); 
socket_getpeername($socket_new, $ip);	$response = mask(json_encode(array('type'=>'system', 'message'=>$ip.' connected')));	send_message($response); 
$found_socket = array_search($socket, $changed);
unset($changed[$found_socket]);
}

foreach ($changed as $changed_socket) {

while(socket_recv($changed_socket, $buf, 1024, 0) >= 1)
{
$received_text = unmask($buf);	$tst_msg = json_decode($received_text, true);	$user_name = $tst_msg['name'];	$user_message = $tst_msg['message'];	$user_color = $tst_msg['color']; 
$response_text = mask(json_encode(array('type'=>'usermsg', 'name'=>$user_name, 'message'=>$user_message, 'color'=>$user_color)));
send_message($response_text);	break 2;	}

$buf = @socket_read($changed_socket, 1024, PHP_NORMAL_READ);
if ($buf === false) {	$found_socket = array_search($changed_socket, $clients);
socket_getpeername($changed_socket, $ip);
unset($clients[$found_socket]);

$response = mask(json_encode(array('type'=>'system', 'message'=>$ip.' disconnected')));
send_message($response);
}
}
}
socket_close($socket);

So you are ready with server side socket program, Now its time to move on front side where we will implement w3c provided client side Web Socket Apis,

Step 5: create a file named index.php for frontend usage with following initial code

$host = 'localhost';
$port = '9000';
$subfolder = "php_ws/";
$colors = array('#007AFF','#FF7000','#FF7000','#15E25F','#CFC700','#CFC700','#CF1100','#CF00BE','#F00');
$color_pick = array_rand($colors);
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
</head>
<body>
<div class="chat-wrapper">
<div id="message-box"></div>
<div class="user-panel">
<input type="text" name="name" id="name" placeholder="Your Name" maxlength="15" />
<input type="text" name="message" id="message" placeholder="Type your message here..." maxlength="100" />
<button id="send-message">Send</button>
</div>
</div>
</body>
</html>

Now add some basic styling in the head section using following code:

<style type="text/css">
.chat-wrapper {
font: bold 11px/normal 'lucida grande', tahoma, verdana, arial, sans-serif;
 background: #00a6bb;
 padding: 20px;
 margin: 20px auto;
 box-shadow: 2px 2px 2px 0px #00000017;
max-width:700px;
min-width:500px;
}
#message-box {
 width: 97%;
 display: inline-block;
 height: 300px;
 background: #fff;
 box-shadow: inset 0px 0px 2px #00000017;
 overflow: auto;
 padding: 10px;
}
.user-panel{
 margin-top: 10px;
}
input[type=text]{
 border: none;
 padding: 5px 5px;
 box-shadow: 2px 2px 2px #0000001c;
}
input[type=text]#name{
 width:20%;
}
input[type=text]#message{
 width:60%;
}
button#send-message {
 border: none;
 padding: 5px 15px;
 background: #11e0fb;
 box-shadow: 2px 2px 2px #0000001c;
}
</style>

Ok Style is all set now need to add a jquery script and create web socket object and handle all events on it as following code need to add before closing of bosy tag:

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script language="javascript" type="text/javascript"> 
var msgBox = $('#message-box');
var wsUri = "ws://".$host.":".$port."/php-ws/server.php"; 
websocket = new WebSocket(wsUri); 

websocket.onopen = function(ev) {	msgBox.append('<div class="system_msg" style="color:#bbbbbb">Welcome to my "Chat box"!</div>');	}
websocket.onmessage = function(ev) {
var response	= JSON.parse(ev.data); 
var res_type	= response.type;	var user_message	= response.message;	var user_name	= response.name;	var user_color	= response.color;	switch(res_type){
case 'usermsg':
msgBox.append('<div><span class="user_name" style="color:' + user_color + '">' + user_name + '</span> : <span class="user_message">' + user_message + '</span></div>');
break;
case 'system':
msgBox.append('<div style="color:#bbbbbb">' + user_message + '</div>');
break;
}
msgBox[0].scrollTop = msgBox[0].scrollHeight;	};

websocket.onerror	= function(ev){ msgBox.append('<div class="system_error">Error Occurred - ' + ev.data + '</div>'); }; 
websocket.onclose	= function(ev){ msgBox.append('<div class="system_msg">Connection Closed</div>'); }; 
$('#send-message').click(function(){
send_message();
});

$( "#message" ).on( "keydown", function( event ) {
 if(event.which==13){
 send_message();
 }
});

function send_message(){
var message_input = $('#message');	var name_input = $('#name'); 
if(message_input.val() == ""){	alert("Enter your Name please!");
return;
}
if(message_input.val() == ""){	alert("Enter Some message Please!");
return;
}
var msg = {
message: message_input.val(),
name: name_input.val(),
color : '<?php echo $colors[$color_pick]; ?>'
};
websocket.send(JSON.stringify(msg));
message_input.val('');	}
</script>

Ok All set, Now need to run the server.php file using following php-cli utility,make sure you have php cli utility installed in your system:


php -q c:\xampp\htdocs\php-ws\server.php

Now you may access the front index.php file via the browser url like following and see a chatbox and connection status, you may use the same url or different browser to check the chat system is working or not.

Introduction

In a previous article we learned about Creating a PHP Daemon Service. Now we are going to learn how to use methods to perform IPC - Inter-Process Communication - to communicate with daemon processes.

Message Queues

In the world of UNIX, there is an incredible variety of ways to send a message or a command to a daemon script and vice versa. But first I want to talk only about message queues - "System V IPC Messages Queues".

A long time ago I learned that a queue can be either in the System V IPC implementation, or in the POSIX implementation. I want to comment only about the System V implementation, as I know it better.

Lets get started. At the "normal" operating system level, queues are stored in memory. Queue data structures are available to all system programs. Just as in the file system, it is possible to configure queues access rights and message size. Usually a queue message size is small, less than 8 KB.

This introductory part is over. Lets move on to the practice with same example scripts.queue-send.php

$key = ftok(__FILE__, 'A'); 
$queue = msg_get_queue($key);

msg_send($queue, 1, 'message, type 1');
msg_send($queue, 2, 'message, type 2');
msg_send($queue, 3, 'message, type 3');
msg_send($queue, 1, 'message, type 1');

echo "send 4 messages
";

queue-receive.php

$key = ftok('queue-send.php', 'A');
$queue = msg_get_queue($key);

for ($i = 1; $i <= 3; $i++) {
 echo "type: {$i}
";

 while ( msg_receive($queue, $i, $msgtype, 4096, $message, false, MSG_IPC_NOWAIT) ) {
 echo "type: {$i}, msgtype: {$msgtype}, message: {$message}
";
 }
}

Lets run on the first stage of the file queue-send.php, and then queue-receive.php.

u% php queue-send.php
send 4 messages
u% php queue-receive.php
type: 1
type: 1, msgtype: 1, message: s:15:"message, type 1";
type: 1, msgtype: 1, message: s:15:"message, type 1";
type: 2
type: 2, msgtype: 2, message: s:15:"message, type 2";
type: 3
type: 3, msgtype: 3, message: s:15:"message, type 3";

You may notice that the messages have been grouped. The first group gathered 2 messages of the first type, and then the remaining messages.

If we would have indicated to receive messages of type 0, you would get all messages, regardless of the type.

while (msg_receive($queue, $i, $msgtype, 4096, $message, false, MSG_IPC_NOWAIT)) {

Here it is worth noting another feature of the queues: if we do not use the constant MSG_IPC_NOWAIT in the script and run the script queue-receive.php from a terminal, and then run periodically the file queue-send.php, we see how a daemon can effectively use this to wait jobs.queue-receive-wait.php

$key = ftok('queue-send.php', 'A');
$queue = msg_get_queue($key);

while ( msg_receive($queue, 0, $msgtype, 4096, $message) ) {
 echo "msgtype: {$msgtype}, message: {$message}
";
}

Actually that is the most interesting information of all I have said. There are also functions to get statistics, disposal and checking for the existence of queues.

Lets now try to write a daemon listening to a queue:queue-daemon.php

$pid = pcntl_fork();
$key = ftok('queue-send.php', 'A');
$queue = msg_get_queue($key);

if ($pid == -1) {
 exit;
} elseif ($pid) {
 exit;
} else {
 while ( msg_receive($queue, 0, $msgtype, 4096, $message) ) {
 echo "msgtype: {$msgtype}, message: {$message}
";
 }
}

posix_setsid();

Shared Memory

We have learned to work with queues, with which you can send small system messages. But then we may certainly be faced with the task of transmitting large amounts of data. My favorite type of system, System V, has solved the problem of rapid transmission and preservation of large data in memory using a mechanism calledShared Memory.

In short, the data in the Shared Memory lives until the system is rebooted. Since the data is in memory, it works much faster than if it was stored in a database somewhere in a file, or, God forgive me on a network share.

Lets try to write a simple example of data storage.shared-memory-write-base.php

$id = ftok(__FILE__, 'A');


$shmId = shm_attach($id);

$var = 1;

if (shm_has_var($shmId, $var)) {
 $data = (array) shm_get_var($shmId, $var);
} else {
 $data = array();
}

$data[time()] = file_get_contents(__FILE__);

shm_put_var($shmId, $var, $data);

Run this script several times to save the value in memory. Now lets write a script only to read from the memory.shared-memory-read-base.php

$id = ftok(__DIR__ . '/shared-memory-write-base.php', 'A');
$shmId = shm_attach($id);
$var = 1; 

if (shm_has_var($shmId, $var)) {
 $data = (array) shm_get_var($shmId, $var);
} else {
 $data = array();
}

foreach ($data as $key => $value) {
 $path = "/tmp/$key.php";
 file_put_contents($path, $value);

 echo $path . PHP_EOL;
} 

Semaphores

So, in general terms, it should be clear for you by now how to work with shared memory. The only problems left to figure out are about a couple of nuances, such as: "What to do if two processes want to record one block of memory?" Or "How to store binary files of any size?".

To prevent simultaneous accesses we will use semaphores. Semaphores allow us to flag that we want to have exclusive access to some resource, like for instance a shared memory block. While that happens other processes will wait for their turn on semaphore.

In this code it explained clearly:shared-memory-semaphors.php

$id = ftok(__FILE__, 'A');

$semId = sem_get($id);

sem_acquire($semId);

$data = file_get_contents(__DIR__.'/06050396.JPG', FILE_BINARY);

$shmId = shm_attach($id, strlen($data)+4096);
$var = 1;
 
if (shm_has_var($shmId, $var)) {
 $data = shm_get_var($shmId, $var);

 $filename = '/tmp/' . time();
 file_put_contents($filename, $data, FILE_BINARY);

 shm_remove($shmId);
} else {
 shm_put_var($shmId, $var, $data); 
}

sem_release($semId); 

Now you can use the md5sum command line utility to compare two files, the original and the saved file. Or, you can open the file in image editor or whatever prefer to compare the images.

With this we are done with shared memory and semaphores. As your homework I want to ask you to write code that a demon will use semaphores to access shared memory.

Conclusion

Exchanging data between the daemons is very simple. This article described two options for data exchange: message queues and shared memory.

Post a comment here if you have questions or comments about how to exchange data with daemon services in PHP.

Hey There,
I am expecting you are familiar with PHP. In this post I will be using the Laravel framework to create a small blog system. I am showing here very simple steps to create blogs, If you want this complete code then please message me.
What are major Prequisites for Laravel:
* PHP version >= 5.6
* Composer should be installed in system

Create a project with name tiny_blog with following command

composer create-project laravel/laravel --prefer-dist tiny_blog

enter into the laravel project

cd tiny_blog

create a migration file using following artisan command
<pre>php artisan make:migration create_blog_table</pre>
After this command you will found a new file created in database/migrations folder in your project, Just edit the file having 'create_blog_table' appended in its name

Now replace following code to create table schema with function up(), So now the method will look like following:

public function up()
{
 Schema::create('blogs', function (Blueprint $table) {
$table->increments('id');
$table->integer('user_id');
$table->string('category');
$table->string('title');
$table->text('description');
$table->timestamps();
});

}

replace following snippet with down method, it will look like following:

public function down()
 {
 Schema::dropIfExists('blogs');
 }

Its time to run the migration file we have created

php artisan migrate

After running,It will create the blogs table in database.Now time to create form and insert data into the table

Laravel itsef provide authentication , use following artisan command :

php artisan make:auth

Now start Larvel:

php artisan serve

it will start the laravel development server at http://127.0.0.1:8000

Now if you run that url the basic default ui will be created and login & register link you can see in Top right position of header

You can register and login now.this feature is provided by authentication module.
Now we need to create a controller for manage blogs with following command:

php artisan make:controller BlogController

will create a file namedBlogController.php in** app/HTTP/controllers** folder location

Now we need to create a Model also, use following command

php artisan make:model Blog

will create a file namedBlog.php in app folder location

Now in Controller we need to create a method for create blogs and available that method in Routes to access it via url. Just editroutes/web.php file and add the following line

Route::get('blog/create','BlogController@createBlog');

/create/blog/ will be url route that land on Blog Controller's createBlog method using get method.

Now before running this route just go to the app/Http/Controllers folder and Edit BlogController.php file and Add the createBlog method in that class as following

public function createBlog()
{
 return view('blog.create');
}

This code will try to load the view from/resources/views/blog/create.blade.php

In Laravel blade is a template engine. As we had not created the view file yet, so we need to create a blog folder inside/resources/views/ folder then inside blog folder create a file create.blade.php with following form

@extends('layouts.app')

@section('content')
<div class="container">
@if ($errors->any())
 <div class="alert alert-danger">
 <ul>
 @foreach ($errors->all() as $error)
 <li>{{ $error }}</li>
 @endforeach
 </ul>
 </div><br />
@endif
 <div class="row">
 <form method="post" action="{{url('blog/create')}}">
 <div class="form-group">
 <input type="hidden" value="{{csrf_token()}}" name="_token" />
 <label for="title">Title:</label>
 <input type="text" class="form-control" name="title"/>
 </div>
 <div class="form-group">
 <label for="title">Category/Tags:</label>
 <input type="text" class="form-control" name="category"/>
 </div>
 <div class="form-group">
 <label for="description">Description:</label>
 <textarea cols="10" rows="10" class="form-control" name="description"></textarea>
 </div>
 <button type="submit" class="btn btn-primary">Submit</button>
 </form>
 </div>
</div>
@endsection

Now we need to add a additional route to handle the post request on blog/create route, Just edit routes/web.php file and just add following line in last:

Route::post('blog/create','BlogController@saveBlog'); 

post route to handle the form post on route blog/create


Now create a method name saveBlog to save the user input data in the form

 public function saveBlog(Request $request)
 {
 $blog = new Blog();
 
 $this->validate($request, [
 'title'=>'required',
'category'=>'required',
 'description'=> 'required'
 ]);
 
 $blog->createBlog($request->all());
 return redirect('blog/index')->with('success', 'New blog has been created successfully :)'); }

Notice This method is using Blog object that we don't know that where it comes from? , So to make above code working we need to include the model which we created earlier need to include in our controller file So use following code to include it before the class created.

use App\Blog;

Now following line shows that there is a method named createBlog in Model(app/Blog.php), but in actual it is not there:

$blog->createBlog($data);

So go to the file app/Blog.php and Edit it and inside the class add following method:

 public function createBlog($data)
{

$this->user_id = auth()->user()->id;
$this->title = $data['title'];
$this->description = $data['description'];
$this->category = $data['category'];
$this->save();
return 1;
}

Now the creation of blog task has been done , Its time to show the created Entries So just create a route blog/index in routes/web.php

Route::get('blog/index','BlogController@showAllBlogs');

get route blog/index to show all the created blogs by current user


Now just add a method in controller

public function showAllBlogs()
 {
 $blogs = Blog::where('user_id', auth()->user()->id)->get();
 
 return view('blog.index',compact('blogs'));
 }

This method requires to create a index view in blog folder , So create a file named index.blade.php in /resources/views/blog/ folder with following code

@extends('layouts.app')

@section('content')
<div class="container">
 @if(\Session::has('success'))
 <div class="alert alert-success">
 {{\Session::get('success')}}
 </div>
 @endif
 <a type="button" href="{{url('blog/create')}}" class="btn btn-primary">Add New Blog</a>
 <br>
 <table class="table table-striped">
 <thead>
 <tr>
 <td>ID</td>
 <td>Title</td>
 <td>Category</td>
 <td>Description</td>
 <td colspan="2">Action</td>
 </tr>
 </thead>
 <tbody>
 @foreach($blogs as $blog)
 <tr>
 <td>{{$blog->id}}</td>
 <td>{{$blog->title}}</td>
 <td>{{$blog->category}}</td>
 <td>{{$blog->description}}</td>
 <td>Edit</td>
 <td>Delete</td>
 </tr>
 @endforeach
 </tbody>
 </table>
<div>
@endsection

Now all code is ready but we need to add 1 line of code to prevent the blog controller without authentication or without login

just add the following constructor method in BlogController class

 public function __construct()
 {
$this->middleware('auth');
 }

this constructor method will call very first when user will try to access any of BlogController class method, and the middleware will check whether user is logged in then only it will allow to access that method otherwise it will redirect to login page automatically.


After It Run your Code and you will able to create and listing your created blogs/articles. but the Edit and Delete links are not working right now, If you want that also working then please comment here or message me. If we get multiple requests then definitely i will write its part 2 article


Thanks very much for reading this blog, if you have any doubt about it then let me know in comments or by messaging me.

Following is the final code for BlogController.php

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;
use App\Blog;



class BlogController extends Controller
{
 public function __construct()
 {
 $this->middleware('auth');
 }

 public function createBlog()
{
 return view('blog/create');
}


public function saveBlog(Request $request)
 {
 $blog = new Blog();
 
 $this->validate($request, [
 'title'=>'required',
'category'=>'required',
 'description'=> 'required'
 ]);
 
 $blog->createBlog($request->all());
 return redirect('blog/index')->with('success', 'New blog has been created successfully :)');
 }

 public function showAllBlogs()
 {
 $blogs = Blog::where('user_id', auth()->user()->id)->get();
 
 return view('blog.index',compact('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.

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