Develop apps and explore the world (wide web)

BJJ Tracker

World Wide Web

The web, as a platform, is open and free. Unlike native app markets, we don’t have to wait for software to be approved by any third-party. It works across any device or operating system that has a web browser. (Which is why standards across browsers is so important). But, until recently web-apps faced limitations. Not having full access to a device’s hardware and operating system was an issue – but that’s being fixed as more native APIs are being added to modern web browsers.

A disadvantage of having a web-only app was losing out on the discoverability that comes with having it listed in a searchable marketplace. Adding a web-app to your device home screen, from a web browser, is not intuitive to average users. Fortunately, the Google Play Market allows us to upload an app file that links to a progressive web app.

This involves a new protocol,  Trusted Web Activities, as “a way to integrate your web-app content such as your PWA with your Android app“. The PWA leverages Digital Asset Links to “declare that it is associated with a specific Android app.

Progressive web apps

I decided to try this out with one of my web-apps, BJJ Tracker. You can read about how I first built it on another blog post.

I had to make sure it qualified as a PWA. It needed offline support, as well as any other features that would make it feel like a native app. Google Chrome’s developer tools has a section called “Audits” that helped me identify such opportunities.

progressive web app audit

The first step was to create a “service worker” JavaScript file, and register it when BJJ Tracker loads.

if('serviceWorker' in navigator) {
  navigator.serviceWorker
           .register('/serviceWorker.js')
           .then(function() { console.log("Service Worker Registered"); })
           .catch(error => {
	        	console.log(error.message)
	    	})
}

I added the above code to a shared file that loads on every page of my app.  Below is an example service worker file. This file downloads any vital assets to a user’s device, and later loads them from the cache. Including a polyfill ensures that the cache methods exist (in case the browser does not support them natively). “We need to use the polyfill because the Cache API is not yet fully supported in all browsers.

importScripts('/cache-polyfill.js');

self.addEventListener('install', function(e) {
 e.waitUntil(
   caches.open('bjjtracker').then(function(cache) {
    return cache.addAll([
       '/',
       '/index',
       '/index?login',
       '/create-record?class',
       '/create-record',
       '/create-record?competition',
       '/view-record',
       '/view-month',
       '/privacy-policy',
       '/contact',
       '/view-more-data',
       '/account',
       '/css/bootstrap.min.css',
       '/css/bootstrap.min.css',
       '/css/bootstrap-theme.min.css',
       '/css/main.css',
       '/simpleMobileMenu/styles/jquery-simple-mobilemenu.css',
       'https://use.fontawesome.com/releases/v5.3.1/css/all.css',
       'https://fonts.googleapis.com/css?family=Roboto|Eczar&display=swap',
       'https://ajax.googleapis.com/ajax/libs/jquery/1.11.2/jquery.min.js',
     ]);
    }).catch(error => {
        console.log(error.message)
    })
 );
});

self.addEventListener('fetch', function(event) {
	event.respondWith(
		caches.match(event.request).then(function(response) {
			return response || fetch(event.request);
		}).catch(error => {
	        console.log(error.message)
	    })
	);
});

Read the documentation on Google’s developer portal.

Next, I created a “manifest” file. This file is written in JSON format. It helps describe how the web-app behaves once “installed”. It handles things such as app icon images and meta data.

{
  "name": "BJJ Tracker",
  "lang": "en-US",
  "short_name": "BJJ Tracker",
  "start_url": "/",
  "display": "standalone",
  "background_color": "#2a4d69",
  "theme_color": "#2a4d69",
  "description": "Track Brazilian Jiu Jitsu progress and fitness goals.",
  "icons": [{
    "src": "img/homescreen48.png",
    "sizes": "48x48",
    "type": "image/png"
  }, {
    "src": "img/homescreen72.png",
    "sizes": "72x72",
    "type": "image/png"
  }, {
    "src": "img/homescreen96.png",
    "sizes": "96x96",
    "type": "image/png"
  }, {
    "src": "img/homescreen144.png",
    "sizes": "144x144",
    "type": "image/png"
  }, {
    "src": "img/homescreen168.png",
    "sizes": "168x168",
    "type": "image/png"
  }, {
    "src": "img/homescreen192.png",
    "sizes": "192x192",
    "type": "image/png"
  }, {
    "src": "img/homescreen512.png",
    "sizes": "512x512",
    "type": "image/png"
  }]
}

I created the image assets using open source software.

Image assets created with GIMP
Image assets created with GIMP

The manifest needs to be referenced by the app. I added a link tag to a shared <head> file. Additionally, I included a few other meta tags that let browsers know to treat this website as an app.

<link rel="manifest" href="/manifest.json">
<meta name="theme-color" content="#005b96"/>
<meta name="mobile-web-app-capable" content="yes">
<meta name="apple-mobile-web-app-capable" content="yes">
<meta name="msapplication-starturl" content="/">

Android Studio

A signed app bundle is generated from Android Studio.  I use a sample project from Google Chrome Labs as a template. We can clone that repository, and update the “/svgomg-twa/app/build.gradle” settings to point to our PWA.

app gradle settings
TWA to wrap SVGOMG in an Android App

The app’s icon files can be generated using an online tool. The downloadable bundle can be dropped into “/svgomg-twa/app/src/main/res/“.

icon generator
https://romannurik.github.io/AndroidAssetStudio/icons-launcher.html

When creating the app bundle (“Build > Generate Signed Bundle/APK”) we’ll need a signing key. I created a new one, and named the file mykeystore.keystore.

An “assetlinks.json” file needs to be uploaded to the web app’s host to satisfy the Digital Asset Links requirement.  “The Digital Asset Links protocol and API enable an app or website to make public, verifiable statements about other apps or websites.” This confirms ownership of the PWA so that it can be linked to our app in the Play Store. To generate this file, first we’ll need to get the fingerprint from the signing key we used:

keytool -list -v -keystore mykeystore.keystore -alias mykeystore -storepass password-here  -keypass password-here

That command shows us the certificate fingerprints. Copy the SHA256 value. It is used with Google’s Statement List Generator to create the contents of the assetlinks.json file. The statement file is then placed in a “.well-known” directory on the root of our PWA domain (eg. https://www.bjjtracker.com/.well-known/assetlinks.json)

Finally, I visited the Google Play Console. Besides uploading the .apk file, I also needed to include screenshots, featured image files, and complete a content rating survey – amongst other things. Since my app has been approved, you can now find it in the Google Play Market.

BJJ Tracker in the Google Play Store.

This app is a side project I use to toy with new web technologies. I’m trying to drive traffic to it so that I can experiment with optimizing conversions. I’m using it as a trial grounds for another software service called SplitWit. SplitWit is focused on optimizing conversions for the web, and helping digital marketers reach their goals. You can read about it on another post from this blog.

bjj tracker app

SplitWit for split testing

Product development and SAAS

SplitWit is a digital product. It is a “software as a service” platform that helps split test websites and apps. That means it allows us to make changes to a website, that only half of visitors will see, and then determine which version has better results (sales, sign-ups, etc.).

Foundational code and design

I used a template to quickly get things prototyped and working. It came with a user account engine to handle registration, login, and more.

The front-end design utilizes basic principles that focus on user experience. I iterated through various color pallets, and ended with a blue-shaded scheme. Subtle textured patterns applied to background sections help add a finished look. And of course, FontAwesome is my go-to icon set.

SplitWit.com
https://www.SplitWit.com

I used a CSS rule on the main container of each page to have a minimum height of 100% of the viewport. This ensures that the page footer doesn’t end up in the middle of the screen if there is not enough content.

.main-content.container{
  min-height: 100vh;
}

The contact form at the bottom of the homepage is powered by AWS SES.

Visual optimizer and editor

After setting up an account, users can create experiments that target certain pages of a website. The visual optimizer lets changes be made easily between the control and variation versions.

visual editor

The editor loads up a website as an iFrame on the right side of the page. Once a page is loaded, SplitWit adds an overlay to the iFrame. This way, instead of interacting with the page, clicks can be intercepted. Any elements that get clicked are loaded up as HTML into the “make a change” section of the editor. Any changes made are saved to that variation, and will be displayed to half of visitors.

Here is an example of the code that powers the overlay and connects it to the editor:

pageIframe.contents().find("body").prepend(overlay);
 
pageIframe.contents().find("body *").css("z-index", 1).mouseenter(function(){
  $(this).addClass('highlighted'); 
  testSelectorEl = $(this);
  
}).mouseout(function(){

  $(this).removeClass('highlighted');   

}).click(function(e){

  e.preventDefault();
  var value = testSelectorEl.getPath()
  selectNewElement(value);
  //scroll user to selector input
  $([document.documentElement, document.body]).animate({
    scrollTop: $(".page-editor-info").offset().top
  }, 1000);

});

function selectNewElement(value){
  
    testSelectorElPath = value;
    testSelectorEl = pageIframe.contents().find(value);
    $(".change-indicator").hide()
    $(".el-input").removeAttr("disabled");
    $(".element-change-save-btn").attr("disabled", "disabled");
    $(".find-selector").hide();
    $(".element-change-wrap .selector-input").val(testSelectorElPath);

    $(".toggable-section").hide();
    $(".element-change-wrap").show();
    $(".multiple-elements").hide();

    if(testSelectorEl.attr("src") && testSelectorEl.attr("src").length > 0){
      $(".img-url").val(testSelectorEl.attr("src"));
      $(".img-url-wrap").show();
      testSelectorElImage = testSelectorEl.attr("src");
    }else{
      testSelectorElImage = "";
      $(".img-url").val("");
      $(".img-url-wrap").hide();
    }
    if(testSelectorEl.attr("href") && testSelectorEl.attr("href").length > 0){
      $(".link-url").val(testSelectorEl.attr("href"));
      $(".link-url-wrap").show();
      testSelectorElLink = testSelectorEl.attr("href");
    }else{
      testSelectorElLink = "";
      $(".link-url").val("");
      $(".link-url-wrap").hide();
    }

    if(testSelectorEl.html() && testSelectorEl.html().length > 0){
      $(".html-input").val(testSelectorEl.html());
      $(".html-input-wrap").show();
      testSelectorElHtml = testSelectorEl.html();
    }else{
      testSelectorElHtml = "";
      $(".html-input").val("");
      $(".html-input-wrap").hide();
    }

    $(".elem-css-group").show();
    if(testSelectorEl.is(":visible")){
      originalVisibilityState = "visible";
      $("#visible-radio").attr("checked", "checked");
      $("#hidden-radio").removeAttr("checked");
    }else{
      originalVisibilityState = "hidden";
      $("#hidden-radio").attr("checked", "checked");
      $("#visible-radio").removeAttr("checked");

    }
    originalValues['height'] = testSelectorEl.css("height");
    $(".height").val(originalValues['height']);
    originalValues['width'] = testSelectorEl.css("width");
    $(".width").val(originalValues['width']);
    originalValues['border'] = testSelectorEl.css("border");
    $(".border").val(originalValues['border']);
    originalValues['font-family'] = testSelectorEl.css("font-family");
    $(".font-family").val(originalValues['font-family']);
    originalValues['font-size'] = testSelectorEl.css("font-size");
    $(".font-size").val(originalValues['font-size']);
    originalValues['font-weight'] = testSelectorEl.css("font-weight");
    $(".font-weight").val(originalValues['font-weight']);
    originalValues['font-style']= testSelectorEl.css("font-style");
    $(".font-style").val(originalValues['font-style'])
    originalValues['text-decoration'] = testSelectorEl.css("text-decoration")
    $(".text-decoration").val(originalValues['text-decoration'])
    originalValues['background'] = "";
    $(".background").val(originalValues['background'])

} //end selectNewElement()

The editor has lots of built in options, so users can change the style and behavior of a page without needing to know how to code. A marketer can use this tool without the help of a developer.

Metrics and statistical significance

A key feature of SplitWit is to measure conversion metrics and performance indicators. The platform determines which variation is a winner based on the metrics set. Three types of metrics are offered: page views, click events, and custom API calls.

Algorithms calculate statistical significance based on the number of visitors an experiment receives and the conversion metrics configured. This makes sure that the result is very unlikely to have occurred coincidently.

The code snippet

Each project setup in SplitWit generates a code snippet. Once this snippet is added to a website, SplitWit is able to do its magic. Using JavaScript, it applies variation changes, splits user traffic between versions, and measures key metrics about the experiments running.

The platform uses a relational database structure. As changes are made to experiments, the details are saved and written to a unique snippet file. When the snippet file loads, the first thing is does is check to see if there are any experiments that should be running on the current page. Each experiment can be configured to run on various URLs. The configuration rules contain three parts: a URL pattern, a type (target or exclude), and a match type (exact, basic, or substring). You can read SplitWit documentation to find an explanation of these match types.

experiment settings

Here is the code used to test a URL against an experiment’s configuration rules:

function testUrl(testurl, conditions){
			
	if(testurl.search(/(?:[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?\.)+[a-z0-9][a-z0-9-]{0,61}[a-z0-9]/) < 0){
		return window.inputError($(".test-url-input"), "Please test a valid URL.");
	}
	var valid = false;
	var arr  = [],
	keys = Object.keys(conditions);

	for(var i=0,n=keys.length;i<n;i++){
		var key  = keys[i];
		arr[i] = conditions[key];
	}

	conditions = arr;
	for (i = 0; i < arr.length; i++) { 
		var url = conditions[i].url;
		var matchtype = conditions[i].matchtype;
		var conditiontype = conditions[i].conditiontype;

		if(matchtype == "exact" && conditiontype == "target" && url == testurl){
			valid = true;
		}
		if(matchtype == "exact" && conditiontype == "exclude" && url == testurl){
			valid = false;
		}

		if(matchtype == "basic"){
			var cleanTestUrl = testurl.toLowerCase();
			var cleanUrl = url.toLowerCase();

			if(cleanTestUrl.indexOf("?") > 0) {
				cleanTestUrl = cleanTestUrl.substring(0, cleanTestUrl.indexOf("?"));
			}
			if(cleanUrl.indexOf("?") > 0) {
				cleanUrl = cleanUrl.substring(0, cleanUrl.indexOf("?"));
			}
			if(cleanTestUrl.indexOf("&") > 0) {
				cleanTestUrl = cleanTestUrl.substring(0, cleanTestUrl.indexOf("&"));
			}
			if(cleanUrl.indexOf("&") > 0) {
				cleanUrl = cleanUrl.substring(0, cleanUrl.indexOf("&"));
			}
			if(cleanTestUrl.indexOf("#") > 0) {
				cleanTestUrl = cleanTestUrl.substring(0, cleanTestUrl.indexOf("#"));
			}
			if(cleanUrl.indexOf("#") > 0) {
				cleanUrl = cleanUrl.substring(0, cleanUrl.indexOf("#"));
			}
			cleanTestUrl = cleanTestUrl.replace(/^(?:https?:\/\/)?(?:www\.)?/i, "");
			cleanUrl = cleanUrl.replace(/^(?:https?:\/\/)?(?:www\.)?/i, "");
			cleanTestUrl = cleanTestUrl.replace(/\/$/, "");
			cleanUrl = cleanUrl.replace(/\/$/, ""); 

			if(conditiontype == "target" && cleanUrl == cleanTestUrl){
				valid = true;
			}
			if(conditiontype == "exclude" && cleanUrl == cleanTestUrl){
				valid = false;
			}

		}
		if(matchtype == "substring"){
			if(testurl.includes(url) && conditiontype == "target"){
				valid = true;
			}
			if(testurl.includes(url) && conditiontype == "exclude"){
				valid = false;
			}
		} 
	}
	
	return valid;

}

Subscription billing workflow

Stripe is used to bill customers. In the billing dashboard we can create a product, and assign it a monthly pricing plan.

Subscription products

The payment processor handles re-billing customers each month. Our software is responsible for keeping track of each account’s payment status. In the database we record the date of when an account will be considered delinquent. Upon registration each account has this field set to 15 days in the future, affording a two week trial. At this point, users have not entered any credit card information.

Initial payment

Stripe’s JavaScript SDK is used during initial payment to tokenize credit card information before passing it along to the server.

activate your subscription
Stripe’s JS library handles card validation and tokenization.

Below is the HTML used for a Stripe payment element:

<div id="stripe-payment-modal" class="modal stripe-payment-modal" style="display: none;">

	<!-- Modal content -->
	<div class="modal-content">
		<p>
		  <button type="button" class="dismiss-modal close" >&times;</button>
		</p>
		<p>Activate your account subscription.</p>
		<form id="payment-form">
		  <div class="form-row">
		    <!-- <label for="card-element">
		      Credit or debit card
		    </label> -->
		    <div id="card-element">
		      <!-- A Stripe Element will be inserted here. -->
		    </div>

		    <!-- Used to display Element errors. -->
		    <div id="card-errors" role="alert"></div>
		  </div>

		  <button type="button" class="btn submit-payment">Submit Payment</button>
		</form>

  	</div>

</div>

And the JavaScript:

<script src="https://js.stripe.com/v3/"></script>
<script type="text/javascript">
var stripe = Stripe('your-public-key-goes-here');

var elements = stripe.elements();

// Custom styling can be passed to options when creating an Element.
var style = {
  base: {
    color: '#32325d',
    fontFamily: '"Helvetica Neue", Helvetica, sans-serif',
    fontSmoothing: 'antialiased',
    fontSize: '16px',
    '::placeholder': {
      color: '#aab7c4'
    }
  },
  invalid: {
    color: '#fa755a',
    iconColor: '#fa755a'
  }
};

// Create an instance of the card Element.
var card = elements.create('card', {style: style});

// Add an instance of the card Element into the `card-element` div.
card.mount('#card-element');

// Handle real-time validation errors from the card Element.
card.addEventListener('change', function(event) {
  var displayError = document.getElementById('card-errors');
  if (event.error) {
    displayError.textContent = event.error.message;
  } else {
    displayError.textContent = '';
  }
});

// Handle form submission.
var form = document.getElementById('payment-form');
form.addEventListener('submit', function(event) {
  event.preventDefault();

  stripe.createToken(card).then(function(result) {
    if (result.error) {
      // Inform the user if there was an error.
      var errorElement = document.getElementById('card-errors');
      errorElement.textContent = result.error.message;
    } else {
      // Send the token to your server.
      stripeTokenHandler(result.token);
    }
  });
});

// Submit the form with the token ID.
function stripeTokenHandler(token) {
  // Insert the token ID into the form so it gets submitted to the server
  var form = document.getElementById('payment-form');
  var hiddenInput = document.createElement('input');
  hiddenInput.setAttribute('type', 'hidden');
  hiddenInput.setAttribute('name', 'stripeToken');
  hiddenInput.setAttribute('value', token.id);
  form.appendChild(hiddenInput);
  
  var data = $("#payment-form").serialize();
  $.ajax({
  	url:"stripe-payment-service.php",
  	method: "POST",
  	data: data,
  	complete: function(response){
  		console.log(response);
  		window.location.reload();
  	}
  })
}

$(".submit-payment").click(function(){
	stripe.createToken(card).then(function(result) {
    if (result.error) {
    	// Inform the customer that there was an error.
    	var errorElement = document.getElementById('card-errors');
    	errorElement.textContent = result.error.message;
    } else {
	$(".submit-payment").attr("disabled", "disabled").html('Working...');
      	// Send the token to your server.
      	stripeTokenHandler(result.token);
    }
  });
});
</script>

The above code creates a new Stripe object using a public API key. That object injects a credit card form into our ‘#card-element’ div, with custom styles attached. It listens for any changes, and displays validation errors. When the form is submitted, the Stripe object creates a token from the payment information. That token is passed to our back-end. Stripe’s PHP library is used to finish the transaction:

<?php
function subscribe(){
        require_once('stripe-php-6.43.0/init.php');
        \Stripe\Stripe::setApiKey('sk_XXXX');
	$stripe_token = $_POST['stripeToken'];
	$conn = $this->connection;
	
	if(isset($_SESSION['email'])){
		$email = $_SESSION['email'];
	}else{
		die("No email found.");
	}
	
	if(strlen($email)>0){
		$sql = "SELECT * FROM `account` WHERE email = ?"; 
		$result = $conn->prepare($sql); 
		$result->execute(array($email));
		$row = $result->fetch(PDO::FETCH_ASSOC);
	}
	$customer_id = $row['stripe_customer_id'];
	//check if this account already has a stripe_customer_id
	if(strlen($customer_id) < 1){
		//if not, create the customer
		$customer = \Stripe\Customer::create([
		  'email' => $email,
		  'source' => $stripe_token,
		]);
		$customer_id = $customer['id'];
		//write stripe ID to db
		$sql = "UPDATE `account_table` SET stripe_customer_id = ? WHERE email = ?"; 
		$result = $conn->prepare($sql); 
		$result->execute(array($customer_id, $email));
	}

	// Create the subscription
	$subscription = \Stripe\Subscription::create([
	  'customer' => $customer_id,
	  'items' => [
	    [
	      'plan' => 'plan_XXX', //setup in Stripe dashboard.
	    ],
	  ],
	  'expand' => ['latest_invoice.payment_intent'],
	  'billing_cycle_anchor' => time()
	]);
	$subscription_status = $subscription['status'];
	$subscription_id = $subscription['id'];
	if($subscription_status == "active"){
		//set current_period_end to 32 days (1 month plus some leeway) in the future. set past_due as false 
		$sql = "UPDATE `account_table` SET stripe_subscription_id = ?, current_period_end = ?, past_due = 0 WHERE email = ?"; 
		$result = $conn->prepare($sql);
		$past_due = false;
		$current_period_end = new DateTime;  
		$current_period_end->modify( '+32 day' );
		$current_period_end = $current_period_end->format('Y-m-d H:i:s'); 
		$result->execute(array($subscription_id, $current_period_end, $email));
	}

}
?>

On the server side our secret API key is used. A customer record is created in Stripe using the payment token and user’s email. The Stripe customer ID is then used to create a subscription. We record the the customer ID and subscription ID to our database. The account’s new subscription period end is updated to 32 days in the future.

Cancel a subscription

The user is able to cancel their subscription from the SplitWit account dashboard.

cancel subscription

We retrieve their subscription from Stripe, and cancel it, using their subscription ID. They will no longer be billed. We update our database to turn off the account’s experiments, delete any Stripe details, mark their subscription as delinquent, and re-write their snippet file.

<?php

function cancelSubscription(){
	require_once('stripe-php-6.43.0/init.php');
        \Stripe\Stripe::setApiKey('sk_XXXX');

	$conn = $this->connection;
	if(isset($_SESSION['userid'])){
		$accountid = $_SESSION['userid'];
	}else{
		die("No userid found.");
	}
	
	if(strlen($accountid)>0){
		$sql = "SELECT * FROM `account` WHERE accountid = ?"; 
		$result = $conn->prepare($sql); 
		$result->execute(array($accountid));
		$row = $result->fetch(PDO::FETCH_ASSOC);
	}
	$stripe_subscription_id = $row['stripe_subscription_id'];
	$subscription = \Stripe\Subscription::retrieve($stripe_subscription_id);
	$subscription->cancel();
	
	//turn off experiments and update snippets. clear stripe IDs. set current_period_end to yesterday. set past_due = 1
	$current_period_end   = new DateTime;  
	$current_period_end->modify( '-1 day' );
	$current_period_end = $current_period_end->format('Y-m-d H:i:s'); 
	$sql = "UPDATE `account` SET stripe_customer_id = '', stripe_subscription_id = '', past_due = 1, current_period_end = ? WHERE accountid = ?"; 
	$result = $conn->prepare($sql); 
	$result->execute(array($current_period_end, $accountid));

	//turn off all experiments
	$status = "Not running";
	$sql = "UPDATE `experiment` set status = ? where accountid = ?";
	$result2 = $conn->prepare($sql); 
	$result2->execute(array($status, $accountid));

	//update all snippets for this account (1 snippet per project)
	$sql = "SELECT * FROM `project` WHERE accountid = ?";
	$result3 = $conn->prepare($sql); 
	$result3->execute(array($accountid));
	$rows3 = $result3->fetchAll(PDO::FETCH_ASSOC);
	foreach ($rows3 as $key3 => $value3) {
		$projectid = $value3['projectid'];
    	        $databaseProjectService = new DatabaseProjectService();
		$databaseProjectService -> writeSnippetFile(false, false, $projectid);
	}

	$this->status = "complete";
}

?>

Re-billing subscriptions

As long as an account has an active subscription in Stripe, they will be automatically re-billed each month. When this event takes place, Stripe can deliver data about it to an end-point of our choice (commonly known as a webhook).

stripe webhooks

SplitWit listens for an event called “invoice.payment_succeeded”, which occurs when a customer’s monthly payment is successful. When that happens the account’s subscription period end is updated to 32 days in the future.

<?php
function webhookPaymentSuccess(){
	require_once('stripe-php-6.43.0/init.php');
	\Stripe\Stripe::setApiKey('sk_XXX');
	$payload = @file_get_contents("php://input");
	
	$endpoint_secret = "whsec_XXX";

	$sig_header = $_SERVER["HTTP_STRIPE_SIGNATURE"];
	$event = null;

	try {
	  $event = \Stripe\Webhook::constructEvent(
	    $payload, $sig_header, $endpoint_secret
	  );
	} catch(\UnexpectedValueException $e) {
	  // Invalid payload
	  http_response_code(400); // PHP 5.4 or greater
	  exit();
	} catch(\Stripe\Error\SignatureVerification $e) {
	  // Invalid signature
	  http_response_code(400); // PHP 5.4 or greater
	  exit();
	}
	
	if($event->type == 'invoice.payment_succeeded'){

		$invoice = $event->data->object;
		$customer_id = $invoice['customer'];
		//update their accocunt current_period_end
		$conn = $this->connection;
		$sql = "UPDATE `account` SET  current_period_end = ?, past_due = 0 WHERE stripe_customer_id = ?"; 
		$result = $conn->prepare($sql);
		$past_due = false;
		$current_period_end = new DateTime;  
		$current_period_end->modify( '+32 day' );
		$current_period_end = $current_period_end->format('Y-m-d H:i:s'); 
		$result->execute(array($current_period_end, $customer_id));
	}else{
		http_response_code(400);
	        exit();
	}
	
	http_response_code(200);
}

?>

What if payment fails or never happens? The account’s subscription period end never gets updated.

A daily scheduled task checks each active account’s subscription period end date. If that date is in the past, we mark the account as past due, turn off all experiments, and update its snippet files.

The value of experimentation

Driving digital conversions is a science. Experimentation should be a constant exercise in this respect. Take any field and we can benefit from testing the waters and adjusting our sail. Our ability to interpret that data is the bottle neck to making good decisions. The best lesson I’ve learned is that intuition is usually not enough. It’s better to look at the numbers and trust data.

Influencing users through a funnel of action, finally leading to a conversion, is a challenge. Optimizing conversions, sales, and leads can be broken down into a system based approach.  SplitWit focuses on that point.

www.SplitWit.com

My experience building digital products

digital product

When writing about digital problem solving, I tell stories about past projects. On top of a tech perspective, I also dig into the business, design, marketing, and inter-personal aspects. I’ve been fortunate enough to have a wide breadth of tech experience through my career. It has helped me dive deep into principles and ideas about building digital products. This range of experience was afforded by continually pursuing new work. Finding room for side projects and extra gigs is a great way to grow.

After a daily, hour-long commute I could barely sneak an hour or two for my creative projects and side gigs. But I always did. Side projects were often for paying clients, but sometimes just for fun. They would include not just programming, but also design, marketing, networking, and infrastructure. On top of this, I always made sure my hobbies would serve my overall goals. Reading good books, playing quality games, and being physically competitive all lead to a better life and career.

The key take-away is to work on a variety of projects. Be ready to try different technologies and new platforms. In general, keep trying new things.

Understand infrastructure. Survive some horror stories.

Web infrastructure and hosting setup are skills often missed out on by both casual programmers and professionals. Configuring domain names, email, web hosting, and load balancers is usually reserved for system administrators. Working as one-stop-shop, on your own or in a company, can give you the opportunity to manage all of these details.

I’ve gotten to work with many third-party services and vendors. I’ve seen the good and the bad, and even worse. AWS (Amazon Web Services) has been the best infrastructure provider that I have used. I’ve had horrible experiences from other companies.

Once having had my web servers infected by ransom-ware, HostGator wanted to charge nearly a thousand dollars, to solve the problem. This was the only solution they offered while multiple web properties were infected and out of commission. I fixed the issue myself in less than a few hours by purging all data from the servers and redeploying source code from version control. That was a nightmare.

Another time servers provided by OLM went down for multiple days. This was in 2014. During this time, they wouldn’t answer telephones, letting them ring. I stood on hold for at least 30 minutes, multiple times per day trying to get through. After nearly a week, things started working again, with no explanation provided. That was one of the most unprofessional experiences of my career. I will forever shout them out about this.

Get your hands dirty

Looking forward, I’m excited to explore more of AWS. I’m currently learning through online courses from Udemy: “Certified Solutions Architect” and “Certified Developer”, and plan to take the certification tests. Next, I want to jump into their “Machine Learning” and “Internet of Things” services.

I regularly use AWS services for cloud computing, storage, and databases. My go-to for a new project is to spin up a EC2 instance. If I know I’m using WordPress, I may use a Bitnami AMI. Other times, I’ll create a basic Linux box, and setup Apache, MySql, and PHP myself. Here is the documentation I regularly reference: Install a LAMP Web Server on Amazon Linux 2. This process usually includes configuring a domain name, and setting up SSL: Configure SSL/TLS on Amazon Linux 2.

I’ll continue this post as a series. I plan tell stories about my experiences in building digital products. I’ll cover topics such as design, marketing software, customization, and APIs. Follow me on Instagram for regular updates: @AntPace87

Remove subdirectories from a URL string

javascript

I use GitHub to manage code that I’ll want to re-use. I had trouble finding a canned function to remove the subdirectory path from a URL string – so I wrote one and added it to my latest public repository: https://github.com/pacea87/ap-utils

I’ll keep adding useful code to it – and feel free to make a pull request and contribute yourself. This code should focus on utility functions for manipulating data in interesting ways. Below is the JavaScript code for removing the subdirectories from a URL string. This will also strip away any query string parameters.

function removeSubdirectoryFromUrlString(url){
  
  var ssl = false;
  if(url.indexOf("https://")){
    ssl = true;
  }

  url = url.replace("http://", "");
  url = url.replace("https://", "");
  var pathArray = url.split("/")
  url = pathArray[0];
  if(ssl){
    url = "https://" + url;
  }else{
    url = "http://" + url;
  }

  return url;
}

Now, you can get the current page’s URL, and strip off everything after the host name:

var url = window.location.href;
var baseUrl = removeSubdirectoryFromUrlString(url);
console.log(baseUrl);

Another example:

var url = "https://www.antpace.com/blog/index.php/2018/12/";
var baseUrl = removeSubdirectoryFromUrlString(url);

//This will return "https://www.antpace.com"
console.log(baseUrl); 

I used this code to re-write all URL references in an iFrame to be absolute. My implementation loops through all image, anchor, and script tags on the source site. It determines if each uses an absolute reference, and if not re-writes it as one. This was part of a project that uses a visual editor to allow users to manipulate a remote site. Check out my source code below.

pageIframe.contents().find("img").each(function(){
  var src = $(this).attr("src");
  if(src && src.length > 0 && src.indexOf("//") == -1){  //if not absolute reference
    var url = iframeUrlString;
    if(src.charAt(0) == "/"){ //only do this if the src does not start with a slash
      url = removeSubdirectoryFromUrlString(url); 
    }
    src = url+"/"+src
  }
  $(this).attr("src", src);
});

pageIframe.contents().find("script").each(function(){
  var src = $(this).attr("src");
  if(src && src.length > 0 && src.indexOf("//") == -1){
    var url = iframeUrlString;
    if(src.charAt(0) == "/"){
      url = removeSubdirectoryFromUrlString(url); 
    }
    src = url+"/"+src
  }
  $(this).attr("src", src);
});

pageIframe.contents().find("link").each(function(){
  var src = $(this).attr("href");
  if(src && src.length > 0 && src.indexOf("//") == -1){
    var url = iframeUrlString;
    if(src.charAt(0) == "/"){
      url = removeSubdirectoryFromUrlString(url); 
    }
    src = url+"/"+src
  }
  $(this).attr("href", src);
});

If you liked this, check out my other post about my reusable code framework for web apps, A framework for web apps and startups.

Top 3 graphic design apps for social media marketing

Modern software has given creators the tools they need to showcase their work to the world. Here are the best free apps that I’ve been using that will help your talent shine in 2019:

AppWrap – Do you want to feature your latest website or app design to your followers? Are you building a portfolio for the UI/UX projects you worked on? This app is a great way to wrap your screenshots in a mobile device view. You can add effects, backgrounds, and text to really polish the look and feel. Their template gallery will give you inspiration to make something gorgeous. http://www.appwrap.in/

AntPace.com mobile device view

Canva – This is one of my favorites. With a library of over 60,000+ templates, this app has something for every platform. Whether you need to create a great looking post, story, or cover image, this app has designs for Instagram, Facebook, YouTube and much more. If you want your online presence to look professionally designed, check this one out! https://www.canva.com/

Anthony Pace creativity takes courage

Hatchful – Do you need a logo for your brand, business, or product? This app let’s you create one quickly. By customizing templates, you can draft, and iterate designs. Having logo design done fast, cheap, and easily allows you to focus on the actual product. It’s important to not get hung up on the logo, especially early into your venture, and instead focus on the actual value your service proposes. https://hatchful.shopify.com/

antpace.com

I’ve used all of these apps, and personally gained value from them. What apps do you use for your graphic design?

A template for web app startups

Having a framework in place when you start up will let you hit the ground running. This applies not just to software, but also business, health, fitness, and just about everything else in life. Having the dots ready to connect helps you to draw the right picture.

I recently released BJJ Tracker as a web app. You can read about it here. I built it knowing that I would want to reuse its code, and have it serve as a framework for future projects. I cleaned it up into a GitHub repository, trying to make it as generic as I could. Here is the link: https://github.com/pacea87/ap-template.

BJJ Tracker

I wanted to create a template to rapidly roll out digital products and software. This source code is a starting point. The goal is to be quick and cheap, without sacrificing quality. It runs in a LAMP environment. If you want to run this software on your computer, look into WAMP or MAMP.

This code base provides a front-end that leverages modern web technologies and standard best practices. A basic layout is described, including a header, menu drawer, feature buttons, and detail pages. It uses Bootstrap, jQuery, Font Awesome, Google Fonts, and Google Charts.

The back-end is object oriented, RESTful, and secure. Code that talks to the database, or to 3rd party APIs, has been separated out into *-service.php files. It includes SQL to create a user database. The database interacts with a custom registration and login engine. It allows for anonymous users, so that data can be saved before signing up, and a password is not needed to get started. It provides a reset password mechanism for users. It seamlessly integrates with Mailchimp and Facebook login. Redirects are in place to force SSL and WWW, and to remove file extensions from URLs. Next versions will address technical SEO and new API integrations.

source code

If you’d like to contribute to this repo, feel free to fork it, and make a pull request.

GitHub

Writing, engineering, and creativity

It was 2006 and I had just installed WordPress on a web server. I would draft blog posts nightly, before getting ready for bed. At the time I was a philosophy major and wrote prose more than code. That was my first venture into web development and digital marketing. It started with writing.

Writing blog posts and publishing software have a lot in common. For both, “perfect” is the opposite of ready. It’s easy to keep editing your own work. It’s even easier to keep adding half-done features and clutter. That’s why having a plan before you start helps so much. When I write, my first draft tends to be bullet points and a vague outline. The same goes for software. If I’m building something complex, I write comments explaining its functionality before any code. It’s my way of “thinking out loud”, and making sure that what I plan on doing even makes sense.

It’s been over a decade since I’ve maintained a blog. Creative tasks require hard work, lest they bear no fruit. (“Writer’s block is for amateurs”). Problem solving, in its many shapes, is the highest form of creativity. It’s how we build our reality. Modern technology gives us creative leverage through tools, knowledge, and community. We’re being given opportunities to build and create things, to grow and be better, at an unprecedented scale. It’s the best time in history to be CEO of your own life; creative director of your destiny. This also sets the bar higher to stand out.

My plan here is to write regularly, and discuss what I’ve been working on and learning, as well as what’s next. This gives me a chance to explore my thoughts, and prune the branches from which they stem. Hopefully, working at this will help to make me a better storyteller too.

BJJ Tracker, a fitness app

www.BJJTracker.com

BJJ Tracker is a fitness app for tracking Brazilian jiu jitsu training. It’s the sort of fitness app I was looking for, but couldn’t find. Version 1.0 is a bare bones MVP, but has a list of features on the way. Future versions will add gamification (including challenges and goals), UX/UI enhancements, training recommendations, and more.

The app allows users to record their training sessions, with details about drilling and sparring, as well as competition. This data is visualized over charts and calendars. The idea started from physically writing my training sessions onto an actual calendar, with a minimum goal per week. Building it has been a great exercise in digital product development, software design, and UI/UX strategy.

fitness tracker calendar

Software

BJJ Tracker is a web app, hosted on a AWS Linux server, running Apache, PHP, and MySql. I used Initializr to generate a bootstrap template to get my front-end started. One goal of this project was to build a web app framework that I could use to quickly get future projects running. This code would include user registration and login services, as well as other back-end concerns, on top of a front-end. I’ve cleaned most of this code into a generic repo on GitHub. You can read my post explaining its features.

Design

This app was designed with “mobile first” in mind, assuming that most users will be on a smart phone. The look and feel of the color palette, font-choice, and UI layout took some experimenting and visual research. It’s not final, and will be subject to split testing over time. I used Font Awesome to add icons as visual cues, giving the app a more finished look. The three lined (hamburger) menu in the top right comes as standard UI, using Simple MobileMenu, a jQuery plugin. Other UI elements include a top status message, and “In-Your-Face” status message, both of which are custom built notifications that I’ve wrapped as javascript plugins. Having a calendar section was important to me, and I consider to be a primary feature of the app. I use Full Calendar to generate the full month view. The homepage (dashboard) focuses on a week view. Google charts is used for the “techniques” graph.

logo design

The logo is a work-in-progress. The textual part was easy – pick a font, add a sharp outline, and a drop shadow. I always start with a 1024×1024 canvas. The symbol begins with simple shapes, triangles and circles. I left this process for last, saving my focus for the actual product. This allowed me to rapidly iterate design versions, and see how it would look directly in the user interface. Below is the current portrayal – and I’m excited for next versions.

bjj tracker

Challenges and next steps

One goal of this project was to get started fast, so people could begin using it. Deciding what to include out of a long list of ideas proved challenging. I could have kept adding features, and never been ready to make the site public. I meant to keep functionality basic, but still wanted the thing to be useful. The design needed to be simple, yet still had to look finished. I won’t know how close I came to getting this right until I analyze user feedback. The real plan is to do a little bit better next time, and to keep iterating. Using this as foundation will let future ventures start a step ahead. Already, I’ve begun implementing updates, and getting ready to deploy to the App Store and Google Play. Look out for coming updates and other products that are in the works! Don’t forget to visit the BJJ Tracker blog.

bjj tracker

Solutions, results, and leverage

The plan for my blog is to explore problem solving and creativity. It talks a lot about software development and technology. I cover coding and programming topics, as well as the business and marketing that goes along with building digital products. I showcase real examples of creating things of value, how to get started, and the many forms that engineering can take.

Engineering – 
‘The action of working artfully to bring something about’

The goal of all this is to explore the concepts behind developing solutions, getting results, and using leverage. I’ll cover subjects that I’m interested in such as programming, business, video games, grappling, fitness, food, and lifestyle design. You’ll get to see what I’m working on and what I’m into.

‘The price of anything is the amount of life you exchange for it.’
— Henry David Thoreau