June 15, 2021

How to connect to Ethereum using PHP

Overview

PHP is a very popular choice among developers and has a vast community due to its long presence in web development. In this guide, we’ll cover how to connect to Ethereum with PHP using the web3.php library.

Prerequisites
  • A text editor
  • CLI

What is PHP?

PHP, which initially stood for Personal Home Page, is now a recursive acronym for PHP: Hypertext Preprocessor. It is a general-purpose scripting language most commonly used for building back-ends of websites. PHP code is processed on the server-side by a PHP interpreter. PHP can be embedded in HTML, used in standalone files, and on the command line. It is open-source and cross-platform compatible. PHP 7+ is speedy,  used by nearly 80% of websites, and has active development. It is high in demand and can be used to make dynamic websites, template systems, process user-submitted data, e-commerce websites, etc.

Why use PHP?

  • PHP is mature, well tested, and predictable.
  • It has lots of open source libraries so that you can do many things with it right away.
  • Though it is derived from the C++ family, PHP codes are comparatively shorter.
  • It Integrates easily into the HTML/CSS stack, unlike other languages.
  • It has many impressive frameworks such as Symfony and Laravel.
  • It has a short learning curve when compared to JSP and ASP.
  • It allows developers to achieve many complex things very quickly and easily.

Characteristics of PHP?

  • Scalability - helps to build scalable web applications.
  • Flexibility - Works with major operating systems.
  • Simplicity - Easy and straightforward to use compared to other scripting languages.
  • Case Sensitive - PHP is a case-sensitive language at the time of variable declaration. All keywords, classes, functions, and user-defined functions are not case-sensitive.
  • Loosely typed - In PHP, variables can be declared without the data type. It’s determined at the time of interpretation based on the kind of data it contains.
  • Interpreted - PHP is an interpreted language, which means there’s no need for compilation.
  • Open Source - It is open source, which means free to use and well maintained.

What is web3.php?

Web3.php is a PHP interface for connecting and interacting with the Ethereum blockchain. It is open-source, and can be used to get blockchain data and interact with deployed contracts. It has inbuilt support for eth, web3, net, and shh JSON RPC modules of Ethereum.

For our purpose today, we’ll fetch the latest block number of the Ethereum blockchain to demonstrate a connection between our code and Ethereum. 

We’ll use web3.php and an Etherum node. 

Installing PHP and web3.php

Before installing the web3.php, let’s check if we have PHP installed on our system. To do so, copy-paste and run the following in your terminal/cmd.

php -v

It should return the PHP version. If not installed, download the operating system-specific PHP by following the instructions on the official PHP website’s download page.

We’ll need to install the PHP gmp extension. You can either uncomment it from the php.init file or install it manually using the following.

sudo apt-get install php-gmp

Note: We should enable gmp using only one of the methods mentioned above. 

For mac:

Reinstalling PHP with brew can help to enable the gmp extension. 

Run the following commands:

brew reinstall php@7.2
export PATH="/usr/local/opt/php@7.2/bin:$PATH"
brew services restart php@7.2
php -info | grep "GMP"

We’ll use composer, a tool to manage PHP libraries/dependencies. Check if composer is installed on your system by running the following in your terminal/cmd:

composer 

If not installed, download and install it by following the Composer website’s downloads page.

Now create a JSON file named composer.json in your project directory and copy-paste the following in it.

{
    "require": {
        "sc0vu/web3.php": "dev-master"
    }
}

Then run the following command to install the required dependencies in the directory.

composer install


Note: If you encounter any error on Linux at this point, try installing the following dependency: 

sudo apt-get install php-mbstring

Booting our Ethereum node

We could use pretty much any Ethereum client; such as Geth or OpenEthereum (fka Parity), for our purposes today. Since that is a bit too involved for just querying the block height, we'll grab a free trial endpoint from QuickNode to make this easy. It can be a testnet (like Ropsten, Rinkeby or Kovan) or Mainnet. After you've created your free Ethereum node, copy your HTTP Provider endpoint:
 
 

You'll need this later, so copy and save it.

Connecting to Ethereum with PHP

Now, make a PHP script file index.php in your project directory and copy-paste the following in it.

<?php

require_once "vendor/autoload.php";

use Web3\Web3;
use Web3\Providers\HttpProvider;
use Web3\RequestManagers\HttpRequestManager;

$web3 = new Web3(new HttpProvider(new HttpRequestManager("ADD_YOUR_ETHEREUM_NODE_URL")));

$eth = $web3->eth;

$eth->blockNumber(function ($err, $data) {
        echo "Latest block number is: ". $data . " \n";
});
?>

Make sure to replace `ADD_YOUR_ETHEREUM_NODE_URL` with the HTTP provider from the section above.

Explanation of the code above.

Line 1: Starting the PHP script with PHP opening tag.

Line 3-7: Importing the installed dependencies.

Line 9: Initializing the web3 instance, a HttpProvider instance, and supplying the node URL.

Line 11: Making a new variable eth and connecting the web3 instance with eth to use eth methods using our node.

Line 13: Getting the latest block number from the chain using the blockNumber() method, which under the hood uses eth_blockNumber. We then print the block number along with a string.

Save the file and run the PHP script by typing the following in your terminal/cmd:

$ php index.php

If everything goes well, you will see an output that shows the latest block number.

Conclusion

Congratulations on connecting to the Ethereum network using PHP. Now, you can take advantage of the Ethereum network by integrating it into your server-side applications, making them more secure and robust. 


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