<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="catalog_product_save_after">
        <observer name="test_name" instance="RahahaRahahaWebServiceObserverProductsaveafter" />
    </event>
</config>

<?php
namespace RahahaRahahaWebServiceObserver;

use MagentoFrameworkEventObserverInterface;
use MagentoFrameworkEventObserver;

class Productsaveafter implements ObserverInterface
{
    protected $_request;
    protected $_resource;
    protected $_scopeConfig;
    protected $_rahaha;

    public function __construct(
        MagentoFrameworkAppRequestInterface $request,
        MagentoFrameworkAppResourceConnection $resource,
        MagentoFrameworkAppConfigScopeConfigInterface $scopeConfig
    )
    {
        $this->_request = $request;
        $this->_resource = $resource;
        $this->_scopeConfig = $scopeConfig;

        $storeScope = MagentoStoreModelScopeInterface::SCOPE_STORE;
        $rahaha_username = $this->_scopeConfig->getValue("adminsample/rahaha_module_credentials_grp/rahaha_username", $storeScope);
        $rahaha_password = $this->_scopeConfig->getValue("adminsample/rahaha_module_credentials_grp/rahaha_password", $storeScope);
        $rahaha_api_key = $this->_scopeConfig->getValue("adminsample/rahaha_module_credentials_grp/rahaha_api_key", $storeScope);
        $rahaha_module_status = $this->_scopeConfig->getValue("adminsample/rahaha_module_status_grp/rahaha_module_status", $storeScope);

        $rs = $this->_resource;

        $this->_rahaha = new RahahaRahahaWebServiceModelRahahaRahaha($rahaha_username, $rahaha_password, $rahaha_api_key, $rahaha_module_status, $rs);
    }

    public function execute(MagentoFrameworkEventObserver $observer)
    {
        $post_data = $this->_request->getPost()->toArray();

        //save stuff here...
    }
}