Checkout Redirection in Magento 2

[Abhi2244]

I am building a custom payment module that will redirect to a payment gateway page and want to know that how the data is flowing in the magento 2 architecture and how to send the data to an external payment gateway in magento 2. 

[Dmitry_Fedyuk]

Just use Xdebug to trace a code execution flow.

[Abhi2244]

Thanks for the Xdebug and also i want to send the order details to an external payment gateway please help me with that.

[Dmitry_Fedyuk · Accepted solution]

How to request an external web API:  

\Magento\Framework\HTTP\ZendClient

• How does the Authorizenet module request the payment gateway
• How does the DHL module request the carrier API
• How does the Magento OAuth server request a consumer
• How does the PayPal module request the PayPal Payflow API
• How does the USPS module request the carrier API
• How does the backend currency rates import work
• How does Magento 2 request the New Relic API

\Magento\Framework\HTTP\Adapter\Curl

• How does the backend check a web accessibility of the app/etc/config.php
• How does the backend request the official notification feed
• How does the Marketplace module retrieves the Magento partners list
• How does the PayPal module request the PayPal NVP API
• How does the ProductVideo module load a video preview image from YouTube or Vimeo

The plain \Zend_Http_Client

• How does the UPS module request the carrier API

The plain curl_exec:

• How does the Fedex module request the carrier API

\Magento\Payment\Gateway\Http\Client\Soap

• How does \Magento\Payment\Gateway\Http\Client\Soap work

\Magento\Payment\Gateway\Http\Client\Zend

• How does \Magento\Payment\Gateway\Http\Client\Zend work

[Abhi2244]

I am having a problem with the place order button, whenever i am pressing it, it's redirecting to itself and also there are some variables inside the url like ?form-key etc.

[Abhi2244]

Thanks for the support it has been resolved but one last question.

When i am pressing place order button it is redirecting me to the cart.

[Ankit_Drc]

Can you please provide details in simple way

[Lina_R]

Try to use capture payment action rather than authorize in config.xml file as following:

1-  <can_capture>1</can_capture>

2- <payment_action>capture</payment_act