External Host Interface (EHI) Integration Guide

1. Overview

Payblr supports an External Host Interface (EHI) integration for real-time transaction authorization and transaction event delivery.

This guide explains how your system receives EHI messages from Payblr, validates each request, processes the original EHI payload, and returns the required JSON response.

The required response depends on the message type. Authorization messages require an authorization decision. Advice, reversal, financial, chargeback, and cut-off messages generally require an acknowledgement or cut-off result.

1.1 EHI Transaction Message Flow

The EHI transaction flow delivers real-time card and payment-related messages in JSON format. Payblr forwards the original EHI payload to the external host URL endpoint configured for your system and relays your response through the transaction flow. Message types may include authorizations, advice messages, reversals, financial/presentment messages, financial reversals, chargebacks, chargeback reversals, and cut-off messages.