MeS Payment Gateway Developer's Guide

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Introduction to the Merchant e-Solutions (MeS) Payment Gateway - An affordable API solution for payment processing that's easy on your IT resources.

MeS Payment Gateway Overview
MeS Payment Gateway Brochure

MeS Payment Gateway Developer's Guide

1. Getting Started

2. Technical Overview

3. Additional Services

4. Certified Shopping Carts & Third Parties

5. Reporting Options

6. Chargebacks

7. List of Reference Materials

8. Guides and SDKs


1. Getting Started

This site identifies the process and provides the documentation necessary for sending transactions to the MeS Payment Gateway. The first part of the document addresses using the MeS Payment Gateway for basic credit card processing. Optional features follow with each having their own sectional heading. Some section headings will reference specific documents. These can also be accessed through the list of Reference Materials link.

The MeS Payment Gateway enables merchants to run live credit card transactions by acting as a bridge between a point of sale system, and the MeS payment network. It does this by receiving a name-pair value URL constructed by the merchant's website, processing the request, then returning the proper result.

To effectively implement the MeS Payment Gateway, basic API programming knowledge is required. While transactions are submitted as a URL, it is recomended to use a server-side scripting language to build the HTTP request.

Note: The language used is completely up to the developer. The API document contains examples covering Java, Javascript, PHP, and C#.
Certification Process

This section identifies the steps taken by the developer and MeS to validate the transactions submitted to the MeS Payment Gateway contain the proper fields to qualify transactions at desired Interchange rates.

  1. Developer Downloads API documents from this site
    • Payment Gateway Certification Request Form - After filling out this form, any questions may be emailed to mes_certification@merchante-solutions.com. This request form is used to customize the certification process.
    • Payment Gateway Certification Update Form - This form  is used to request updates to a certification which is already complete.
    • MeS Gateway Specifications - This document provides information on the tools provided by the Back Office. The guide also provides a demo login that can be used for training purposes.
    • Once the completed certification request form is received, the certification manager contact information is provided.
    • Optional Services - Download and review additional services if desired.
    • Certification questions may be directed to mes_certification@merchante-solutions.com
  2. Systems Development & Certification Testing
    • Upon receipt of the completed Certification Request Form, a Development Profile ID (PID) is delivered to the developer.
    • When development is complete, the developer notifies the MeS Certification Manager.
    • The MeS Certification Manager then provides a test script based upon the transaction sets identified in the Certification Request Form.
    • Once the client processes the transactions according to the script, the Certification Manager reviews the transactions to ensure all necessary fields required for successful processing and interchange compliance are present.
  3. Production
    • A Certification Letter is sent by MeS to the client with a production PID.
    • Client updates the Certification PID with the Production PID, and begins processing live transactions.
    • Production transactions are reviewed by MeS for a period of 3-5 days after the start of processing. If there are any issues with interchange qualification or transaction rejects, the client is notified with detailed information on how to resolve.

An optional fourth step involves Regression and Enhancement testing. A new development PID is assigned for additional testing. Regression PIDs are pointed to the payment simulator, so that all transactions are processed in our test environment.

System Architecture

The MeS Payment Gateway is a state of the art system utilizing multiple director and server technology to efficiently route traffic and provide multiple layers of redundancy. The system is easily scalable and coded in a manner that accommodates a flexible development environment. Merchant e-Solutions maintains systems at two different sites that are always on, with traffic routed to both systems. If any service interruption is detected, traffic is automatically re-routed to the other site to maintain service levels and processing availability.

2. Technical Overview

MeS Payment Gateway API Specification
Current Version 4.10
Minimum Transaction Requirements

The makeup of the url is as follows. This is the bare minimum required to process a sale.

Example sale request
POST /mes-api/tridentApi HTTP/1.1
      Content-Type: application/x-www-form-urlencoded
      Cache-Control: no-cache
      Pragma: no-cache
      User-Agent: Java/1.7.0_21
      Host: cert.merchante-solutions.com
      Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2
      Connection: keep-alive
      Content-Length: 578
profile_id=94100009999900000001&profile_key=A7B8C9A7A7B8C9A7A7B8C9A7A7B8C9A7&
transaction_type=D&card_number=4262369999996102&card_exp_date=0409&
transaction_amount=.15&cardholder_street_address=920&cardholder_zip=99212&
invoice_number=12345&tax_amount=0.01

Where profile_id is a 20-digit number and profile_key is a 32-character string both provided by the MeS Certification Manager. The transaction_type, transaction_amount, card_number and card_exp_date are variables for each transaction.

The basic approval response contains five (5) fields.

Example response URL
transaction_id=XXXX&error_code=000&auth_response_text=Approval TXXXXX&avs_result=0&auth_code=TXXXXX

The transaction_id is unique for each transaction processed. It is a 32-character string.
The error_code returns 000 with a successful authorization. Additional error codes are provided in the MeS Payment Gateway API Document in the list of Reference Materials section.
The auth_response_text is a textual representation of why the transaction approved/declined. If there is an error processing the transaction, an easy to understand reason corresponding with the error_code will display here.
The Avs_result displays 0 if no address or zip information is submitted.
The auth_code will always be a 6 digit response from an issuing bank.

Authorizations from the Payment Simulator will always begin with a "T".

For additional transaction types and fields such as AVS, CVV, and invoice see the MeS Payment Gateway Specification.

3. Additional Services

Corporate and Purchasing Card Processing
MeS Payment Gateway Corporate Card Specification
Current Version 1.1

Corporate Card processing is used by the government and large corporations to make business-to-government and business-to-business purchases. These transactions are typically authorized by end users presenting what are called Purchasing Cards, or 'P' Cards for payment. American Express cards are usually referred to as Corporate Cards.

Corporate card processing provides specific data about the purchase such as item description, quantity, unit-of-measure, price, sales tax, as well as detailed merchant and cardholder information. This data is captured by the payment processor, and passed on to the card issuer. The intent of this program is to replace the traditional paper Purchase Order process. The card issuer then provides this detail to the cardholder/purchaser in the form of a monthly statement or web-based reporting.

The above supplemental guide details the additional requirements needed to process these transactions and qualify at the preferred Level III Interchange rates for Visa and MasterCard as well as comply with American Express Corporate Card requirements (CPC). This is a companion guide to the MeS Payment Gateway Specification, and clients must certify all other basic transaction sets prior to implementation of corporate card processing as some key elements are required as part of the overall corporate card implementation.

3D Secure
MeS Payment Gateway 3D Security
Current version 1.2

3D Secure functionality allows a merchant to process Verified by Visa and MasterCard SecureCode through a single payment gateway. Use of this functionality provides additional chargeback protection and preferred Interchange rates. This process involves the additional requirement of posting a URL for the consumer to either register their card or perform the secure code process as part of their transaction request.

4. Certified Shopping Carts & Third Parties

5. Reporting Options

MeS Reporting API
MeS Reporting API
Current Version 2.4

The Reporting API is an interface to the MeS reports, available to all merchants. The API allows you to run custom queries on all report types including batches, deposit history and chargebacks spanning the merchant's entire processing history.
The query can be further customized by setting a starting/ending date and encoding type.

MeS Back Office
MES Payment Gateway Back Office User Guide
Current Version V2.5

The MeS Back Office provides a comprehensive set of tools to be used in conjunction with the MeS Payment Gateway Interface:

  • Administration: to set up AVS and CVV acceptance flags, batch close time, and batch summary email notifications.
  • Transaction: simple 'virtual terminal' for manual exception processing.
  • Reports: unsettled, settled, and rejected transaction reports.

6. Chargebacks

The chargeback API allows for upload of documentation pertaining to chargeback rebuttals.
Chargeback API Request Form


7. List of Reference Materials

MeS Payment Gateway Specification
Payment Gateway Certification Request Form
MeS Payment Gateway Corporate Card Specification
MeS Reporting API
MeS Payment Gateway Retry Processing Guide
MeS Payment Gateway 3D Security
MeS Payment Gateway Back Office User Guide
MeS FX Currency Code Table

Document Repository


8. Guides and SDKs

CSharp Client Library
PHP Client Library
Python Client Library
Transparent Redirect Tokenization

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