Step-by-Step Guide: Real Time Currency Conversion using SAP Integration Suite (CPI)

Introduction

Business Scenario

Input Payload (Source System to CPI)

The source system (ie, Postman) sends a simple JSON payload:

Mandatory Fields

• sourceCurrency – currency to convert From
• targetCurrency – currency to convert To
• sourceAmount – amount to be converted

NOTE:

High‑Level Architecture

The integration flow consists of:

1. HTTPS Sender – receives the request 
2. Content Modifier – stores RapidAPI host and key securely 
3. Groovy Script – validates input and extracts fields 
4. Request Reply – calls external exchange‑rate API 
5. JSON to XML Converter – prepares response for XSLT  
6. XSLT Mapping – beautifies output into HTML 
7. Mail Adapter – sends result to user 
8. Exception Subprocess – handles all runtime failures

STEP 2: Content Modifier – Managing API Credentials

STEP 3: Groovy Script – Input Extraction & Validation

The Groovy script performs hard validation for the incoming payload.

Here is the Groovy Script:

 So in this Groovy script, I have :

This hard validation is crucial because CPI does not throw errors for missing JSON fields by default.

Because of this, invalid messages are stopped immediately and routed to the Exception Subprocess 

STEP 4: Request Reply – Calling the Exchange Rate API

The Request Reply step dynamically calls the external RapidAPI Currency Exchange endpoint using:

• Source currency
• Target currency
• Secure headers from the Content Modifier

And If the API:

• Times out
• Returns an error
• Is unreachable

Exception Subprocess handles the failure gracefully.

STEP 5: JSON to XML Converter

Since XSLT only works with XML, so i converted the API’s JSON response into XML.

• Mapping easier
• Formatting predictable
• Transformation logic much cleaner

STEP 6: XSLT Mapping – Beautified HTML Output

Here is the XSLT Script:

Features that i have focused for beautification includes:

• A green glowing success card 
• Currency symbols 
• Proper decimal formatting 
• Email‑safe inline CSS 
• Readable and user friendly

STEP 7: Mail Adapter – Delivering the Result

The Mail Adapter sends:

• The formatted HTML
• Clean layout
• No broken styling
• Compatible with Outlook, Gmail, mobile clients

STEP 8: Exception Subprocess – For Error Handling

The Exception Subprocess ensures there are no silent failures and handles errors effectively.

Here’s what the Groovy script does:

• Captures runtime errors
• Identifies what actually went wrong
• Categorizes the error:
  • Missing mandatory fields
  • Malformed JSON
  • External API failure
  • Script execution error
• Generates modern card formation using HTML for Beautification 

Here what the Error Mail Adapter does:

• Send a structured and well formatted HTML error email, just like as for success mail

Success Email Output:

• Gives successful currency conversion information dynamically

Error Email Output:

• Gives Error message and its possible causes in case of any error

Key benefits of this approach 

1. Robust mandatory field validation
2. Secure credential handling
3. Professional, email‑ready output
4. User‑friendly error messages
5. Reusable iFlow pattern for other APIs
6. Fully Externalized Parameters 

Conclusion

This implementation helped me better understand how to design flexible and maintainable integration flows, especially when dealing with real-world requirements.

I hope this experience helps others who are working on similar scenarios in SAP Cloud Integration.

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