Disclaimer
Multipart/form-data is a complex content type used to send HTML forms with binary (non-ASCII) data via HTTP POST, as specified in RFC-2045. Finding a standard method for this in SAP Integration Suite can be challenging, but there’s a workaround.
In this article, we explore practical solutions for handling multipart/form-data with SAP Integration Suite. Learn how to set up custom flows and ensure smooth data transmission.
Problems
Inconsistent Line Endings:
- One common issue noted in a blog post on SAP Community is the discrepancy in line endings. It was observed that Postman on Windows creates "correct" line endings, while SAP Integration Suite often generates UNIX line endings, which some APIs cannot handle.
Lack of Built-in Solution:
- Checking the SAP roadmap, there is no built-in solution for this specific problem. You can review the latest updates here.
Solution
When dealing with multipart/form-data in SAP Integration Suite, especially for systems that require strict adherence to standards and can only accept binary data, implementing a solution that meets these requirements can be challenging. Below is a script tailored to address these needs, ensuring proper handling of multipart/form-data with binary data.
The Script
Here's a script to handle multipart/form-data with binary attachments, adhering to RFC 2045 standards:
import com.sap.gateway.ip.core.customdev.util.Message
import java.util.Map
import javax.activation.DataHandler
import java.util.Random
import java.io.ByteArrayOutputStream
// Method to process the data
def Message processData(Message message) {
// Extract attachments
Map<String, DataHandler> attachments = message.getAttachments()
// Check if there are any attachments in the message
if (attachments.isEmpty()) {
// No attachments, return the message unchanged or perform other logic
return message
} else {
def bodyBuilder = new ByteArrayOutputStream()
def boundary = generateBoundary()
// Iterate through all attachments
attachments.values().each { attachment ->
def content = attachment.getInputStream().bytes
// Ensure boundary is not within the attachment content
while (new String(content).contains(boundary)) {
boundary = generateBoundary()
}
// Add boundary delimiter
bodyBuilder.write("--${boundary}\r\n".getBytes())
// Add attachment headers
bodyBuilder.write("Content-Disposition: form-data; name=\"file\"; filename=\"${attachment.getName()}\"\r\n".getBytes())
bodyBuilder.write("Content-Type: application/pdf\r\n".getBytes()) // Adjust the content type as needed
bodyBuilder.write("\r\n".getBytes())
// Add the attachment content in binary form
bodyBuilder.write(content)
bodyBuilder.write("\r\n".getBytes())
}
// Closing boundary delimiter
bodyBuilder.write("--${boundary}--\r\n".getBytes())
// Set the Content-Type header
message.setHeader("Content-Type", "multipart/form-data; boundary=${boundary}")
// Set the message body
message.setBody(bodyBuilder.toByteArray())
return message
}
}
// Method to generate a random boundary
def String generateBoundary() {
def chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
def boundary = new StringBuilder("WebKitFormBoundary")
def rand = new Random()
(1..16).each {
boundary.append(chars.charAt(rand.nextInt(chars.length())))
}
return boundary.toString()
}
Key Considerations
Binary Data Handling: The script ensures binary data is handled correctly by checking for boundaries within the attachment content and adjusting as necessary. This prevents issues with boundary markers appearing in the binary data.
Boundary Handling: The generateBoundary() method creates a unique boundary string to separate parts of the multipart message. The script includes a check to avoid boundary collisions within the attachment content.
Compliance with RFC 2045: While the script adheres to multipart/form-data standards, it’s important to note that escaping binary data using encoding (like base64) would be more compliant with RFC 2045 for handling non-ASCII data. However, for specific system constraints where binary data is required, this implementation meets those needs.
Error Handling: The script does not include explicit error handling, which is crucial for production environments. Implement proper exception handling to manage issues such as file read errors or boundary generation failures.
Additional Resources
These resources provide valuable information and solutions, but this article presents a practical script to effectively address multipart/form-data challenges.
