AS2 vs SFTP for EDI: What's the Difference?
AS2 and SFTP are two of the most common methods used to exchange EDI documents between trading partners. Both support secure file transfer, but they work in different ways and are used for different business needs.
What Is AS2?
AS2 stands for Applicability Statement 2. It is a protocol used to send EDI or other business documents securely over HTTP or HTTPS.
AS2 is widely used in enterprise EDI because it supports:
- Encryption
- Digital signatures
- Secure direct transmission
- Message integrity checks
- MDN acknowledgments
AS2 is commonly preferred when businesses need strong tracking and immediate confirmation that a message reached the receiving AS2 server.
What Is SFTP?
SFTP stands for Secure File Transfer Protocol. It is used to transfer files securely between systems over SSH.
In EDI workflows, SFTP is often used to upload and download files from partner-specific folders on a secure server.
SFTP is commonly chosen for:
- Batch file exchange
- Scheduled integrations
- Simpler partner setups
- Secure folder-based processing
It is straightforward and widely supported across many platforms.
Key Difference Between AS2 and SFTP
The main difference is how files are delivered and acknowledged.
- AS2 sends a message directly from one system to another
- SFTP places files on a secure server for pickup or download
AS2 is more message-oriented, while SFTP is more file-drop oriented.
Security Comparison
Both AS2 and SFTP are secure, but they use different security models.
AS2 Security
AS2 typically uses:
- SSL/TLS for transport security
- Certificates for encryption and signing
- MDNs for delivery confirmation
SFTP Security
SFTP typically uses:
- SSH-based encrypted communication
- Username/password or SSH key authentication
- Secure directory access controls
Both can be secure when implemented correctly, but AS2 usually offers stronger message-level visibility in EDI environments.
Acknowledgment and Tracking
One of the biggest advantages of AS2 is the MDN, or Message Disposition Notification.
An MDN confirms that the receiving AS2 server got the message at the transport level. This makes AS2 useful when trading partners require proof of delivery.
SFTP does not normally provide the same built-in acknowledgment mechanism. A file may be uploaded successfully, but additional application logic is usually needed to confirm whether it was processed correctly.
AS2 is often better when:
- Trading partners require MDNs
- Real-time or near real-time transmission matters
- Strict compliance or partner requirements exist
- Direct partner-to-partner communication is needed
SFTP is often better when:
- File exchange is batch-oriented
- Partner setup needs to stay simple
- Scheduled drop-and-pick workflows are acceptable
- Existing infrastructure already uses secure folders
Operational Considerations
When choosing between AS2 and SFTP, businesses should also consider:
- Trading partner requirements
- Certificate management
- Key rotation and credential handling
- Retry behavior
- Monitoring and alerting
- File processing workflows
AS2 often requires more setup and certificate management, while SFTP may be easier to start with but needs extra controls for processing visibility.
Common Use in Modern EDI Platforms
Many modern EDI platforms support both AS2 and SFTP.
A strong EDI platform can:
- Receive files from AS2 and SFTP
- Validate incoming EDI documents
- Route them to the correct workflows
- Track acknowledgments and failures
- Maintain centralized logs and audit history
Conclusion
AS2 and SFTP are both important for EDI communication, but they serve different operational needs.
AS2 is ideal when businesses need secure direct transmission with delivery acknowledgment, while SFTP is a practical option for secure file-based exchange and scheduled processing.
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