Transport Protocols
Technical specifications for AS4, AS2 and other transmission protocols enabling secure data transfer and message routing within the Peppol network infrastructure.
Transport protocols form the technical foundation of the Peppol network, ensuring reliable, secure, and standardized communication between Access Points across borders and systems.
AS4 Protocol
The modern standard for Peppol message exchange, offering enhanced security, reliability, and performance for enterprise-grade document transmission.
Security Standards
Built-in encryption, digital signatures, and authentication mechanisms ensure confidential and tamper-proof document exchange.
Reliable Delivery
Guaranteed message delivery with acknowledgments, retry mechanisms, and comprehensive error handling for mission-critical documents.
Peppol Transport Standards
Understanding the technical protocols that power secure document exchange in the Peppol ecosystem.
AS4: The Modern Standard
AS4 (Applicability Statement 4) represents the current generation of Peppol transport protocol, adopted as the mandatory standard for all new Access Point implementations. Built on web services and SOAP messaging, AS4 provides a robust framework for secure, reliable, and interoperable business document exchange.
The protocol offers significant advantages over its predecessor AS2, including better support for modern security standards, improved error handling, and native support for large file transfers. AS4 implements the OASIS ebMS3 specification, ensuring global interoperability beyond the Peppol network.
- WS-Security for message-level security
- Reliable messaging with delivery guarantees
- Support for large payload optimization
- Comprehensive error and exception handling
- Built-in message receipt and acknowledgment
AS2: Legacy Support
AS2 (Applicability Statement 2) served as the initial transport protocol for Peppol networks. While still supported for backward compatibility, AS2 is being phased out in favor of AS4. Organizations currently using AS2 are encouraged to migrate to AS4 to benefit from enhanced capabilities and continued support.
AS2 operates over HTTP/HTTPS and uses S/MIME for security. It provides basic reliable messaging through Message Disposition Notifications (MDNs), enabling senders to confirm successful delivery to recipients.
Protocol Selection Guidelines
New Access Point implementations must support AS4 as the primary protocol. Existing AS2 deployments should plan migration to AS4 within the timeline specified by OpenPeppol. Access Points may support both protocols during transition periods to ensure continuity of service.
Implementation Specifications
Detailed technical requirements and standards for implementing Peppol transport protocols.
Security Requirements
Transport protocols implement multiple layers of security to protect business documents during transmission. All Peppol communications require TLS 1.2 or higher for transport-level encryption, ensuring confidentiality of data in transit.
Security Architecture
- Transport Security: TLS 1.2+ encryption for all HTTP communications
- Message Security: XML digital signatures for document integrity and non-repudiation
- Authentication: Certificate-based identification of Access Points and participants
- Authorization: Validation of sender and receiver rights through SMP lookup
- Audit Trail: Comprehensive logging of all message exchanges and status updates
Message Structure
Peppol messages consist of multiple components packaged within the transport protocol envelope. The Standard Business Document Header (SBDH) provides routing information, while the payload contains the actual business document in UBL or other supported formats.
Each message includes metadata for addressing (sender and receiver identifiers), document type specifications, process identifiers, and unique message identifiers. This structured approach ensures reliable routing and processing throughout the Peppol network.
Error Handling
Robust error handling mechanisms ensure reliable message delivery even in challenging conditions. Protocols define standard error codes and handling procedures for various failure scenarios including network issues, validation errors, and business logic exceptions.
- Connection failures: Automatic retry with exponential backoff
- Invalid recipient: Immediate rejection with appropriate error code
- Schema validation failures: Detailed error messages for correction
- Duplicate messages: Detection and appropriate handling
- Timeout conditions: Configurable retry and fallback procedures
Getting Started with Transport Protocols
Practical guidance for implementing and configuring Peppol transport protocols in your infrastructure.
Access Point Requirements
Implementing a Peppol Access Point requires adherence to specific technical standards and operational procedures. Access Points must be certified by Peppol Authorities before joining the production network, ensuring compliance with all technical and governance requirements.
Technical Specifications
Follow OpenPeppol's detailed technical specifications for AS4 implementation, including message exchange patterns and security profiles.
Security Certificates
Obtain and maintain valid certificates from approved certificate authorities for authentication and encryption purposes.
Performance Standards
Ensure adequate infrastructure to handle message volumes with appropriate response times and availability guarantees.
Testing & Validation
Complete comprehensive testing in the Peppol test environment before certification for production deployment.
Integration Considerations
Organizations implementing transport protocols should consider both technical and operational aspects. Choose between building a custom Access Point, deploying open-source solutions, or partnering with certified service providers based on your technical capabilities and business requirements.
Key factors include message volume expectations, required service level agreements, internal IT capabilities, compliance requirements, and total cost of ownership. Many organizations opt for managed service providers to avoid the complexity of Access Point operation while maintaining full Peppol network connectivity.
Technical Documentation
Access detailed specifications, implementation guides, and technical resources for Peppol transport protocols.
AS4 Profile Specification
The official OpenPeppol AS4 profile documentation with complete technical specifications and implementation requirements.
Message Envelope Specification
Detailed documentation on Standard Business Document Header (SBDH) and message packaging requirements.
OpenPeppol Downloads
Access technical specifications, schemas, testing tools, and reference implementations from OpenPeppol.
Open Source Components
Explore OpenPeppol's GitHub repositories with reference implementations, validators, and code samples.
Need Support with Transport Protocols?
Whether you're implementing your own Access Point or evaluating service providers, we can help you navigate the technical requirements and ensure successful Peppol network integration.