What is AS2?
AS2’s core purpose and function revolves around secure data transmission in the business world. At its heart, AS2 serves as a protocol that enables companies to send sensitive business information over the internet using standard HTTP or HTTPS connections. Think of it as a specialized courier service for digital data – it takes your business documents, wraps them in layers of security, and ensures they reach their destination safely. What makes AS2 particularly valuable is its ability to handle EDI (Electronic Data Interchange) files, which are the standardized formats businesses use to exchange information. Unlike regular email or file transfers, AS2 provides a structured, secure pathway specifically designed for business communications.
What are the key features of AS2?
The key features of AS2 form a comprehensive security framework that makes it trustworthy for business use. Digital certificates act like electronic ID cards, allowing businesses to verify who they’re communicating with. The encryption process transforms readable data into coded information that can only be decrypted by the intended recipient, much like a sophisticated digital safe. Digital signatures serve as electronic fingerprints, ensuring that messages haven’t been tampered with during transit. One of AS2’s most practical features is its automatic receipt system (MDNs), which provides proof of delivery – similar to a return receipt in postal mail. Since AS2 operates over standard web protocols, it can easily work within existing corporate networks and through firewalls, making it both practical and secure.
More details on the Message Disposition Notification (MDN)
MDN Types:
- Synchronous MDNs: Sent back immediately through the same HTTP/HTTPS connection
- Asynchronous MDNs: Sent as a separate transmission, useful when immediate confirmation isn’t possible
- Signed MDNs: Include a digital signature for added security and non-repudiation
How MDNs Work:
- When sending an AS2 message, the sender requests an MDN in the message headers
- The receiving system processes the message
- The receiver generates an MDN containing:
- Original message ID
- Processing status (success/failure)
- Timestamp
- Error details if applicable
- The MDN is sent back to the sender
MDN Status Messages:
- “Message received/processed”: Successful delivery and decryption
- “Message failed”: Issues with decryption, verification, or processing
- “Message pending”: Still being processed
- Specific error codes for troubleshooting
Business Benefits:
- Proof of delivery for legal compliance
- Automated tracking of message status
- Quick identification of transmission problems
- Audit trail for all communications
- Undeniable proof of receipt when signed MDNs are used
Common MDN Configurations:
- Both sync and async MDNs may be enabled for redundancy
- Signed MDNs for sensitive transactions
- Retry settings for failed MDN deliveries
- Timeout settings for expected MDN receipt for identifying missing transactions
AS2 Certificates
AS2 certificates are digital identification documents (like a digital ID card) that prove who you are when sending AS2 messages. Here are the main third-party certificate authorities (CAs) that issue and verify AS2 certificates:
Major Certificate Authorities:
- DigiCert (formerly Verisign)
- Entrust
- GlobalSign
- Sectigo (formerly Comodo)
- IdenTrust
These certificates serve two main purposes:
- Encryption: Scrambling the data so only the intended recipient can read it
- Digital Signatures: Proving who sent the message and that it hasn’t been changed
Certificate Types:
- Self-signed certificates (created by your own organization)
- Third-party signed certificates (created and verified by a Certificate Authority CA)
Most large businesses prefer third-party signed certificates because they:
- Are widely trusted
- Meet compliance requirements
- Reduce setup problems with trading partners
- Come with support if issues arise
- Include verification of your organization’s identity
The process to get a certificate typically involves:
- Creating a Certificate Signing Request (CSR)
- Providing proof of your organization’s identity
- Paying the CA’s fee
- Receiving your signed certificate
- Installing it in your AS2 software
What are common uses of AS2?
When it comes to common uses, AS2 has become deeply embedded in modern business operations. Companies routinely use it to transmit EDI documents that manage their supply chains, sending purchase orders to suppliers, receiving invoices from vendors, and sharing real-time inventory data with partners. For example, a retail chain might use AS2 to automatically send purchase orders to suppliers when inventory runs low, receive shipping notifications when goods are on the way, and process electronic invoices for payment. This automation and security make AS2 particularly valuable in industries where timing and accuracy are crucial, such as retail, manufacturing, and logistics. The protocol’s popularity stems from its perfect balance of security, speed, and cost-effectiveness – it’s more secure than traditional FTP transfers, operates at internet speeds, and doesn’t require expensive private networks to function.
What are the advantages to using AS2 over a Value Added Network (VAN)?
Cost Structure: AS2 typically has lower ongoing costs since it uses the internet instead of requiring VAN subscription fees. While AS2 has upfront costs for setup and certificates, these are usually offset by eliminating monthly VAN charges. VANs charge by volume of data transferred, while AS2 uses your existing internet connection.
Speed and Control: AS2 offers direct, real-time transmission between trading partners. Data moves immediately from sender to receiver, unlike VANs which may store and forward messages through intermediary servers. This direct connection gives businesses more control over their data flow and timing.
Security Features: AS2 provides point-to-point encryption, digital signatures, and automatic receipts (MDNs). While VANs also offer security, AS2’s end-to-end encryption means data is protected directly between trading partners rather than moving through third-party servers.
Technical Requirements: AS2 requires more technical expertise to set up and maintain compared to VANs. You need to:
- Manage digital certificates
- Configure software
- Handle direct connections with partners
- Maintain your own infrastructure
Scalability: AS2 works well for organizations with:
- Higher transaction volumes (cost becomes more favorable)
- Regular trading partners
- Technical resources to manage connections
- Need for real-time data exchange
However, VANs might still be preferable for:
- Smaller businesses with low transaction volumes
- Companies lacking technical resources
- Organizations needing to connect with many occasional trading partners
- Situations requiring additional VAN services like data transformation
What are the differences between AS2 and AS4?
Let me break down the key differences between AS2 and AS4:
Protocol Structure:
- AS2 uses HTTP/HTTPS for transport
- AS4 builds on web services (ebMS 3.0/SOAP), making it more flexible for complex messaging patterns
Message Handling:
- AS2 primarily handles point-to-point communication (one sender to one receiver)
- AS4 supports advanced patterns like multi-hop messaging, message pulling, and store-and-forward capabilities
Security Features:
- AS2 provides basic encryption and digital signatures
- AS4 offers enhanced security with WS-Security standards, supporting more encryption methods and security tokens
Receipt Management:
- AS2 uses MDNs (Message Disposition Notifications) for simple receipt confirmation
- AS4 has more sophisticated receipt options, including non-repudiation and message status tracking
File Handling:
- AS2 typically handles one payload per message
- AS4 can manage multiple payloads in a single message and supports message splitting/joining for large files
Adoption and Use:
- AS2 is widely used in retail and supply chain, especially in North America
- AS4 is more common in European markets and complex B2B scenarios, particularly in government and healthcare
While AS4 is technically more advanced, AS2’s simplicity and widespread adoption make it sufficient for many business needs. AS4 is typically chosen when organizations need its additional features like message pulling or multi-hop capabilities.
What Happened to AS3?
AS3 (Applicability Statement 3) was developed as a potential successor to AS2, but it never gained widespread adoption in the market. Here’s what happened:
AS3 was designed to use FTP/FTPS instead of HTTP/HTTPS for transport, which initially seemed promising because:
- FTP was familiar to many businesses
- It could handle larger file transfers more efficiently
- It offered built-in resume capabilities for interrupted transfers
However, AS3 failed to catch on for several reasons:
- By the time it was introduced, many businesses had already invested heavily in AS2 infrastructure
- HTTP/HTTPS proved more firewall-friendly than FTP
- Security concerns around FTP made organizations hesitant to adopt it
- AS2 continued to evolve and meet most business needs
- The benefits weren’t significant enough to justify switching from AS2
This led to AS3 being largely skipped over, with development efforts moving directly from AS2 to AS4. Today, AS3 is rarely used, and most organizations either use AS2 or have moved to AS4 for more complex needs.
Like most subject matters in the world of electronic data interchange, things can get complicated quick. While most AS2 setup is fairly straightforward, it can get more complicated as the number of connections increase and troubleshooting communications between trading partners. Using a managed EDI provider like Surpass Solutions means you don’t have to worry about the details. Experts configure, maintain your trading partners preferred communications channels like AS2 and AS4, so that you can focus on what you do best.
