What Is the AS2 Protocol? A Complete Guide

There are numerous electronic data interchange protocols and frameworks, each designed to facilitate streamlined communication between trading partners. One of the most widely used protocols is Applicability Statement 2, commonly called “AS2.”

In this guide, we’ll discuss AS2 to help you determine whether this framework aligns with the needs of your organization and the requirements of your trading partners.

What is AS2?

AS2 is a transmission protocol that uses HTTP or HTTPS to send EDI messages quickly, securely, and affordably. It provides a standard set of rules that devices or networks use to transport and exchange data using the internet.

Retail and consumer goods businesses often rely on AS2 as their preferred EDI communication protocol due to its security benefits. During an AS2 transmission, data is encrypted to ensure it’s safeguarded as it moves from one system or device to another. 

Using this set of protocols requires an AS2 certificate. You can generate your own certificates with your preferred software or use certificates issued and verified by a third-party certification authority. Third-party certification demonstrates your compliance with the American National Standards Institute’s EDI communication standards.

ANSI creates and vets standards used in various industries, including the EDI protocols facilitating B2B communication between trading partners. This particular set of protocols is known as X12 EDI protocols.

Comparing AS2 to other data exchange frameworks

AS2 isn’t the only framework that facilitates communication abiding by X12 and ANSI standards. Here are a few others and how they stack up against AS2:

AS2 versus FTP

File transfer protocol (FTP) is one of the most basic frameworks for exchanging data between two computers. Under this framework, users send and receive data in an unencrypted state. 

This protocol requires password and username authentication but doesn’t guarantee a secure connection. Fortunately, you can easily secure your connection using a virtual private network (VPN) or other security mechanism.

AS2 features more built-in security provisions, which is why many trading partners prefer it. In many instances, it’s also more cost-effective, as you don’t have to implement secondary security mechanisms.

AS2 protocol versus SFTP

Compared to FTP, secure file transfer protocol (SFTP) offers additional security by encrypting your data during transfer — similar to AS2. However, AS2 provides a few notable security advantages.

Namely, SFTP doesn’t require you and your trading partners to share digital certificates before opening a connection. Instead, it relies on public or private keys for authentication.

EDI VAN versus AS2

AS2 facilitates communication between two devices or systems on different networks by providing a unified set of standards and rules. Conversely, EDI value-added networks (VANs) provide trading partners with a dedicated, secure communication network.

With an EDI VAN, each authorized company has its own mailbox for exchanging various EDI documents, including invoices and purchase orders. 

AS2 offers a reasonable level of security and is relatively cost-effective to implement. By comparison, a VAN provides much safer communication pathways but is often time-consuming and costly to implement.

How does AS2 work?

AS2 provides an envelope for EDI data to securely transfer it via the internet. The process includes the following steps:

• EDI document preparation: Documents are translated into the standard EDI format.
• AS2 packaging: The document is “packaged” according to AS2 protocols, typically including compression, signing, and encryption.
• Message delivery: The message is transmitted over HTTPS using file transmission services or software.
• Unpackaging: The recipient’s server unpackages the document and, if necessary, decrypts it. If the sender signed the document, the receiver’s server will also verify the signature’s authenticity.
• EDI processing: The AS2 receiver transfers the EDI document to the back-end software for processing.
• MDN reply: The receiver uses EDI or AS2 software to extract the message and send confirmation to the sender in the form of a message disposition notification (MDN).

After the sender receives the MDN, they’ll validate the receipt signature to verify its authenticity. 

What is an AS2 MDN?

An MDN is a digital acknowledgment that a message has been received. The recipient of an AS2-based message sends an MDN after they receive and unpack the original message. It verifies that an AS2 transfer reached the recipient without errors or alterations.

Both parties must be online during an AS2 exchange, as undelivered messages can’t be stored on a server or digital mailbox. If one party is offline, the message is lost and must be resent.

AS2 requirements

You’ll need a few tools and credentials to engage in AS2-based communication, including the following:

• An AS2 identification (Global Location Number, or GLN)
• Public keys for each of your partners’ certificates
• AS2-capable software
• AS2 certificates

AS2 certificates

AS2 certificates facilitate secure data exchange and ensure you meet certain security standards. As mentioned, you can obtain third-party AS2 certificates or issue and sign your own. Third-party certificates are generally considered more secure than certificates you issue and sign yourself.

AS2 benefits

AS2 is widely used in the retail and consumer goods sphere for the following reasons:

• Security
• Cost-effective implementation 
• Versatility
• Real-time transmission responses
• Reliability

That said, AS2 also has some drawbacks, which you should keep in mind when selecting an EDI framework.

AS2 disadvantages

Potential disadvantages of AS2 include the following:

• The requirement for a direct, continuous internet connection between parties
• The need to exchange keys
• Labor-intensive maintenance processes

Remember that these potential drawbacks will also impact your trading partners. You should also consider their needs when selecting an EDI communication framework.

The role of AS2 in EDI

AS2 is often mentioned in the same breath as EDI due to its ubiquity in the retail and consumer goods industries. AS2 is a communication protocol that facilitates the secure transmission of EDI documents, but it isn’t the only framework available. It’s not even the most recent applicability statement. 

Released just over a decade ago, Applicability Statement 4 (AS4) became an ISO standard in 2020. This modern iteration of the applicability statement protocol set includes additional provisions to enhance security and streamline communication, including SOAP-based receipt acknowledgments with XML digital signatures.

Is AS2 the right solution for your business?

The AS2 and AS4 protocols are some of the most widely used protocols for EDI-based transmissions in verticals like consumer goods and retail. While they certainly provide advantages, many factors determine which protocol best suits your organization.

Leveraging a modern EDI solution like Orderful’s can transform your business and allow you to overcome the limitations of the AS2 protocol.

Contact us today to talk to an expert and learn more about our EDI solutions. Our knowledgeable team will help you proactively avoid major time-wasters during your EDI implementation so you can enjoy the benefits in days, not months.