API Management

What is AS4, the bridge between API and EDI?

What is AS4

How you integrate your applications and data flows with your suppliers, customers, partners, and regulators are more than an IT issue. It’s also a critical business issue. Since B2B processes (such as order fulfillment, delivery, invoicing and payments) affect everything from revenue and expenses, to risk management and compliance, to growth strategies and multinational M&A.

In a previous article about API versus EDI, I have analyzed the differences between EDI and API for B2B exchanges, as well as their complementary nature. In this article, I will explain what is AS4.

It’s on SOAP and XML, but it’s used in the industry ecosystems as a replacement for EDI, after a lengthy period of standardization on profile and message formats. In this context, it may be thought of as an API from a technical point of view, but as EDI from a use case and business point of view.


In a recent research article published by Gartner, the authors state:
“One of the most important decisions for API design is the choice of REST or SOAP. REST and JSON are generally preferred because they are more suited to mobile and web and being lightweight when compared to SOAP and XML.

For example, a freight forwarder may give an API so that clients’ employees can look up the location of a shipment, returning data from a sensor.

Because these APIs are often consumed by mobile or web, they are most likely defined as REST APIs. In B2B, however, SOAP and XML are still quite commonly used. To communicate complex documents, such as product catalogs, between trading partners, APIs may take the form of SOAP web services such as AS4. SOAP is also suited to large messages (compared to REST) and has a well-defined (though complex) security model.”

What is AS4?

AS4 is an interoperability protocol that simplifies and standardizes the use of web services for B2B data exchange and integration. It is gaining adoption in some EDI communities, and you can consider it for your future EDI integration projects.

AS4 is not created from scratch. It is the latest of a series of B2B standards that started in 2002 with ebXML, and became Oasis standard in 2013, and ISO standard now.

Being an open standard, it ensures that there will be no vendor locking. You can procure solutions in a competitive environment where vendors are encouraged to innovate continuously.
AS4 meets the requirements that are expected of any B2B protocol:

  • Automation: Exchange of structured and unstructured payloads, as well as metadata that allows the receiver to reroute messages, and be able to correlate messages with earlier or future messages.
  • Security:
    • The integrity of message content, which cannot be modified in transit without it being detected
    • Confidentiality, so that third parties do not access your sensitive data
    • Non-repudiation, so the sender and receiver cannot deny having sent or received a message.
    • Reliability: in case of temporary network disturbance, the message is resent. AS4 further ensures that a message is only received once, which means that received duplicates are detected and eliminated.

Seamless operation

AS4 is based on SOAP and Web Services, which makes it different from AS2. It is, therefore, more compatible with standard environments because many organizations use these technologies for their internal integration. Extending the use of these technologies for external integration becomes a very natural and seamless operation.

AS4 provides rich support for metadata. It is not only a protocol for data exchanges. You can transport any type of payload: legacy EDI, binary, XML, JSON, or so on. You can also carry multiple payloads if needed.

Security is based on WS-Security and allows for a whole range of crypting algorithms. You can agree on the quality of service with your partners, which allows you to define, such as whether you need encryption or not. AS4 is layered over HTTP only, and transport security can be achieved with TLS.

AS4 differentiators and business drivers

From a functional point of view, it’s similar in available EDIINT protocols. AS4 is a next-generation protocol from AS2. There are some differences:
AS4 is a modern version of AS2, based on technology standards that are aligned with the IT landscape of organizations: SOAP, Web Services, etc.

AS4 allows for service-oriented architecture exchanges, not only document interchange. This means you can extend your SOA to reach out to your ecosystem.

AS4 allows for a push, as well as for the pull. This means that applications that are not always online, that do not have a permanent IP address or that is behind a firewall to connect occasionally and pull available messages.

AS4 is a superset of AS2, but with modern technologies. It enables you to rollout Web-Services to large communities. You will only need a single platform for all your partner connectivity, via legacy EDI as well as via more interactive transactions. You can reach out to small and large partners. Those who do not, or cannot afford to have an application running 24/7.

Being set

AS4 is set to last for two decades. It is in this sense safe to start with unless your project requires REST/JSON protocol.

Even though it is a rather recent standard, AS4 gains more and more interest from organizations that want to expand their B2B/B2C capabilities. The following is a non-exhaustive list of communities, excluding individual private enterprises, who are adopting AS4:

  • Europe:  ENTSOG (European Network of Transmission System Operators for Gas)
  • Europe:  EESSI (Electronic Exchange of Social Security Information)
  • Europe:  PEPPOL(Pan-European Public Procurement Online)
  • Europe:  e-CODEX (e-Justice Communication via Online Data Exchange)
  • Japan:  JEITA(Japan Electronics and Information Technology Industries Association)
  • Australia:  Superstream(Australian pensions declaration and payment)
  • Global:  IATA (International Air Transport Association) for e-Cargo e-Business. You can also check out one of my previous articles about IATA NDC API

In production

The European initiatives are in production use in Austria, Belgium, France, Germany, Hungary, Netherlands, and Poland.

If you want to choose a vendor for AS4, you should look for one who is Drummond certified, preferably with a long and proven record in AS2 and ebXML, and one who is a player in both the API space, as well as in the EDI space.

If you want to choose a vendor for AS4, read more in our white paper.


I hope you now have a better understanding of what is AS4 and its benefits. Check out this article on AS4 for further information.