Home - Blog - AS4, what’s in it for EDI exchanges ?

AS4, what’s in it for EDI exchanges ?

Protocole AS4

AS4 is a message exchange protocol. It follows on from AS2. The nature and intensity of electronic exchanges between companies are increasing rapidly. Communication standards are evolving to meet the need for security and interoperability between information systems.

AS4 is the latest in the series of AS, Applicability Statement, protocols. Its promise is to be an open standard for secure business-to-business exchanges. And to take service-oriented architectures into account.


In this article, we’ll find out what the AS4 protocol is, how it works. And the benefits it brings to the deployment of EDI projects.



The AS4 protocol


AS (Applicability Statement) protocols were developed for transporting data over the Internet. They meet corporate requirements for reliability and security.


AS protocols


The various AS1, AS2 and AS3 protocols meet the needs and uses of companies for data and document transfers. They focus on the security and reliability of message transmission. They are based on the various data transfer standards used on TCP/IP and Internet networks.




AS1, developed in the early 90s, is an SMTP (Simple Mail Transfer Protocol) messaging protocol for sending files as attachments. Files can be signed and encrypted. An NDM, Message Disposition Notification, can be returned to the sender.




AS2 was created in 2002 by the IETF (Internet Engineering Task Force). It is based on HTTP (Hypertext Transfer Protocol). This protocol is used to transport structured data point-to-point over the Internet between a server and a client. AS2 has enabled the transition from EDI to EDIINT, i.e. the transport of EDI messages over the Internet. It has also made it possible to move away from VAN or VAN networks, which are often too costly for small and medium-sized businesses.




AS3 is an evolution of AS2 based on FTP (File Transfer Protocol). For companies, AS3 enables secure file transfers via FTP. AS3 is used by MFT solutions. AS3 is also push-pull, i.e. it does not require a permanent connection, unlike AS2.


AS4 = AS2 + Web Services + XML


Defined as an open standard in 2013, AS4 was developed by OASIS (Organization for the Advancement of Structured Information Standards). The main objective of this new standard is to improve the interoperability of corporate Information Systems. Whatever their SaaS, hybrid or on-premise architecture. And whatever software they use.


AS4 features :

  • It is a superset of AS2, i.e. it can address both AS2 and AS4 partners,
  • Based on SOAP (Simple Object Access Protocol) and WSDL (Web Services Description Language) technologies for internal integration,
  • Rely on HTTP protocol for data transfer,
  • Exchange all types of business documents: EDI, ebXML, gzip, …
  • Use WS-Security for enhanced security and encryption of documents sent,
  • Secure data transfers between cloud-based SAAS software solutions,
  • Make EDI exchanges accessible to all small and medium-sized businesses via Web Services.



Operating mode


AS4 fonctionnement


Both sender and receiver use an AS4-compliant Messaging Services Handler (MSH). MSHs communicate with internal business applications.


AS4, message structure



AS4 Structure de messages


Advantages for the automation of B2B exchanges


The AS4 protocol is becoming the standard for exchanging documents and business information between companies.

The main reasons for using AS :

  • Simplified integration with business software using Web Services and APIs,
  • A high level of security,
  • ebXML standard support,
  • Better traceability of communications, ensuring that the recipient has read the message,
  • No need to call into question investments made in AS2.


AS4 is also ideally suited to the exchange of data and documents between different SaaS application platforms. It enables interoperability between different clouds.


The PEPPOL network, which makes AS4 mandatory for its access points, demonstrates the qualities of AS4 for commercial and financial exchanges. For the same reasons of security, flexibility of use and interaction between distinct business applications, AS4 has been adopted by numerous professional groups in the transport and energy sectors, such as IATA (International Air Transport Association) and ENSOG (European Network of Gas Transmission System Operators).



Why choose AS4 for your EDI project ?


As with AS2, AS4 enables a point-to-point connection to be established for data transfer. AS4 guarantees non-repudiation, authentication and identification of each party.

For an EDI project, choosing AS4 over AS2 offers three advantages for companies.


AS4 is a superset of AS2


In other words, the AS4 platform can be used to address AS2 recipients. You do not require your EDIINT AS2 partners to migrate to AS4.


A more modern protocol than AS2


Or to benefit from new functionalities not available with AS2 :

  • WS-Security standard for exchange security,
  • Acknowledgement of receipt with digital signature,
  • push and pull, so that recipients don’t have to be connected at all times to listen for messages to be received.


A denser network of EDI partners


This protocol is simpler and less costly to implement in companies than AS2. In fact, implementing AS4 is simpler and less costly than implementing AS2. To ensure security, AS2 accesses must be isolated from internal systems using firewalls or DMZs. And AS2 connections must be kept open to receive messages in the absence of push-pull.

This will make it easier for small and medium-sized companies to join your EDI partner network, even for occasional EDI flows.

This will enable you to extend EDI exchanges to your entire ecosystem.



AS4 modernizes EDI


With its ability to support Web Services and APIs, the AS4 protocol adapts EDI exchanges to new service-oriented technologies. EDI integration for BtoB automation becomes more optimal, opening up new channels. Easier, less costly implementation enables new business partners to convert to EDI.

For over 30 years, Tenor has been supporting business partners in Electronic Data Interchange. The company offers EDI SaaS, EDI OnPremise and WebEDI solutions.