This blog was originally published here.
- Part I: Introduction
- Part II: Messaging Overview
- Part III: Reliability
- Part IV: Security
- Part V: Are you ready for AS4?
The content of this blog post series has also been presented during an Integration Monday session of the Integration User Group, within the Microsoft community. Check out the video, which includes some nice demos of the interoperability of Microsoft .NET with AS4.
What is AS4?
AS4 defines a standardized, secure and reliable exchange of messages, containing one or multiple payloads. These are the key features of the messaging standard:
- Interoperable: AS4 is defined as an OASIS standard. It is built on top of existing standards, which have proven interoperability in the past: MIME, SOAP and WS-Security.
- Secure: AS4 uses a subset of the WS-Security features in order to assure message non repudiation and data confidentiality.
- Reliable: AS4 guarantees once-and-only-once delivery, via the exchange of acknowledgements and additional requirements on both send and receive side.
- Payload agnostic: AS4 can exchange any kind of payloads (XML, JSON, HL7, EDI, binary …) and it supports also multiple payloads being sent in one AS4 message.
A short history
AS4 originates from ebXML (Electronic Business XML), which enables enterprises to conduct business over the internet. Here’s a short overview of how AS4 was originated:
- 2002 – ebMS 2.0 : ebXML Messaging Services version 2.0 defines a communications-protocol neutral method for exchanging electronic business messages, using a flexible enveloping technique.
- 2007 – ebMS 3.0 Core Features : ebXML Messaging Services version 3.0 core specification defines message packaging and provides several options to deal with message exchange patterns, error handling, security and reliability.
- 2010 – ebMS 3.0 Advanced Features : ebXML Messaging Services version 3.0 advanced features adds some extra features and scenarios to ebMS 3.0. The most important are: multi-hop messaging, message bundling and a split/join mechanism for large messages.
- 2013 – AS4 Profile of ebMS 3.0 : this AS4 profile has the success of AS2 in mind and applies the same “just enough” design principles in order to narrow down the options of ebMS 3.0, which results in a simplified usage profile of ebMS 3.0. AS4 defines 3 possible conformances clauses: minimal client (minimal feature set), light client and the eb handler (richest feature set).
This history makes AS4 a rather difficult standard to read, as it is spread across multiple specifications.
Where is AS4 applied?
Even though it is a rather recent standard, AS4 gains more and more interest from organizations that want to expand their B2B/B2C capabilities. In Europe, eSENS e-delivery promotes and funds the usage of AS4 for all cross-border communication between member states. This results in many large-scale projects that are looking into AS4. Also outside the European borders, AS4 is adopted. Here’s a non-exhaustive list of known projects / organizations that are applying AS4, spread over different sectors, with implementation levels going from design phase, over piloting, until production ready.
- Australia: Superstream Pensions
- Europe: PEPPOL (Pan-European Public Procurement Online)
- Europe: ENTSOG (European Network of Transmission System Operators for Gas)
- Europe: EESSI (Electronic Exchange of Social Security Information)
- Europe: e-CODEX (e-Justice Communication via Online Data Exchange)
- Japan: JEITA (Japan Electronics and Information Technology Industries Association)
- World Wide: IATA (International Air Transport Association)