What is AS4?

AS4 (Applicability Statement 4) is a secure data exchange protocol for standardized B2B messaging between business partners such as between gas transmission system operators (TSOs) and their partners, in Europe. It is used, among other things, in balancing and bottleneck handling. Compared to AS2 (Applicability Statement 2), which has previously been used for this type of message, AS4 is based on web services. As the data exchange format, Edig@s-XML is used for messages about communication processes:

  • NOMINT (balancing)
  • NOMRES (balancing) and
  • CHACAP (capacity management)


Where is AS4 used?

Based on Commission Regulation (EU) 2015/703 of 30 April 2015 establishing a network code for provisions on interaction and data exchange, message formats AS4 and Edig @ s-XML are mandatory in gas trading, for messages in the communication process:

  • Bottleneck Management Renewal Management (CHACAP)
  • Nomination, renomination and confirmation of their balancing (NOMINT, NOMRES)

In many European countries, such as Sweden, Germany, Denmark and Italy, this became mandatory in 2017. Therefore, those directly affected are all market partners who nominate, assign to each other or obtain capacity reports for the market area and across borders at the transmission points of the respective transmission network operator. In light of this, ENTSOG (European Network of Transmission System Operators) has defined a specific subset that describes communication via AS4 in detail and standardizes the association with various market partners (AS4 usage profile).


Why use AS4?

AS4 is a secure data protocol based on web services. The creator is guaranteed with digital signatures and data security with encryption. The transmitter receives a digital receipt that can be used to document delivery on time.

Compared to AS2, data exchange is possible with AS4 not only with "push" but also with "pull". The recipient can actively retrieve messages as the AS4 server responds continuously. The HTTP connection is established at the communication event and data can be received at any time by associated systems. Data is exchanged regardless of opening hours and server availability.


How does AS4 work with Compello?

Compello provides effective support to European utilities: When it comes to data exchange via AS4, Compello offers its customers the Compello AS4 Gateway, either as a SaaS service or an On-Premise service.

All options were originally designed to focus on the requirements of gas transmission network operators, but they can be upgraded at any time for the electricity sector or expanded beyond the ENTSOG standard.

The Compello AS4 Gateway (standalone solution) can be installed in parallel with existing market communication programs. It is usually operational within one day.

Relevant terms: AS2 | ENTSOG | Edig@s-XML | CHACAP | NOMRES | NOMINT, network code on interoperability and data exchange rules | Wedservice | Data exchange