ENTSOG published a document that provides guidance on its use of AS4 and ebCore Agreement Update.  

The current version Rev_3 of the ENTSOG AS4 profile [AS4TSO] introduces the concept of agreements and agreement updates to the ENTSOG AS4 profile. The agreement concept is an established ebXML concept for (versions of) messaging technical configurations that is applied to AS4 [AS4]. In ENTSOG AS4, it is used for certificate updates.  Agreement Update, a generalisation of peer-to-peer online certificate exchange, is standardised at OASIS in the separate ebCore Agreement Update specification [AU]. Together, agreements and agreement updates enable a flexible mechanism for exchanging certificates and for managing and updating security configurations for signing and encryption of ENTSOG AS4 messages.  

As AS4 implementations for use with the ENTSOG profile will be required to support these new features from 1 July 2017, this document explains some of the consequences of the use of these concepts with AS4 and the impact and requirements on AS4 implementations and their deployments, in order to allow solution providers to determine if their products need any enhancements or adjustments to support this features and to make any adjustments in time for use by their users. 

The audience for this document are providers of solutions supporting the AS4 Usage Profile for TSO [AS4TSO] and implementers of those solutions within the gas industry. This document is informative only. It is only intended to help implementers, but does not replace or overrule the functionality specified in the ENTSOG AS4 profile and the underlying AS4 and ebCore Agreement Update specifications. This document complements the “Setting Up and AS4 System” document [AS4SETUP].