Information on the transition to the Binary API interface for automated communication of the Intraday Electricity Market and the Intraday Gas Market

OTE informs market participants of a planned modification to the automated communication interfaces of the Intraday Electricity Market and the Intraday Gas Market. As part of this change, the XML message format will be replaced by the binary data format Protocol Buffers.

This change does not affect users accessing the systems via the Intraday Electricity Market and the Intraday Gas Market applications or via mobile applications.

The automated communication interfaces of the Intraday Electricity Market and the Intraday Gas Market towards market participants are currently implemented using the AMQP protocol with XML-based message exchange. Within the framework of the SIDC project (Single Intraday Coupling), and in order to ensure adequate performance and stability of the central XBID system, as well as to support future development of intraday trading and compliance with legislative requirements for the transition of intraday cross-border capacity allocation to the Flow-Based methodology, a change of the communication message format will be implemented for data exchanges between the central XBID solution and local trading systems (LTS) operated by NEMOs. As a result, the XML-based message format will be replaced by binary content using the Protocol Buffers data format. The overall communication concept (the existing portfolio of communication scenarios and the AMQP communication protocol) remains unchanged. To ensure the performance and latency improvements are also reflected in the interface between OTE and market participants, it will be necessary to adapt the communication interface to the intended binary Protocol Buffers format also on the CS OTE side.

The change of the communication format will apply to automated communication interfaces for both the Intraday Electricity Market and the Intraday Gas Market towards market participants. The provided documentation includes the following:

• Updated message formats for electricity and gas reflecting the new communication message format. In addition, XLSX mapping tables electricity and gas are available, which provide mapping of the existing XML attribute names to their corresponding Binary API attribute names – see the downloadable materials below.
• The protobuf definitions (.proto files) will be published according to the following timeline:
• For electricity by 20 March 2026
• For gas by 15 May 2026

Implementation Timeline:

• Start of testing with market participants: Q4 2026
• Go-live of the change: Q1 2027

Further information and details regarding the testing phase will be communicated on an ongoing basis via the OTE website and through official email communication.