Idd part 1 Interfaces with bsc parties and their Agents




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4.7.2 Message Subject Naming


Subject names are used not only to provide an insight into the kind of data contained within the message, but also to divide the data into logical segments. TIBCO subject names consist of a string of characters that is divided into elements by a dot(.), and so data is organised hierarchically by assigning a specific meaning to each element in a subject name.

4.7.2.1 Base subject name


All subject names published by the BMRA system will have the following prefix:-

BMRA


It is important to prefix all messages from the BMRA system with an ‘identity key’ to allow BMRA data to be distinguished from other TIBCO message data. By establishing a prefix for BMRA messages now, possible confusion or corruption of data may be avoided in the future.

4.7.2.2 Sub-division of data through Subject Names


Published data will further be divided by data type - that is that all BM related data will be grouped together under an extended prefix, all system related data will be grouped together and all dynamic data will be grouped together.

The following table lists the subject name prefixes that the different types of data will be grouped under:



Data Group

Subject name prefix

System related data

BMRA.SYSTEM

BM related data

BMRA.BM.

Dynamic Data

BMRA.DYNAMIC.

Party Related Data

BMRA.BP.


Informational

BMRA.INFO

System Data will contain all data that applies at a national (or zonal) level, rather than at BM Unit level. This includes all forecasting data, system warnings, National Demand Out-turn and estimated Buy and Sell prices (derived).

BM related data will contain the principal data relating to the Balancing mechanism. This includes FPN, QPN, B-O pairs, Acceptances, Maximum Import and Export Limits, Acceptance Volumes (derived) and B-O Cash Flows (derived).

Dynamic data will contain all the dynamic data relating to a BM Unit.

Party related data will contain all published data related to a participant. At present, this will include only Credit Default notices.

Information data will contain subjects relating to the BMRS itself. Its initial use will be for test messages and heartbeats for the TIBCO messaging protocol. These should currently be ignored by participants but the message definitions are given here for completeness.

This sub-division of data by subject name has been done to ease subscription to data by grouping related data types together. This means that wildcards may be used to subscribe to a selection of subject names which may all be plotted on the same graph, or listed in the same table. For example, much of the BM data may be viewed on the same graph and much of the dynamic data may be listed in the same table.


4.7.3 Message Formats


The messages are published using TIBCO Rendezvous software, using a subject-based addressing system and self describing data. A standard TIBCO message is composed of a header which contains the subject name, and an optional reply subject name, following by a string of data fields. Each field contains a single element of data together with details describing the data for platform independence.

Messages are built from a list of defined field types which have been identified to describe all of the data published by BMRA. Each of these two character BRMA Field Types is described later in this section, and has associated with it a unique field name and data types. No message will be published by BMRA containing fields outside of this set.



Note that the message definitions in this document contain only the data fields created by BMRA. Additional fields added to messages by Rendezvous - such as header fields and data description elements - will also be present in the published messages, but these are not listed in the definitions given in this document. Details of the standard TIBCO header fields may be found in TIBCO Rendezvous documentation.

4.7.4 Field Type Definitions


This section identifies and defines all of the fields which are used to compose the BMRA messages. Each field in a message is associated with a Field Name, TIB Data type and a valid set of values. The fields are described using the following format :-

Field Data Type :

The data the field represents.

Field Type :

The reference identity of the field type, as used in message definitions.

Field Name :

The field name used within the message to identify the field.

Description :

A brief description of the data the field represents.

TIB Data Type :

The data type used in the TIB wire format of the message. This is a data type defined in and used internally by the TIBCO Rendezvous software. They are platform and network independent.

C/Java Type :

The C and Java data types which correspond to the TIB data type. The TIBCO Rendezvous software will convert the incoming TIB data type into this data type when the API is used for bespoke applications. Due to the nature of the C data type “float”, it should be noted that where the data type “float” is given, it is the responsibility of the participant’s API software to perform rounding to the appropriate accuracy (see section 4.4.7 and its subsections for additional information).

Messages containing field :

The TIB message types which are broadcast by BMRA which contain the field.

Additional Information :

Any additional information - such as the units of the data and the valid set of values if appropriate (note that £ and £/MWh are always to 2 decimal places).
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