Piotr P. Nikiel, August 2019
The configuration file of the SCA OPC-UA server describes different aspects such as:
A sample configuration per SCA taken from the NSW DCS is:
What is expected (and confirmed by users) is that often content
as above is likely to be repetitive - e.g. same contents between
SCA tags will be used, only with different name and address
attributes.
The problem is that redundant content is difficult to manage.
It is proposed that XML entity references are used.
Each repetitive part (e.g. in the example above, everything
contained within SCA tags - excluding SCA themselves) can be put
in a separate XML file - let's say here it is put into
SCA_type1.xml.
Then the external entity is defined as below (before
configuration tag)
The contents of sca-entity.xml can then be inserted in a chosen
place(s) of the config file by:
&SCA_TYPE_1;
Of course, there can be multiple entities defined and each entity
can be reused any number of times.